Asimovs Biographical Encyclopedia Of Science And Technology Isaac Asimov 941p.pdf

ASIMOV’S BIOGRAPHICAL ENCYCLOPEDIA of SCIENCE and TECHNOLOGY The Lives and Achievements o f 1510 Great Scientistsfrom Ancient Times to the Present Chronologically Arranged by

ISAAC ASIMOV

Second Revised Edition

v|

Doubledßy NEW YORK LONDON TORONTO SYDNEY AUCKLAND

Published by Doubleday, a division of Bantam Doubleday Dell Publishing Group, Inc., 666 Fifth Avenue, New York, New York 10103 Doubleday and the portrayal of an anchor with a dolphin are trademarks of Doubleday, a division of Bantam Doubleday Dell Publishing Group, Inc. PICTURE CREDITS Numbers 4, 16, 17, 19, 20, 21, 27, 34, 39, 41, 42, 43, 45, 49, 50, 51, 52, 54, 55, 56, 57, 61, 62, 63, 64, 65, 73, 74: The Bettmann Archive Numbers 66, 67, 68, 69, 70, 71, 77, 78, 79, 86, 92: Wide World Photos Numbers 59, 72, 75, 76: Lotte Jacobi Number 3: Musée du Louvre Number 25: Town Hall Committee of the Manchester Corporation Numbers 80, 81, 82, 83, 84, 85, 87, 88, 89, 90, 91, 93: United Press International Photos ISBN: 0-385-17771-2 LIBRARY OF CONGRESS CATALOG CARD NUMBER 81-47861 c o p y r ig h t © 1964, 1972, 1982 by Isa a c a sim o v ALL RIGHTS RESERVED PRINTED IN THE UNITED STATES OF AMERICA 9 BG

TO MY DAUGHTER, ROBYN, FOR HER PATIENCE AND FOR HER GOODNESS OF HEART

HOW TO USE THIS BOOK The 1510 biographical entries are arranged in chronological order, not alpha­ betical. They are numbered from 1 to 1510 and this numbering system I con­ sider more significant than the page numbers. It is, in my opinion, the individual biography and not the page that should be taken as the unit of reference. For this reason the index references at the end are by biography number and not by page number. In a very few cases, this means searching through several pages; in most, it means a glance through less than one page. To help find individual scientists to begin with, I have supplied a table of con­ tents at the start in which all the biographical entries are listed in alphabetical order, with the biography number given for each. In the body of each biography I have inserted numerous cross references (again to biography number rather than page number). It may be that some readers dipping into the book at random, or with the purpose of looking up a particular individual, will be lured into looking up the cross references, then into chasing after the new cross references. If they do so assiduously enough, they will find that, no matter where they start, they are likely to end by reading the whole book. But then, science is a complex skein, intricately interknotted across the arti­ ficial boundaries we draw only that we may the more easily encompass its parts in our mind. Pick up any thread of that skein and the whole structure will fol­ low. And so it is with this book. I saac A sim o v

PREFACE TO THE SECOND REVISED EDITION This time I have introduced no changes in the format of the Encyclopedia; I have merely enlarged it. I have added 310 additional biographies, about half of them taken from contemporary scientists and half distributed through time. The total is now 1510. Of the biographies that were present in the previous edition, most have been slightly enlarged as I gathered additional information about each scientist. This edition is, therefore, substantially larger than the previous one. Nevertheless, it is still entirely a one-man job. No one else but myself (and my good editor) has touched it. This means that, although I have corrected a number of errors and misstatements in the earlier editions, I am very likely to have overlooked some and to have introduced others. I take the full responsi­ bility for that and, as always, I welcome corrections and comments from my readers. New York, New York April 1981

I saac A sim o v

PREFACE TO THE FIRST REVISED EDITION The differences between this revised edition and the first are as follows: (1) Almost every biography has been enlarged and, when necessary, altered, in accordance with the findings of my continuing researches over the last five years. (2) Nearly two hundred new biographies, including recent Nobel Prize win­ ners and a number of earlier individuals (even a few ancient Greeks), have been added. (3) I have abolished the system of main biographies and “footnote” biog­ raphies as an element of artificiality and now list all entries, without exception, in strict chronological order according to birth. (4) I have added a contents section at the front of the book in which all en­ tries are listed alphabetically, with their biography number, for easy reference. I must now repeat what I said in the preface to the first edition, to the effect that I alone am responsible for the choice of those to include and for the deci­ sion as to how much space to give each person— and, of course, for all errors, omissions, and infelicities. The “alone” part is stronger than some people realize, I think, for from a number of comments I have received in connection with the first edition, I have detected some tendency to take it for granted that the book is a community en­ deavor and that I have headed a sizable team engaged in research and in writing. This is not so! I alone have done every bit of the necessary research and writ­ ing; and without any assistance whatever, not even that of a typist. This is not because of any parsimony on the part of Doubleday & Company, my esteemed publishers. They have been generous in their offers to finance research and secretarial assistance but I have— quite deliberately— refused those offers. It means, of course, that, as a lone worker, I am incomplete in places where some help might have brought matters to completion; and wrong outright, in some places where a little help might have righted me. On the other hand, be­ cause the book is the product of one mind and two hands and no more (except for the invaluable editing the manuscript received at Doubleday) it has its own particular flavor, style, and point of view— whether for good or ill— throughout. And besides, the book is a labor of love, and I loved it far too much to want to share it in the slightest. New York, New York

August 1971

I saac A sim o v

FROM THE PREFACE TO THE FIRST EDITION It is not likely that anyone will be overcome by the novelty of a history of science. There are any number of such histories. Therefore I had better explain just how this one differs and why I feel justified in adding it to the list. First: In this book the history of science is told through biographies (biog­ raphies that concentrate on the subjects’ scientific labors, of course, rather than their private lives). This has its shortcomings, for it makes it easy to leave gaps and to become repetitious. Yet it has the great merit, in my opinion, of stressing the fact that scientific knowledge is the painfully gathered product of thousands of wonderful, but fallible, human minds. Nor are these scientists more than human. In writing of them I have tried to stress this fact and to show that even the greatest among them went wrong on occasion or stubbornly lost step. Second: There is no attempt to divide the sciences into separate categories and devote chapters to each, as is often done in histories of science. When this is done, the sense of the panorama is easily lost. The scientists included in this book are listed in chronological order of birth. You will encounter what might seem a bewildering succession of chemists, mathematicians, inventors, explor­ ers, physicists, astronomers, biologists, and physicians. But in real life, after all, that is precisely how science advances, and a chemist does his work in a world in which not only chemistry has reached a certain point but all other branches of science as well. There is interaction among the branches, as I hope this book will show, and the nature of the interaction depends upon the point which all the branches, and not only one, have reached. Third: I have resisted, to a greater extent than is usual, the temptation to fade off as modem times are approached. The foundations of modem science were laid in the days of ancient Greece during the five centuries from 600 B.c. to 100 B.c. and in early modem times from a .d . 1600 to 1800. Since foundations are extremely important, these centuries are stressed in most histories of science and it is not uncommon to give them more than half the total space. On the other hand, the period after 1800, and particularly after 1900, wit­ nesses so remarkable an increase in the complexity of science and in its rate of growth that it is quite impractical to attempt to deal with all of it. The tempta­ tion is to grow sketchier as the present is approached, and I have had to do this to a certain extent. It is said, after all, that ninety percent of all scientists who have ever lived are alive now. It is also said that as many scientific papers have been published in the years since 1950 as were published in all the centuries be­ fore 1950. Clearly I could not devote nine-tenths of this book to living scientists and half of it to post-1950 developments. XV

I have, however, done my best to give recent decades as much room as is rea­ sonable, after giving all due space to the foundations. This means that the book ends by being considerably longer than either my publishers or I had expected. All decisions as to whom to include or exclude, to whom to devote much space and to whom little, were made by me. And, of course, for all errors of fact I am likewise responsible. Naturally the book cannot help but reflect my own intellectual shortcomings. While I try to acquaint myself with as much of science as I can, it is not possi­ ble for the human mind to encompass all of it. There are some segments of science I understand less than others, and I’m sure the book will show which those are. During the many months I have lived with this book, I gained a feeling of continuity in the steady progression of scientists and technologists. The refer­ ences back and forth across space and time gave me the illusion that all was happening at once, that across the centuries as well as the oceans there was a brotherhood of the mind. This brotherhood is a small one, to be sure. If it is true that five percent of all the human beings who have ever lived are now alive— as I have heard said— then sixty billion men and women have lived and died upon this planet since our species arose. Out of the sixty billion more than one thousand have biog­ raphies in this book. Certainly my listing is not complete. Though I believe I have included most of the major contributors to scientific advance, I am willing to admit that the total number who have contributed significantly may be ten times as great. Even so, this would mean that the advance of science throughout history has de­ pended on the eagerly working minds of no more than one man in six million! West Newton, Massachusetts March 1964

xvi

I saac A sim o v

ALPHABETICAL LIST OF BIOGRAPHICAL ENTRIES

{Numbers in brackets are entry numbers, not page numbers.) ABBE, Cleveland [738] ABEGG, Richard Wilhelm Heinrich [978] ABEL, Sir Frederick Augustus [673] ABEL, John Jacob [877] ABEL, Niels Henrik [527] ABELARD, Peter [88] ABELSON, Philip Hauge [1383] ABNEY, Sir William de Wiveleslie [765] ACHESON, Edward Goodrich [863] ADAMS, John Couch [615] ADAMS, Walter Sydney [1045] ADDISON, Thomas [482] ADELARD OF BATH [89] ADLER, Alfred [984] ADRIAN, Edgar Douglas, Baron [1137] AGASSIZ, Jean Louis Rodolphe [551] AGRICOLA, Georgius [132] AHMOSE [2] AIRY, Sir George Biddell [523] ALBATEGNIUS [83] ALBERTI, Leone Battista [117] ALBERTUS MAGNUS [96] ALCMAEON [11] ALCUIN [77] ALDER, Kurt [1254] ALDEROTTI, Tadeo [101] ALFONSO X [100] ALFRED THE GREAT [81] ALFVEN, Hannes Olof Gosta [1335] ALHAZEN [85] AL-KHWARIZMI, Muhammed ibn Musa [79] ALLBUTT, Sir Thomas Clifford [720] ALPINI, Prospero [160]

ALVAREZ, Luis Walter [1363] AMAGAT, Emile Hilaire [751] AMBARTZUMIAN, Victor Amazaspovich [1338] AMICI, Giovanni Battista [447] AMONTONS, Guillaume [244] AMPERE, André Marie [407] AMUNDSEN, Roald Engelbregt [1008] ANAXAGORAS [14] ANAXIMANDER [4] ANAXIMENES [5] ANDERSON, Carl David [1292] ANDERSON, Philip Warren [1458] ANDREWS, Roy Chapman [1091] ANDREWS, Thomas [580] ANFINSEN, Christian Boehmer [1403] ANGSTROM, Anders Jonas [585] APIAN, Peter [133] APOLLONIUS [49] APPERT, Nicolas [359] APPLETON, Sir Edward Victor [1158] AQUINAS, Saint Thomas [102] ARAGO, Dominique François Jean [446] ARBER, Werner [1485] ARCHER, Frederick Scott [577] ARCHIMEDES [47] ARCHYTAS [25] ARGELANDER, Friedrich Wilhelm August [508] ARISTARCHUS [41] ARISTOTLE [29] ARKWRIGHT, Sir Richard [311] ARMSTRONG, Edwin Howard [1143] ARMSTRONG, Neil Alden [1492] ARNOLD OF VILLANOVA [103] xvii

CONTENTS

ARREST, Heinrich Ludwig d’ [639] ARRHENIUS, Svante August [894] ARTSIMOVICH, Lev Andreevich [1343] ASTBURY, William Thomas [1210] ASTON, Francis William [1051] AUDUBON, John James [443] AUER, Karl, Baron von Welsbach [890] AVERROËS [91] AVERY, Oswald Theodore [1054] AVICENNA [86] AVOGADRO, Amedeo, count of Quaregna [412] AXELROD, Julius [1374]

BARTON, Sir Derek Harold Richard [1427] BASOV, Nikolai Gennadievich [1453] BATES, Henry Walter [656] BATESON, William [913] BAUMANN, Eugen [786] BAWDEN, Sir Frederick Charles [1337] BAYER, Johann [170] BAYLISS, Sir William Maddock [902] BEADLE, George Wells [1270] BEAUMONT, William [444] BECHER, Johann Joachim [222] BECQUEREL, Alexandre Edmond [623] BECQUEREL, Antoine Henri [834] BAADE, Walter [1163] BEDE [75] BABBAGE, Charles [481] BEEBE, Charles William [1050] BABINET, Jacques [486] BEER, Wilhelm [499] BACON, Francis [163] BEGUYER DE CHANCOURTOIS, Alexandre-Émile [622] BACON, Roger [99] BEHRING, Emil Adolf von [846] BAEKELAND, Leo Hendrik [931] BEUERINCK, Martinus Willem [817] BAER, Karl Ernst von [478] BEILSTEIN, Friedrich Konrad [732] BAEYER, Johann Friedrich Wilhelm BÉKÉSY, Georg von [1220] Adolf von [718] BELL, Alexander Graham [789] BAFFIN, William [178] BELLINGSHAUSEN, Fabian Gottlieb BAILY, Francis [406] von [426] BAKER, Henry [265] BELON, Pierre [148] BALARD, Antoine Jérôme [529] BENACERRAF, Baruj [1442] BALBOA, Vasco Nunez de [128] BENEDEN, Édouard Joseph BALFOUR, Francis Maitland [823] Louis-Marie van [782] BALMER, Johann Jakob [658] BERG, Paul [1470] BALTIMORE, David [1508] BERGER, Hans [1014] BANKS, Sir Joseph [331] BERGIUS, Friedrich Karl Rudolf BANTING, Sir Frederick Grant [1152] [1098] BÀRANY, Robert [1040] BERGMAN, Torbem Olof [315] BARDEEN, John [1334] BERING, Vitus Jonassen [250] BARGHOORN, Elso Sterrenberg [1399] BERLINER, Émile [819] BARKHAUSEN, Heinrich [1079] BERNARD, Claude [578] BARKLA, Charles Glover [1049] BERNOULLI, Daniel [268] BARNARD, Christiaan Neethling BERT, Paul [702] [1452] BERTHELOT, Pierre Eugène Marcelin BARNARD, Edward Emerson [883] [674] BARRINGER, Daniel Moreau [905] BERTHOLLET, Claude Louis, Comte BARTHOLIN, Erasmus [210] [346] BARTLETT, Ned [1499] BERZELIUS, Jons Jakob [425] xviii

CONTENTS

BESSARION, John [116] BESSEL, Friedrich Wilhelm [439] BESSEMER, Sir Henry [575] BEST, Charles Herbert [1218] BETHE, Hans Albrecht [1308] BICHAT, Marie François Xavier [400] BIELA, Wilhelm von [434] BINET, Alfred [878] BIOT, Jean Baptiste [404] BITTNER, John Joseph [1277] BJERKNES, Jacob Aall Bonnevie [1205] BLACK, Davidson [1096] BLACK, Joseph [298] BLACKETT, Patrick Maynard Stuart [1207] BLAKESLEE, Albert Francis [1029] BLANCHARD, Jean Pierre François [362] BLOCH, Felix [1296] BLOCH, Konrad Emil [1369] BLOEMBERGEN, Nicolaas [1436] BLUMBERG, Baruch Samuel [1467] BLUMENBACH, Johann Friedrich [357] BODE, Johann Elert [344] BODENSTEIN, Max [994] BOERHAAVE, Hermann [248] BOETHIUS, Anicius Manlius Severinus [71] BOHR, Aage Niels [1450] BOHR, Niels Henrik David [1101] BOK, Bart Jan [1302] BOLTWOOD, Bertram Borden [987] BOLTZMANN, Ludwig Edward [769] BOLYAI, Janos [530] BOND, George Phillips [660] BOND, William Cranch [464] BONDI, Sir Hermann [1433] BONNET, Charles [291] BOOLE, George [595] BORDEN, Gail [524] BORDET, Jules Jean Baptiste Vincent [986] BORELLI, Giovanni Alfonso [191] BORN, Max [1084]

BOSCH, Karl [1028] BOSE, Sir Jagadischandra [893] BOSE, Satyendranath [1170] BOTHE, Walther Wilhelm Georg Franz [1146] BOUCHER DE CRÈVECOEUR DE PERTHES, Jacques [458] BOUGAINVILLE, Louis Antoine de [303] BOUGUER, Pierre [264] BOUSSINGAULT, Jean Baptiste Joseph Dieudonné [525] BOUVARD, Alexis [392] BOVERI, Theodor [923] BOVET, Daniele [1325] BOYD, William Clouser [1264] BOYLE, Robert [212] BRACONNOT, Henri [430] BRADLEY, James [258] BRAGG, Sir William Henry [922] BRAGG, Sir William Lawrence [1141] BRAHE, Tycho [156] BRAHMAGUPTA [73] BRAID, James [494] BRAND, Hennig [216] BRANDT, Georg [260] BRATTAIN, Walter Houser [1250] BRAUN, Karl Ferdinand [808] BRAUN, Wernher Magnus Maximilian von [1370] BRETONNEAU, Pierre Fidèle [419] BREUER, Josef [755] BREWSTER, Sir David [433] BRIDGMAN, Percy Williams [1080] BRIGGS, Henry [164] BRIGHT, Richard [465] BROCA, Pierre Paul [653] BRONSTED, Johannes Nicolaus [1061] BROOM, Robert [959] BROUNCKER, William, 2d Viscount [202] BROUWER, Dirk [1258] BROWN, Herbert Charles [1373] BROWN, Robert [403] BRUNO, Giordano [157] BUCH, Christian Leopold von [405] xix

CONTENTS

BUCHNER, Eduard [903] BUCHNER, Hans Ernst Angass [813] BUDD, William [570] BUFFON, Georges Louis Leclerc, comte de [277] BUNSEN, Robert Wilhelm Eberhard [565] BURBANK, Luther [799] BURIDAN, Jean [108] BURNET, Sir Frank Macfarlane [1223] BURT, Sir Cyril Lodowic [1086] BUSH, Vannevar [1139] BUTENANDT, Adolf Friedrich Johann [1265] BUTLEROV, Alexander Mikhailovich [676] BYRD, Richard Evelyn [1129]

CHADWICK, Sir James [1150] CHAIN, Ernst Boris [1306] CRALLIS, James [535] CHAMBERLAIN, Owen [1439] CHAMBERLAND, Charles Edouard [816] CHAMBERLIN, Thomas Chrowder [766] CHANCE, Britton [1384] CHANDRASEKHAR, Subrahmanyan [1356] CHAPTAL, Jean Antoine Claude, comte de Chanteloup [368] CHARCOT, Jean Martin [662] CHARDONNET, Louis Marie Hilaire Bernigaud, comte de [743] CHARGAFF, Erwin [1291] CHARLEMAGNE [78] CAILLETET, Louis Paul [698] CHARLES, Jacques Alexandre César CALLINICUS [74] [343] CALLIPPUS [32] CHARPENTIER, Johann von [449] CALVIN, Melvin [1361] CHÂTELET, Gabrielle Emilie le CANDOLLE, Augustin Pyrame de [418] Tonnelier de Breteuil, marquise de CANNIZZARO, Stanislao [668] [274] CANNON, Annie Jump [932] CHERENKOV, Pavel Alekseyevich CANNON, Walter Bradford [998] [1281] CANO, Juan Sebastiân del [124] CHEVREUL, Michel Eugène [448] CANTON, John [290] CHLADNI, Ernst Florens Friedrich CANTOR, Georg [772] [370] CARDANO, Girolamo [137] CLAIRAUT, Alexis Claude [283] CARNOT, Nicolas Léonard Sadi [497] CLAPEYRON, Benoit Pierre Émile CARO, Heinrich [706] [507] CAROTHERS, Wallace Hume [1190] CLARK, Alvan Graham [696] CARREL, Alexis [1016] CLAUDE, Albert [1222] CARRINGTON, Richard Christopher CLAUDE, Georges [989] [667] CLAUS, Carl Ernst [495] CARROLL, James [849] CLAUSIUS, Rudolf Julius Emmanuel CARVER, George Washington [937] [633] CASSINI, Giovanni Domenico [209] CLAVIUS, Christoph [152] CAUCHY, Augustin Louis, Baron [463] CLEVE, Per Teodor [746] CAVALIERI, Bonaventura [186] COBLENTZ, William Weber [1021] CAVENDISH, Henry [307] COCKCROFT, Sir John Douglas [1198] CAVENTOU, Joseph Bienaimé [493] COHN, Ferdinand Julius [675] CAYLEY, Arthur [629] COLOMBO, Realdo [140] CELSIUS, Anders [271] COLUMBUS, Christopher [121] CELSUS, Aulus Cornelius [57] COMPTON, Arthur Holly [1159] xx

CONTENTS

CONON [44] COOK, James [300] COOLIDGE, William David [1020] COOPER, Leon N. [1489] COPE, Edward Drinker [748] COPERNICUS, Nicolas [127] CORI, Cari Ferdinand [1194] CORI, Gerty Theresa Radnitz [1192] CORIOLIS, Gustave Gaspard de [480] CORMACK, Allan MacLeod [1461] CORNFORTH, Sir John Warcup [1417] CORRENS, Karl Franz Joseph Erich [938] COSTER, Dirk [1135] COULOMB, Charles Augustin [318] COUPER, Archibald Scott [686] COURNAND, André Frédéric [1181] COURTOIS, Bernard [414] COUSTEAU, Jacques-Yves [1353] COWAN, Clyde Lorrain [1434] CRAFTS, James Mason [741] CRAIG, Lyman Creighton [1305] CRICK, Francis Harry Compton [1406] CRONIN, James Watson [1497] CRONSTEDT, Axel Fredrik [292] CROOKES, Sir William [695] CROSS, Charles Frederick [862] CTESIBIUS [46] CURIE, Marie Sklodowska [965] CURIE, Pierre [897] CURTIS, Heber Doust [1007] CUVIER, Georges Léopold Chrétien Frédéric Dagobert, Baron [396] CYSAT, Johann [180] D’ABANO, Pietro [106] DAGUERRE, Louis Jacques Mandé [467] DAIMLER, Gottlieb Wilhelm [708] DALE, Sir Henry Hallett [1034] D’ALEMBERT, Jean le Rond [289] DALTON, John [389] DAM, Cari Peter Henrik [1177] DANIELL, John Frederic [470] DART, Raymond Arthur [1162] DARWIN, Charles Robert [554]

DARWIN, Erasmus [308] DARWIN, Sir George Howard [777] DAUBRÊE, Gabriel Auguste [584] DAUSSET, Jean [1411] DAVISSON, Clinton Joseph [1078] DAVY, Sir Humphry [421] DEBIERNE, André Louis [1026] DE BROGLIE, Louis Victor Pierre Raymond, Prince [1157] DEBYE, Peter Joseph Wilhelm [1094] DEDEKIND, Julius Wilhelm Richard [688] DE DUVE, Christian René [1418] DE FOREST, Lee [1017] DELAMBRE, Jean Baptiste Joseph [350] DE LA RUE, Warren [589] DELBRÜCK, Max [1313] D’ELHUYAR, Don Fausto [367] DELISLE, Joseph Nicolas [255] DEL RIO, Andrés Manuel [382] DEMARÇAY, Eugène Anatole [825] DEMOCRITUS [20] DE MOIVRE, Abraham [246] DE MORGAN, Augustus [549] DEMPSTER, Arthur Jeffrey [1106] DENIS, Jean Baptiste [227] DESAGULIERS, John Théophile [253] DESCARTES, René [183] DESMAREST, Nicolas [296] DE VRIES, Hugo Marie [792] DEWAR, Sir James [759] D’HÉRELLE, Félix Hubert [1012] DICAEARCHUS [33] DICKE, Robert Henry [1405] DIDEROT, Denis [286] DIELS, Otto Paul Hermann [1039] DIESEL, Rudolf [886] DIOCLES [34] DIOPHANTUS [66] DIOSCORIDES [59] DIRAC, Paul Adrien Maurice [1256] DÖBEREINER, Johann Wolfgang [427] DOBZHANSKY, Theodosius [1224] DOISY, Edward Adelbert [1169] DOLLOND, John [273] XXI

CONTENTS

DOLOMIEU, Dieudonné de Gratet de [353] DOMAGK, Gerhard [1183] DONATI, Giovanni Battista [671] DONDERS, Franciscus Comelis [605] DOPPLER, Christian Johann [534] DORN, Friedrich Emst [795] DOUGLASS, Andrew Ellicott [963] DRAKE, Edwin Laurentine [614] DRAKE, Frank Donald [1491] DRAPER, Henry [723] DRAPER, John William [566] DUBOIS, Marie Eugène François Thomas [884] DU BOIS-REYMOND, Emü Heinrich [611] DUBOS, René Jules [1235] DU FAY, Charles François de Cisternay [266] DUGGAR, Benjamin Minge [1010] DUJARDIN, Félix [517] DULBECCO, Renato [1388] DULONG, Pierre Louis [441] DUMAS, Jean Baptiste André [514] DUNNING, John Ray [1330] DÜRER, Albrecht [126] DUTTON, Clarence Edward [753] DU VIGNEAUD, Vincent [1239] DYSON, Freeman John [1459] EASTMAN, George [852] ECCLES, Sir John Carew [1262] ECKERT, John Presper, Jr. [1431] EDDINGTON, Sir Arthur Stanley [1085] EDELMAN, Gerald Maurice [1486] EDISON, Thomas Alva [788] EDLEN, Bengt [1316] EHRENBERG, Christian Gottfried [491] EHRLICH, Paul [845] EIGEN, Manfred [1477} EUKMAN, Christiaan [888] EINSTEIN, Albert [1064] EINTHOVEN, Willem [904] EKEBERG, Anders Gustaf [391] xxii

ELSASSER, Walter Maurice [1279] ELSTER, Johann Philipp Ludwig Julius [858] ELVEHJEM, Conrad Arnold [1240] EMPEDOCLES [17] ENCKE, Johann Franz [475] ENDERS, John Franklin [1195] EOTVÜS, Roland, Baron von [794] EPICURUS [35] ERASISTRATUS [43] ERATOSTHENES [48] ERICSSON, John [533] ERLANGER, Joseph [1023] ERLENMEYER, Richard August Carl Emü [661] ESAKI, Leo [1464] EUCLID [40] EUDOXUS [27] EULER, Leonhard [275] EULER-CHELPIN, Hans Karl August Simon von [1011] EUPALINUS [8] EUSTACHIO, Bartolomeo [141] EWING, William Maurice [1303] FABRICIUS AB AQUAPENDENTE, Hieronymus [151] FABRICIUS, David [167] FABRY, Charles [962] FAHRENHEIT, Gabriel Daniel [254] FALLOPIUS, Gabriel [149] FALSE GEBER [107] FARADAY, Michael [474] FECHNER, Gustav Theodor [520] FERDINAND II OF TUSCANY [193] FERMAT, Pierre de [188] FERMI, Enrico [1243] FERNEL, Jean François [134] FERRIER, Sir David [761] FESSENDEN, Reginald Aubrey [958] FEYNMAN, Richard Philips [1424] FIBONACCI, Leonardo [95] FIELD, Cyrus West [621] FINSEN, Niels Ryberg [908] FISCHER, Emil Hermann [833] FISCHER, Ernst Otto [1429]

CONTENTS

FISCHER, Hans [1076] FISHER, Sir Ronald Aylmer [1142] FITCH, John [330] FITCH, Val Logsden [1454] FITZGERALD, George Francis [821] FITZROY, Robert [544] FIZEAU, Armand Hippolyte Louis [620] FLAMMARION, Nicolas Camille [756] FLAMSTEED, John [234] FLEMING, Sir Alexander [1077] FLEMING, Sir John Ambrose [803] FLEMMING, Walther [762] FLEROV, Georgii Nikolaevich [1381] FLOREY, Howard Walter, Baron [1213] FLORY, Paul John [1354] FOLKERS, Karl August [1312] FONTENELLE, Bernard le Bovier de [239] FORBES, Edward [590] FORD, Henry [929] FORSSMAN, Werner [1283] FOUCAULT, Jean Bernard Léon [619] FOURCROY, Antoine François, comte de [366] FOURIER, Jean Baptiste Joseph, Baron [393] FOX, Sidney Walter [1371] FRAENKEL-CONRAT, Heinz [1355] FRANCK, James [1081] FRANK, Ilya Mikhaylovich [1340] FRANKLAND, Sir Edward [655] FRANKLIN, Benjamin [272] FRANKLIN, Kenneth Linn [1455] FRANKLIN, Rosalind Elsie [1440] FRASCH, Herman [824] FRAUNHOFER, Joseph von [450] FREDERICK II [97] FREGE, Friedrich Ludwig Gottlob [797] FREMY, Edmond [582] FRERE, John [324] FRESNEL, Augustin Jean [455] FREUD, Sigmund [865] FRIEDEL, Charles [693] FRIEDMAN, Herbert [1407]

FRIEDMANN, Alexander Alexandrovich [1125] FRISCH, Karl von [1110] FRISCH, Otto Robert [1284] FRONTINUS, Sextus Julius [62] FUCHS, Leonhard [136] FULTON, Robert [385] FUNK, Casimir [1093] GABOR, Dennis [1230] GADOLIN, Johan [373] GAFFKY, Georg Theodor August [805] GAGARIN, Yuri Alekseyevich [1502] GAHN, Johann Gottlieb [339] GAJDUSEK, Daniel Carleton [1456] GALEN [65] GALILEO [166] GALL, Franz Joseph [371] GALLE, Johann Gottfried [573] GALOIS, Evariste [571] GALTON, Sir Francis [636] GALVANI, Luigi [320] GAMOW, George [1278] GASCOIGNE, William [195] GASSENDI, Pierre [182] GASSER, Herbert Spencer [1126] GATLING, Richard Jordan [609] GAUSS, Johann Karl Friedrich [415] GAY-LUSSAC, Joseph Louis [420] GEBER [76] GEGENBAUR, Karl [669] GEIGER, Hans Wilhelm [1082] GEISSLER, Heinrich [583] GELLIBRAND, Henry [184] GELL-MANN, Murray [1487] GEMMA FRISIUS, Reiner [138] GERARD OF CREMONA [90] GERBERT [84] GERMAIN, Sophie [410] GESELL, Arnold Lucius [1070] GESNER, Konrad von [147] GIAEVER, Ivar [1484] GIAUQUE, William Francis [1178] GIBBS, Josiah Willard [740] GILBERT, Walter [1498] GILBERT, William [155] xxiii

CONTENTS

GILL, Sir David [763] GUETTARD, Jean Étienne [287] GLASER, Donald Arthur [1472] GUILLAUME, Charles Édouard [910] GLASHOW, Sheldon Lee [1500] GUILLEMIN, Roger [1460] GLAUBER, Johann Rudolf [190] GULDBERG, Cato Maximilian [721] GMELIN, Johann Georg [280] GULLSTRAND, Allvar [919] GMELIN, Leopold [457] GUTENBERG, Beno [1133] GODDARD, Robert Hutchings [1083] GUTENBERG, Johann [114] GÖDEL, Kurt [1301] GUTHRIE, Samuel [435] GOEPPERT-MAYER, Marie [1307] GUYOT, Arnold Henry [552] GOETHE, Johann Wolfgang von [349] GUYTON DE MORVEAU, Baron GOLD, Thomas [1437] Louis Bernard [319] GOLDBACH, Christian [256] GOLDBERGER, Joseph [1027] HABER, Fritz [977] GOLDHABER, Maurice [1362] HADFIELD, Sir Robert Abbott [892] GOLDMARK, Peter Carl [1319] HAECKEL, Ernst Heinrich Philipp GOLDSCHMIDT, Johann (Hans) August [707] Wilhelm [909] HAFFKJNE, Waldemar Mordecai GOLDSCHMIDT, Victor Moritz [1123] Wolfe [901] GOLDSTEIN, Eugen [811] HAHN, Otto [1063] GOLGI, Camillo [764] HALDANE, John Burdon Sanderson GOMBERG, Moses [950] [1160] GOODRICKE, John [381] HALE, George Ellery [974] GOODYEAR, Charles [516] HALES, Stephen [249] GORGAS, William Crawford [853] HALL, Asaph [681] GOUDSMTT, Samuel Abraham [1255] HALL, Charles Martin [933] GRAAP, Regnier de [228] HALL, Granville Stanley [780] GRAEBE, Karl James Peter [752] HALL, Sir James [374] GRAHAM, Thomas [547] HALL, Marshall [469] GRAM, Hans Christian Joachim [841] HALLER, Albrecht von [278] GRAMME, Zénobe Théophile [666] HALLEY, Edmund [238] GRANIT, Ragnar Arthur [1232] HALSTED, William Stewart [830] GRASSMAN, Hermann Günther [556] HAMILTON, Sir William Rowan [545] GRAUNT, John [201] HAMPSON, William [851] GRAY, Asa [562] HANNO [12] GRAY, Stephen [262] HARDEN, Sir Arthur [947] GREENSTEIN, Jesse Leonard [1345] HARE, Robert [428] GREGOR, William [377] HARKINS, William Draper [1022] GREGORY, David [240] HARRISON, John [259] GREGORY, James [226] HARTLINE, Haldan Keffer [1276] GREW, Nehemiah [229] HARTMANN, Johannes Franz [940] GRIGNARD, François Auguste Victor HARVEY, William [174] [993] HASSEL, Odd [1197] GRIMALDI, Francesco Maria [199] HATCHETT, Charles [383] GROSSETESTE, Robert [94] HAUKSBEE, Francis [245] GROVE, Sir William Robert [568] HAÜY, René Just [332] GUERICKE, Otto von [189] HAVERS, Clopton [237] XXIV

CONTENTS

HAWKING, Stephen William [1510] HAWKINS, Gerald Stanley [1481] HAWORTH, Sir Walter Norman [1087] HAYFORD, John Fillmore [970] HEAVISIDE, Oliver [806] HECATAEUS [9] HEEZEN, Bruce Charles [1462] HEISENBERG, Wemer Karl [1245] HELLRIEGEL, Hermann [689] HELMHOLTZ, Hermann Ludwig Ferdinand von [631] HELMONT, Jan Baptista van [175] HENCH, Philip Showalter [1188] HENDERSON, Thomas [505] HENLE, Friedrich Gustav Jakob [557] HENRY THE NAVIGATOR [111] HENRY, Joseph [503] HERACLEIDES [28] HERACLITUS [10] HERMITE, Charles [641] HERO [60] HEROPHILUS [42] HÉROULT, Paul Louis Toussaint [925] HERSCHEL, Caroline Lucretia [352] HERSCHEL, Sir John Frederick William [479] HERSCHEL, Sir William [321] HERSHEY, Alfred Day [1341] HERTZ, Gustav Ludwig [1116] HERTZ, Heinrich Rudolf [873] HERTZSPRUNG, Ejnar [1018] HERZBERG, Gerhard [1286] HESS, Germain Henri [528] HESS, Harry Hammond [1304] HESS, Victor Francis [1088] HESS, Walter Rudolf [1073] HEVELIUS, Johannes [194] HEVESY, Gyôrgy [1100] HEWISH, Anthony [1463] HEYROVSKŸ, Jaroslav [1144] HILBERT, David [918] HILL, Archibald Vivian [1108] HILLARY, Sir Edmund Percival [1432] HILLIER, James [1401] HINSHELWOOD, Sir Cyril Norman [ 1200]

HINTON, Christopher, Baron [1238] HIPPARCHUS [50] HIPPOCRATES [22] HISINGER, Wilhelm [390] HITTORF, Johann Wilhelm [649] HITZIG, Julius Eduard [731] HJELM, Peter Jacob [342] HOAGLAND, Mahlon Bush [1447] HODGKIN, Alan Lloyd [1387] HODGKIN, Dorothy Crowfoot [1352] HOFMANN, August Wilhelm von [604] HOFMEISTER, Wilhelm Friedrich Benedikt [651] HOFSTADTER, Robert [1395] HOLLEY, Robert William [1449] HOLMES, Arthur [1138] HOLMES, Oliver Wendell [558] HONDA, Kotaro [985] HOOKE, Robert [223] HOPKINS, Sir Frederick Gowland [912] HOPPE-SEYLER, Ernst Felix Immanuel [663] HORROCKS, Jeremiah [200] HOUSSAY, Bernardo Alberto [1115] HOWE, Elias [616] HOYLE, Sir Fred [1398] HUBBLE, Edwin Powell [1136] HUGGINS, Charles Branton [1242] HUGGINS, Sir William [646] HUMASON, Milton La Salle [1149] HUMBOLDT, Friedrich Wilhelm Heinrich Alexander, Baron von [397] HUTTON, James [297] HUXLEY, Andrew Fielding [1419] HUXLEY, Thomas Henry [659] HUYGENS, Christiaan [215] HYATT, John Wesley [728] HYPATIA [69] IMHOTEP [1] INGENHOUSZ, Jan [306] INNES, Robert Thorburn Ayton [915] IPATIEFF, Vladimir Nikolaevich [966] ISIDORE OF SEVILLE [72] TVANOV, Ilya Ivanovich [988] IVANOVSKY, Dmitri Iosifovich [939] XXV

CONTENTS

JACKSON, Charles Thomas [543] JACOB, François [1438] JACOBI, Carl Gustav Jacob [541] JAMES, William [754] JANSKY, Karl Guthe [1295] JANSSEN, Pierre Jules César [647] JEANS, Sir James Hopwood [1053] JEFFERSON, Thomas [333] JEFFREYS, Sir Harold [1147] JENNER, Edward [348] JENSEN, Johannes Hans Daniel [1327] JOHANNSEN, Wilhelm Ludwig [872] JOLIOT-CURIE, Frédéric [1227] JOLIOT-CURIE, Irène [1204] JONES, Sir Harold Spencer [1140] JOSEPHSON, Brian David [1509] JOULE, James Prescott [613] JUNG, Carl Gustav [1035] JUSSIEU, Antoine Laurent de [345] KAMEN, Martin David [1385] KAMERLINGH ONNES, Heike [843] KANT, Immanuel [293] KAPITZA, Peter Leonidovich [1173] KAPTEYN, Jacobus Cornelius [815] KARMAN, Theodore von [1075] KARRER, Paul [1131] KASTLER, Alfred [1252] KATZ, Sir Bernard [1359] KEELER. James Edward [879] KEESOM, Willem Hendrik [1042] KEILIN, David [1113] KEKULÉ VON STRADONITZ, Friedrich August [680] KELVIN, William Thomson, Baron [652] KENDALL, Edward Calvin [1105] KENDREW, John Cowdery [1415] KENNELLY, Arthur Edwin [916] KEPLER, Johann [169] KERST, Donald William [1367] KETTERING, Charles Franklin [1044] KHORANA, Har Gobind [1448] KIDD, John [409] KIDDINU [37] XXVI

KING, Charles Glen [1193] KIPPING, Frederic Stanley [930] KIRCHER, Athanasius [187] KIRCHHOF, Gottlieb Sigismund Constantin [380] KIRCHHOFF, Gustav Robert [648] KIRKWOOD, Daniel [586] KITASATO, Baron Shibasaburo [870] KJELDAHL, Johann Gustav Christoffer [801] KLAPROTH, Martin Heinrich [335] KLEIN, Christian Felix [800] KLEIST, Ewald Georg von [269] KOCH, (Heinrich Hermann) Robert [767] KÖHLER, Wolfgang [1112] KOLBE, Adolph Wilhelm Hermann [610] KOLLER, Carl [882] KÖLLIKER, Rudolf Albert von [600] KOPP, Hermann Franz Moritz [601] KORNBERG, Arthur [1422] KOSSEL, (Karl Martin Leonhard) Albrecht [842] KOVALEVSKI, Alexander Onufriyevich [750] KOVALEVSKY, Sonya [804] KOZYREV, Nikolai Alexandrovich [1336] KRAFFT-EBING, Baron Richard von [749] KREBS, Sir Hans Adolf [1231] KROGH, Shack August Steenberg [1030] KRONECKER, Leopold [645] KUHN, Richard [1233] KÜHNE, Wilhelm (Willy) Friedrich [725] KUIPER, Gerard Peter [1297] KUNDT, August Adolph Eduard Eberhard [744] KURCHATOV, Igor Vasilevich [1261] LACAILLE, Nicolas Louis de [284] LA CONDAMINE, Charles Marie de [270]

CONTENTS

LAËNNEC, Théophile René Hyacinthe [429] LAGRANGE, Joseph Louis, comte de [317] LALANDE, Joseph Jérôme Le Français de [309] LAMARCK, Jean Baptiste Pierre Antoine de Monet, chevalier de [336] LAMBERT, Johann Heinrich [299] LAMONT, Johann von [546] LAND, Edwin Herbert [1344] LANDAU, Lev Davidovich [1333] LANDSTEINER, Karl [973] LANGERHANS, Paul [791] LANGEVIN, Paul [1000] LANGLEY, Samuel Pierpont [711] LANGMUIR, Irving [1072] LAPLACE, Pierre Simon, marquis de [347] LARSON, John Augustus [1161] LARTET, Édouard Armand Isidore Hippolyte [519] LASSELL, William [509] LAUE, Max Theodor Felix von [1068] LAURENT, Auguste [553] LAVERAN, Charles Louis Alphonse [776] LAVOISIER, Antoine Laurent [334] LAWES, Sir John Bennett [588] LAWRENCE, Ernest Orlando [1241] LAZEAR, Jesse William [955] LEAKEY, Louis Seymour Bazett [1268] LEAVITT, Henrietta Swan [975] LEBEDEV, Pyotr Nicolaievich [952] LE BEL, Joseph Achille [787] LEBLANC, Nicolas [328] LE CHÂTELIER, Henri Louis [812] LECOQ DE BOISBAUDRAN, Paul Émile [736] LEDERBERG, Joshua [1466] LEE, Tsung-Dao [1473] LEEUWENHOEK, Anton van [221] LEGENDRE, Adrien Marie [358] LE GENTIL, Guillaume Joseph Hyacinthe Jean Baptiste [295] LEIBNIZ, Gottfried Wilhelm [233]

LEISHMAN, Sir William Boog [948] LELOIR, Luis Frederico [1314] LEMAITRE, Abbe Georges Edouard [1174] LENARD, Philipp Eduard Anton von [920] LENOIR, Jean Joseph Etienne [635] LENZ, Heinrich Friedrich Emil [536] LEONARDO DA VINCI [122] LEUCIPPUS [15] LEUCKART, Karl Georg Friedrich Rudolf [640] LEVENE, Phoebus Aaron Theodor [980] LEVERRIER, Urbain Jean Joseph [564] LEWIS, Gilbert Newton [1037] LEXELL, Anders Johan [326] LEY, Willy [1315] LI, Choh Hao [1382] LIBAVIUS [162] LIBBY, Willard Frank [1342] LIEBIG, Justus von [532] LILIENTHAL, Otto [793] LIND, James [288] LINDBERGH, Charles Augustus [1249] LINDBLAD, Berth [1185] LINDE, Karl Paul Gottfried von [758] LINDEMANN, Carl Louis Ferdinand von [826] LINNAEUS, Carolus [276] LIOUVILLE, Joseph [555] LIPMANN, Fritz Albert [1221] LIPPERSHEY, Hans [168] LIPPMANN, Gabriel Jonas [778] LIPSCOMB, William Nunn, Jr. [1435] LISTER, Joseph, Baron [672] LISTER, Joseph Jackson [445] LOBACHEVSKI, Nikolai Ivanovich [484] LOCKYER, Sir Joseph Norman [719] LODGE, Sir Oliver Joseph [820] LOEB, Jacques [896] LOEWI, Otto [1015] LÖFFLER, Friedrich August Johannes [828] LOMONOSOV, Mikhail Vasilievich [282] xxvii

CONTENTS

LONDON, Fritz Wolfgang [1226] LONG, Crawford Williamson [594] LORENTZ, Hendrik Antoon [839] LORENZ, Konrad [1271] LOSCHMIDT, Johann Joseph [628] LOVE, Augustus Edward Hough [926] LOVELL, Sir Alfred Charles Bernard [1386] LOWELL, Percival [860] LOWER, Richard [219] LUCRETIUS [53] LUDWIG, Karl Friedrich Wilhelm [597] LURIA, Salvador Edward [1377] LWOFF, André Michael [1253] LYELL, Sir Charles [502] LYNEN, Feodor [1360] LYOT, Bernard Ferdinand [1196] LYSENKO, Trofim Denisovich [1214]

MAUNDER, Edward Walter [818] MAUPERTUIS, Pierre Louis Moreau de [267] MAURY, Matthew Fontaine [548] MAXIM, Sir Hiram Stevens [745] MAXWELL, James Clerk [692] MAYER, Julius Robert [587] MAYOW, John [230] McADAM, John Loudon [369] McCOLLUM, Elmer Verner [1062] McMILLAN, Edwin Mattison [1329] MECHNIKOV, Ilya Dich [775] MEDAWAR, Sir Peter Brian [1396] MEITNER, Lise [1060] MELA, Pomponius [58] MELLONI, Macedonio [504] MENAECHMUS [30] MENDEL, Gregor Johann [638] MENDELÉEV, Dmitri Ivanovich [705] MENZEL, Donald Howard [1237] MACH, Ernst [733] MERCATOR, Gerardus [144] MACLAURIN, Colin [263] MERSENNE, Marin [181] MÄDLER, Johann Heinrich [488] MESMER, Franz Anton [314] MAGELLAN, Ferdinand [130] MESSIER, Charles [305] MAGENDIE, François [438] METON [23] MAIMAN, Theodore Harold [1479] MEYER, Julius Lothar [685] MAIMONIDES, Moses [92] MEYER, Viktor [796] MALPIGHI, Marcello [214] MEYERHOF, Otto Fritz [1095] MALTHUS, Thomas Robert [387] MICHAELIS, Leonor [1033] MALUS, Étienne Louis [408] MICHAEL SCOT [98] MANSON, Sir Patrick [771] MICHELL, John [294] MANTELL, Gideon Algernon [468] MICHELSON, Albert Abraham [835] MARCONI, Marchese Guglielmo [1025] MIDGLEY, Thomas, Jr. [1132] MAREY, Étienne Jules [683] MIESCHER, Johann Friedrich [770] MARGGRAF, Andreas Sigismund [279] MILLER, Dayton Clarence [953] MARIGNAC, Jean Charles Galissard de MILLER, Jacques Francis Albert Pierre [599] [1494] MARIOTTE, Edmé [203] MILLER, Stanley Lloyd [1490] MARIUS, Simon [171] MILLER, William Hallowes [518] MARKOVNIKOV, Vladimir Vasilevich MILLIKAN, Robert Andrews [969] [729] MILNE, Edward Arthur [1186] MARSH, Othniel Charles [690] MILNE, John [814] MARTIN, Archer John Porter [1350] MINKOWSKI, Hermann [935] MASKELYNE, Nevil [310] MINKOWSKI, Rudolph Leo B. [1179] MATTHIAS, Bern Teo [1425] MINOT, George Richards [1103] MAUCHLY, John William [1328] MITCHELL, Maria [608] xxviii

CONTENTS

MITCHELL, Peter Dennis [1441] MITSCHERLICH, Eilhardt [485] MÖBIUS, August Ferdinand [471] MOHL, Hugo von [542] MOHOROVICIC, Andrija [871] MOHS, Friedrich [401] MOISSAN, Ferdinand Frédéric Henri [831] MONDINO DE’ LUZZI [110] MONGE, Gaspard [340] MONIZ, Antonio Caetano de Abreu Freire Egas [1032] MONOD, Jacques Lucien [1347] MONTGOLFIER, Jacques Étienne and Joseph Michel [325] MOORE, Stanford [1379] MORGAGNI, Giovanni Battista [251] MORGAN, Thomas Hunt [957] MORGAN, William Wilson [1298] MORGENSTERN, Oskar [1248] MORLEY, Edward Williams [730] MORSE, Samuel Finley Breese [473] MORTILLET, Louis Laurent Gabriel de [630] MORTON, William Thomas Green [617] MOSANDER, Carl Gustav [501] MOSELEY, Henry Gwyn-Jeffreys [ 1121] MÖSSBAUER, Rudolf Ludwig [1483] MOTT, Sir Nevill Francis [1294] MOTTELSON, Ben Roy [1471] MOULTON, Forest Ray [1003] MUELLER, Erwin Wilhelm [1364] MULDER, Gerardus Johannes [531] MÜLLER, Franz Joseph [323] MULLER, Hermann Joseph [1145] MÜLLER, Johannes Peter [522] MÜLLER, Otto Friedrich [304] MÜLLER, Paul Hermann [1216] MULLIKEN, Robert Sanderson [1191] MURCHISON, Sir Roderick Impey [477] MURDOCK, William [363] MURPHY, William Parry [1154] MUSSCHENBROEK, Pieter van [257]

NAGAOKA, Hantaro [946] NAGELI, Karl Wilhelm von [598] NANSEN, Fridtjof [914] NAPIER, John [159] NATHANS, Daniel [1482] NATTA, Giulio [1263] NECKAM, Alexander [93] NEEDHAM, John Turberville [285] NÉEL, Louis Eugène Félix [1285] NE’EMAN, Yuval [1465] NEF, John Ulric [921] NEISSER, Albert Ludwig Sigismund [859] NERNST, Hermann Walther [936] NEUMANN, John von [1273] NEWCOMB, Simon [713] NEWCOMEN, Thomas [243] NEWLANDS, John Alexander Reina [727] NEWTON, Sir Isaac [231] NICHOLAS OF CUSA [115] NICHOLSON, Seth Barnes [1151] NICHOLSON, William [361] NICOL, William [394] NICOLLE, Charles Jules Henri [956] NIEPCE, Joseph Nicéphore [384] NIEUWLAND, Julius Arthur [1058] NILSON, Lars Fredrik [747] NIRENBERG, Marshall Warren [1476] NOBEL, Alfred Bernhard [703] NODDACK, Ida Eva Tacke [1187] NODDACK, Walter Karl Friedrich [1166] NORDENSKIÜLD, Nils Adolf Erik [700] NORMAN, Robert [161] NORRISH, Ronald George Wreyford [1206] NORTHROP, John Howard [1148] OBERTH, Hermann Julius [1172] OCHOA, Severo [1293] OCKHAM, William of [109] OENOPIDES [18] OERSTED, Hans Christian [417] OHM, Georg Simon [461] XXIX

CONTENTS

O’KEEFE, John Aloysius [1412] OKEN, Lorenz [423] OLBERS, Heinrich Wilhelm Matthäus [372] OLIPHANT, Marcus Laurence Elwin [1244] OMAR KHAYYAM [87] O’NEILL, Gerard Kitchen [1475] ONSAGER, Lars [1272] OORT, Jan Hendrik [1229] OPARIN, Alexander Ivanovich [1171] ÖPIK, Ernst Julius [1168] OPPENHEIMER, J. Robert [1280] OSBORNE, Thomas Burr [900] OSTWALD, Friedrich Wilhelm [840] OTIS, Elisha Graves [569] OTTO, Nikolaus August [694] OUGHTRED, William [172] OWEN, Sir Richard [539] PACIOLI, Luca [120] PALADE, George Emil [1380] PALMIERI, Luigi [550] PANDER, Christian Heinrich [489] PANETH, Friedrich Adolf [1118] PAPIN, Denis [235] PAPPUS [68] PARACELSUS [131] PARE, Ambroise [139] PARKER, Eugene Newman [1478] PARKES, Alexander [581] PARKINSON, James [365] PARMENIDES [13] PARSONS, Sir Charles Algernon [850] PASCAL, Blaise [207] PASCHEN, Louis Carl Heinrich Friedrich [941] PASTEUR, Louis [642] PAULI, Wolfgang [1228] PAULING, Linus Carl [1236] PAVLOV, Ivan Petrovich [802] PAYEN, Anselme [490] PEACOCK, George [472] PEANO, Giuseppe [889] PEARSON, Karl [875] PEARY, Robert Edwin [866] XXX

PELLETIER, Pierre Joseph [454] PENZIAS, Amo Allan [1501] PEREGRINUS, Petrus [104] PERKIN, Sir William Henry [734] PERRIN, Jean Baptiste [990] PERRINE, Charles Dillon [964] PERUTZ, Max Ferdinand [1389] PETIT, Alexis Thérèse [476] PETRIE, Sir (William Matthew) Flinders [838] PETTENKOFER, Max Joseph von [612] PEURBACH, Georg von [118] PFEFFER, Wilhelm [773] PHILOLAUS [19] PHILON [45] PIAZZI, Giuseppe [341] PICARD, Jean [204] PICCARD, August [1092] PICKERING, Edward Charles [784] PICKERING, William Henry [885] PICTET, Raoul Pierre [783] PIERCE, John Robinson [1351] PINCUS, Gregory [1266] PINEL, Philippe [338] PLANCK, Max Karl Ernst Ludwig [887] PLANTÉ, Gaston [709] PLASKETT, John Stanley [949] PLATO [24] PLINY [61] PLÜCKER, Julius [521] POGSON, Norman Robert [679] POINCARÉ, Jules Henri [847] POISEUILLE, Jean Léonard Marie [500] POISSON, Simeon Denis [432] POLHEM, Christopher [242] POLO, Marco [105] PONCELET, Jean Victor [456] PONNAMPERUMA, Cyril [1457] PONS, Jean Louis [376] POPE, Sir William Jackson [991] POPOV, Alexander Stepanovich [895] PORTA, Giambattista della [150] PORTER, George [1443]

CONTENTS

POSEIDONIUS [52] POULSEN, Valdemar [983] POWELL, Cecil Frank [1274] PRAXAGORAS [36] PREGL, Fritz [982] PRELOG, Vladimir [1310] PRÉVOST, Pierre [356] PRIESTLEY, Joseph [312] PRIGOGINE, Ilya [1414] PROCLUS [70] PROCTOR, Richard Anthony [724] PROKHOROV, Alexander Mikhailovich [1409] PROUST, Joseph Louis [364] PROUT, William [440] PRZHEVALSKY, Nikolay Mikhaylovich [742] PTOLEMY, Claudius [64] PUPIN, Michael Idvorsky [891] PURCELL, Edward MiUs [1378] PURKINJE, Jan Evangelista [452] PYTHAGORAS [7] PYTHEAS [39]

REED, Walter [822] REGIOMONTANUS [119] REGNAULT, Henri Victor [561] REICH, Ferdinand [506] REICHSTEIN, Tadeusz [1201] REID, Harry Fielding [898] REINES, Frederick [1423] REINHOLD, Erasmus [143] REMAK, Robert [591] REMSEN, Ira [781] RETZIUS, Anders Adolf [498] RHAZES [82] RHETICUS [145] RHINE, Joseph Banks [1182] RICCIOLI, Giovanni Battista [185] RICHARDS, Dickinson W. [1184] RICHARDS, Theodore William [968] RICHARDSON, Sir Owen Will ans [1066] RICHER, Jean [217] RICHET, Charles Robert [809] RICHTER, Burton [1493] RICHTER, Hieronymus Theodor [654] RICHTER, Jeremias Benjamin [378] QUETELET, Lambert Adolphe Jacques RICKETTS, Howard Taylor [992] [496] RICKOVER, Hyman George [1225] RIEMANN, Georg Friedrich Bernhard RABI, Isidor Isaac [1212] [670] RIGHI, Augusto [810] RAINWATER, Leo James [1420] RAMAN, Sir Chandrasekhara Venkata RINGER, Sydney [717] [1130] RITTER, Johann Wilhelm [413] RAMÖN Y CAJAL, Santiago [827] ROBBINS, Frederick Chapman [1410] ROBERTS, Richard Brooke [1357] RAMSAY, Sir William [832] RANKINE, William John Macquom ROBINSON, Sir Robert [1107] [625] ROCHE, Édouard Albert [627] ROEMER, Olaus [232] RAOULT, François Marie [684] ROENTGEN, Wilhelm Konrad [774] RAWLINSON, Sir Henry Creswicke [559] ROOZEBOOM, Hendrik Willem RAY, John [213] Bakhuis [854] RORSCHACH, Hermann [1099] RAYLEIGH, John William Strutt, 3d Baron [760] ROSE, William Cumming [1114] RÉAUMUR, René Antoine Ferchault de ROSS, Sir James Clark [512] [252] ROSS, Sir Ronald [876] ROSSE, William Parsons, 3d earl of REBER, Grote [1368] REDFIELD, William C. [462] [513] ROSSI, Bruno Benedetto [1289] REDI, Francesco [211] xxxi

CONTENTS

ROUS, Francis Peyton [1067] ROUX, Pierre Paul Émile [844] ROWLAND, Henry Augustus [798] RUBNER, Max [848] RUDBECK, Olof [218] RUMFORD, Benjamin Thompson, Count [360] RUSKA, Ernst August Friedrich [1322] RUSSELL, Bertrand Arthur William, 3d Earl [1005] RUSSELL, Henry Norris [1056] RUTHERFORD, Daniel [351] RUTHERFORD, Ernest [996] RUTHERFURD, Lewis Morris [596] RUZICKA, Leopold Stephen [1119] RYDBERG, Johannes Robert [857] RYLE, Sir Martin [1428] SABATIER, Paul [856] SABIN, Albert Bruce [1311] SABINE, Sir Edward [459] SABINE, Wallace Clement Ware [972] SACCHERI, Girolamo [247] SACHS, Julius von [699] SAGAN, Cari [1504] SAINTE-CLAIRE DEVILLE, Henri Étienne [603] SAKHAROV, Andrey Dmitriyevich [1444] SALAM, Abdus [1468] SALK, Jonas Edward [1393] SANCTORIUS, Sanctorius [165] SANDAGE, Allan Rex [1469] SANGER, Frederick [1426] SAUSSURE, Horace Bénédict de [322] SAVER Y, Thomas [236] SCALIGER, Joseph Justus [154] SCHAEBERLE, John Martin [836] SCHAEFER, Vincent Joseph [1309] SCHALLY, Andrew Victor [1474] SCHAUDINN, Fritz Richard [997] SCHEELE, Karl Wilhelm [329] SCHEINER, Christoph [173] SCHIAPARELLI, Giovanni Virginio [714] SCHLEIDEN, Matthias Jakob [538] x x x ii

SCHLIEMANN, Heinrich [634] SCHMIDT, Bernhard Voldemar [1065] SCHMIDT, Maarten [1488] SCHOENHEIMER, Rudolf [1211] SCHÖNBEIN, Christian Friedrich [510] SCHÖNER, Johannes [129] SCHRIEFFER, John Robert [1495] SCHRÖDINGER, Erwin [1117] SCHULTZE, Max Johann Sigismund [657] SCHWABE, Heinrich Samuel [466] SCHWANN, Theodor [563] SCHWARZSCHILD, Karl [1019] SCHWEIGGER, Johann Salomo Christoph [422] SCHWINGER, Julian Seymour [1421] SCOTT, Robert Falcon [971] SEABORG, Glenn Theodore [1372] SECCHI, Pietro Angelo [606] SEDGWICK, Adam [442] SEEBECK, Thomas Johann [398] SEFSTRÖM, Nils Gabriel [451] SEGRE, Emilio [1287] SELEUCUS [51] SEMENOV, Nikolay Nikolaevich [1189] SEMMELWEISS, Ignaz Philipp [607] SERTÜRNER, Friedrich Wilhelm Adam Ferdinand [437] SERVETUS, Michael [142] SHANKS, William [572] SHANNON, Claude Elwood [1404] SHAPLEY, Harlow [1102] SHARPEY-SCHAFER, Sir Edward Albert [807] SHEMIN, David [1358] SHERMAN, Henry Clapp [1036] SHERRINGTON, Sir Charles Scott [881] SHKLOVSKII, Iosif Samuilovich [1408] SHOCKLEY, William Bradford [1348] SIDGWICK, Nevil Vincent [1013] SIEBOLD, Karl Theodor Ernst von [537] SIEGBAHN, Karl Manne Georg [1111] SIEMENS, Sir William [644] SILLIMAN, Benjamin [424]

CONTENTS

SIMON, Sir Franz Eugen Francis [1165] SIMPSON, Sir James Young [567] SITTER, Willem de [1004] SLIPHER, Vesto Melvin [1038] SMITH, Hamilton Othanel [1496] SMITH, Philip Edward [1090] SMITH, Theobald [899] SMITH, William [395] SNELL, George Davis [1275] SNELL, Willebrord van Roijen [177] SNOW, John [576] SOBRERO, Ascanio [574] SOCRATES [21] SODDY, Frederick [1052] SOLVAY, Ernest [735] SOMMERFELD, Arnold Johannes Wilhelm [976] SØRENSEN, Søren Peter Lauritz [967] SOSIGENES [54] SPALLANZANI, Lazzaro [302] SPEDDING, Frank Harold [1259] SPEMANN, Hans [981] SPENCER, Herbert [624] SPERRY, Elmer Ambrose [907] SPITZER, Lyman, Jr. [1390] SPRENGEL, Christian Konrad [354] STAHL, Georg Ernst [241] STANLEY, Wendell Meredith [1282] STARK, Johannes [1024] STARLING, Ernest Henry [954] STAS, Jean Servais [579] STAUDINGER, Hermann [1074] STEFAN, Josef [715] STEIN, William Howard [1365] STEINMETZ, Charles Proteus (originally Karl August) [944] STEPHENSON, George [431] STENO, Nicolaus [225] STERN, Otto [1124] STEVINUS, Simon [158] STEWART, Balfour [678] STOCK, Alfred [1043] STOKES, Sir George Gabriel [618] STONEY, George Johnstone [664] STRABO [56] STRASBURGER, Eduard Adolf [768]

STRASSMAN, Fritz [1251] STRATO [38] STROHMEYER, Friedrich [411] STRUVE, Friedrich Georg Wilhelm von [483] STRUVE, Otto [1203] STURGEON, William [436] STURTEVANT, Alfred Henry [1153] SUESS, Eduard [687] SUMNER, James Batcheller [1120] SUTHERLAND, Earl Wilbur, Jr. [1402] SUTTON, Walter Stanborough [1047] SVEDBERG, Theodor H. E. [1097] SWAMMERDAM, Jan [224] SWAN, Sir Joseph Wilson [677] SYDENHAM, Thomas [208] SYLVIUS, Franciscus [196] SYNGE, Richard Laurence Millington [1394] SZENT-GYÜRGYI, Albert [1167] SZILARD, Leo [1208] TAKAMINE, Jokichi [855] TALBOT, William Henry Fox [511] TAMM, Igor Yevgenyevich [1180] TARTAGLIA, Niccolè [135] TATUM, Edward Lawrie [1346] TAYLOR, Frederick Winslow [864] TEISSERENC DE BORT, Léon Philippe [861] TELLER, Edward [1332] TEMIN, Howard Martin [1505] TENNANT, Smithson [375] TESLA, Nikola [867] THABIT IBN QURRA [80] THALES [3] THEAETETUS [26] THEILER, Max [1217] THÉNARD, Louis Jacques [416] THEOPHRASTUS [31] THEORELL, Axel Hugo Teodor [1267] THOMSEN, Christian Jurgensen [460] THOMSEN, Hans Peter Jørgen Julius [665] THOMSON, Sir Charles Wyville [682] THOMSON, Elihu [837] xxxiii

CONTENTS

THOMSON, Sir George Paget [1156] THOMSON, Sir Joseph John [869] THOMSON, Robert William [637] TINBERGEN, Nikolaas [1326] TING, Samuel C. C. [1507] TISELIUS, Arne Wilhelm Kaurin [1257] TITIUS, Johann Daniel [301] TODD, Alexander Robertus, Baron [1331] TOMBAUGH, Clyde William [1299] TOMONAGA, Shin’ichiro [1300] TORRICELLI, Evangelista [192] TOSCANELLI, Paolo [113] TOWNES, Charles Hard [1400] TRAVERS, Morris William [1001] TREVITHICK, Richard [399] TRUMPLER, Robert Julius [1109] TSAI LUN [63] TSCHERMAK VON SEYSENEGG, Erich [999] TSIOLKOVSKY, Konstantin Eduardovich [880] TSVETT, Mikhail Semenovich [1006] TURING, Alan Mathison [1375] TWORT, Frederick William [1055] TYNDALL, John [626] UHLENBECK, George Eugene [1234] ULUGH BEG [112] URBAIN, Georges [1002] UREY, Harold Clayton [1164] VALENTIN, Gabriel Gustav [560] VAN ALLEN, James Alfred [1392] VAN DE GRAAF, Robert Jemison [1246] VAN DE HULST, Hendrik Christoffell [1430] VAN DE KAMP, Peter [1247] VAN DER WAALS, Johannes Diderik [726] VANT HOFF, Jacobus Henricus [829] VAN VLECK, John Hasbrouck [1219] VAUQUELIN, Louis Nicolas [379] VAVILOV, Nikolay Ivanovich [1122] VEKSLER, Vladimir Iosifovich [1324] xxxiv

VENETZ, Ignatz [453] VENN, John [710] VERNADSKY, Vladimir Ivanovich [924] VERNIER, Pierre [179] VESALIUS, Andreas [146] VESPUCIUS, Americus [123] VIETA, Franciscus [153] VILLARD, Paul Ulrich [906] VIRCHOW, Rudolph Carl [632] VIRTANEN, Artturi Ilmari [1176] VITRUVIUS [55] VIVIANI, Vincenzo [206] VOGEL, Hermann Carl [757] VOIT, Karl von [691] VOLTA, Alessandro Giuseppe Antonio Anastasio, Count [337] VOLTAIRE [261] VON EULER, Ulf Svante [1288] VONNEGUT, Bernard [1391] WAAGE, Peter [701] WAGNER VON JAUREGG, Julius [874] WAKSMAN, Selman Abraham [1128] WALD, George [1318] WALDEN, Paul [928] WALDEYER-HARTZ, Heinrich Wilhelm Gottfried von [722] WALDSEEMÜLLER, Martin [125] WALLACE, Alfred Russel [643] WALLACH, Otto [790] WALLIS, John [198] WALTER, William Grey [1349] WALTON, Ernest Thomas Sinton [1269] WARBURG, Otto Heinrich [1089] WASSERMAN, August von [951] WATSON, James Dewey [1480] WATSON, John Broadus [1057] WATSON-WATT, Sir Robert Alexander [1155] WATT, James [316] WEBER, Ernst Heinrich [492] WEBER, Wilhelm Eduard [540] WEGENER, Alfred Lothar [1071]

CONTENTS

WEIERSTRASS, Karl Theodor Wilhelm [593] WEINBERG, Steven [1502] WEISMANN, August Friedrich Leopold [704] WEISS, Pierre [942] WEIZMANN, Chaim [1031] WEIZSÄCKER, Carl Friedrich, Baron von [1376] WELLER, Thomas Huckle [1397] WENDELIN, Godefroy [176] WERNER, Abraham Gottlob [355] WERNER, Alfred [960] WESTINGHOUSE, George [785] WHEATSTONE, Sir Charles [526] WHEELER, John Archibald [1366] WHEWELL, William [487] WHIPPLE, Fred Lawrence [1317] WHIPPLE, George Hoyt [1059] WHITEHEAD, Alfred North [911] WHITNEY, Eh [386] WIECHERT, Emil [917] WIELAND, Heinrich Otto [1048] WIEN, Wilhelm [934] WIENER, Norbert [1175] WIGNER, Eugene Paul [1260] WILDT, Rupert [1290] WILKINS, John [197] WILKINS, Maurice Hugh Frederick [1413] WILKINS, Robert Wallace [1320] WILKINSON, Sir Geoffrey [1445] WILLIAMS, Robert Runnels [1104] WILLIAMS, Robley Cook [1339] WILLIAMSON, Alexander William [650] WILLIS, Thomas [205] WILLSTÄTTER, Richard [1009] WILSON, Charles Thomson Rees [979] WILSON, Edmund Beecher [868] WILSON, Robert Woodrow [1506] WINDAUS, Adolf [1046] WINKLER, Clemens Alexander [739]

WISLICENUS, Johannes [716] WITHERING, William [327] WITTIG, Georg Friedrich Karl [1199] WOHLER, Friedrich [515] WOLF, Maximilian Franz Joseph Cornelius [927] WOLFF, Kaspar Friedrich [313] WOLLASTON, William Hyde [388] WOODWARD, Robert Bums [1416] WOOLLEY, Sir Charles Leonard [1069] WREN, Sir Christopher [220] WRIGHT, Orville [995] WRIGHT, Thomas [281] WRIGHT, Wilbur [961] WROBLEWSKI, Zygmunt Florenty von [779] WUNDERLICH, Carl Reinhold August [592] WUNDT, Wilhelm Max [697] WURTZ, Charles Adolphe [602] WYCKOFF, Ralph Walter Graystone [ 12 0 2 ]

XENOPHANES [6] YALOW, Rosalyn Sussman [1446] YANG, Chen Ning [1451] YERKES, Robert Mearns [1041] YOUNG, Charles Augustus [712] YOUNG, Thomas [402] YUKAWA, Hideki [1323] ZEEMAN, Pieter [945] ZENO [16] ZEPPELIN, Ferdinand Adolf August Heinrich, Count von [737] ZERNICKE, Fritz [1127] ZIEGLER, Karl [1215] ZINN, Walter Henry [1321] ZOSIMUS [67] ZSIGMONDY, Richard Adolf [943] ZWICKY, Fritz [1209] ZWORYKIN, Vladimir Kosma [1134]

XXXV

ASIMOV’S BIOGRAPHICAL ENCYCLOPEDIA OF SCIENCE AND TECHNOLOGY [1] IMHOTEP (im-hoh'tep) Egyptian scholar Born: near Memphis Flourished 2980-2950 b .c . Imhotep is remarkable for being the first historic equivalent, known by name, of what we would today call a scientist. There was not to be another for over two thousand years. The one definite feat that is attributed to him is that of being the architect of the “step pyramid” at the modern village of Sakkara (near the site of ancient Memphis) in Egypt. This was the ear­ liest of the Egyptian pyramids, and if Imhotep was indeed the architect, he may be credited with a literally monu­ mental first. The memory of Imhotep was saddled with all sorts of other achievements, the tales certainly not dwindling in the tell­ ing as generations passed. Most of all, he was remembered for his powers of heal­ ing, which the tales eventually magnified to the point of magic. In fact, by Ptole­ maic times, he had come to be deified as the son of the great god Ptah and as himself the god of medicine. His tomb at Sakkara became a shrine where people came in search of cures as today they come to Lourdes. A ruin thought to be this shrine was uncovered in 1965. Our first scientist is thus unique in another way, for no scientist since has been made into a god. The Greeks identified Imhotep (whom they called Imouthes) with Asklepios, their own god of medicine, and his leg­

end may also have influenced their own tales of Daedalus, who, if he did not build a pyramid, was at least sup­ posed to have built the Cretan labyrinth. Some ancient manuscripts speak of Imhotep as having counseled Zoser (the Pharaoh for whom the step pyramid had been built) as to the methods of appeas­ ing the gods after a succession of seven consecutive failures of the Nile floods had brought a seven-year famine. Might not this have influenced the later He­ brews in their legends of Joseph? [2] AHMOSE (ah'mose) Egyptian scribe Lived about 1650 b .c . Ahmose is known only because his name is on a mathematical treatise headed “Directions for Attaining Knowl­ edge of All Dark Things.” It was discov­ ered in Egypt in the mid-nineteenth cen­ tury and is now in the British Museum. Ahmose is merely the copyist of the papyrus, which deals with the solution of various types of simple equations, with devices for handling fractions with unit numerators, with finding areas and vol­ umes and so on. The actual authors are lost in the past. The papyrus attests to the ancientness of Egyptian mathematics. It also lacks any sign that the Egyptians generalized their methods. Each problem discussed is treated as a special case, with a detailed description of the method of handling the particular numerical values contained 1

[3]

THALES

in the problem. No rules are given for solving a particular type of problem for all possible sets of conditions. Perhaps it is assumed that the reader will work out the rule for himself from the cases given. Perhaps the rules are given on some other papyrus not yet found, or possibly forever lost. Perhaps the priestly caste kept the general rules a secret, just as the followers of Pythag­ oras [7] many years later were to keep certain mathematical discoveries secret. Certainly, considering the technical pro­ ficiency of the Egyptians in mathe­ matics (for the builders of the pyramids could by no means have been mathe­ matical novices) it is hard to believe that generalization did not exist. Nevertheless the fact remains that there is no documentary sign of general­ ization in mathematics until the time of Thales [3], who lived a thousand years after Ahmose. [3] THALES (thay'leez) Greek philosopher Bom: Miletus, 624 b .c . Died: Miletus, 546 b .c . The later Greeks considered Thales the founder of Greek science, mathe­ matics, and philosophy, and they cred­ ited to him the origin of almost every branch of knowledge. It is hard to say how much of this is later embroidery. He is supposed to have been bom of a Phoenician mother, though this is doubted by some. Perhaps the legend only signifies that he was educated in Eastern science. Certainly he visited Egypt and probably Babylonia. It may be that what seemed to the Greeks a multiplicity of achievement was simply the lore of the more ancient peoples. For instance, the single deed that most secured his reputation, according to the tale told a century and a half later by the Greek historian Herodotus, was his prediction of an eclipse of the sun, an eclipse which then proceeded to take place in the very year for which it was predicted. (When it occurred it fright­ ened the Medes and Lydians, who were on the point of advancing into battle,

2

THALES

[3]

and convinced them of the beauties of peace. They signed a treaty and the ar­ mies returned home.) Modem astro­ nomical research showed that the only eclipse that took place in Asia Minor in Thales’ time was on May 28, 585 b .c ., so that the aborted battle is the first human historical event that can be dated with certainty to the exact day. Nevertheless Thales’ feat seems not so miraculous when we consider that the Babylonians had worked out systems for the accurate prediction of lunar eclipses at least two centuries before his time. His ability to predict this solar eclipse, and to the year rather than to the day, was, therefore, almost certainly acquired in the East. Thales was the first Greek to maintain that the moon shone by reflected sunlight and this, too, may rep­ resent Babylonian lore. Thales also borrowed Egyptian geome­ try, but here he made a fundamental ad­ vance. He converted it into an abstract study, being the first man we know of to consider it as dealing with imaginary lines of zero thickness and perfect straightness, rather than with actual lines, thick and imperfect, scraped in the sand or scratched on wax. (If the Egyp­ tians or Babylonians had already made this advance, it is still true that Thales was the first to place such views on rec­ ord in a form that has reached us, via the works of later philosophers.) Thales seems also to have been the first to go about proving mathematical statements by a regular series of argu­ ments, marshaling what was already known and proceeding step by step to the desired proof as inevitable conse­ quence. In other words, he invented de­ ductive mathematics, which was to be systematized and brought to a high pol­ ish two and a half centuries later by Euclid [40], Certain specific geometric theorems were later supposed to have been discov­ ered by him; for instance, that the diam­ eter of a circle divides it into two equal parts, that vertical angles are equal, and that the base angles of an isosceles trian­ gle are equal. He was also supposed to have mea­ sured the height of an Egyptian pyramid

[3]

THALES

by comparing the length of its shadow to that of the shadow of a stick of known size—which represents the concept of trigonometry. In the physical sciences, he was the first to study magnetism. More impor­ tant, he is the first man we know of who asked the question: Of what is the uni­ verse made? and to answer it without in­ troducing gods or demons. His own answer was that the funda­ mental stuff (the “element,” we would now say) of the universe was water, and the earth was only a flat disc floating on an infinite ocean. This answer was a most reasonable guess for the times, since it was clear that life, at least, depended on water. But the question itself was far more important than the answer, for it inspired later philosophers, who flour­ ished in the same region, near Miletus, among them Anaximander [4], Anaxi­ menes [5], and Heraclitus [10], to specu­ late on the same subject. It was this line of thought that led eventually, after two thousand years of painful intellectual struggle, to modern chemistry. Thales in addition to being a philoso­ pher was, according to later tradition, a practical man of affairs. In politics he shrewdly urged a political union of the various Greek cities of Ionia (the mod­ ern southwest coast of Turkey), of which Miletus was one, for self-defense against the encroaching non-Greek king­ dom of Lydia. This, the following cen­ turies amply demonstrated, was the only way the Greeks could defend themselves against the surrounding nations. How­ ever, the Greek passion for disunity rose triumphant over all and was the cause of the country’s ruin. Aristotle [29] said that Thales, stung by jibes to the effect that if he were so wise, it was strange that he wasn’t rich, quietly bought up the olive-presses in Miletus and surrounding territory in a year when his knowledge of weather told him the olive crop would be a good one. Charging monopoly prices for the use of the presses, he grew rich in one season. Then, having proved his point, he aban­ doned business and returned to the world of the mind. This may have been invented merely

ANAXIMANDER

[4]

to point a moral. If so, Plato [24] in­ vented another tale to point another moral. While walking along and studying the stars, Plato said, Thales fell into a well. An old woman coming in response to his cries, helped him out, but said with contempt, “Here is a man who would study the stars and cannot see what lies at his feet.” Already in the time of Plato and Aris­ totle, two and a half centuries after Thales, the old philosopher’s views were remembered imperfectly and made the subject of legend. In valuing philosophical speculation over the practical applications of science, Thales set the tone for later Greek think­ ing. As a result the work of Greek engi­ neers and inventors was largely ignored by later Greek writers and badly under­ estimated, in consequence, by all later generations. We have only very slight in­ formation about Thales’ younger con­ temporary, Eupalinus [8], who in his way may have been as accomplished a sage. In later centuries, when the Greeks made up lists of the “seven wise men,” Thales was invariably placed first. [4] ANAXIMANDER (a-nak'si-man-der) Greek philosopher Born: Miletus, 610 b .c . Died: Miletus, a b o u t 546 b .c . Like Thales, whose pupil he was, Anax­ imander helped introduce the science of the ancient East to Greece. He was the first Greek to make use of the sun­ dial, for instance, which had been known for centuries both in Egypt and Bab­ ylonia. No better timekeeper was to be found until the days of Ctesibius [46], over three centuries later. Anaximander was also the first to attempt to draw a map of the whole earth as he knew it. He recognized that the heavens re­ volved about the Pole star and so he pic­ tured the sky as a complete sphere and not merely as a semispherical arch over the earth. For the first time the notion of spheres invaded astronomy; this was to culminate eventually in the sophisticated 3

[5]

ANAXIMENES

(but erroneous) picture of the universe drawn up by Ptolemy [64]. He also recognized that the earth’s surface must be curved, to account for the change in the position of the stars as one traveled. He felt a north-south cur­ vature was enough, however, so he pic­ tured the earth as a cylinder about an east-west axis with a height one-third its diameter. The notion of a spherical earth had to wait several decades for Pythag­ oras [7] and his followers. Anaximander’s idea of the basic ele­ ment of the universe was far more mysti­ cal than Thales’ plain and undramatic notion that it was water. Anaximander envisaged a formless mass that was both the source and the destination of all ma­ terial things. He called this unobservable substance apeiron, meaning infinite. Nev­ ertheless, he conceded this much to water—he thought life originated there. In this he was quite correct. The treatise Anaximander wrote de­ scribing his views is thought to be the first work of consequence in Greek prose. His works are now lost. [5] ANAXIMENES (an'ak-sim'ih-neez) Greek philosopher Born: Miletus, about 570 b .c . Died: about 500 b . c . Little is known about Anaximenes ex­ cept that he may have been a pupil of Anaximander [4], and that he believed air to be the fundamental element of the universe. By compression, he supposed, it could take on the form of water and, eventually, earth. By rarefaction, it heats and becomes fire. He is supposed to have been the first Greek to distinguish clearly between planets (such as Mars and Venus) and stars and to have maintained that the rainbow was a natural phenome­ non rather than a goddess. [6] XENOPHANES (zee-nof'uh-neez) Greek philosopher Born: Colophon, Ionia, about 570 B.C. Died: about 480 b .c . 4

PYTHAGORAS

[7]

Like Pythagoras [7], his contemporary, Xenophanes left Ionia after 545 b .c . when Persia had conquered the region. He settled in the town of Elea. He wrote on Pythagorean doctrine, but was less mystical than most of the school. He did not believe in transmigration of souls or in the primitive Greek gods but in a monotheism not at all characteristic of Greek thought. He guessed that earth might be the fundamental element of the universe, but he is best known for his theory, derived from the fact that seashells were some­ times found on mountain heights, that the physical characteristics of the earth changed with time. Mountains, he main­ tained, must have originally been cov­ ered by the sea and, with time, risen to their present heights. This was a remarkable forecast of later geologic thinking, but it remained an isolated ray of light until Hutton [297], twenty-three centuries later, founded geology and made sober sense of Xenophanes’ seemingly wild guess. [7] PYTHAGORAS (pih-thag'oh-rus) Greek philosopher Born: Samos (an Aegean island), about 560 b .c . Died: Metapontum (in southern Italy), about 480 b .c . Pythagoras, like the other early sages of Greece, was reputed to have traveled widely in Egypt and the East, and he may well have done so. He is also re­ ported to have studied under Anax­ imander [4] or even under Thales [3] himself. However, the first event in his life that seems reasonably certain is his departure from Samos in 529 b .c . and his emigra­ tion to Croton in southern Italy. (By that time the coasts of southern Italy and eastern Sicily had been colonized by the Greeks and the region remained Greek in culture well into the Middle Ages.) Pythagoras’ move, according to tradition, was brought about by the harsh, oneman rule over Samos on the part of the tyrant Polycrates. Whatever the cause, the move extended the philosophic and

[7]

PYTHAGORAS

scientific tradition—begun by Thales at the eastern rim of the Greek world—to the far west of the Greek world. In Croton, Pythagoras broke with the rationalism of the east-Greek tradition and founded a cult marked by secrecy, asceticism, and mysticism. The cult, Pythagoreanism, forbade, for instance, the poking of fire with an iron poker and the eating of beans. It also taught the doctrine of the transmigration of souls. There is a story, for instance, that Pythag­ oras ordered a man to stop beating a dog, claiming he recognized the voice of a dead friend of his. This may merely have been a humane impulse on Pythag­ oras’ part—or it may have been invented by the cult’s many enemies to cast ridi­ cule upon it. In many ways Pythagoreanism was like the mystery cults prevalent in Greece then and afterward, but it differed from them in the interest the followers of Pythagoras had in mathe­ matics and astronomy. The cult achieved important political power in Pythagoras’ later years and was usually to be found on the side of the aristocrats. Even dur­ ing the lifetime of Pythagoras, however, the democrats had started to gain the upper hand in southern Italy and the cult began to suffer persecution. Pythag­ oras was exiled from Croton about ten years before his death. Pythagoreanism survived as an active cult for only a cen­ tury after its founder’s death. The unpopularity it brought upon it­ self by its political activity resulted in a violent wave of persecution that spread over all the Greek world. By 350 b .c . Pythagoreanism was wiped out. The influence of its ideas, however, has lasted into modern times, and Pythagoras re­ mains the most famous of the earlier Greek philosophers. It is he, indeed, who is supposed to have coined the word “philosopher.” Because of the secrecy shrouding the beliefs of Pythagoreans, it isn’t always easy to tell what they were, or how much of what was attributed to them by later Greek writers is correct. In particu­ lar, it is hard to say for what Pythagoras himself was responsible, and what was

PYTHAGORAS

[7]

originated by his many disciples, espe­ cially Philolaus [19]. The greatest scientific success at­ tributed to Pythagoras was in his study of sound. He found that the strings of musical instruments delivered sound of higher pitch as they were made shorter. Furthermore he found that the rela­ tionship of pitch could be simply cor­ related with length. For instance, if one string was twice the length of another, the sound it emitted was just an octave lower. If the ratio of the strings was three to two, the musical interval called a fifth was produced, and if it was four to three, the interval called a fourth was produced. Increasing the tension of the strings also raised the pitch. Thanks to these observations, the study of sound was the one branch of physics in which Greek views remained unaltered in mod­ ern times. This study may have led Pythagoras to the belief that the whole universe rested on numbers and their relationship, for he (or his followers) proceeded to invest numbers with all sorts of mystic significance. Today these notions seem foolish, but they did encourage the inves­ tigation of the mathematical properties of the numbers. For instance, it was the Pythagoreans who discovered that the square root of two (that is, the number which, multiplied by itself, gives a prod­ uct of exactly two) could not be ex­ pressed as the ratio of two numbers. No conceivable fraction, however compli­ cated, will give the product of two when multiplied by itself. Here was a very simple concept that could not be put into whole numbers. How then could numbers account for something as complicated as the whole universe? The Pythagoreans were sup­ posed to have vowed themselves to se­ crecy concerning such “irrational num­ bers” lest outsiders scoff. It slipped out anyway and there is a story that the Pythagoreans executed one of their fel­ lows whose tongue had wagged too freely on the subject, though this may be another slander circulated by the antiPythagoreans. Pythagoras is most famous, perhaps, for having been the first to work out the 5

[8 ]

EUPALINUS

proposition (by strict mathematical de­ duction) that the square of the length of the hypotenuse of a right triangle is equal to the sum of the squares of the lengths of its sides. This is still known as the Pythagorean theorem. Pythagoras was the first Greek to rec­ ognize that the morning star (Phos­ phorus) and the evening star (Hesperus) were in fact one star. After his time it was called Aphrodite, and we know it now as the planet Venus. He was also the first to note that the orbit of the moon is not in the plane of the earth’s equator but is inclined at an angle to that plane. He was the first man known to us who taught that the earth was spherical. He was also the first Greek philosopher to point out that the sun, moon, and vari­ ous planets did not partake of the uni­ form motion of the stars, but that each had a path of its own and was at a different distance from the earth. Thus began the notion that in addition to the heavenly sphere that Anaximander had postulated, separate spheres had to be provided for the various planets. For seven hundred years thereafter, the num­ ber of spheres necessary to account for the planetary movements was to multi­ ply, and over twenty-one hundred years passed before Kepler [169] wiped them out. [8] EUPALINUS (yoo-puh-ly'nus) Greek architect Born: Megara (20 miles west of Athens); flourished in the sixth century b.c. It is obvious that the ancients pos­ sessed their share of great engineers, for some of their feats of construction were as great as anything we can do today, considering the primitive nature of the tools and techniques available to them. It is a pity that we know so little of them. Except for the semilegendary Im­ hotep [I], nothing is known about indi­ vidual pre-Greek engineers, and very lit­ tle is known about engineers in Greece’s golden age. An exception is Eupalinus, whose name is at least attached to a 6

HECATAEUS

[9]

specific accomplishment. He specialized in water systems, building one for his na­ tive city in Megara about 530 b.c. Later, he was engaged by Polycrates, the tyrant of the Aegean island of Samos, to build an aqueduct there. For this project, Eu­ palinus had to tunnel through a hill for over half a mile. The ancients were profoundly impressed that Eupalinus started the tunnel at both ends and the two halves met only a couple of feet ofi center. [9] HECATAEUS (hek-uh-tee'us) Greek traveler Born: Miletus, about 550 b.c. Died: about 476 b.c. Hecataeus carried on the rationalist tradition of Thales [3] and applied it par­ ticularly to the surface of the earth. He traveled widely through the Persian Em­ pire (which in his time dominated Asia Minor) and wrote a book on Egypt and Asia which, however, has not survived. In Egypt he is supposed to have become aware of the true stretch of previous his­ tory when the Egyptians showed him records going back hundreds of genera­ tions. Hecataeus continued the work, begun by Anaximander [4], of attempting to map the world. He divided the land area into a northern half (Europe) and a southern half (Asia) with the east-west structures of the Mediterranean Sea and the Caucasus Mountains forming the di­ viding line. Both continents were drawn as semicircles and the whole was en­ circled by Oceanus, the “ocean river.” The Greeks, however, were not the out­ standing travelers and explorers of the time. That honor was held by the far less articulate (and therefore less advertised and less remembered) Phoenicians, of whom Hanno [12] bears off the palm, if the vague remnants of his tale are to be credited. Hecataeus rationalized history as well as geography, writing the first Greek ac­ count of the deeds of men which did not accept gods and myths at face value. In fact, Hecataeus took a skeptical and downright scornful view of myths. His

[ 10]

HERACLITUS

HANNO

[ 12]

of its power, was naturally a Pythag­ orean. He had some mystical notions, such as that the human body was a microcosm, reflecting in small the uni­ verse or macrocosm. This, however, did not prevent him from being an accurate and careful observer. He is the first individual known to have conducted dissections of the human body. He recorded the existence of the optic nerve and the tube connecting the ear and mouth (which are now called Eustachian tubes after Eustachio [141], their rediscoverer, who lived two thou­ sand years later). Alcmaeon distin­ guished arteries from veins, though he did not recognize the former as blood vessels, since in cadavers the arteries are empty. He felt that the brain was the center of intellectual activity and so did Democ­ ritus [20] and Hippocrates [22] two [10] HERACLITUS (her-uh-kly'tus) generations later. This view, however, Greek philosopher Born: Ephesus (about 30 miles was not accepted by Aristotle [29] and it north o f Miletus), about 540 b . c . did not come into its own until modern times. Died: about 475 B.c. The work of Heraclitus survives only in fragments. His pessimistic view of life [12] HANNO Carthaginian navigator and the universe led to his being called Born: Carthage (near the site of the “weeping philosopher.” To him the modern Tunis), about 530 b .c . most permanent thing about the universe Died: date unknown seemed to be impermanence, and the one fact that was unchangeable was that change was certain. For instance, he The Phoenicians (of whom the Car­ thought so little of the unchangeability thaginians were a branch) were the great of even so glorious an object as the sun, navigators and explorers of the ancient as to suggest it was made fresh each world but only a dim tale of Hanno, morning so that every day saw a dif­ with sixty vessels and thirty thousand men and women (numbers undoubtedly ferent sun. It made sense to him, then, that fire, exaggerated) and his explorations down itself ever-changing and capable of the African coast survives. Herodotus, bringing about change in other things, the Greek historian, describes the voyage should be the fundamental element of and declares that Hanno claimed to have circumnavigated Africa. Concerning this, the universe. Herodotus expresses his doubts, because the Carthaginians reported that in the far south the noonday sun was in the [11] ALCMAEON (alk-mee'on) northern half of the sky. This Herodotus Greek physician Born: Croton (in southern Italy), felt to be impossible. Nevertheless, this is the case in the southern hemisphere and about 535 b .c . it is unlikely that anyone would make up Died: date unknown so ridiculous a tale unless he had actu­ Alcmaeon, bom in the center of Py- ally witnessed the phenomenon. Thus, thagoreanism and living during the height the very point at which the ordinarily history did not survive but undoubtedly served as an inspiration for his greater successor, Herodotus, a couple of gener­ ations later. Because Herodotus’ history did survive (and deservedly so, for it remains one of the greatest of all times, in sheer charm of style, if not always in accuracy), it is the later historian, who is known as the father of history, though Hecataeus may better deserve the title. Like Thales, Hecataeus was a shrewd politician, and he opposed the revolt of the Greek cities of Asia Minor against Darius I of Persia in 499 B.C. His advice was not followed, the revolt was disas­ trously suppressed, and the scientific pre-eminence of the Greek cities of Asia Minor, which had lasted a century and a half, came to an end.

7

[13]

PARMENIDES

credulous Herodotus balks is the point that is most convincing to moderns. It may be, then, that Hanno the Carthagin­ ian was the first man of the Mediter­ ranean world to have crossed the equa­ tor. [13] PARMENIDES (pahr-men'ih-deez) Greek philosopher Bom: Elia (modem Velia), Italy, about 515 b .c . Died: a fte r 450 b .c . Parmenides was a follower of those notable Ionian exiles Pythagoras [7] and Xenophanes [6] and was the first major philosopher native to Italy. He opposed the notions of Heraclitus [10] and, far from accepting change as the universal truth, denied the possibility of change since one object, he held, could not turn into another object fundamentally different. It was more reasonable, he insisted, to suppose that creation (some­ thing from nothing) and destruction (nothing from something) were impossi­ ble. Since change was all about us despite this reasoning, Parmenides had to choose between the senses and reason; he chose reason. The senses were untrustworthy, in his opinion, and not to be used as guides. This view was the cornerstone of the Eleatic school, which he founded and of which the best-known member, Zeno [16], was to carry the distrust of the senses into a set of famous paradoxes. Plato [24] entitled one of his dialogues “Parmenides” and in it describes a meet­ ing between the aged Parmenides and the youthful Socrates [21]. [14] ANAXAGORAS (an-ak-zag'oh-rus) Greek philosopher Born: Clazomenae (75 miles north o f Miletus), about 500 b .c . Died: Lampsacus (modern Lâpseki, Turkey), about 428 b .c . As is the case for almost all the early Greek philosophers, tradition states that Anaxagoras, the son of wealthy parents, traveled widely during his youth. He is

8

ANAXAGORAS

[14]

sometimes said to have studied under Anaximenes [5] but this is probably in order to maintain an Ionian continuity. Anaximenes is almost sure to have been dead before Anaxagoras was old enough to be a student. About 462 b .c ., Anaxagoras migrated to Athens from his Asia Minor home­ land. Athens at the time was at the height of its golden age and the pinnacle of Greek culture. By his move Anax­ agoras, the last of the Ionians, carried to Athens the scientific tradition of Thales [3] as, two generations earlier, Pythag­ oras [7] had carried it to Italy. How­ ever, whereas Pythagoras had empha­ sized mysticism, Anaxagoras was a ra­ tionalist. He explained—accurately—the phases of the moon and eclipses of both moon and sun in terms of the move­ ments of those bodies. To him the universe originated not through the creative act of any deity, but through the action of abstract Mind upon an infinite number of “seeds.” These seeds were a form of the atoms whose existence was being postulated si­ multaneously by Leucippus [15]. The result, according to Anaxagoras, was that the heavenly bodies were brought into existence by the same processes that formed the earth, and therefore heavens and earth were com­ posed of the same materials. The exis­ tence of a stony meteorite that fell on the north shore of the Aegean in 468 b . c . may have helped him come to this conclusion. The stars and planets were flaming rocks, and the sun he believed to be an incandescent rock about the size of the Peloponnesus (which is roughly as large as Massachusetts). As for the moon, he regarded it as an earthlike body and possibly even inhabited. These were irreligious views that shocked con­ servative Athenians. Anaxagoras taught in Athens for thirty years and his school was the beginning of the philosophic pre-eminence of Athens in the Greek world, a pre­ eminence that was to be maintained for nearly a thousand years. (Even in late Roman times, when Athens’ early mili­ tary and political glory was a faded and ancient dream, it kept the scholarly aura

[15]

LEUCIPPUS

of the University town, much as Oxford does today in England.) He is supposed to have written one book, some time after 467 b .c . Anaxagoras was not, however, allowed to pursue his studies and teachings in peace. The Athens of his day was not yet ready to accept his rationalism (as the Greeks of Italy had not been ready to accept Pythagoras’ aristocratic mys­ ticism). Anaxagoras was accused of im­ piety and atheism and brought to trial, the first scientist we know to have had this kind of legal conflict with a state religion. Anaxagoras was a friend of the most respected Athenian citizens, includ­ ing Euripides, the great playwright, and even Pericles, the uncrowned king of the city. This hurt rather than helped Anax­ agoras, for the enemies of Pericles, un­ able to strike at the leader himself, ea­ gerly attempted to hurt him through his friend the philosopher. Pericles faced the court in his friend’s defense and man­ aged, with difficulty, to secure his acquit­ tal of the charge of impiety (a happier fate than was to befall Socrates [21] on a similar charge a generation later). Anaxagoras believed the atmosphere of the city to be unsafe, however, and in 434 b .c . he retired to Lampsacus on the Hellespont, where he died six years later. The mark of the trial endured. To be sure, a younger contemporary, Meton [23], continued astronomical researches at Athens, but the city’s thinkers turned away from natural philosophy to take up moral philosophy. [15] LEUCIPPUS (lyoo-sip'us) Greek philosopher Born: Miletus, about 490 B.C. Died: date unknown Almost nothing is known of Leu­ cippus, not even that he really lived. If he did, he represented the final flash of the old tradition of Asia Minor, some­ how surviving the destruction of the coastal cities by Persia. He is supposed to have been a pupil of Zeno [16]. He was, apparently, the inventor of atomism, the teacher of Democritus [20], and the first to state the rule of causality,

ZENO

[ 16]

that is, that every event has a natural cause. [16] ZENO Greek philosopher Born: Elea (modem Velia), southern Italy, about 490 b .c . Died: Elea, about 425 b .c . Zeno is the chief of the Eleatic school of philosophy (the name being taken from the town of Elea, where it was cen­ tered). He may have been a student of Parmenides [13], He appears to have lived in Athens for a time according to Plato [24] and is supposed to have taught Pericles, among others. His life ended, according to one account, when he was on the wrong side of a political argument and was executed for treason. The Eleatic school denied the use­ fulness of the senses as a means of at­ taining truth. In fact the Eleatics at­ tempted to demonstrate that by reason they could show that the message of the senses must be ignored. Zeno presented the Greek thinkers with four famous paradoxes, all of which seemed to disprove the possibility of mo­ tion as it was sensed. Tlie best known is that of Achilles and the tortoise. Suppose Achilles can ran ten times as fast as a tortoise and the tortoise has a ten-yard head start. It follows then that Achilles can never overtake the tortoise because while he covers the ten yards’ difference, the tortoise will have moved ahead one yard. When Achilles covers that one yard, the tortoise will have moved on a tenth of a yard and so on. Since our senses, however, clearly show us a fast runner overtaking and passing a slow runner, our senses must be false. These paradoxes, although all based on fallacies, were of the utmost impor­ tance to science, for they stimulated thought. Aristotle [29], for instance, pre­ sented arguments against them, and down to our own day, others have taken up positions either for or against the Eleatic view. Since Zeno’s paradoxes were all based on the assumption that space and time are infinitely divisible, it encouraged men 9

[17]

EMPEDOCLES

like Democritus [20] to avoid the para­ doxes by searching for indivisibility and finding it in the atoms of which they claimed matter to be composed. This view did not win general favor in Greek times, but it did win out twenty-two cen­ turies later with Dalton [389]. The no­ tion of infinite divisibility was further erased, a hundred years after Dalton, by the theories of Planck [887] concerning the ultimate particles of energy. In pure mathematics, it was shown al­ most twenty-one centuries later, by James Gregory [226], that such things as converging series existed, in which an infinite number of terms nevertheless added up to a finite sum. The Achillesand-the-tortoise paradox involved (with­ out Zeno’s knowledge) such a converg­ ing series. Then, too, methods for han­ dling the infinitely divisible (even were that supposed to exist) were not devel­ oped until Newton [231] and his inven­ tion of the calculus. Zeno was completely defeated in the end, but he deserves a chorus of thanks just the same for the values that grew out of more than two millennia of intel­ lectual struggle required to defeat him. (Zeno of Elea is sometimes confused with another Zeno, Zeno of Citium, who founded the Stoic school of philosophy almost two centuries after the time of the earlier Zeno.) [17] EMPEDOCLES (em-ped'oh-kleez) Greek philosopher Born: Akragas (modern Agrigento), Sicily, about 492 b .c . Died: Mount Etna (?), about 432 B.C.

Empedocles was one philosopher who, at least in younger life, did not hesitate to immerse himself in politics. He was a moving spirit in the overthrow of a tyr­ anny in his native town of Akragas. The grateful citizens offered him the tyrant’s seat in reward but, in a self-denial not often found among Greeks of the time, Empedocles refused. He preferred to spend his time on philosophy. Empedocles was, to a considerable ex­ tent, under the influence of the teachings 10

EMPEDOCLES

[17]

of Pythagoras [7], This is shown in the strong vein of mysticism in his teachings. He had no objection to being looked upon as a prophet and miracle-worker and was even supposed to have brought dead people back to life. According to one tradition, he let it be known that on a particular day he would be taken up to heaven and made a god. On that day he is supposed to have jumped into the cra­ ter of Mount Etna in order that, by disappearing mysteriously, he might be thought to have made good on his pre­ diction. (It is also possible he believed his own story and jumped into the crater in despair when the heavenly chariot failed to appear. It is even more possible the whole story is false, for there are some who say he traveled to Greece in later life and died there.) Some of Empedocles’ views were ratio­ nal enough. He believed the moon shone by reflected light from the sun. He believed the heart was the center of the blood-vessel system (which is true) and therefore the seat of life (which is cer­ tainly not an unreasonable guess). This notion was passed on to Aristotle [29], from whom it has descended to our day. We still speak of “not having the heart to do it” when we mean not having the will. We say we are “lion-hearted” when we mean brave, “broken-hearted” when we mean disappointed, and so on. He also had a dim notion of an evolutionary process through natural selection and felt that some creatures, ill-adapted to life, had perished in the past. This was a foretaste of Darwin [554]. Another influential notion arose when Empedocles combined some of the views of the Asia Minor school. Where Thales [3] had thought the basic element of the universe was water, Anaximenes [5] air, Heraclitus [10] fire, and Xenophanes [6] earth, Empedocles hit on merging all these. All things, he believed, were made up of various combinations and arrange­ ments of these. Substances changed in nature when the elements broke apart and recombined in new arrangements under the action of forces akin to what humans recognize as “love” and “strife.” The notion was taken up and im­ proved by Aristotle and remained the

[18]

OENOPIDES

basis of chemical theory for more than two thousand years. It lasts in the com­ mon language even today, for we speak of the “raging of the elements” when we mean that air and water are being lashed into fury by a storm.

DEMOCRITUS

[20 ]

Philolaus were highly mystical. One thought, however, was of particular in­ terest, for within the Pythagorean non­ sense there were occasional shrewd (or lucky) guesses, as was the case with Xenophanes [6]. In Philolaus’ case the shrewd guess was that the earth was not the center of the universe but that it moved through space. The earth, he thought, along with the sun, moon, Mercury, Venus, Mars, Jupiter, Saturn, and the stars circled in separate spheres about a central fire, of which the visible sun was only a reflec­ tion. This meant nine circling spheres, so Philolaus invented a tenth, occupied by a counter-earth, a planet always hidden from us on the other side of the sun. This whole scheme was designed merely to take advantage of the magical powers of the number 10 (magical because it was the sum of 1, 2, 3, and 4). Whatever the motivation, however, this was the first known speculation that the earth moves through space. When, two thousand years later, Copernicus [127] was to advance his theory of the universe, in which the earth and planets were pictured as moving about the sun, it was branded by some of his opponents a Pythagorean heresy.

[18] OENOPIDES (ee-nop'ih-deez) Greek philosopher Born: Chios (an Aegean island), a b o u t 480 b .c . Died: date unknown Nothing is known about Oenopides ex­ cept for mentions in the surviving works of other Greeks. Pythagoras [7] probably knew that the path marked out by the sun was at an angle to the celestial equator, something called the obliquity of the ecliptic. In modem terms, this means that earth’s axis of rotation is at an angle to a line perpendicular to its plane of revolution about the sun. The Babylonians knew this before Pythagoras. It may be, though, that Oenopides was the first actually to put a figure to the amount of tipping, and that he placed it at about 24°, which is only a half-degree greater than the true value. He may also have fixed the length of the year at 365% days, which is a trifle longer than the actual length, which is nearly 365%. [20] DEMOCRITUS (de-mok'rih-tus) Greek philosopher Born: Abdera, Thrace, about 470 B.C. [19] PHILOLAUS (fil-oh-lay'us) Greek philosopher Died: perhaps as late as 380 b .c . Born: Tarentum or Croton (in southern Italy), about 480 b . c . Like Thales [3] and Pythagoras [7] be­ Died: date unknown fore him, Democritus is supposed to have traveled widely in Egypt and the Philolaus was the most eminent (after East before settling down to philosophy Pythagoras [7] himself) of the Pythag­ at home in Greece. He also picked up orean school and was the first, ap­ the rationalist world view of Asia Minor parently, to publish Pythagorean views through his teacher, Leucippus [15], who for the general public. He suffered in the was of Miletus, as Thales himself had course of the persecutions to which the been. Like all the early rationalists, he Pythagoreans were subjected in southern had some startlingly modem-sounding Italy and had to flee (at least tempo­ notions. He maintained, for instance, rarily) to Thebes, on the Greek main­ that the Milky Way was a vast conglom­ land. Later he returned to Tarentum, the eration of tiny stars and that the moon last stronghold of Pythagoreanism. was an earthlike world with mountains The majority of the contributions of and valleys. 11

[20 ]

DEMOCRITUS

Democritus was, indeed, the most suc­ cessful of the Greek natural philosophers in the uncanny accuracy of his ideas (at least from our present viewpoint), but he lived in the shadow of his contemporary, Socrates [21], whose disciples rejected Democritus’ notion of the universe. Al­ most none of Democritus’ work, some seventy-two books in all, has survived and we know of him entirely as a result of references (often unfriendly) in the works of others. Democritus was widely known as the Laughing Philosopher, either because his philosophy was an essentially cheerful one, or because he was viewed as laugh­ ing at the follies of mankind. He is best known for his atomic theory. He believed that all matter consisted of tiny particles, almost infini­ tesimally small, so small that nothing smaller was conceivable. Hence they were indivisible; the very word “atom” means “indivisible.” The atoms, he held, were eternal, unchangeable, inde­ structible. Besides themselves only the void—that is, the space between the atoms—existed. Even the human mind and the gods (if any) were made up of atom combinations. The atoms, said Democritus, differed from each other physically, and in this difference was to be found an explana­ tion for the properties of various sub­ stances. The atoms of water were smooth and round so that water flowed and had no permanent shape. The atoms of fire were thorny, which was what made bums so painful. The atoms of earth were rough and jagged, so that they held together to form a hard and stable substance. Apparent changes in the nature of substances consisted merely in the separation of joined atoms and their rejoining in a new pattern. These views were reminiscent of the apeiroti of Anaximander [4]. The motions and behavior of the atoms, according to Democritus, are im­ posed upon them by definite and un­ breakable laws of nature and are not the result of the whims of gods or demons. Democritus was thus one of the earliest of the thoroughgoing mechanists, believ­ 12

SOCRATES

[21 ]

ing that the workings of the universe were as mindless and determinate as those of a machine. To Democritus, even the creation of the universe was the blind result of swirling motions set up in great numbers of atoms. These motions ended in the clumping together of atoms, forming worlds. In all this, there is a recognizable simi­ larity to modern theories of the structure of matter and of cosmogony, but there is also a key difference. The conclusions of Democritus were bom of introspection and intuition. Modem theories which seem similar are based on quantitative experiment and on orderly mathematical reasoning. Democritus’ views, being merely intuitive, could be opposed by other views, equally intuitive, and the choice would then be a matter of per­ sonal predilection. The ancient philoso­ phers, by and large, chose to follow Socrates and his disciples rather than Democritus and his. That atomism did not die out com­ pletely was to the credit of Epicurus [35] who, over a century later, made use of atomism in his own popular teachings. [21] SOCRATES (sok'ruh-teez) Greek philosopher Born: Athens, a b o u t 470 b .c . Died: Athens, 399 b .c . All that is known of Socrates is through the words of others, for he left no writings of his own. The man pic­ tured in those reports was a sort of pagan saint. In personal appearance he was ugly: short and stout with a broad face, prominent eyes, a wide pug nose. He won over nearly everyone, however, with his good humor, his wit, and the fascination of his conversation. He was fearless in battle and in poli­ tics. Neither an armed foe nor the Athe­ nian government could compel him to act against his judgment. He was inter­ ested only in his quest for knowledge, living a life of poverty in utter content, and scorning luxury, though he could be a bon vivant when it suited him. He is even renowned for his bad-tempered

[21]

SOCRATES

wife, Xanthippe, who has become pro­ verbial as a shrew and whom he bore with patience (although, considering what a poor provider Socrates was, she had some reason for complaint). She had three children by Socrates, none of whom amounted to anything. Socrates in his discussions pretended a disarming ignorance (Socratic irony) and then by shrewd questioning forced his listeners, disciples, and opponents to admit their own ignorance and the wrongness of their casually accepted in­ tuitions. He was the gadfly of Athens, and no less an institution whom the oracle at Delphi proclaimed to be the wisest of the Greeks (to which Socrates replied that if he were the wisest it was only because he alone knew that he knew nothing). His methods also made him enemies, for no one actually likes to be proved wrong and least of all out of one’s own mouth. Although Socrates was trained in the rational science of Asia Minor (he may have been a pupil of Anaxagoras [14] or of one of Anaxagoras’ disciples) he questioned the importance of knowledge concerning the universe. He was far more interested in questions of ethics, in the right code of behavior. He wished to understand the workings of virtue rather than of the heavenly bodies. This had a profound effect on the his­ tory of science. It is rather surprising that the Greeks failed in science after having made such an excellent start with Thales [3], having available the as­ tonishing guesses of Democritus [20], the shrewd views of Eratosthenes [48] and Aristarchus [41] and the inventiveness of Archimedes [47], There are indeed many factors involved in the failure, but one, at least, lay in the views of Socra­ tes. The larger part of Greek intellect was, through admiration of him and of his chief disciple Plato [24], channeled into the field of moral philosophy, while natural philosophy (what we now call science) was allowed to wither. In the end Socrates was too sharp a gadfly to be left to himself. He was brought to trial in 399 u.c. on charges of atheism and treason—and, it seems, cor­

HIPPOCRATES

[22 ]

ruption of the young. Both charges were, in a sense, justified. He certainly did not believe in the Greek gods according to the ancient fashion (few of the Greek intellectuals of the time did). As for treason, he never approved of the Athe­ nian democracy and several of his favor­ ite pupils, notably Alcibiades and Critias, proved to be active traitors. Others, such as Xenophon and Plato, were an­ tidemocratic and pro-Spartan. Even so, Socrates would have been ac­ quitted if he had made the least attempt to defend himself rationally. He deliber­ ately goaded on the jury of five hundred men until they voted the death sentence in spite of themselves, and then only by a small majority of 280 to 220. Socrates spent a month between sen­ tence and execution, refusing to escape although escape could easily have been arranged. With utter calmness, dying as courageously as he had lived, he drank the poison hemlock. He was seventy years old and had lived what was in his own eyes a good life. [22] HIPPOCRATES (hih-pok'ruh-teez) Greek physician Born: Cos (an Aegean island), 460 b .c . Died: Larissa (now Larisa), Thes­ saly, about 370 b .c . Virtually nothing concrete is known about Hippocrates. He was, it was said, bom of a family who were members of a hereditary guild of magicians on the is­ land of Cos and who were reputedly de­ scended from Asklepios, the Greek god of medicine. According to tradition, he visited Egypt early in life, and there stud­ ied medical works attributed to Imhotep [1], Some traditions make him a student of Democritus [20]. Hippocrates is supposed to have taught at various places, including Athens, but eventually he founded a school of medicine on Cos that was the most rational the ancient world had to offer. It is because of his founding of this school, and not because he was the “first” physician, that he is properly 13

[2 2 ]

HIPPOCRATES

known today as the father of medicine. As a matter of fact, he was not the first physician, for there were able individual students of the human body before his time, as, for instance, Alcmaeon [11], More than fifty books (called the Hip­ pocratic collection) have been attributed to him, but it is more than doubtful that these are really his. They are rather the collected works of several generations of his school, brought together at Alex­ andria in the third century B.C., and at­ tributed to him that they might be the more impressive. But the writings are certainly in his tradition, and in the best of them there is a high order of ra­ tionalism, careful observation, and hon­ orable standards of conduct. Among the rule-of-thumb comments in the Hip­ pocratic collection are a number that have become famous adages. Included are “desperate diseases require desperate remedies,” for instance, and “one man’s meat is another man’s poison.” The Hippocratic school believed in moderation of diet, in the efficacy of cleanliness and rest for a sick or wounded man (and cleanliness for the physician too). They thought that the physician should interfere as little as pos­ sible with the healing processes of nature (and in view of how little was then known about the human body and its disorders, this was excellent advice). Disease was looked upon as a purely physical phenomenon, something not to be ascribed to the arrows of Apollo or to possession by demons. Epilepsy, for in­ stance, was considered by the men of the times to be a “sacred disease” because the patient in a fit seemed to be in the grip of a god or demon. The Hippocratic school ascribed even epilepsy to natural causes and considered it curable by phys­ ical remedies, not exorcism. In general, the Hippocratic school believed disease to result from an imbalance of the vital fluids (“humors”) of the body, a notion first advanced by Empedocles [17]. These were eventually listed as four in number: blood, phlegm, black bile, and yellow bile. As for Hippocratic ethics, this is reflected in the oath (ascribed to Hip­ 14

PLATO

[24]

pocrates) that is still taken by medical students upon completing their course of training. A statue discovered on Cos in 1933 is thought to be a representation of Hip­ pocrates. [23] METON (mee'ton) Greek astronomer Born: Athens, ab o u t 440 b .c . Died: date unknown Meton’s great achievement was his dis­ covery in 432 b .c . that 235 lunar months made up just about 19 years. This meant that if one arranged to have 12 years of 12 lunar months and 7 years of 13 lunar months, every 19 years, the lunar calen­ dar could be made to match the seasons. This is the Metonic cycle, named in the astronomer’s honor, although the cycle was undoubtedly known to the Babylon­ ian astronomers long before Meton’s time. The Greek calendar was based on the Metonic cycle, since it had an arrange­ ment of lunar years that repeated itself every 19 years. This remained the calen­ dar of the ancient world until 46 b .c ., when the Julian calendar was established by Julius Caesar with the help of Sosig­ enes [54], The Jews have retained the Greek calendar and so the Metonic cycle is in use even today for religious pur­ poses. In fact, there are traces in Chris­ tianity as well, for the date of Easter is calculated through the use of the Me­ tonic cycle. [24] PLATO Greek philosopher Born: Athens, about 427 B.C. Died: Athens, about 347 B.c. The original name of this Athenian aristocrat was Aristocles, but in his school days he received the nickname Platon (meaning “broad”) because of his broad shoulders. (He is not the only great man to be known universally by a nickname. The Roman orator Cicero is another. )

[24]

PLATO

In early life Plato saw war service and had political ambitions. However, he was never really sympathetic to the Athenian democracy and he could not join whole­ heartedly in its government. He was a devoted follower of Socrates [21] whose disciple he became in 409 B.C., and the execution of that philosopher by the dem­ ocrats in 399 b .c . w as a crushing blow. He left Athens, believing that until “kings were philosophers or philosophers were kings” things would never go well with the world. (He traced his descent from the early kings of Athens and per­ haps he had himself in mind.) For several years he visited the Greek cities of Africa and Italy, absorbing Pythagorean notions, and then in 387 b .c . he returned to Athens. (En route, he is supposed to have been captured by pirates and held for ransom.) There, for the second half of his long life, he de­ voted himself to philosophy. In the west­ ern suburbs he founded a school that might be termed the first university. Be­ cause it was on the grounds that had once belonged to a legendary Greek called Academus, it came to be called the Academy, and this term has been used for schools ever since. Plato remained at the Academy for the rest of his life, except for two brief periods in the 360s. At that time he visited Syracuse, the chief city of Greek Sicily, to serve as tutor for the new king, Dionysius II. Here was his chance to make a king a philosopher. It turned out very badly. The king insisted on behav­ ing like a king and of course made the Athenian democrats look good by com­ parison. Plato managed only with dif­ ficulty to return safely to Athens. His end was peaceful and happy, for he is supposed to have died in his sleep at the age of eighty after having attended the wedding feast of one of his students. Plato’s works, perhaps the most consis­ tently popular and influential philosophic writings ever published, consist of a series of dialogues in which the discus­ sions between Socrates and others are presented with infinite charm. Most of our knowledge of Socrates is from these dialogues, and which views are Socrates’

PLATO

[24]

and which are Plato’s is anybody’s guess. (Plato cautiously never introduced him­ self into any of the dialogues.) Like Socrates, Plato was chiefly inter­ ested in moral philosophy and despised natural philosophy (that is, science) as an inferior and unworthy sort of knowl­ edge. There is a famous story (probably apocryphal and told also of Euclid [40]) of a student asking Plato the application of the knowledge he was being taught. Plato at once ordered a slave to give the student a small coin that he might not think he had gained knowledge for noth­ ing, then had him dismissed from school. To Plato, knowledge had no practical use; it existed for the abstract good of the soul. Plato was fond of mathematics be­ cause of its idealized abstractions and its separation from the merely material. Nowadays, of course, the purest mathe­ matics manages to be applied, sooner or later, to practical matters of science. In Plato’s day this was not so, and the mathematician could well consider him­ self as dealing only with the loftiest form of pure thought and as having nothing to do with the gross and imperfect every­ day world. And so above the doorway to the Academy was written, “Let no one ignorant of mathematics enter here.” Plato did, however, believe that math­ ematics in its ideal form could still be applied to the heavens. The heavenly bodies, he believed, exhibited perfect geometric form. This he expresses most clearly in a dialogue called Timaeus in which he presents his scheme of the uni­ verse. He describes the five (and only five) possible regular solids—that is, those with equivalent faces and with all lines and angles, formed by those faces, equal. These are the four-sided tetrahe­ dron, the six-sided hexahedron (or cube), the eight-sided octahedron, the twelve-sided dodecahedron, and the twenty-sided icosahedron. Four of the five regular solids, according to Plato, represented the four elements, while the dodecahedron represented the universe as a whole. (These solids were first dis­ covered by the Pythagoreans, but the fame of this dialogue has led to their 15

[24]

PLATO

being called the Platonic solids ever since.) Plato decided also that since the heavens were perfect, the various heav­ enly bodies would have to move in exact circles (the perfect curve) along with the crystalline spheres (the perfect solid) that held them in place. The spheres were another Pythagorean notion, and the Pythagorean preoccupation with sound also shows itself in Philolaus’ [19] belief that the spheres of the various planets made celestial music as they turned—a belief that persisted even in the time of Kepler [169] two thousand years later. We still use the phrase “the music of the spheres” to epitomize heav­ enly sounds or the stark beauty of outer space. This insistence that the heavens must reflect the perfection of abstract mathe­ matics in its simplest form held absolute sway over astronomical thought until Kepler’s time, even though compromises with reality had to be made constantly, beginning shortly after Plato’s death with Eudoxus [27] and Callippus [32]. In the dialogue Timaeus, by the way, Plato invented a moralistic tale about a thoroughly fictitious land he called Atlantis. If there is a Valhalla for philos­ ophers, Plato must be sitting there in endless chagrin, thinking of how many foolish thousands, in all the centuries since his time, down to the very present day—thousands who have never read his dialogue or absorbed a sentence of his serious teachings—nevertheless believed with all their hearts in the reality of Atlantis. (To be sure, recent evidence of an Aegean island that exploded vol­ canically in 1400 b .c . may have given rise to legends that inspired Plato’s fiction.) Plato’s influence extended long past his own life and, indeed, never died. The Academy remained a going institution until a .d . 529, when the Eastern Roman Emperor, Justinian, ordered it closed. It was the last stronghold of paganism in a Christian world. Plato’s philosophy, even after that date, maintained a strong influence on the thinking of the Christian Church throughout the early Middle Ages. It was 16

ARCHYTAS

[25]

not until the thirteenth century that the views of Aristotle [29] gained domi­ nance. [25] ARCHYTAS (ahr-ky'tus) Greek mathematician Born: Tarentum (now Taranto), Italy, about 420 b .c . Died: about 350 b .c . Archytas was a Pythagorean who lived in Tarentum when it was the last re­ maining center of Pythagoreanism. He labored, as a number of Greek scholars did in the fourth century b .c . to per­ suade the Greek cities to unite against the increasing strength of the non-Greek world. As was true of all the others, Archytas failed, and the Greeks persisted in suicidal strife among themselves to the last possible moment. Archytas was interested in one of the three great problems of the Greek math­ ematical world; the duplication of the cube. Given a cube, in other words, the problem was to construct another cube with just twice the volume of the first, making use of a compass and straight­ edge only. Under those conditions, the solution is impossible (as was discovered in later times) but in making the effort, Archytas evolved theorems concerning means; that is, lines or values midway between two extremes. He solved the problem by means of an ingenious three­ dimensional construction, making use of somewhat more liberal devices than the strictest interpretations of the rules of the game would allow. He was the first Greek mathematician who tried to apply his pure art to me­ chanics, when he worked out a theory of sound and pitch based on his means. He invented the notion of harmonic progres­ sion (1, %, Vi, Vi . . .) as opposed to arithmetic progression (1, 2, 3, 4 . . .) and geometric progression (1, 2, 4, 8 . . .) and maintained that the pitch of sound depended on the speed of vibra­ tion of air. He was right, but he did not quite have the concept of wave motion. He believed that sounds of high pitch traveled faster through the air, bodily,

[26]

THEAETETUS

EUDOXUS

[27]

than sounds of low pitch, which was miles to school every morning and five miles back every evening. wrong. After graduating, he traveled to Egypt He is also supposed to have invented for what we would today call post­ the pulley. graduate work in astronomy. Thereafter he established a school of his own in Cyzicus on the northwestern coast of [26] THEAETETUS (thee'uh-tee'tus) what is now Turkey. Eventually he Greek mathematician transferred it to Athens, where he taught Born: Athens, about 417 B.C. for many years. As a now successful and Died: Athens, 369 b .c . established philosopher, he visited his old Plato again and was rewarded Theaetetus was the son of a rich Athe­ teachera banquet in his honor. (He may nian whose money was apparently with even have served as active head of the squandered by those in charge of it be­ Academy while Plato was in Sicily in fore it could reach the young heir. De­ 367 b .c .) spite that, he had apparently the advan­ During those years he introduced tage of the kind of education and up­ geometric proofs that later found bringing that wealth could bring, study­ many their way into the summarizing work of ing at Plato’s Academy. Plato [24] Euclid [40]. He also began to work with thought enough of him, apparently, to systematic of lengths and make him a character in two of his areas thatapproximations could not be dialogues, one of them called “Theae­ directly, something developeddetermined further a tetus.” He died in action in battle against century later by Archimedes [47]. the city of Corinth in one of the endless accepted Plato’s notion that stupid wars the Greek cities fought theEudoxus planets moved in perfect circles as a against each other in those days. matter of necessity, but, having observed The Pythagoreans had discovered the the motions of the planets, he could not irrationality of the square root of two. help but realize that the actual planetary Theaetetus apparently systematized the motions were not those of objects mov­ study of these irrationals to show that ing evenly in perfect circles. there were large numbers of them and, He was the first to try to adjust Plato’s apparently, an infinite number. That theory to actual observation to “save the rather drew the fangs of their mystery. appearances” as it was called. He One is an anomaly; many are normal. suggested that the sphere into which a He studied the five regular solids of planet was set had its poles set into an­ Plato and may have been the first to other sphere which had set into demonstrate that there were, in fact, still another sphere andits poles so on. Each only those five and that no other regular sphere rotated evenly, but the combina­ polygons could exist. tion of speeds and the inclination of the poles of one sphere to those of the next resulted in the overall motion of the planet being the irregular one that was [27] EUDOXUS (yoo-dok'sus) Greek astronomer and mathe­ actually observed. Thus, by combining perfect regularities, the observed imper­ matician Bom: Cnidus (on what is now fection of irregularity was achieved. The the Turkish coast), about 400 b .c . appearances were saved, and so was Plato. Died: Cnidus, about 347 B.C. Eudoxus also drew a new map of the Eudoxus studied under Archytas [25] earth, better than that of Hecataeus [9] and also at Plato’s [24] Academy under and was the first Greek to attempt a map difficult circumstances. Being poor, he of the stars. He divided the sky, for this lived in Piraeus, Athens’ port city, where purpose, into degrees of latitude and lon­ quarters could be obtained more gitude, a notion eventually transferred to cheaply. This meant he had to walk five the surface of the earth itself. In later 17

[28]

HERACLEIDES

centuries, Cicero considered Eudoxus the greatest of the Greek astronomers, though this may be unjust to Hipparchus [50], Unfortunately, none of the writings of Eudoxus survive. [28] HERACLEIDES (her-uh-kly'deez) Greek astronomer Born: Heraclea Pontus (modem Bander Eregli, on Black Sea shore about 150 miles east of Istanbul, Turkey), about 388 b . c . Died: Athens, 315 b .c . Heracleides (often called Heracleides Ponticus after his birthplace) traveled to Athens as a young man, for it was then the center of the philosophic universe, and studied in Plato’s Academy. He must have done well, for there is a story that when Plato [24] went to Sicily in his ill-fated venture to make a king a philos­ opher, Heracleides was left in charge of the school (other stories say Eudoxus [27] was). Heracleides wrote a good deal on as­ tronomy and geometry, but little of his work survives. He is known today only for certain suggestions in astronomy that were very important, although they re­ mained uninfluential in his own time. The heavenly objects generally, and in particular the fixed stars, take part in an even rotation about the earth from east to west. It had always been assumed that this apparent rotation was a real one, that the vault of heaven actually turned. Heracleides pointed out that the same effect would be observed if the heavens stood still and if the earth rotated about its axis from west to east once every day. Heracleides was the first man we know of to suggest the rotation of the earth, but the idea was not to become domi­ nant in the world of astronomy until the time of Copernicus [127], eighteen hun­ dred years later. Against the background of the stars (considered as unmoving points), the sun, moon, and five known planets— Mercury, Venus, Mars, Jupiter, Saturn— moved from west to east in rather erratic fashion. It was this erratic west-to-east 18

ARISTOTLE

[29]

motion superimposed on the motion of the starry vault that Eudoxus had tried to explain by assigning each body a number of separate spheres. Of these various bodies, the motions of two, Mercury and Venus, were pecu­ liar in that they were never very far from the position of the sun. The spheres of Eudoxus could explain this, at least approximately, but it seemed to Hera­ cleides that a more straightforward ex­ planation was the supposition that Mer­ cury and Venus revolved about the sun and therefore could not depart very far from that body. Heracleides kept the earth in the cen­ ter of the universe but was nevertheless the first to suggest the revolution of one heavenly body about another. He differed from Philolaus [19] in suggesting a revolution about a visible and actual body, the sun, and not about a mystical and unseen one such as the “central fire.” This beginning of a heliocentric theory was carried further by Aristarchus [41] a century later but lost out to the contrary views of Hipparchus [50]. This portion of Heracleides’ concept had also to await Copernicus for vindication. [29] ARISTOTLE (ar'is-totl) Greek philosopher Born: Stagira (in northern Greece), 384 b .c . Died: Chalcis (on the Aegean is­ land of Euboea, now Evvoia), 322 b .c . Inland from Stagira was the semi­ Greek kingdom of Macedon, with which Aristotle’s family was closely connected. Aristotle’s father, for instance, had been court physician to the Macedonian king, Amyntas II. Aristotle lost both parents while a child and was brought up by a friend of the family. He is supposed to have spoken with a lisp and to have been something of a dandy. At the age of seventeen Aristotle trav­ eled to Athens for a college education and after Plato [24] returned from Syra­ cuse, the young man joined Plato’s Academy, where he studied assiduously.

[29]

ARISTOTLE

Eventually he was to become by far the most renowned of all the pupils of Plato. Plato called him “the intelligence of the school.” When Plato died in 347 b .c ., Aristotle left the school. The reason he gave was that he disapproved of the growing em­ phasis on mathematics and theory in the Academy and the continuing decline in natural philosophy. However, it is possi­ ble that he may have been displeased that Plato, on his deathbed, designated his nephew, an undistinguished person, as his successor, passing over the merits of Aristotle. It is also true that Athens and Macedon were enemies at the time and Aristotle may have felt uneasily con­ scious of being considered pro-Mac­ edonian. In any case Aristotle found it expedi­ ent to set out upon a journey that car­ ried him to various parts of the Greek world, particularly to Asia Minor. While there he married and engaged in the study of biology and natural history, al­ ways his chief love. In 342 b . c . he was called to Macedon. The son of Amyntas II had succeeded to the throne of Macedon as Philip II while Aristotle was at the Academy, and now the king wanted the son of his father’s physician back at court. The purpose was to install him as tutor for his four­ teen-year-old son, Alexander. Aristotle held this position for several years. Since Alexander was to become Alexander the Great, the conqueror of Persia, we have the spectacle of the greatest soldier of ancient times being tutored by the greatest thinker. In 336 b .c . Philip II was assassinated and his son succeeded as Alexander III. Alexander had no further time for edu­ cation so Aristotle left Macedon the next year and went back to Athens, while Alexander went on to invade the Persian Empire in a great conquering campaign. Aristotle’s nephew, Callisthenes, accom­ panied Alexander, but Aristotle’s in­ fluence over his erstwhile pupil was not very great for in 327 b .c . Callisthenes was executed by the increasingly megalo­ maniac monarch. Meanwhile, in Athens, Aristotle founded a school of his own, the Ly­

ARISTOTLE

[29]

ceum, so called because Aristotle lec­ tured in a hall near the temple to Apollo Lykaios (Apollo, the Wolf-God). It was also called the “peripatetic school” (“walk about”) because Aristotle, at least on occasion, lectured to students while walking in the school’s garden. He also built up a collection of manuscripts, a very early example of a “university li­ brary.” It was this which eventually served as the kernel for the great Library at Alexandria. The school continued under Aristotle’s directorship quite successfully, empha­ sizing natural philosophy. In 323 b .c ., however, the news arrived of the death of Alexander the Great in Babylon. Since Aristotle was well known to have been Alexander’s tutor, he feared that an anti-Macedonian reaction in Athens might lead to trouble. And, indeed, the accusation of “impiety” was raised. Aris­ totle had no mind to suffer the fate of Socrates [21]. Saying he would not allow Athens to “sin twice against philos­ ophy” he prudently retired to Chalcis, his mother’s hometown, and died there the next year. Aristotle’s lectures were collected into nearly a hundred and fifty volumes and represent almost a one-man encyclopedia of the knowledge of the times, much of it representing the original thought and observation of Aristotle himself. Nor was it confined entirely to science, for Aris­ totle dealt with politics, literary criticism, and ethics. Altogether, of the volumes attributed to him, some fifty have sur­ vived (not all of which are certainly au­ thentic), a survival record second only to that of Plato. This survival came about through a fortunate chance. Many of his manu­ scripts were found in a pit in Asia Minor about 80 b . c . by men in the army of the Roman general Sulla. They were then taken to Rome and recopied. The one field for which Aristotle is not noted is mathematics, but even here he may be credited with a glancing blow, for he is the virtual founder of the sys­ tematic study of logic, which is allied to mathematics. He developed, in great and satisfying detail, the art of reasoning from statement to necessary conclusion 19

[29]

ARISTOTLE

and thereby demonstrating the validity of a line of thought. His system stood without major change until the nine­ teenth-century development of symbolic logic by Boole [595], which converted logic into a branch of mathematics in form as well as spirit Aristotle’s most successful scientific writings were those on biology. He was a careful and meticulous observer who was fascinated by the task of classifying ani­ mal species and arranging them into hierarchies. He dealt with over five hun­ dred animal species in this way and dis­ sected nearly fifty of them. His mode of classification was reasonable and, in some cases, strikingly modern. He was particularly interested in sea life and ob­ served that the dolphin brought forth its young alive and nourished the fetus by means of a special organ called a pla­ centa. No fish did this, but all mammals did, so Aristotle classed the dolphin with the beasts of the field rather than with the fish of the sea. His successors did not follow his lead, however, and it took two thousand years for biologists to catch up to Aristotle in this respect. It was J. Müller [522] who finally confirmed Aris­ totle in this respect. Aristotle also stud­ ied viviparous sharks, those that bear live young—but without a mammalian pla­ centa. He also noted the odd ability of the torpedo fish to stun its prey though, of course, he knew nothing of the electric shock with which it managed it. He was also wrong on occasion, as when he de­ nied sexuality in plants. Nineteen cen­ turies were to pass before Alpini [160] was to correct this particular error. His formation of a hierarchy of living things led him irresistibly toward the idea that animals represented a chain of progressive change, a sort of evolution. Other Greek philosophers groped simi­ larly in this direction. However, barring any knowledge as to the physical mecha­ nism whereby evolutionary changes could be brought about, such theories in­ variably became mystical. A rational theory of evolution had to await Darwin [554], twenty-two hundred years after the time of Aristotle. Aristotle studied the developing em­ 20

ARISTOTLE

[29]

bryo of the chick and the complex stom­ ach of cattle. He decided that no animal had both tusks and horns, and that no single-hooved animal had horns. But his intuition sometimes led him astray. He believed the heart was the center of life and considered the brain merely a cool­ ing organ for the blood. In physics Aristotle was far less suc­ cessful than in biology, perhaps because he was too Platonic. He accepted the heavenly spheres of Eudoxus [27] and Callippus [32] and even added further to them, reaching a total of 54. He seemed to think of the spheres as having an ac­ tual physical existence whereas Eudoxus probably thought of them as imaginary aids to calculation, as we consider the lines of latitude and longitude we draw on a map. Aristotle also accepted the four elements of Empedocles [17] but re­ stricted them to the earth itself. He suggested a fifth element, “aether,” of which all the heavens were composed. (We still use phrases such as “ethereal heights” today.) This fine of reasoning led him to agree with the Pythagoreans that earth and heaven were subjected to two different sets of natural law. On the earth all things were changeable and corrupt, while in the heavens all was permanent and unchanging. On earth the four ele­ ments each had its own place, and mo­ tion was an attempt to reach that place. Earth was in the center, water above it, air above that, and fire highest of all the earthly substances. Therefore an object composed largely of earth, such as a rock, would, if suspended in air, fall downward, while bubbles of air trapped underwater would move upward. Again, rain fell, but fire rose. It also seemed to Aristotle that the heavier an object was, the more eagerly it would strive to achieve its proper place, since the heaviness was the mani­ festation of its eagerness to return. Hence a heavier object would fall more rapidly than a lighter one. (Nineteen centuries later, a reconsideration of this problem by Galileo [166] was to lead to momentous consequences.) The motion of heavenly objects, on the other hand, was no attempt to get

[29]

ARISTOTLE

anywhere. It was a steady, permanent motion, even and circular. Aristotle, apparently, was not an ex­ perimentalist for all that he was a close observer. He observed that rocks fell more quickly than feathers, but he made no attempt to arrange an observation of the falling of rocks of graded weight. Furthermore, neither he nor any other ancient scholar properly appreciated the importance of precise, quantitative mea­ surement. This was not mere perversity on their part, for the state of instru­ mentation was rudimentary indeed in an­ cient times and there were few clear methods of making accurate measure­ ments. In particular, they could not mea­ sure small intervals of time accurately, a deficiency that was to remain for two thousand years until the time of Huygens [215]. Aristotle rejected Democritus’ atom­ ism, dooming that concept through an­ cient and medieval times. On the other hand, he accepted the Pythagorean no­ tion of the roundness of the earth, pre­ senting his reasoning in a fashion that remains valid today. The most telling ar­ gument was that as one travels north, new stars appear at the northern horizon while old ones disappear at the southern. If the earth were flat, all stars would be equally visible from all points on its sur­ face. It was Aristotle’s championing of this view that kept it alive through the darkest days that were to follow. Upon Aristotle’s retirement, leadership of the Lyceum fell to his friend and pupil Theophrastus [31] and after him to Strato [38], under whom the Lyceum continued to be a vital and progressive force. Aristotle’s system of philosophy was never as influential in ancient times as Plato’s. Indeed, Aristotle’s works may not have been published for some cen­ turies after his death. After the fall of Rome, his work was largely lost to Europe (only Organon, his work on logic, was saved) while Plato’s works were, for the most part, retained. How­ ever, Aristotle’s books survived among the Arabs, who valued them highly. Christian Europe regained Aristotle from the Arabs, translating his books

THEOPHRASTUS

[31]

into Latin in the twelfth and thirteenth centuries. From that time Aristotle re­ placed Plato as the Philosopher. His views came to be regarded as possessing an almost divine authority, so that if Aristotle said it was so, it was so. By a queer fatality, it almost seemed as though his statements were most ac­ cepted when they were most incorrect. This cannot be blamed on Aristotle, who was himself no believer in blind obedience to authority. Nevertheless, fol­ lowing the era of over-adulation, he be­ came the very symbol of wrongness, and when the Scientific Revolution took place in the sixteenth and seventeenth centuries, its first victories involved the overthrow of Aristotelian physics. In the centuries since, Aristotle has, as a conse­ quence, too often been viewed as an enemy of science, whereas actually he was one of the truly great scientists of all time and even his wrongness was ratio­ nal. No man should be blamed for the stubborn orthodoxy of those who many centuries later insist they speak in his name. [30] MENAECHMUS (mih-nek'mus) Greek mathematician Born: about 380 b .c . Died: date unknown Nothing is known of Menaechmus’ life except that he may have been a stu­ dent of Eudoxus [27]. He seems to have been the first to take up the geometry of the cone system­ atically and to show that ellipses, parab­ olas and hyperbolas are all curves pro­ duced by the intersection of a cone and a plane. This work was continued by Archimedes [47] and Apollonius [49] and was to be given startling and pro­ found application to the real universe by Newton [231]. [31] THEOPHRASTUS (thee-oh-fras'tus) Greek botanist Born: Eresus, Lesbos (an Aegean island), about 372 b .c . Died: Athens, about 287 b .c . 21

[32]

CALLIPPUS

DIOCLES

[34]

Theophrastus came to Athens at an early age to study under Plato [24]. Aris­ totle [29] first met Theophrastus on Lesbos, during the period after Plato’s death, and a lifelong friendship ensued. In fact, Theophrastus (“divine speech”) is really a nickname bestowed upon the man by Aristotle because of the latter’s delight in his conversation. His real name was Tyrtamus. Theophrastus conducted the Lyceum after Aristotle’s retirement and served as guardian of his old teacher’s children. He inherited Aristotle’s library and re­ mained in charge of the school until his own death thirty-five years later. The school was at its peak of prosperity under him and is supposed to have had as many as two thousand students. Theophrastus carried on the Aris­ totelian tradition of biology, concen­ trating chiefly on the plant world and describing over five hundred and fifty species, some from as far away as India, for the conquests of Alexander the Great had opened wider horizons to Greek science. Theophrastus is usually considered the founder of botany, as Aristotle was the founder of zoology. Two botanical works are all that have survived of some two hundred scientific volumes he produced, one of which was a general history of science that would have been priceless if but one copy had survived. As it is, he is best known for no scientific work at all, however, but for a delightful series of character portraits that bear the mark of universality. The human “types” satirized by Theophrastus are easily recognized today.

adjusted. He added eight more spheres, making thirty-four in all. He also measured the length of the seasons accurately and obtained a mea­ sure of the year that was closer to the true value than was that of Oenopides [18].

[32] CALLIPPUS (kuh-lip'us) Greek astronomer Born: Cyzicus, about 370 b .c . Died: about 300 B.c. Callippus, having studied under Eu­ doxus [27], improved on his master. His observations of planetary movements showed him that the spheres of Eudoxus, even though they numbered twenty-six in all, did not exactly account for reality no matter how their movements were

[34] DIOCLES (dy'uh-kleez) Greek physician Born: Carystus, Euboea, about 350 b . c . Died: date unknown Diodes, the son of a physician, was held in great esteem by the ancients as second only to Hippocrates [22] himself. He studied at the Lyceum under Aris­ totle [29], He may have been the first to assem­

22

[33] DICAEARCHUS (dy-see-ahrikus) Greek geographer Born: Messina, Sicily, about 355 B.C. Died: a b o u t 285 b .c . As a young man Dicaearchus went to Athens, studying at the Lyceum under Aristotle [29] and becoming a close friend of Theophrastus [31]. Interested mostly in moral philosophy he never­ theless wrote a history of Greece and a geography in which he described the world in words and maps, being the first to consider such a map as part of a sphere. He estimated the heights of Greek mountains and showed they did not upset the notion of the sphericity of the earth by arguing that their height was very small compared to the width of the terrestrial sphere. He had the advantage of being able to use the descriptions brought back by the far-ranging officers of Alexander the Great. Dicaearchus’ most notable contri­ bution was that of being the first to draw a line of latitude from east to west across his maps, this marking the fact that all points on that line saw the noonday sun (on any given day) at an equal angle from the zenith.

[35]

EPICURUS

ble the writings of the Hippocratic school, and he made use of them in his own works, of which fragments survive. He is thought to have been the first per­ son to write a book on anatomy and the first to use the word itself to describe the study. He became prominent enough to treat some of the Macedonian princes and generals of the time of Alexander the Great. He seems also to have been the first Greek to write a manual on how to rec­ ognize different plants, and on how they might be used nutritionally and medi­ cally. This book served as the basic au­ thority on pharmacy until it was re­ placed by that of Dioscorides [59] nearly four centuries later. [35] EPICURUS (ep-ih-kyoo'rus) Greek philosopher Born: Samos, 341 b .c . Died: Athens, 270 b .c . Epicurus was the son of an Athenian schoolmaster and, after teaching in vari­ ous places in the Greek world, he settled in Athens in 306 b .c . There he founded an enormously popular school and es­ tablished the philosophy known as Epi­ cureanism. This maintained an unbroken tradition for seven centuries until the tide of Christianity in the late Roman Empire washed out all the pagan philos­ ophies. His school was the first to admit women students, which both shocked and titillated the scholarly world of the time. Epicurus’ philosophy was mechanistic and found pleasure the chief human good. Epicurus himself held that the highest pleasure consisted of living mod­ erately and behaving kindly and in re­ moving the fear of the gods and of death. His later followers were more self-indulgent in their definition of plea­ sure and Epicureanism is nowadays unjustly used as a synonym for hedo­ nism. Epicurus may have been the stu­ dent of Nausiphanes who was himself a student of Democritus [20]. In any case, Epicurus adopted the atoms of Democ­ ritus as a satisfactorily mechanistic ex­ planation of the universe.

KIDDINU

[37]

Although of his voluminous writings (consisting, supposedly, of three hun­ dred treatises), practically nothing sur­ vives, they lasted long enough to convert the Roman Lucretius [53] some two and a half centuries later, and, in turn, Lu­ cretius’ writings lasted into modern times. Democritus’ atoms, though voted down by philosophers, were never wholly forgotten. Epicureanism, as a philosophy, en­ dured till nearly the end of the Roman Empire, but then perished with the rise of Christianity. [36] PRAXAGORAS (prak-sag'oh-ras) Greek physician Born: Cos, about 340 b .c . Died: date unknown Praxagoras, the son and grandson of physicians, was supposed to have been the teacher of Herophilus [42] and to have been a strong defender of the hu­ moral theory of Hippocrates [22]. Praxagoras distinguished between veins and arteries, recognizing that there were two different kinds of blood vessels, though some attribute this discovery to Alcmaeon [11]. The arteries, however, he thought carried air (they are usually empty in corpses) and the name of these vessels is derived from that belief. He thought moreover they tapered into very fine vessels (which they do) that led into the nerves (which they do not). He also noted the physical connection between the brain and spinal cord but thought the heart was the seat of the in­ tellect [37] KIDDINU Babylonian astronomer Born: Babylonia, about 340 b .c . Died: date unknown It is certain that Babylonian astron­ omy was flourishing at a time when Greek astronomy was merely in its be­ ginnings. If the Babylonians did not, to our knowledge, work out the intricate (and often terribly mistaken) theories of the Greeks, they at least had centuries of 23

[38]

STRATO

PYTHEAS

[39]

careful observations to their credit. Their names and individual accomplishments are shadowy indeed, however, so that they are unjustly neglected in a bio­ graphical work such as this. There is mention of Kiddinu in Strabo [56] and Pliny [61], where he is called Kidenas or Cidenas. He was the head of the astronomical school at the Babylo­ nian city of Sippar and worked out the precession of the equinoxes, paving the way for Hipparchus’ [50] more accurate work. He also devised, apparently, compli­ cated methods of expressing the irregular movement of the moon and other plane­ tary bodies, departing from the assump­ tion that they must move at constant velocities (something the Greeks insisted upon) and consequently getting close ap­ proximations of their actual movements.

first to argue that, in falling, a body accelebrated; that is, moved more quickly with each successive unit of time. (It was the measurement of this acceleration by Galileo [166] that was to mark the birth of the new physics nineteen cen­ turies later.) Strato also seems to have understood the law of the lever, but he did not work it out as Archimedes [47] was to do later in the century. Where Aristotle had felt that sound traveled by a succession of impacts on air and that sound could not be conducted in the absence of air (he was right), Strato went further and seemed to be on the point of recognizing sound as a wave motion. After Strato’s death the Lyceum de­ clined. Primacy in philosophy remained in Athens with the Platonic Academy, but scientific endeavor was making its home increasingly in Alexandria.

[38] STRATO (stray'toh) Greek physicist Born: Lampsacus, a b o u t 340 b .c . Died: Athens, about 270 b .c . Born in the city where two centuries earlier Anaxagoras [14] had died in exile and where Epicurus [35] had taught be­ fore moving on to Athens, Strato carried on in the tradition of Asia Minor. In youth, he studied at the Lyceum, then traveled to Alexandria, an Egyptian city founded by Alexander the Great. While there, he is supposed to have tutored the son of Ptolemy I, the Macedonian gen­ eral who had become Egypt’s king. He also helped establish Alexandria as a scientific center, a position it was to hold through the remainder of ancient times. Strato returned to Athens on the death of Theophrastus [31] to become third di­ rector of the Lyceum. Strato was a more advanced physicist than Aristotle [29], was favorable to Democritus’ [20] atomic theory, and apparently conducted ex­ periments. He was called Strato Physicus in ancient references. He described methods for forming a vacuum although he agreed with Aris­ totle that no vacuum existed in nature. He also agreed that heavier bodies fell faster than lighter ones, and he was the

[39] PYTHEAS (pith'ee-us) Greek geographer and explorer Bom: Massalia (modern Mar­ seille, France), about 330 b .c . Died: date unknown Pytheas lived in a time of great outflowing of Greek energies. His con­ temporaries led Greek culture as far east as what are now the nations of Afghani­ stan and Pakistan. Pytheas, dwelling in Massalia, west­ ernmost of the Greek-colonized cities of the Mediterranean, turned in the other direction, not at the head of armies, but on board a ship. He sailed westward through the Pillars of Hercules (now the Strait of Gibraltar) and up the north­ western coast of Europe. His accounts, which have not survived directly but reach us through references in later writers, seem to show that he ex­ plored the island of Great Britain and then sailed northward to “Thule,” which was possibly Norway. There fog stopped the intrepid navigator and he turned back to explore northern Europe and penetrate the Baltic Sea as far as the Vistula. Pytheas’ accounts, in the main truth­ ful, as nearly as we can tell, were disbe­

24

[40 ]

EUCLID

lieved by contemporaries, who were much readier to believe fantasies. Even Pliny [61] some centuries later, who rou­ tinely swallowed five or six new impossi­ bilities each morning before breakfast, balked at Pytheas’ tales and the geogra­ pher, Strabo [56] was particularly abu­ sive. A similar fate had befallen Hanno [12] two centuries before Pytheas and was to befall Marco Polo [105] fifteen centuries after Pytheas. Pytheas was a scientific geographer as well as an explorer. Following the teach­ ings of the contemporary Dicaearchus [33], he determined the latitude of his hometown, Massalia, by careful observa­ tions of the sun, and did so with praise­ worthy accuracy. He was also the first to point out that the North Star was not ex­ actly at the pole and that it therefore shifted position, making a small circle in the course of a day. He improved on Eudoxus [27] in this respect. His voyages beyond Gibraltar led him into the open ocean, where he could ob­ serve the tides, which in the land-locked Mediterranean were almost nonexistent. What was most amazing was that, being the first Greek to observe real tides, he also produced the correct explanation for them, attributing them to the influence of the moon. In this, however, he was even further ahead of his time, for it was to be two thousand years before this ex­ planation was accepted and then only when Newton [231] had managed to ex­ plain lunar attraction as part of a grand scheme of the universe. [40] EUCLID (yoo'klid) Greek mathematician Born: a b o u t 325 b .c . Died: Alexandria, about 270 B.c. Euclid, who may have studied at Plato’s [24] Academy in Athens, is an­ other who marks the passage of scientific pre-eminence from Athens to Alexandria. After the death of Alexander the Great, his generals snatched at portions of his empire, fighting among themselves blood­ ily and inconclusively for a generation. One general, Ptolemy, seized Egypt and established his capital at the new city of

EUCLID

[40 ]

Alexandria. He founded a line of kings, all named Ptolemy, that lasted for two and a half centuries. (The last monarch of the line was the famous queen Cleo­ patra.) Ptolemy and his immediate successors were patrons of science and labored to establish Alexandria as the intellectual capital of the world. In this, they suc­ ceeded. They built a splendid library and a famous university called the Museum, because it was a kind of temple to the Muses, who were the patron goddesses of science and the fine arts. Among the earliest scholars to be attracted to the new establishment was Euclid. Euclid’s name is indissolubly linked to geometry, for he wrote a textbook (Ele­ ments) on the subject that has been stan­ dard, with some modifications, of course, ever since. It went through more than a thousand editions after the invention of printing and it was not so long ago that the phrase “I studied my Euclid” was synonymous with “I studied geometry.” Euclid is, therefore, the most successful textbook writer of all time. And yet, as a mathematician, Euclid’s fame is not due to his own research. Few of the theorems in his textbook are his own. What Euclid did, and what made him great, was to take all the knowledge accumulated in mathematics since the days of Thales [3] and codify the two and a half centuries of labor into a single work. In doing so, he evolved, as a start­ ing point, a series of axioms and postu­ lates that were admirable for their brev­ ity and elegance. He then arranged theorem after theorem in a manner so logical as almost to defy improvement. The only theorem that tradition defi­ nitely ascribes to Euclid himself is the proof he presented for the Pythagorean theorem. Although most of his great treatise dealt with geometry, it also took up ratio and proportion and what is now known as the theory of numbers. It was Euclid who proved that the number of primes is infinite. He also proved that the square root of two was irrational (the fact first discovered by Pythagoras [7] and his fol­ lowers) by a line of argument so neat that it has never been improved upon. 25

[41]

ARISTARCHUS

He made optics a part of geometry, too, by dealing with light rays as though they were straight lines. Of course Euclid does not include all of Greek mathematics, or even all of Greek geometry. Greek mathematics re­ mained vital for a considerable time after Euclid, and such men as Apol­ lonius [49] and Archimedes [47] added a great deal. Yet Euclid as an individual remains an impenetrable mystery. It is not known where or just when he was bom or when he died. The figure given here, 325 b .c . is a pure guess, but he did work at Alex­ andria during the reign of Ptolemy 1 (305-285 b .c .). About the only personal aspect of Euclid’s life that reaches us is his re­ ported remark to King Ptolemy when the latter, studying geometry, asked if Euclid couldn’t make his demonstrations a little easier to follow. Euclid said, un­ compromisingly, “There is no royal road to geometry.” There is also a doubtful legend that gives him a shrewish wife. For many centuries it was considered that there was something objectively and eternally true about the principles of mathematics and, in particular, about the axioms on which Euclid’s work was based: that the whole is equal to the sum of its parts, for instance, or that a straight line is the shortest distance be­ tween two points. It was only in the nineteenth century that it came to be re­ alized that axioms are merely agreedupon statements rather than absolute truths. Mathematics was broadened by men such as Lobachevski [484] and Riemann [670], and non-Euclidean geome­ tries, on which the theories of Einstein [1064] came to be based, were devel­ oped. [41] ARISTARCHUS (ar-is-tahrikus) Greek astronomer Born: Samos, about 310 b .c . Died: Alexandria, about 230 b .c . Virtually nothing is known about the personal life of Aristarchus except that he must have come to Alexandria, then the Mecca for scientists, in his youth and 26

ARISTARCHUS

[41]

may have studied under Strato [38]. Enough is known about his work, how­ ever, to stamp him as the most original and, from the modern view, successful of the Greek astronomers. Aristarchus combined the Pythagorean view of the moving earth with the con­ tention of Heracleides [28] that some planets moved about the sun. Aris­ tarchus pointed out, about 260 b .c ., that the motions of the heavenly bodies could easily be interpreted if it were assumed that all the planets, including the earth, revolved about the sun. Since the stars seemed motionless, except for the diur­ nal motion due to the rotating earth, they must be infinitely far away. Because of this view, Aristarchus has been known as the Copernicus of Antiq­ uity and, indeed, Copernicus [127] seems to have known of Aristarchus’ views, mentioning them in a passage he later eliminated, as though not wishing to compromise his own originality. Aristarchus’ heliocentric hypothesis was too revolutionary to be accepted by the scholars of his time and his book on the subject did not survive. His theory would be forgotten today but for the mention of it in the writings of Archi­ medes [47] and of Plutarch, the Greek historian. The age was sufficiently enlightened, however, to protect Aristarchus from the dangers that had befallen Anaxagoras [14] two and a half centuries earlier for much less radical views. Yet, at least one important philosopher of the time, Cleanthes the Stoic, accused him of im­ piety and believed he should be made to suffer for it. From Aristarchus’ own writings we know of work he did to determine the size and distance of the moon and sun. At the moment when the moon is ex­ actly half-illuminated, the earth, moon, and sun must occupy the apices of a right triangle. By geometry one can then determine the relative lengths of the sides of the triangle and determine the ratio of the distance of the sun from the earth (the hypotenuse of the triangle) to the distance of the moon from the earth (the short leg of the triangle). In theory this method is correct, but unfortunately

[42]

HEROPHILUS

ERASISTRATUS

[43]

view was that the body of man meant very little in comparison with his soul. The dead body was then a mere lump of flesh that could be cut with impunity. To the Egyptian natives, however, human dissection was a serious impiety. (Some centuries later the early Christian Fa­ thers held it as an example of pagan cru­ elty that vivisections—the dissections of living bodies—were performed. This was taken from statements by Celsus [57] and was probably exaggeration. It seems quite certain that deliberate vivisection was not practiced. Even ordinary dissec­ tion of dead bodies was all too limited, or the ancients wouldn’t have made some of their anatomical errors.) Herophilus was particularly interested in describing the brain. He divided nerves into sensory (those which re­ ceived sense impressions) and motor (those which stimulated motion). He also described the liver and spleen. He described and named the retina of the eye and he named the first section of the small intestine, the duodenum. His inves­ tigation of the genital system led to a de­ scription of the ovaries and of the tubes leading to the ovaries from the uterus. He also observed and named the prostate gland. He noted that arteries, unlike veins, pulsate and timed the pulsations with a water clock, but he failed to see the con­ nection between this arterial pulse and the heartbeat. He held that the arteries [42] HEROPHILUS (hee-rofih-lus) Greek anatomist carried blood and he also felt that blood­ letting had therapeutic value. This em­ Born: Chalcedon (the modern Kadikoy, a suburb of Istanbul, phasis on bleeding was to have a dele­ Turkey), about 320 b .c . terious effect on medicine for two thou­ sand years. His work was worthily car­ Died: date unknown ried on by his successor Erasistratus The biological sciences as well as the [43], but thereafter the Alexandrian physical ones reached new heights in school of anatomy declined. Alexandria’s early days. Working there, Herophilus, who may have studied under Praxagoras [36], established himself as [43] ERASISTRATUS (er-uh-sis'tra-tus) the first careful anatomist and the first to Greek physician perform dissections in public, perhaps as Bom: Chios (now Khios; an Ae­ many as six hundred altogether. He la­ gean island), about 304 B.c. bored hard to compare the human mech­ Died: Mycale, a b o u t 250 b .c . anism with that of animals. There was no serious objection among the Greeks Erasistratus, according to tradition, to anatomical dissections in those pre­ was trained in Athens, then traveled to Christian days and indeed the Platonic Asia where he served as court physician Aristarchus had no instruments capable of measuring angles accurately and his estimates of what those angles must be were rather off. He concluded that the sun was about twenty times as far as the moon, whereas in fact it is about four hundred times as far. Aristarchus then worked out the actual size of the moon by noting the size of the shadow thrown by the earth during an eclipse of the moon. By a correct line of argument, again marred by the inac­ curacy of his measurements, he con­ cluded that the moon had a diameter one-third that of the earth. This is only a slight overestimate. If the sun were twenty times as distant as the moon, and yet the same size in appearance, it must be twenty times the diameter of the moon or about seven times the diameter of the earth. Actually we now know the sun is over a hundred times the diameter of the earth, but even Aristarchus’ too-small value was enough to make it seem illogi­ cal, to him, that the sun revolved about the earth. It seemed to him that the smaller object should revolve about the larger. Unfortunately this logic, which seemed so solid to him (and which seems so solid to us), did not impress his contem­ poraries.

27

[43]

ERASISTRATUS

for Seleucus I, who controlled the major portion of what had once been the Per­ sian Empire. Erasistratus then moved west, where he continued the work of Herophilus [42] at Alexandria. In later life, Erasis­ tratus devoted himself to research and, according to tradition, committed suicide when afflicted with an incurable ulcer in the foot. He, too, paid particular attention to the brain, which he described as being divided into a larger (cerebrum) and smaller (cerebellum) part. He compared the convolutions in the brain of man with those of animals and decided (cor­ rectly) that the complexity of the con­ volutions was related to intelligence. He noticed the association of nerves with arteries and veins and imagined that each organ of the body was fed by all three, each of them, nerve, artery, and vein, bringing its own fluid to the organ. The nerve, which he and others of the time believed to be hollow, carried “ner­ vous spirit,” according to this view; the artery, “animal spirit”; and the vein, blood. He took a step backward from Herophilus’ views by denying that the arteries carried blood. On the other hand, he believed that air was carried from the lungs to the heart and changed into the “animal spirit” that was carried in the arteries. If we remember that it is oxygen that is carried by the blood and relate oxygenated hemoglobin with “ani­ mal spirit” and ordinary hemoglobin with blood, his views are not so wrong. The difference is mainly one of seman­ tics. In fact, Erasistratus came near to grasping the notion of the circulation of the blood, but not quite. That concept had to wait two millennia for Harvey [174]. He also refused to accept the er­ roneous humor theory of disease which had been made popular by Hippocrates [22]. Unfortunately, Galen [65] returned to it and that proved decisive for the next fifteen centuries. Tradition makes Erasistratus a grand­ son of Aristotle [29] and a pupil of Theophrastus [31]. If so, he broke with his grandfather’s views and accepted the atomism of Democritus. Indeed, Erasis28

PHILON

[45]

tratus believed that all body functions were mechanical in nature. Digestion, for instance, he thought to result from the grinding of food by the stomach. Two thousand years later Borelli [191] was to revive this notion. Egyptian objections to human dissec­ tion prevailed, however, and after the promising start made by Herophilus and Erasistratus, the study of anatomy de­ clined, not to be revived until the time of Mondino de’ Luzzi [110], fifteen cen­ turies later. [44] CONON (koh'non) Greek mathematician Born: Samos, about 300 b .c . Died: Alexandria, date unknown Conon was a pupil of Euclid [40], ac­ cording to tradition, and a teacher of Archimedes [47], It is possible that the mathematical curve usually ascribed to Archimedes and called, therefore, the “spiral of Archimedes” was actually first studied by Conon. Conon is best known for a piece of conscienceless flattery. It seems that about 245 b .c ., Ptolemy III, king of Egypt, was off to the wars and Berenice, his queen, dedicated her hair at the tem­ ple of Aphrodite in order to persuade that goddess to bring him home safe and victorious. The hair disappeared, undoubtedly sto­ len by souvenir hunters, but Conon smoothly assured the sorrowing queen that Aphrodite had snatched the hair up to heaven where it now hung as a brandnew constellation. He pointed out a group of dim stars not previously hon­ ored by the attention of astronomers and that group is known as Coma Berenices (“Berenice’s Hair”) to this day. [45] PHILON (figh'lon) Greek engineer Born: Byzantium, about 300 b .c . Died: date unknown Like Hero [60], Philon experimented with air in a decidedly modem fashion and came to conclusions that were re­

[46]

CTEsmrus

ARCHIMEDES

[47]

markable but were ignored by the philos­ ophers of the time. He found that air expanded with heat, and he may even have groped toward the beginnings of an air thermometer as Galileo [166] was to do thirteen cen­ turies later. He also found that some air in a closed vessel was consumed by a burning torch, an observation from which Lavoisier [334] was to draw revo­ lutionary conclusions fifteen centuries later. He studied catapults carefully and since these were war weapons, those re­ searches were given more notice. He also wrote on the art of besieging a city and of defending it against siege. A book he wrote on secret messages and cryp­ tography is lost.

and Watt [316] some seventeen centuries later. The most famous invention of Ctesib­ ius, however, was his improvement of the ancient Egyptian clepsydra, or water clock. In this, water dripping into a con­ tainer at a steady rate raised a float which held a pointer that marked a posi­ tion on a drum. From that position the hour could be read. The drum was in­ geniously adjusted so that it could be used at various times of the year. (The day and night were each divided into twelve equal hours at all times, which meant that in summer the hours of day were long and those of night were short, while in winter it was the other way around.) The water clock was the best of the ancient timepieces. The mechanical clocks of the Middle Ages, run by falling [46] CTESIBIUS (teh-sib'ee-us) weights, were more convenient, but no more accurate. It was not until the pen­ Greek inventor dulum clock of Huygens [215], eighteen Born: about 300 b .c . Died: date unknown centuries after the time of Ctesibius, that the clepsydra was finally outclassed. Ctesibius founded the engineering tra­ None of Ctesibius’ writings have sur­ dition at Alexandria, a tradition which vived and we know of him only through was to reach its peak with Hero [60] one references in Vitruvius [55] and Hero. century later. In the intellectually arro­ gant Greek world, Ctesibius came by his practical interests legitimately, for he [47] ARCHIMEDES (ahr-kih-mee'deez) was the son of a barber and his first in­ Greek mathematician and engi­ vention was for his father’s benefit. He neer supplied the barber’s mirror with a lump Born: Syracuse, Sicily, about 287 of lead as a counterweight so that it B.C. could more easily be raised and lowered. Died: Syracuse, a b o u t 212 b .c . The lead counterweight was concealed in a pipe, and when it moved rapidly Archimedes, the son of an astronomer, through the pipe a squeaking noise was was the greatest scientist and mathe­ made. It occurred to Ctesibius that a matician of ancient times, and his equal musical instrument could be built on this did not arise until Newton [231] two basis. He therefore constructed a water thousand years later. Archimedes studied organ in which air was forced through in Alexandria, where his teacher Conon different organ pipes not by a falling [44] had, in his own time, been a pupil lead weight, but by the weight of water. of Euclid [40]. In an unusual move for He made use of weights of water and of those days, Archimedes chose not to compressed air in other ways as well, to remain there but to return to his native construct an air-powered catapult, for in­ town. This may have been the result of stance. He undoubtedly had the “feel” of his relationship with the Syracusan king, a mechanical age, but he lacked the Hieron II. Archimedes was an aristocrat proper inanimate power to work with. and a man of independent means and Hero was to discover steam power but did not require the support of the Egyp­ by then the moment had passed, not to tian royal house for his work. return until the time of Newcomen [243] No scientist of ancient times, not even 29

[47]

ARCHIMEDES

Thales [3], had so many stories told about him; and all the stories are so good that it seems cruel to question thenauthenticity. As a small example, tales of his absent-mindedness were lovingly re­ tailed and it was said that in concen­ trating on his thoughts, he could not remember whether he had eaten or not. (Similar stories are told of more recent mathematicians, such as Newton and Wiener [1175]). To pass on to something of impor­ tance, however, Hieron was supposed to have asked his bright relative to deter­ mine whether a crown just received from the goldsmith was really all gold, as it was supposed to be, or whether it con­ tained a grafting admixture of silver. Archimedes was strictly warned to make the determination without damaging the crown. Archimedes was at a loss as to how to proceed until one day, stepping into his full bath, he noted that the water overflowed. In a flash it occurred to him that the amount of water that overflowed was equal in volume to that portion of his body which was inserted into the bath. Well, then, if he dipped the crown into water, he could tell by the rise in water level the volume of the crown. He could compare that with the volume of an equal weight of gold. If the volumes were equal, the crown was pure gold. If the crown had an admixture of silver (which is bulkier than gold), it would have a greater volume. Excited beyond measure by the discov­ ery of this “principle of buoyancy,” Ar­ chimedes dashed out of the bath and, completely naked, ran through the streets of Syracuse to the palace, shout­ ing, “I’ve got it! I’ve got it!” (In connec­ tion with this story, it is important to remember that the ancient Greeks were not as disturbed by nakedness as we are.) Since Archimedes shouted in Greek, what he said was “Eureka! Eu­ reka!” and that has been used ever since as the appropriate remark with which to announce a discovery. (The conclusion of the story is that the crown turned out to be partly silver and that the goldsmith was executed.) Archimedes also worked out the prin­ 30

ARCHIMEDES

[47]

ciple of the lever. Strato [38] had made use of the principle, but it was Archi­ medes who worked it out in full mathe­ matical detail. He showed that a small weight at a distance from a fulcrum would balance a large weight near the fulcrum and that the weights and dis­ tances were in inverse proportion. (Thus, he founded the science of “statics” and developed the notion of a center of gravity. In thus applying the notion of quantitative measurement of weights and distances to scientific obser­ vations, he was two thousand years ahead of his time. In fact, it was the translation of his works into Latin in 1544 that helped inspire renewed efforts in that direction by men such as Stevinus [158] and Galileo [166].) The principle of the lever explained why a larger boulder could be pried up by a crowbar. The force at the end of the long portion of the crowbar (which is just a form of lever) balanced the force of the large weight at the end of the short portion. Archimedes made an­ other famous remark in this connection by saying: “Give me a place to stand on and I can move the world.” (Provided, of course, he also had a lever long enough and rigid enough.) Hieron is supposed to have questioned this remark and dared him to move something startlingly large, even if not as large as the whole world. Archimedes thereupon hooked up a system of com­ pound levers in pulley form, seated him­ self comfortably, and without undue effort (the story goes) singlehandedly pulled a fully laden ship out of the har­ bor and up onto the shore. Archimedes defied the tradition of art for art’s sake made popular by Plato [24] and indulged himself in intensely practi­ cal interests. He is supposed to have in­ vented a hollow, helical cylinder that, when rotated, could serve as a water pump. It is still called the “screw of Archimedes” (though, to be sure, the Egyptians are supposed to have had the device long before the time of Archi­ medes). Archimedes is also supposed to have designed a planetarium in which the motions of the heavenly bodies could be imitated. However, it seems that Ar­

[47]

ARCHIMEDES

chimedes was not exactly proud of his mechanical triumphs, feeling that per­ haps they were not the proper work of a philosopher. He therefore published only his mathematical work. In that field, he calculated a value for pi (the ratio of the length of the circum­ ference of a circle to its diameter) which was better than any other obtained in the classical world. He showed that it lay be­ tween 22-%i and 22%o. To do this, he used a method of calculating the circum­ ferences and diameters of polygons de­ scribed inside and outside a circle. As the polygons were given more and more sides, they approached the circle in shape and area. The circumference of the inner polygon grew longer and that of the outer polygon grew shorter while the circumference of the circle was “trapped” between the two. This is very like some of the methods used in calcu­ lus much later, and it is often stated that Archimedes would have discovered cal­ culus nearly two thousand years ahead of Newton if he had only had a decent system of mathematical symbols to work with. Archimedes is also famous for a trea­ tise in which he calculated the number of grains of sand required to fill the en­ tire universe (making some guesses as to what the size of the universe was). He did this mainly to make the point that nothing real existed that was too large to be measured; or, in other words, that nothing finite was infinite. To do so, he made use of a system for expressing large numbers that is almost equivalent to our own exponential notation. Archimedes did not, however, end his days in peace. In fact, he achieved his greatest fame as a warrior. Rome had, during Archimedes’ old age, been at war with Carthage (a city of North Africa) for the second time. The Carthaginian leader was Hannibal, one of the greatest generals of history. He invaded Italy in 218 b .c . and began to enjoy remarkable success. Hieron II had a treaty of alliance with Rome and remained faithful to that treaty. He died, an extremely old man, and a grandson, Hieronymus, ruled in his place. Rome suffered a disastrous de­

ARCHIMEDES

[47]

feat at Cannae and for a time seemed about to be crushed. Hieronymus, anx­ ious to remain on the winning side, switched to that of Carthage. The Romans, however, were not quite through. They sent a fleet, under the general Marcellus, against Syracuse and thus began a strange three-year war of the Roman fleet against one man, Archi­ medes. According to tradition the Romans would have taken the city quite quickly had it not been for the ingenious devices brought against their fleet by the great scientist. He is supposed to have con­ structed large lenses to set the fleet on fire, mechanical cranes to lift the ships and turn them upside down, and so on. In the end, the story goes, the Romans dared not approach the walls too closely and would flee if as much as a rope showed above it, for they were con­ vinced that the dreaded Archimedes was dooming them with some new and mon­ strous device. Much of this was undoubtedly exag­ gerated in the telling, for the later Greeks (such as Plutarch, from whom the story mainly stems) were only too eager to describe how Greek brains held off Roman brawn. Still, the siege was a long one and it was not until 212 b .c . that Syracuse was beaten down. (In 202 b .c . came the final victory of Rome over Carthage; the too-clever Hieronymus had guessed wrong after all.) During the sack of the city, Archi­ medes, with a magnificent and scholarly disregard for reality, engaged himself in a mathematical problem and was bent over the geometrical figures he had marked in the sand. A Roman soldier or­ dered him to come along, but Archi­ medes merely gestured imperiously, “Don’t disturb my circles.” The Roman soldier, apparently a prac­ tical man with no time for fooling, at once killed Archimedes and went on. Marcellus, who had given orders for Archimedes to be taken alive and treated with distinction (an unusual spirit of generosity for that time—or for any time, perhaps), mourned his death and directed that an honorable burial be 31

[48]

ERATOSTHENES

given him. He also went out of his way to treat Archimedes’ relatives kindly. Archimedes’ tomb was lost track of with time. In 75 b .c ., Cicero, the Roman orator, then governing Sicily, reported having found it Since then, it has been lost to sight once more, though in 1965, Italian archaeologists report a find that possibly is the tomb. [48] ERATOSTHENES (er-uh-tos'-thehneez) Greek astronomer Bom: Cyrene (now Shahat, on the Libyan coast), about 276 b . c . Died: Alexandria, about 196 b .c . Eratosthenes, who was educated in Athens, was a friend of Archimedes [47] and a man with interests as universal as those of Aristotle [29]. He was not only an astronomer and geographer, he was also a historian. He attempted to set up a scientific chronology in which all events were dated from the Trojan war; he was the first man in history to con­ cern himself with the matter of accurate dating. He was even a literary critic and wrote a treatise on Greek comedy. In fact, he was known by the nickname of Beta, the second letter of the Greek al­ phabet, for in several of the directions in which he chose to exert his talents, he proved the second best in all the world. He was the ideal scholar to put in charge of the Library at Alexandria, and after he had graduated from the Athe­ nian schools and had turned out some well-regarded writings, he was sum­ moned to Alexandria by Ptolemy III, about 225 b .c ., for precisely that post. He served also as tutor for Ptolemy’s son. In mathematics Eratosthenes worked out a system for determining prime num­ bers that is still called the “sieve of Eratosthenes.” He suggested the intro­ duction of an extra day every fourth year to keep the Egyptian solar calendar in line with the seasons. Egyptian conser­ vatism would not accept that sensible no­ tion and it was not acted upon till the time of Sosigenes [54] a century and a half later. 32

ERATOSTHENES

[48]

In geography he made a map of the known world, from the British Isles to Ceylon and from the Caspian Sea to Ethiopia, that was better than any drawn before him, though it was to be suc­ ceeded by the still better work of Hip­ parchus [50] and Strabo [56] in the course of the next two centuries. In as­ tronomy he worked out the angle of the earth’s axis to the plane of the sun’s ap­ parent motion in the sky and got an al­ most exact value. This is the determi­ nation of the obliquity of the ecliptic. He also prepared a star map that in­ cluded 675 stars. However, the astonishing achievement for which Eratosthenes is best known, and for which he remained insufficiently appreciated until modern times, was that of determining the size of the earth about 240 b .c . To do this, he made note of the fact that on the day of the sum­ mer solstice, the sun was directly over­ head in Syene (the modem Aswan) in southern Egypt at the same time that it was seven degrees from the zenith in Alexandria. This difference could only be due to the curvature of the earth’s sur­ face between Syene and Alexandria. Knowing the actual north-south distance between Syene and Alexandria, it was possible to calculate the diameter of the earth, if one assumed it were a sphere with equal curvature on all parts of its surface. Eratosthenes carried through the cal­ culation and obtained his results in Greek units of distance (“stadia”). We are not certain how long a stadion is in our units. Taking the most probable length, however, it would seem that Eratosthenes calculated the circum­ ference of the earth at a little over twenty-five thousand miles, which is al­ most correct. From this large figure and the comparatively small area of known land, he suspected the various seas to form a single interconnected ocean, a suspicion that proved true but was not verified till the voyage of Magellan [130] eighteen centuries later. Unfortunately this figure seemed too large to the ancients. It meant that the known world occupied only a small por­ tion of the earth’s total surface, not more

[49]

APOLLONIUS

than a quarter, and much of that quar­ ter was sea. The other three quarters ei­ ther contained other lands, unknown and unheard of, or were entirely water. Both alternatives seemed hard to accept, and the smaller value for the earth’s circum­ ference, worked out by Poseidonius [52], was accepted by the ancients in prefer­ ence. At the age of eighty, Eratosthenes, blind and weary, died of voluntary star­ vation. [49] APOLLONIUS (ap-uh-loh'nee-us) Greek mathematician Born: Perga (on what is now the southern coast of Turkey), about 262 b .c . Died: Alexandria, Egypt, about 190 b .c . Apollonius was educated at the Mu­ seum, possibly studying under Archi­ medes [47], and, in the tradition of Eu­ clid [40], wrote an eight-book treatise (of which the first seven books survive) on the “conic sections.” These books, which gained him the title of the Great Geometer, include three curves, ellipse, parabola, and hyperbola, with which Eu­ clid did not deal. All of these can be produced by cutting through a cone at particular angles (hence, “conic sec­ tion”). For many centuries Apollonius’ conic sections seemed merely the play of math­ ematical ingenuity without practical ap­ plication. In the time of Kepler [169] and Newton [231], however, eighteen centuries later, it was found that the or­ bits of heavenly bodies were not neces­ sarily circles at all but could follow a path described by any of the conic sec­ tions. The most familiar heavenly bodies, the various planets and satellites, includ­ ing the moon and the earth itself, travel in ellipses. Apollonius may have tried to compro­ mise the views of Aristarchus [41] and Eudoxus [27] by supposing the planets to revolve about the sun, and the sun with its attendant planets to revolve about the earth. This was similar to the compro­

HIPPARCHUS

[50]

mise of Tycho Brahe [156] eighteen cen­ turies later, and was just as unsuccessful. Late in life, Apollonius left Alexandria for Pergamum, a city in western Asia Minor which at this time had a library second only to that of Alexandria. He was the last topflight mathe­ matician of the ancient world. [50] HIPPARCHUS (hih-pahrikus) Greek astronomer Born: Nicaea (now Iznik, in northwest Turkey), about 190 b .c . Died: about 120 b .c . Hipparchus was the greatest of the Greek astronomers as Archimedes [47] was the greatest of the Greek mathe­ maticians, and, like Archimedes, Hip­ parchus was unusual in that he did not work at Alexandria, although he may have been educated there. He set up his observatory at Rhodes, an island in the southeastern Aegean, and invented many of the instruments used in naked-eye as­ tronomy for the next seventeen cen­ turies. Hipparchus carried on the work of Aristarchus [41] measuring the size and distance of the sun and moon. He not only made use of Aristarchus’ lunar eclipse method, but also determined the moon’s parallax. We all experience parallax when we note the apparent shift of the position of a near object com­ pared with a far one when we change our own position. (From a train window we can see the trees nearby move against the background of the trees farther off.) The angle through which the near ob­ ject shifts depends both upon the size of your own change of position and upon the distance of the near object. If you know the amount by which you have shifted, you can calculate the distance of the object. To do this, you must know the ratios of the sides of a right triangle for the various angles the sides make with the hypotenuse. The theory was known and some mathematicians man­ aged to work with such ratios. Hip­ parchus, however, was the first to work out an accurate table of such ratios 33

[50]

HIPPARCHUS

and is therefore usually considered the founder of trigonometry. By measuring the position of the moon against the stars under appropriately changing conditions, the moon’s parallax can be determined and its distance calcu­ lated. He found that distance to be thirty times the diameter of the earth, which is correct. If anyone had used the value for the earth’s diameter as determined by Eratosthenes [48], the moon would be shown to be about a quarter million miles from the earth. Unfortunately no other heavenly body is as close to the earth as the moon, and none, therefore, shows so large a paral­ lax. Before the invention of the tele­ scope, no other heavenly body showed a parallax large enough to be measured. The moon, therefore, remained the only heavenly body with a known distance from the earth for nineteen centuries after Hipparchus. In 134 b .c . Hipparchus observed a star in the constellation Scorpio of which he could find no record in previous observa­ tions. This was a serious matter. Nowa­ days we know that stars, ordinarily too faint to be seen with the naked eye, do occasionally explode, increase in brightness, and become visible, but in Greek times no such thing was imagined. Instead there was the definite belief that the heavens were permanent and un­ changeable. Hipparchus could not easily tell whether this star was an example of the contrary because of the unsystematic nature of previous observations. He de­ cided then that future astronomers would not suffer similar difficulties if a new star should appear and proceeded to record the exact positions of a little over a thousand of the brighter stars. This was the first accurate star map and far outclassed the earlier efforts of Eudoxus [27] and Eratosthenes. In order to make his map he plotted the position of each star according to its latitude (angular distance north or south of the equator) and longitude (angular distance east or west of some arbitrary point). It was an easy analogy to plot positions on the earth’s surface in the same way. Latitude and longitude had been used on maps before, notably by 34

HIPPARCHUS

[50]

Dicaearchus [33] a century and a half before, but with Hipparchus they be­ came the organized gridwork that they have remained to this day. Hipparchus’ star map led to another important discovery, for in comparing his observations with those he could find among the reports of his predecessors, he found a uniform shift from west to east. He could account for this by supposing that the north celestial pole moved in a slow circle in the sky, completing one cycle in 26,700 years. This meant the equinox arrived a trifling bit earlier each year and the effect was called the “precession of the equinoxes.” It was not until the time of Copernicus [127] that it was shown that the reason for this mo­ tion was a slow wobble of the earth upon its axis, rather than the star’s movement. And it required Newton [231] eighteen centuries after Hip­ parchus to explain the cause of the precession. Hipparchus was also the first to divide the stars into classes depending on their brightness. The twenty brightest stars of the sky are of “first magnitude.” Then, in order of decreasing brightness there are second, third, fourth, and fifth mag­ nitudes, while those of the sixth magni­ tude are just visible to the naked eye. This system has been kept (although refined and extended) to the present day. Hipparchus’ most ambitious achieve­ ment, however, was to work out a new scheme of the universe, replacing that of Eudoxus. The work of Callippus [32] and Aristotle [29] had filled the heavens with a large number of spheres and the system had become unwieldy. Hip­ parchus therefore tackled the matter from a fresh viewpoint, one that had been suggested, but not developed, by Apollonius [49] a half century before. Hipparchus reduced the number of heavenly spheres within the outermost starry celestial vault to seven, one for each of the planets. The individual planet, however, was not actually part of the sphere. It was part of a smaller sphere and it was the center of that smaller sphere that was on the main sphere. The planet moved in a circle as the small sphere turned, and it also

[50]

HIPPARCHUS

moved along in a larger circle as the center of the small sphere turned as part of the large sphere. The large sphere was the “deferent,” the small sphere the “epi­ cycle.” By adjusting the speeds of the two spheres, by piling smaller epicycle upon larger epicycle, the actual motion of the planet could be duplicated. Hipparchus also helped matters by introducing the notion of the eccentric; that is, the sug­ gestion that a planet did not move about the earth’s center, but about a fictitious point in space that was near the earth’s center, and this fictitious point in turn revolved about the earth’s center. The Hipparchian scheme of the uni­ verse was highly complicated but it pre­ served the axioms of Plato and Aristotle, to the effect that the earth was the un­ moving center of the universe, and that the planets moved in combinations of circles. Actually it might seem as though the Aristarchean view of the planets revolv­ ing about the sun was much simpler in concept and that it ought to have won out. This is not so. In the first place it was hard to think of the whole earth flying through space (unless you are taught it is so when you are a child and will believe anything). In addition the Hipparchian scheme was useful and the Aristarchean was not. The changing po­ sition of the planets was important for ritualistic reasons and in astrology, and what Hipparchus had done was to pro­ duce a mathematical system for calcu­ lating the positions of the planets at any given future time. His scheme of epicycles, deferents, and eccentrics helped him perform his calculations, like the construction lines drawn on geometric figures to help ar­ rive at the proof of a theorem. Looking back at it now, we realize there was no reason to think the “construction lines” were real, but for some sixteen centuries astronomers insisted on thinking they were. Whether the construction lines were real or not, however, Hipparchus’ methods of calculating planetary posi­ tions worked. On the other hand, the views of Aris­ tarchus in which the planets circled the

POSEIDONIUS

[52]

sun were merely a pretty picture. The system was not, to our knowledge, worked out mathematically to yield pre­ dictions of planetary positions. Therefore the scheme was not useful. When Copernicus finally did work out the mathematics of the Aristarchean uni­ verse, the Hipparchian universe was doomed. [51] SELEUCUS (see-lyoo'kus) Greek astronomer Born: Seleucia (on the Tigris River), about 190 B.c. Died: date unknown A contemporary of Hipparchus [50], Seleucus was far the inferior, but he was the one astronomer of note who cham­ pioned the notions of Aristarchus [41] concerning the position of the sun at the center of the planetary system. Hip­ parchus, with his earth-centered system, won out temporarily (if eighteen cen­ turies can be considered temporary), but it was Seleucus who was right just the same. Seleucus groped toward an explanation of the tides, feeling that the moon was responsible and noting that the tides did not come at the same time or in the same manner in different parts of the world. He was hampered here by his re­ fusal to accept Eratosthenes’ [48] view that the earth’s oceans formed a single, interconnected body of water. In this case, he joined Hipparchus in being wrong. Because Seleucus lived in Babylonia, he was commonly called a Chaldean or Babylonian, but he was probably part Greek in descent at least. [52] POSEIDONIUS (pos-ih-doh'nee-us) Greek philosopher Born: Apamea, Syria, about 135 B.C. Died: a b o u t 50 b .c . Poseidonius was a Stoic philosopher who studied at Athens, later headed a school at Rhodes and had great and influential friends among the Romans. 35

[52]

POSEIDONIUS

Cicero and Pompey were among his pu­ pils. Some of his scientific researches were valuable, for he, like Pytheas [39] two and a half centuries earlier, believed the moon caused the tides and he trav­ eled west to the Atlantic Ocean to study them. He also worked out a size for the sun that was larger (and therefore closer to the truth) than that proposed by any other ancient astronomer, even Aris­ tarchus [41], and was the first astrono­ mer to take into account the refraction of the atmosphere in making his obser­ vations. He tried, like Aristotle [29] and Eratosthenes [48] before him, to take all knowledge for his province but was less successful, partly because of the accumu­ lation of knowledge in the two centuries since Aristotle. However, his real importance in his­ tory lies in an erroneous determination he made. He repeated the work of Eratosthenes in determining the size of the earth. He used the position of the star Canopus in place of the sun, which was, indeed, an improvement over Eratosthenes. Poseidonius, however, ap­ parently neglected, in this case, to allow for the shift in the star’s position with atmospheric refraction of light and he therefore obtained the too-low figure of eighteen thousand miles for the earth’s circumference. (It is also possible that Strabo [56], the only source we have for this, for Poseidonius’ own works have not survived, misquoted him a half cen­ tury later.) However that might be, Ptolemy [64] accepted the lower figure in preference to Eratosthenes’ value, and the world of scholarship went along with that decision until the beginning of modem times. Columbus [121], for instance, was en­ couraged to sail westward from Spain because he believed the lower value and thought Asia lay only three or four thou­ sand miles westward. Had he known that Eratosthenes was correct and that it lay twelve thousand miles westward, he would probably never have dreamed of sailing, and if he had, he would certainly have got no one to finance him. In addition Poseidonius helped popu­ larize the doctrines of astrology (that planetary positions influence human 36

LUCRETIUS

[53]

affairs) and make them respectable. Plato [24] was mystical enough to lean in that direction, but astronomers such as Eudoxus [27] had opposed it. With Poseidonius, astrology won and its perni­ cious influence over true astronomy was to endure seventeen centuries, into the time of Kepler [169]. [53] LUCRETIUS (lyoo-kree'shee-us); in full, TITUS LUCRETIUS CARUS Roman philosopher and poet Born: Rome, about 95 b .c . Died: Rome, a b o u t 55 b .c . From 200 b .c . onward, Rome domi­ nated the Mediterranean world politi­ cally, militarily, and economically, but never intellectually. Leadership in sci­ ence was left in Greek hands to the very end of ancient times. When Roman thinkers did concern themselves with sci­ ence, it was as transmitters rather than as originators. Lucretius was the best of these. He was a convinced and ardent follower of Epicurus [35], In his book De Natura Rerum (“On the Nature of Things”), published in 56 b . c ., he expounded a mechanistic Epicurean view of the uni­ verse in a long poem. Lucretius held that all things were composed of atoms, quite in line with the theories of Democritus [20], and this he carried to the ultimate extreme. Even such immaterial objects as the mind and soul, said Lucretius, are made up of atoms, which are, however, finer than the atoms making up gross material things. Lucretius did not deny the existence of gods, but held that they too were com­ posed of atoms and that they did not concern themselves with the affairs of men. Nor did he believe in a life hereaf­ ter, but considered death the prelude to peaceful nothingness and therefore not to be feared. Lucretius envisaged an evolutionary universe, one that developed slowly to its present state, physically, biologically, and sociologically—quite a modem view. He was the first to divide human history, for

[54]

SOSIGENES

instance, into a Stone Age, a Bronze Age, and an Iron Age. Nothing is known of his life except what is drawn from a small handful of references from later writers. From Saint Jerome, writing four and a half centuries later, we learn that he had intervals of insanity, and he is supposed to have died a suicide during one of them, brought on perhaps by a love philter given him by his wife. It is doubtful whether we ought to ac­ cept this, although it is constantly being cited. There is no reference to this ear­ lier and it may have been a tale invented out of distaste for the man and out of a kind of glee that his end should have been so un-genteel. After all, Lucretius was the boldest spokesman in the ancient world of antireligious views. His book was specifically intended to lift what he considered the burden of religious fears from the backs of mankind. He was in­ deed a lonely voice crying in the wilder­ ness in this respect and the pious of an­ cient times viewed him much as those of later times viewed Voltaire [261]. Lucretius’ poem barely survived. It was lost throughout the Middle Ages. A single surviving manuscript was discov­ ered and popularized in 1417 and soon after Gutenberg’s [114] invention of printing, the poem was printed in full and sown broadcast. In this way, Lucre­ tius acted as the transmitter of the no­ tion of atomism from Democritus to Dalton [389] by way of Gassendi [182], [54] SOSIGENES (soh-sij'ih-neez) Greek astronomer Born: about 90 b .c . Died: date unknown Although the Greeks developed mar­ velous mathematical interpretations of a geocentric universe, thanks to Hip­ parchus [50], their calendar remained a primitive one, based on the lunar month and the cycle of Meton [23], The Egyptians had early abandoned the lunar calendar in favor of a solar calendar based on twelve 30-day months plus five extra days. The overall length of such a year, 365 days, was a quarter

VITRUVIUS

[55]

day less than the true year, so that the Egyptian year fell one day behind the sun every four years and made a com­ plete cycle in 1460 years. In Ptolemaic times, the Alexandrian astronomers tried to establish a 36534-day year, but Egyp­ tian conservatism rebelled. The chance came with the Romans. The Roman lunar calendar had fallen into complete chaos because the priests in charge had manipulated it for political reasons, in order to alter the time in office of various functionaries. Julius Caesar accepted the advice of Sosigenes and in 46 b .c . established the Julian Cal­ endar, which consisted of a 365-day year three times in a row to be followed by a 366-day leap year. With minor modifica­ tions, this has lasted until now. Nothing else is known of Sosigenes ex­ cept that he wrote some treatises on as­ tronomy which are now lost and that he mentioned the belief that Mercury re­ volved about the sun. [55] VITRUVIUS (v i-tro o 'v e e-u s) ; in full, MARCUS VITRUVIUS POLLIO Roman a rch itect Born: a b o u t 70 b .c . Died: a b o u t 25 B.C. Virtually all that is known of Vi­ truvius’ life is that he served as a mili­ tary engineer in Africa under Julius Cae­ sar. The Romans are renowned as a “prac­ tical” people, more interested in en­ gineering and applied science than in high-flown speculations of the Greek type. It is interesting, then, that Vi­ truvius, who put out a large volume on architecture, refers constantly to Greek science and scientists, recognizing ap­ parently that engineering rests on sci­ ence. Nor did he underestimate the Greek engineers, for he speaks highly of Ctesibius [46], for instance. Vitruvius’ book remained the chief reference on architectural matters well into the Italian Renaissance. What’s more, he went beyond a mere consid­ eration of architecture in his book. He discussed astronomy, dealt with acous­ 37

[56]

STRABO

CELSUS

[57]

tics, described the construction of vari­ ous sundials and water wheels, and discussed theories that Mercury and Venus went about the sun, without, how­ ever, mentioning the name of Heracleides [28] in that connection. Where the Greek astronomers might conceiv­ ably have viewed the planetary spheres as abstractions, Vitruvius’ intensely prac­ tical mind considered them real and ma­ terial. He envisaged the earth’s axis as set in bearings. On the other hand, he treated the dis­ covery of fire from the scientific rather than the mythological standpoint and recognized the prime importance of that discovery in the history of mankind. Yet, even though Vitruvius' appreci­ ation of Greek science was great and his transmission thereof unusually accurate for a Roman writer, he did make mis­ takes. He gave 3% as the value of pi, and this was less accurate than the value worked out by Archimedes [47] two cen­ turies earlier.

ular value because it is the only geogra­ phy that survives from antiquity and we know of earlier work chiefly through his book. He recognized Vesuvius as a volcano. (It did not erupt in the memory of man until the time of Pliny [61] about half a century after Strabo’s death.) Strabo also discussed the land-forming activity of rivers. He accepted Eratosthenes’ view of the size of the globe and was impressed by the small portion of the earth’s globe covered by the known world. He suggested the existence of unknown con­ tinents, therefore, and this suggestion was to haunt the world for fifteen cen­ turies, till the time of Columbus [121]. He divided the known world into frigid, temperate, and tropic zones, a division we still use. In middle age he settled in Rome, which, after the destruction of Carthage, was rapidly becoming all-powerful in the Mediterranean area. He wrote a long history of Rome but this work has not survived.

[56] STRABO (strayffioh) Greek geographer Born: Amasya, Pontus (about 75 miles south of what is now the Black Sea coast of Turkey), about 63 b .c . Died: about a .d . 25 Strabo, the son of wealthy parents, traveled widely and, in fact, boasted that no geographer had traveled more widely than he. For instance, he traveled up the Nile to the borders of Nubia in 25 b . c . He based his geography (in seventeen volumes, all but one of which is pre­ served) on Eratosthenes [48], to whom, however, he was inferior in mathematics. Because of this, his descriptions quickly become distorted as he leaves the Medi­ terranean area, for his manner of con­ verting from a sphere to a plane is inac­ curate. His work also suffered because he insisted on considering Homer to be accurate and disregarded the better data to be found in Herodotus. His work represents the first attempt to collect all geographical knowledge into a single treatise and possesses partic­

[57] CELSUS, Aulus Cornelius (sel'sus) Roman encyclopedist Born: about 10 B.C. Died: date unknown Celsus, a member of one of the most blue-blooded of the Roman families, gathered together the knowledge and learning of the Greeks and epitomized them for the delectation of the Roman audience. He did so in eight books of el­ egant Latin that eventually earned him the title of the Cicero of Medicine. The “of medicine” comes about be­ cause. by chance, all that has survived of his writings are those concerned with medicine. His books contain a good de­ scription of tonsillectomy and a number of other operations. His books are also the first to discuss heart attacks and in­ sanity in recognizable fashion. He also wrote on dentistry and described the use of the dental mirror. He also described the “cataract,” a condition in which the lens of the eye grows opaque. Celsus’ book was probably drawn for the most part from the collection of writings of

38

[58]

MELA

the school of Hippocrates [22], In fact, he has also been called the Roman Hip­ pocrates. Celsus and his book had an odd echo in early modem times. After being snubbed as a mere popularization in an­ cient times and being totally lost in the Middle Ages, a copy of the medical por­ tion of his book was discovered in 1426 and an edition was printed in 1478, just at the time when medicine was reviving under the humanistic impact of the Re­ naissance. Its Latin terminology made use of numerous anatomical terms, such as cartilage, abdomen, tonsil, vertebra, anus, and uterus. In addition Celsus gained a sudden reputation as a physi­ cian of extraordinary merit (the men of the Renaissance regarded the ancient thinkers with an exaggerated venera­ tion). As a result, some half century after the edition appeared, an eccentric alche­ mist with new theories of medicine adopted the nickname of Paracelsus, which means “beyond Celsus” or “better than Celsus.” There is no question that the name of Celsus remains in the mod­ em consciousness almost entirely as the result of being a part of the name of Paracelsus [131]. [58] MELA, Pomponius (mee'luh) Roman geographer Born: Tingentera, Spain, about 5 B.C. Died: date unknown Mela is known only for a small geog­ raphy book, written a .d . 43 or 44, which was probably intended for popular read­ ing among the general Roman public. It borrowed from the Greek geographers but left out all the mathematics. How­ ever, since it was the one ancient book of geography that was written in Latin, it was particularly important throughout medieval times. In fact, its ideas re­ mained in force until the beginning of the age of exploration some thirteen cen­ turies after the time of Mela. Mela divided the earth into five zones, following Strabo [56], a division we keep right down to the present: North Frigid,

DIOSCORIDES

[59]

North Temperate, Torrid, South Tem­ perate, and South Frigid. Of these, Mela considered only the Temperate zones to be habitable. The known world of the time was located in the North Temperate Zone and Mela believed, by analogy (al­ ways a dangerous route to a conclusion), that a similar world must exist in the South Temperate Zone. This southern land area, though habitable, was forever barred to the men of the north by the burning impenetrable heat of the Torrid Zone. After the Torrid Zone was found to be passable in early modem times, the southern world of Mela was persistently searched for down to the days of Cap­ tain Cook [300]. (Note: From this point on, all dates are a .d . unless specifically noted to be otherwise.) [59] DIOSCORIDES (dy-os-koFih-deez) Greek physician Born: Anazarbus (near Adana, in what is now Turkey), about 20 Died: date unknown Dioscorides was a surgeon who served with the Roman armies under Nero. His chief interest lay in the use of plants as a source of drugs. In this connection he wrote De Ma­ teria Medica in five books, and this was the first really systematic pharmacopeia. It at once replaced the work of Diodes [34] which was primitive in comparison. Dioscorides was an objective observer and both his botanical and pharma­ cological details are accurate and free of superstition. The work, which deals with about six hundred plants and nearly a thousand drugs, was preserved by the Arabs and when translated into Latin served as an inspiration for later botanical research. It finally appeared in a printed edition in 1478. Dioscorides reported the condensation of mercury on the underside of the lid of the container holding it. Some think this observation eventually led to the tech­ 39

[60]

HERO

PLINY

[61]

nique of distillation, in which a liquid is exist and nonslave labor was getting heated and the vapors condensed and more expensive. stored separately. Hero wrote on mechanics, describing the various simple machines (lever, pul­ ley, wheel, inclined plane, screw, wedge) by which effort could be properly chan­ [60] HERO neled and magnified. He made it quite Greek engineer clear that when a force was magnified it Born: about 20 was at the expense of exerting that Died: date unknown magnified force through a corre­ spondingly shortened distance. This was After 150 b .c . Ptolemaic Egypt fell an extension and generalization of Ar­ into decay and by 30 b .c . it had become chimedes’ [47] law of the lever. a Roman province. The great days of In constructing his ingenious devices, Alexandria—and, indeed, of Greek he made use of syphons, syringes, and science—were over. Nevertheless the gears. He used gears, for instance, in curtain did not go down abruptly. There converting wheel revolutions of a chariot were fitful flashes of genius for some to the revolutions of a pointer—a primi­ centuries. tive taximeter. One of those flashes was that of Hero, Hero wrote a book on air that was far who displayed an almost modern apti­ in advance of his time. He demonstrated tude for mechanics. Almost nothing, air was a substance by showing that however, is known of his personal life, water would not enter a vessel already not even, until recently, the century in filled with air unless the air was allowed which he lived. It has been pointed out, to escape. He also maintained, from the however, that a lunar eclipse referred to fact that air was compressible, that it in his writings was visible in Alexandria must be made up of individual particles in 62. We might guess then that he was separated by space. Here was the born about 20. atomism of Democritus [20] again. This He is most famous for his invention of matter of the compressibility of air made a hollow sphere to which two bent tubes no impression on scholars generally in were attached. When water was boiled in Hero’s time, but it was to come up the sphere, the steam escaped through again, more forcefully, fifteen hundred the tubes and as a result of what we now years later with Boyle [212] and his call the law of action and reaction (not successors. stated explicitly until Newton [231]) the Hero also wrote a book on mirrors sphere whirled rapidly about. This was and on light. He felt that vision resulted an early method of converting steam from the emission of light by the eyes power to motion and it is often called a and that these light rays traveled at steam engine. The device is still used as infinite velocity. These conclusions were a rotating lawn sprinkler, in which jets incorrect, but he also said that the angle of water, rather than of steam, are the at which a light ray struck a reflecting surface was equal to the angle at which motivating force. The principle of steam power was es­ it was reflected, and that was correct. tablished, but it was put to use only in the automatic workings of doors and statues (by means of which priests might impose on gullible worshipers), in toys [61] PLINY (plih'nee); in full, GAIUS to amuse children, and so on. The idea PLINIUS CECILIUS SECUNDUS, the Elder of utilizing the energy implicit in inani­ Roman scholar mate nature as a substitute for strained and aching slave muscle seemed to occur Born: Novum Comum (modem Como), Italy, 23 to no one. The idea was not to arise for Died: near Mount Vesuvius, seventeen centuries after Hero and then Italy, August 25, 79 only in regions where slave labor did not 40

[61]

PLINY

Pliny was a man of universal interests and universal curiosity. He had ample opportunity for indulging these in the Rome of his day, for the empire was in its full flush of power. In military service he commanded troops in Germany and had a chance to explore various regions of Europe. He returned to Novum Comum in 52, studied law, and settled down to writing and scholarship. He was an intimate friend of Vespa­ sian, who became Roman emperor in 69. In 70 Pliny was appointed governor over a section of Gaul, and in 73 over a sec­ tion of Spain. Finally he was placed in charge of the Roman home fleet and this, indirectly, proved fatal to him. The fleet was stationed at the naval base at Misenum, just northwest of the Bay of Naples, when in 79 the nearby volcano of Vesuvius erupted, burying Pompeii and Herculaneum. In his eagerness to witness the eruption, Pliny went ashore and delayed too long in retreating from the ashes and vapor. He was found dead afterward. Pliny is the very model of the compul­ sive worker. If he wasn’t reading or hav­ ing books read to him, he was taking notes or writing. He hated sleeping and he considered walking a waste of time, because, if he drove, he could write at the same time. Even in the army he managed to find time to write a history of the Germanic wars and to put down observations on the manner of hurling weapons while on horseback. He scrib­ bled voluminously, and his major work, Natural History, included in thirty-seven volumes a complete summary of ancient knowledge concerning the world. It was first published in 77 and was dedicated to the Emperor Titus, son of Vespasian. Pliny’s Natural History was secondary —a digest drawn from two thousand an­ cient books by nearly five hundred writers. In preparing his digest, Pliny was completely credulous and undiscrim­ inating. If anything interested him, it went in, regardless of its plausibility, though occasionally he did draw the line. He refused to accept the possibility of immortality, for instance. And some­ times the implausible was correct, like Pytheas’ [39] theory that the moon was

FRONTINUS

[62]

responsible for the tides, which Pliny re­ fused to accept. Again, he described the origin of amber correctly, but only after he had also included all the wrong and fanciful theories on the subject that had been advanced. The book dealt with astronomy and geography, where he accepted the sphe­ ricity of the earth, but its major concern was zoology and it was here that he went hog-wild. His tales of monsters and won­ ders lingered on through the Middle Ages under the guise of sober science. He described men without mouths who lived by inhaling the perfumes of flowers; men with large feet, which they used as umbrellas to shade themselves from the heat of the sun; unicorns; mer­ maids; flying horses; and so on. (In Othello, Othello charms Desdemona with tales of wonders taken straight out of Pliny.) The unifying thread throughout Pliny’s work was that of anthropocentrism. Man was the measure of everything; all was designed for the use of men. A plant had to be useful as a food or as a drug; an animal as a food or as a servant. If a plant or animal seemed of no material use to man (or even a danger) then its life and habits taught a moral lesson. To this view the early Christians were sympathetic and this helps to explain the survival of the work. And although Pliny contains more errors per square foot than any other ancient author, he did perform the very useful service of main­ taining, through medieval times, a sense of the wonder and majesty of the natural world. After all, while food for curiosity is supplied, there is always the hope that observation and research will rise anew and that error will be corrected. [62] FRONTINUS, Sextus Julius (fronty'nus) Roman administrator Born: about 30 Died: 104 Frontinus served as governor of Brit­ ain, and during his term of service sub­ dued the hardy tribes of what is now southern Wales. His military career over, 41

[63]

TSAI LUN

he wrote on many branches of applied science—on land surveying and military science, for instance. These books do not survive. In 97 the Emperor Nerva put him in charge of the water system of Rome. As a result, he published a twovolume work describing the Roman aqueducts, probably the most informa­ tive work we possess on ancient en­ gineering. He proudly pointed out the superiority of these useful aqueducts as compared with the useless engineering feats of the Egyptians and the Greeks. However, Roman engineering had al­ ready peaked and the long, slow decline was beginning, with a new period of ad­ vance not slated to begin for sixteen weary centuries. [63] TSAI LUN (tsy loon) Chinese inventor Born: Kueiyang, Kweichow, China, about 50 Died: about 118 Tsai Lun was a eunuch; the only one, perhaps, who can claim a key position in the history of science. Only one deed is recorded of him in the ancient Chinese histories, but that one deed is enough, for in 105 he is sup­ posed to have invented the making of paper from such substances as tree bark, hemp, and rags. Slowly, in the centuries afterward, the secret of papermaking spread westward. It reached Baghdad by a .d. 800 and Europe after the Crusades. It was in time to serve as the material of which to make the flood of books pro­ duced by the printing press invented by Gutenberg [114], thirteen centuries after Tsai Lun’s time. No substance, in the nineteen centuries since Tsai Lun’s time, has come along to supplant paper. [64] PTOLEMY (tol'uh-mee; Latin name), CLAUDIUS PTOLEMAEUS Greek astronomer Born: Ptolemais Hermii (?), about 100 Died: about 170 42

PTOLEMY

[64]

Ptolemy may have been an Egyptian rather than a Greek. He was not a member of the royal family of the Ptole­ mies that ruled Egypt a half century be­ fore his birth but may have attained his name from his supposed birthplace. Some traditions place him at Alexandria over a forty-year period, others say that he died at the age of seventy-eight. As you see, nothing is known of his private life, even his nationality, that goes be­ yond conjecture. As in the case of Euclid [40], Ptolemy is not important for his own work, but rather for the grand synthesis he pro­ duced. He drew principally on the work of Hipparchus [50], but since virtually none of the latter’s writings survive, the sys­ tem of the universe that he obtained from Hipparchus is universally referred to now as the Ptolemaic system. (Some, in fact, go so far as to suppose that Ptolemy was little more than a copyist of Hipparchus. This is probably too ex­ treme, however.) In the Ptolemaic system, the earth is at the center of the universe and the vari­ ous planets revolve about it. The planets, in order of increasing distance from the earth, are the moon, Mercury, Venus, the sun, Mars, Jupiter, and Saturn. To account for their actual motions as seen in the sky, Hipparchus’ epicycles and ec­ centrics are used, and Ptolemy very likely added a few refinements of his own. The Ptolemaic system could be used to predict the positions of the planets for some time into the future and with an accuracy that was good enough for rea­ sonable naked-eye observation. It was not until the time of Tycho Brahe [156], fourteen centuries later, that observa­ tions of the planets were made with sufficient accuracy to require a theory better than Ptolemy’s. In his book Ptolemy also included a star catalogue based on Hipparchus, listed forty-eight constellations to which he gave the names we still use today, and preserved and extended the work of Hipparchus on trigonometry. He even described instruments to be used in as­

[65]

GALEN

GALEN

[65]

and told him to make a physician of his son. He did. Galen spent his youth traveling about the eastern provinces of the Roman Em­ pire, receiving his education. He even visited the medical school at Alexandria. About 159 he was appointed physician to the gladiatorial school at Pergamum, which gave him ample opportunity for some rough and ready observations in human anatomy. In 161 he settled in Rome and spent most of his active life in that city, where for a time he was court physician under the emperor Marcus Aurelius. He was close, also, to two later emperors, Cornmodus and Septimius Severus. Galen’s best work was in anatomy. The dissection of human beings had fal­ len into disrepute and Galen’s work was confined to animals, including dogs, goats, pigs, and monkeys. What he saw, he described with great and meticulous detail, but of course not everything he saw was applicable to human anatomy. For instance, he carefully described a network of blood vessels under the brain, present in many animals but not in man, and assigned it an important role in his scheme of the functioning of the human body. Nevertheless, he did particularly good work on muscles, identifying many for the first time. He noted they worked in teams. He also showed the importance of the spinal cord by cutting it at various levels (in animals) and noting the extent of the resulting paralysis. Galen developed an overall system of physiology that was based to a great ex­ tent on the three-fluid theory of Erasistratus [43]. Galen recognized that the fluid in the left half of the heart must get to the right half somehow and postulated the presence of tiny holes, too small to [65] GALEN (gayflen) see, in the thick muscular wall separating Greek physician Born: Pergamum (now Bergama, the two halves. In this way he missed the true explanation of the circulation of the in Turkey), about 130 blood. On the other hand, he was the Died: probably in Sicily, about first to use the pulse as a diagnostic aid, 200 and he described the flow of urine Galen’s father had been an architect. through the ureters to the bladder. Tradition has it that Asklepios, the god He was a prolific writer who engaged of medicine, came to him in a dream in polemics with other physicians,

tronomic observations. His book was called by the admiring generations that followed Megale mathematike syntaxis (“Great mathematical composition”). Sometimes they said Megiste (“Great­ est”) rather than Megale. After the fall of the Roman Empire, Ptolemy’s works survived among the Arabs, who adopted the Greek word and called the book “The Greatest” using their own al, meaning “the.” The book thus became the Almagest and has re­ mained so ever since. The Arabic ver­ sions of the book were finally translated into Latin in 1175, and dominated Euro­ pean astronomical thinking through the Renaissance. For instance, Ptolemy accepted Hip­ parchus’ correct estimate of the distance of the moon, and also Aristarchus’ [41] incorrect estimate of the distance of the sun. The latter estimate held the field till the time of Kepler [169]. He also treated astrology seriously, following Poseidonius [52] in this respect and this helped that pseudoscience gain a respect it did not deserve. Ptolemy wrote a book on optics in which he discussed the refraction of light and he also wrote a book on geography based on the marchings of the Roman le­ gions through the known world. He in­ cluded maps and painstakingly prepared tables of latitudes and longitudes. How­ ever, he made a serious error in accept­ ing Poseidonius’ rather than Eratosthe­ nes’ [48] estimate of the earth’s size. The geography was translated into Latin, thirteen centuries later, just in time to persuade Toscanelli [113] and, through him, Columbus [121] of the feasibility of a westward voyage from Europe to Asia.

43

[6 6 ]

DIOPHANTUS

thought little of Hippocrates [22], and showed a rather unattractive side to his character in his arrogance, disputa­ tiousness, and pompous self-esteem. He was violently anti-atomist and this helped keep the views of Democritus [20] submerged until modern times. Galen lived at a time when Chris­ tianity was rising in power, and although he was not himself a Christian he de­ veloped a form of monotheism. He believed, somewhat as Pliny [61] did, that everything in the universe was made by God for a particular purpose. This search for design and purpose in the universe and particularly in the human body made his works popular with Christians and ensured the survival of many of his books through the Middle Ages. Galen’s works, then, were the ultimate medical authority for Europeans until the time of Vesalius [146] in anatomy and Harvey [174] in physiology. [66] DIOPHANTUS (dy-oh-fan'tus) Greek mathematician Born: about 210 Died: about 290 The great glory of Greek mathematics was geometry and its great shortcoming was the lack of algebra. It was only in the late twilight of ancient Greek science that a mathematician erased that short­ coming. Nothing is known of Diophantus but his work, not even the century in which he lived. The year of birth given here, 210, is one guess. Others have placed it as early as 50. One problem associated with him requires that his age be de­ duced from data given. If that is autobi­ ographically accurate, he may have lived to be eighty-four. Diophantus solved problems by means of what we would now call algebraic equations, working out a symbolism of his own. His works were preserved by the Arabs and were translated into Latin in the sixteenth century, when they served as inspiration for the great al­ gebraic advances that began at that time. 44

ZOSIMUS

[67]

He is best known for his work with equations for which solutions in terms of integers are required. Sometimes the equation is indeterminate, that is, has no single set of solutions. It has, instead, more than one or even an infinite num­ ber. These are still called Diophantine equations. Diophantus was the first Greek to treat fractions as numbers. [67] ZOSIMUS (zoh'si-mus) Greek alchemist Bom: Panopolis (modern Akhmim), Egypt, about 250 Died: date unknown While the Greeks excelled in mathe­ matics and in abstract schemes of the universe, the Egyptians dealt in a practi­ cal way with materials. This interest in what we would today call chemistry arose, perhaps, out of their efforts to preserve the human body after the death through mummification. After the time of Alexander the Great, Egyptian practice fused with Greek theory to form the science of “khemia.” (Some people find the source of this word in khem, the Egyptian word for land. It means “black” and refers to the fertile black soil watered by the Nile floods, as compared with the tawny soil of the desert areas beyond.) The Arabs eventually inherited this science and placed al (“the”) before the name, so that it became “alchemy.” Very little of the original Greek or Egyptian writings on alchemy survive, but about three hundred, the entire range of alchemical knowledge, were summarized by Zosimus (concerning whose personal life nothing is known) in an encyclopedia made up of twenty-eight books. These books are a riot of mysticism. This is perhaps understandable. If al­ chemy was indeed born of Egyptian mummification procedures, then it began in close association with religion. It was a form of knowledge that would natu­ rally be considered sacred and of pecu­ liar interest to the priestly class. It would

[6 8 ]

PAPPUS

become habitual to discuss it in a jargon that would exclude the uninitiated. It is possible to find, among the ob­ scure references of Zosimus, passages that indicate he may have known of ar­ senic. Also, he seems to have described the formation of lead acetate and to have known of its sweet taste. (It is called “sugar of lead” even today.) The Greek theories of the four ele­ ments led alchemists to think that it was possible to rearrange the elements in a base metal such as lead to form the noble metal gold. This is transmutation. The will-o’-the-wisp of transmutation combined with the tradition of mysticism and obscure symbolism in alchemical writings held back the development of chemistry until the time of Lavoisier [334], who, fifteen centuries after Zo­ simus, finally completed the breaking of the spell. [68] PAPPUS (pap'us) Greek mathematician Born: Alexandria, about 260 Died: Alexandria, date unknown Pappus, like Zosimus [67] and Diophantus [66], brought up the rear guard of Greek science. Like Zosimus, he was primarily an encyclopedist, summarizing in eight rather masterly books (of which major parts of all but the first survive) all of Greek mathematics. He contributed little himself but his collection is of first importance, never­ theless, for it contains almost all we know of Greek mathematicians. Pappus also commented in detail on Ptolemy’s astronomical system and helped keep it popular for the next millennium and a half. [69] HYPATIA (hy-pay'shee-uh) Greek philosopher Born: Alexandria, about 370 Died: Alexandria, 415 Hypatia, the daughter of Theon, who was the last recorded member of the great Museum at Alexandria, is remark­

PROCLUS

[70]

able as the only noted woman scholar of ancient times. This, combined with re­ ports as to her beauty and virtue and the skill and popularity of her lectures, has led to her idealization in later times. Like her father, she contributed nothing original to science but produced useful commentaries on a number of earlier scholars such as Ptolemy [64] and Diophantus [66]. She was a pagan, and, although Chris­ tian bishops were among her pupils, she was the subject of violent antagonism on the part of zealots. In the end she was brutally murdered. Her story was greatly romanticized by Charles Kingsley, in his novel Hypatia, published in 1853. [70] PROCLUS (prohldus) Greek mathematician Born: Constantinople (the modem Istanbul, Turkey), 410 Died: Athens, April 17, 485 Proclus, the son of a lawyer, was vir­ tually the last pagan scientist of any con­ sequence. He was a devotee of Neopla­ tonism, a system of philosophy that stemmed from the work of Plotinus, a Roman philosopher. Plotinus, two cen­ turies before, had modified the system of Plato, adding mysticism in order to make it more capable of competing with the Salvationist Eastern religions then begin­ ning to dominate the Roman Empire. In this, Plotinus failed, but Neo-Platonist el­ ements entered into the thinking of Christianity, which was the ultimate vic­ tor in the battle of ideas. By Proclus’ time it had become dan­ gerous (though not yet fatal) to be a pagan. Proclus, who was the last neo­ Platonist of importance and who taught at the Academy in the last century of its existence and served as its head eventu­ ally, found that out. About 450 he was driven into a year’s exile from Athens. Among his writings Proclus included commentaries on Ptolemy [64] and Eu­ clid [40] and it is there that his impor­ tance to the history of science lies. The flame of science had dimmed to such a feeble flicker that any commentary, how­ 45

[7 1 ]

BOETHIUS

ever primitive, was important, for it added one more book that might be seen and that might survive. [71] BOETHIUS, Anicius Manlius Sev­ erinus (boh-ee'thee-us) Roman philosopher Born: Rome, about 480 Died: Ticinum (modem Pavia), Italy, 524 Boethius, who represented the last spark of the old Greco-Roman world, came of a noble Roman family. One of that family was Olybrius who, for a few months in 472-73, reigned as puppet emperor of Rome. In Boethius’ time, no emperor reigned at Rome, for the last had been deposed in 476, the date usu­ ally taken as the fall of Rome. Boethius, however, was befriended by Theodoric, ruler of the Ostrogoths, and the supreme power in Italy and the lands immediately surrounding. It was a fatal friendship, as it turned out, for Boethius, who was given high office and who, in 522, had the pleasure of seeing his two sons simultaneously raised to the honor­ able office of consul, was tactlessly vocal concerning the abuses visited by the Ostrogothic overlords upon the Roman pop­ ulace. Eventually his attitude was unjustly translated, by an increasingly suspicious Theodoric, into treasonable correspondence with the Eastern em­ peror at Constantinople. Boethius was imprisoned, tortured, and finally exe­ cuted without trial. Boethius’ chief work (written in prison) was a philosophic treatise, On the Consolation of Philosophy. It is a great work, rather pagan in its discussion of virtue and free will, although Boethius is considered to have been a Christian. He was the last Roman writer who un­ derstood Greek, and his service to sci­ ence lies in his having prepared trans­ lations of and commentaries on Aristotle [29] and summaries on various scientific subjects. His works were the only source from which the Europeans of the early Middle Ages could draw for information on Greek science until Arabic works were translated into Latin about six cen­ turies after the time of Boethius. 46

BRAHMAGUPTA

[73]

[72] ISIDORE OF SEVILLE Spanish scholar Born: Seville, about 560 Died: Seville, April 4, 636 Isidore was a great controversialist, defending Christianity against the Jews, and Catholicism against the heresy of Arianism. In 609 he was made Arch­ bishop of Seville. Between 622 and 633 Isidore published an encyclopedia in which, like Bede [75] a few decades later, he salvaged all he could of the learning of the Greeks, borrowing, again like Bede, from Pliny in particular. This book, called Etymologies in English, was very influential in early medieval times. It was so popular that a thousand medi­ eval manuscripts of the book still sur­ vive. Isidore accepted the validity of astrol­ ogy and this contributed to its accep­ tance in medieval Europe, even though Biblical verses could be quoted against it. He also dealt with the mystic significance of numbers after the fashion of Pythagoras [7]. His work, on the whole, tended to darken the intellectual world rather than enlighten it; but like Pliny he kept alive a sense of wonder, and that is important, too. [73] BRAHMAGUPTA (brah'muhgoop'tuh) Hindu astronomer and mathe­ matician Born: about 598 Died: about 665 When Greek learning was spreading eastward, during and after the time of the Arabic conquest of the Near East, it penetrated as far as the Indian subcon­ tinent. The men of science who arose there had little influence on subsequent developments in the West but Brah­ magupta, as perhaps the best among them, ought to be mentioned. He worked at Ujjain, in west-central India, which, for several centuries before and after him, was the center of Hindu science. Brahmagupta’s astronomy was summarized in a book written in 628 and in it he denied the rotation of the

[74]

CALLINICUS

earth, which a few Hindu astronomers supported. The most notable feature of the book is the application of algebraic methods to astronomical problems. Hindu mathe­ maticians were indeed of prime service to the world, for sometime within the next two centuries some nameless mathe­ matician devised the notion of a symbol for “zero.” This made positional notation practical, and a number system based on such notation was adopted. It spread to Arabs such as al-Khwarizmi [79] and from them was introduced (as the “Ara­ bic numerals” we use today) to Europe by men such as Fibonacci [95]. [74] CALLINICUS (kal-ih-nyTcus) Born: Heliopolis, Egypt (?), about 620 Died: date unknown Actually, nothing at all is known about the personal life of Callinicus. The birth date given above is not more than an educated guess, and some think he was bom in Syria rather than in Egypt or that he was Jewish rather than Chris­ tian. Whether Syrian or Egyptian, Jewish or Christian, he fled to Constantinople ahead of the conquering Arabian armies and in Constantinople invented Greek fire. This was a mixture containing an inflammable petroleum fraction, plus potassium nitrate to supply oxygen, plus quicklime perhaps to supply further heat through reaction with water. The exact secret of the composition is lost, but be­ cause of the nature of modern war weapons, Greek fire is not important to rediscover, except out of historical curi­ osity. It burned on water and therefore could be used to destroy a wooden fleet. The Greeks of the Byzantine Empire used Greek fire in 670 to repel the ships of an Arabic naval onslaught on Con­ stantinople and in this way, this one in­ vention, an authentic “secret war weapon,” may well have radically changed the course of history. It may be that Constantinople would have fallen without the use of Greek fire. If so, it is possible that the Muhammadan faith would have swept Europe.

BEDE

[75]

[75] BEDE (beed) English scholar Born: Jarrow, Durham, 673 Died: Jarrow, May 26, 735 When the Germanic invaders had sub­ merged Roman civilization in the West, those scraps of ancient learning re­ mained that were preserved by the monk­ ish copyists and summarizes. One of the most notable of these was Bede. He received an ecclesiastical training from childhood, having entered the mon­ astery at Jarrow, where he was to spend his life, at the age of seven. He was finally ordained priest at thirty and might eventually have become an abbot, but he refused higher office in order to write. This he did, spending a quiet and idyllic life immersed in his writing and his religious duties, never traveling more than fifty miles from home. He is commonly called the Venerable Bede, this being an old-fashioned ecclesi­ astical title. Some, taking the word in its later meaning, have thought it referred to extreme age and put forth the notion that he lived a hundred years or more. This is not so. In his writings Bede gives an account of the history of the early centuries of Anglo-Saxon England, and also all the knowledge he has managed to accumu­ late. This consisted largely of bits of Pliny [61]. He also deals with such as­ tronomy as was necessary for the proper dating of Easter, concerning which there was much controversy in his time. He noted that the vernal equinox had slipped to a point three days earlier than the traditional March 21. This imper­ fection of Sosigenes’ [54] Julian calendar was to lead to a reform and a slight ad­ justment of the number of leap years per millennium. The reform did not come in a hurry, though; it came nine centuries after Bede’s observation. He maintained that the earth was a sphere, and even this much was valuable at a time when scholarship in western Europe was close to bottom. Nor was it only the most primitive bits of knowl­ edge he preserved. He revived the sug­ gestion of Pytheas [39] that the tides were governed by the phases of the 47

[76]

GEBER

moon, an effect that was to escape the great Galileo [166] nine centuries later. He also realized, like Seleucus [51], eight centuries before, that high tide did not occur everywhere at once and that tide tables had to be prepared separately for each port. This is considered the only original scientific contribution in western Europe, during some eight centuries after the end of Greek learning. A more trivial point, but one that affects us all very intimately, is that in his historical works he dated events from the birth of Jesus rather than from the creation of the world. In this respect, we have all come to follow him. Bede worked to the last, completing his translation of St. John on his death­ bed. He was canonized in 1899 by Pope Leo XIII and is a Doctor of the Church. [76] GEBER (jee'ber); Arabic name, ABU MUSA JABIR IBN HAYYAN Arabian alchemist Born: possibly in Al-Kufah (in what is now Iraq), about 721 Died: possibly in Al-Kufah, about 815 After the coming of the prophet Mu­ hammad, the Arabian tribes, in a great burst of expansionist energy, swept over western Asia and northern Africa. They disrupted, but did not destroy, the East­ ern Roman Empire, which had survived the barbarian onslaughts that had wiped out the empire in the West. The Eastern Empire, particularly after the Arabian conquests, came to be known as the Byzantine Empire after its capital, By­ zantium. The Arabs occupied Syria in the 630s and Egypt in the 640s. In so doing, they fell heir to much of Greek science, and this proved of importance and even benefit to the history of science. The ad­ vance of science in what remained of Roman dominions came to a complete halt. For a thousand years of Byzantine history the only name worth mentioning is Callinicus [74]. Western Europe was in 48

GEBER

[76]

darkness. It was the Arabs alone who were in a position to preserve and trans­ mit the accumulated knowledge of the ancients. They not only preserved but also, in some cases, made advances, notably in alchemy. The first of the important Ara­ bian alchemists was Geber (as he was known to Europeans after his works were translated into Latin) and he was also the best. He carried the science far beyond the point it had reached in the time of Zosimus [67]. Geber’s lifetime corresponded with the very height of Arabic power, falling as it did at the time of the reign of the cele­ brated Harun al-Rashid, the famous Caliph of the Thousand and One Nights. Geber, the son of a druggist, was a personal friend of Harun’s vizier Ja’far al-Sadiq, and was also an adherent, it would seem, of the sect of the Sufis, which gave rise to the notorious Assas­ sins (who fed on hashish—hence their name—and performed political assassi­ nations on command). The sect was never popular with outsiders, and small wonder. Then, to make matters worse, Ja’far fell from power and was executed. On both scores, Geber felt his life inse­ cure. He went into retirement in his na­ tive village and there died in peace. Meanwhile, though, he had written nu­ merous works on alchemy. It is doubtful that all the books attributed to him are really his, for later alchemists often at­ tempted to gain greater respect for thenwork by attributing them to an earlier man of renown. This remained true as long as the publication of books was a matter of arduous hand labor so that only comparatively few could appear in any numbers at all. It was only after the invention of printing, when almost any­ one could see his book appear in large editions, that the habit of surrendering credit died out. The older habit seems saddest when a great man of science retreats into un­ deserved anonymity by his own choice. Thus, a much later alchemist wrote under Geber’s name and is now known only as the “false Geber” [107]. Geber’s most influential contribution to alchemy was his modification of the

[77]

ALCUIN

Greek doctrine of the four elements. Geber felt that these combined to form two different kinds of solid substances— sulfur and mercury. The former was the idealized principle of combustibility, the latter that of metallic properties. By the appropriate combination of the two any metal could be formed. Therefore, lead could be separated into sulfur and mer­ cury, which could then be recombined in new proportions to form gold. This transmutation could be brought about through a mysterious substance that he, or later Arabs, called al-iksir from a Greek word for a dry, medicinal powder. This came down in Latin as “elixir.” Following Geber’s initial impulse, al­ chemists for a thousand years sought this “philosopher’s stone,” as the dry material was popularly termed. Since any sub­ stance capable of forming gold must also have other miraculous properties, alche­ mists surmised it could cure all disease, restore youth, confer immortality. It was therefore also named the “elixir of life.” Among these mistaken theories, how­ ever, Geber published accurate descrip­ tions of valuable chemical experiments. He described ammonium chloride and showed how to prepare white lead. He prepared weak nitric acid and he also distilled vinegar to obtain strong acetic acid. He worked with dyes and varnishes and dealt with methods for refining metals. Most important, he described various chemical operations with great care. Unfortunately, later alchemists fol­ lowed Geber’s mistaken theories into wilder and deeper morasses. For the most part they abandoned Geber’s sys­ tem of practical, straightforward descrip­ tions of worthwhile experiments. [77] ALCUIN (al'kwin) English scholar Born: York, about 732 Died: Tours, France, May 19, 804 Alcuin’s teacher had been a pupil of Bede [75] and Alcuin carried on the earlier scholar’s tradition. The school at York, where he studied, was the most re­

CHARLEMAGNE

[78]

nowned in its time, in western Europe, and in 778, Alcuin became its head. However, he never rose beyond the sta­ tus of deacon. Alcuin visited Rome in 781 and there he met Charlemagne [78], The latter, having established a strong rule over most of western Europe, aspired to cul­ ture. He therefore invited Alcuin to serve as head of an educational system for his empire. Alcuin accepted and brought English learning (little enough, but better, at the moment, than anything available in Charlemagne’s dominions) to the continent. Charlemagne himself learned to read under Alcuin’s tutelage, though writing remained beyond his powers. Alcuin was installed at Tours as abbot and there es­ tablished a school where scribes were trained for the careful copying of manu­ scripts. In order to crowd as much writ­ ing as possible onto a piece of parch­ ment, yet leave it legible, Alcuin de­ signed a way of writing in condensed fashion (“Carolingian minuscule” from Carolus [Magnus], the Latin name of Charlemagne) which is the ancestor of our “small letters.” Under Alcuin’s influence, there was a brief graying (the Carolingian Renais­ sance) of the darkness, which, however, soon returned. The first slow glimmers of the actual dawn were still more than two centuries in the future. [78] CHARLEMAGNE (shahr-luhmain') Frankish emperor Born: Aachen, Germany, about 742 Died: Aachen, January 28, 814 Charlemagne is one of the great monarchs of Western tradition and one about whom myths have clustered with almost the same fantastic concentration that they cling to the legendary Arthur of Britain. For our purposes, however, his impor­ tance lay in his realization that his realm lay under a barbarous blanket of igno­ rance that was both disgraceful and dan­ gerous to any state aspiring to prosperity 49

[79]

AL-KHWARIZMI

and greatness. In 789 he began to estab­ lish schools in which the elements of mathematics, grammar, and ecclesiastical subjects could be taught, and Alcuin [77] was made the educational coordinator of the empire. Charlemagne himself undertook to learn to read and write, and managed the former. There are touching tales of his unsuccessful efforts to force his fingers, in mature life, to shape the tiny letters properly and his failure to do so. The Carolingian Renaissance did not outlast the great Charles, but no spark of light truly dies, perhaps, and his work left dim traditions that were to be car­ ried onward a few centuries later.

THABIT IBN QURRA

[80]

merals”) were transmitted to Europe via the work of Fibonacci [95], Their slow adoption revolutionized mathematical manipulations, making long division, for instance, a technique for children, rather than for experts only. While an improved symbolism does not directly advance science it does free men from undue preoccupation with mere techniques and makes possible fur­ ther advances in theory by simply giving them more time to think. Al-Khwarizmi was supported by the Caliph Mamun, under whom the power of Baghdad reached its height. (Mamun ruled from 813 to 833.) With that sup­ port, al-Khwarizmi prepared a world ge­ ography based largely on Ptolemy [64], In contrast to Ptolemy, al-Khwarizmi [79] AL-KHWARIZMI, Muhammad ibn overestimated the size of the earth, giv­ Musa (al-khwah'riz-mee) ing it a circumference of forty thousand Arabian mathematician miles. Born: Khwarizm (modern Khiva, in the Uzbek SSR of the Soviet Union), about 780 [80] THABIT IBN QURRA Died: about 850 Arabian mathematician Born: Harran, in what is now Al-Khwarizmi’s best claim to immor­ southeastern Turkey, 836 tality lies in a word in the title of a work Died: Baghdad, February 18, 901 in which he preserved and extended the mathematics of Diophantus [66], The Although Thabit lived in a Muslim so­ title of his book was ilm al-jabr wa’l ciety, he was not a Muslim but was a muqabalah, which means “the science of member of a Sabian sect that traced transposition and cancellation.” The Ara­ back to the pre-Muslim Babylonian soci­ bic word al-jabr (“transposition”) be­ ety. He was to the Muslims what the came “algebra” in the Latin translitera­ Neo-Platonists were to the Christians. tions of the title and that in turn became He came of wealthy parents; he was the name of the entire branch of mathe­ himself a money changer; and he was matics that Diophantus had founded. It apparently an accomplished linguist, is the branch that involves the solution being fluent in both Greek and Arabic, of equations by such devices as transpo­ in addition to his native Syriac. An Ara­ sitions and cancellations. bic mathematician, encountering him Al-Khwarizmi’s own name was dis­ and admiring his knowledge and obvious torted into “algorism,” which came to intelligence, invited him to come to mean “the art of calculating,” something Baghdad where he would have the we now call “arithmetic.” (“Arithmetic” chance to obtain a thorough education. when used in ancient times is what we This he did and to such good effect now call “theory of numbers.”) that he became a great scholar; this A more important contribution at­ meant that when he returned home, he tributed to al-Khwarizmi rests on the was greeted with the utmost hostility by fact that he drew on Hindu sources as his own sect, which accused him as hav­ well as Greek, for he picked up the ing left the fold. He was condemned by Hindu numerals, including the zero. their religious court and it seemed only When his work was translated into Latin, prudent to him to return to Baghdad, those numerals (miscalled “Arabic nu­ where he remained the rest of his life. 50

[81]

ALFRED THE GREAT

There he advanced rapidly and was in the retinue of the Caliph al-Mutadid. He translated many of the works of the Greek scientists; and wrote commen­ taries on them as well, thereby becoming a powerful factor in making Greek sci­ ence available to the Muslim world. He himself also did work of his own, particularly in mathematics and, for in­ stance, considered the matter of Euclid’s parallel postulate, something that nearly a thousand years later, at the hands of Bolyai [530] and Lobachevski [484] would lead to non-Euclidean geometry. [81] ALFRED THE GREAT English monarch Born: Wantage, Berkshire, 849 Died: Winchester, Hampshire, October 28, 900 In the deepest Dark Ages, Alfred the Great, like Charlemagne [78], offered a spark of light, an earnest of things to come in the slowly developing west Eu­ ropean civilization that was arising out of the ruins of the classical world. Alfred is best known for his indomi­ table battles against the Danish invaders, battles through which his persistence, bravery, and skill finally saved half the island and kept it firmly in Saxon hands. Both for his accomplishments and his character, Alfred was clearly the best of the Anglo-Saxon rulers of England. Alfred was not merely interested in learning for himself but felt a deep con­ cern that his subjects have learning avail­ able to them. For that reason he made every effort to have worthwhile Latin books translated into Anglo-Saxon. He did much of the work himself, translat­ ing the works of Boethius [71] and Bede [75]. [82] RHAZES (ray'zeez); Arabic name, ABU-BAKR MUHAMMAD IBN ZAKARIYYA AR-RAZI Persian physician and alchemist Born: Rhages (now Rai near Te­ heran, in what is now Iran), about 845 Died: Rhages, about 930

ALBATEGNIUS

[83]

Rhazes (the Latinized version of his name) had no such close connection with the caliph’s court as Geber [76], but he at least had the distinction of being born in Harun al-Rashid’s hometown. In 880 or thereabouts Rhazes visited Baghdad and there, so we are told, came across an old apothecary who fascinated him with stories of medicine and disease. Rhazes decided to study medicine and ended as chief physician of Baghdad’s largest hospital. He is supposed to have been the first to differentiate clearly be­ tween smallpox and measles. Rhazes, like Geber, described his ex­ periments so carefully that modern chemists can repeat them and check on his work. He prepared what we now call plaster of Paris, for instance, and de­ scribed the manner in which it could be used to form casts holding broken bones in place. He also studied and described metallic antimony. He shared with Aristotle [29] a delight in classifying and was the first, so far as is known, to divide all substances into the grand classification of animal, vege­ table, and mineral. He also subclassified minerals into metals, volatile liquids (spirits), stones, salts, and so on; a divi­ sion that was much the most useful up to his time. He went along with Geber’s notions concerning mercury and sulfur as the basic ingredients of solid substances and added to it salt as a third. He was a thoroughgoing rationalist, by the way, who dismissed miracles and mysticism. He thought religion harmful as the cause of hatred and wars. He ac­ cepted a materialist atomism as his view of the universe. Naturally, he was greatly vilified for these views. [83] ALBATEGNIUS (al-buh-teg'neeus); Arabic name, ABU-’AB­ DULLAH MUHAMMAD IBN JABIR AL-BATTANI Arabian astronomer Born: Haran (in what is now southeastern Turkey), about 858 Died: near Samarra, Iraq, 929 Greek astronomy as finally refined by Ptolemy [64] was preserved by the 51

[84]

GERBERT

Arabs, but little more. The only ad­ vances, minor ones, were made by Albategnius, the son of a builder of astro­ nomical instruments and the greatest of Islamic astronomers. Albategnius went over Ptolemy’s cal­ culations carefully and inserted a few improvements. He noticed, for instance, that the point at which the sun was smallest in apparent size (a point now called the aphelion) was no longer lo­ cated where Ptolemy said it was. From this he deduced that the position moved slowly and obtained a fairly correct value for that motion. He used better instruments than the Greeks did (the advantage of being the son of his father) and so got more accu­ rate results for the length of the year. (This value was used in the Gregorian reform of the Julian calendar seven cen­ turies later.) He also determined the time of equinox to within an hour or two and got an excellent value for the angle at which the earth’s axis was tipped to its plane of revolution. He introduced new types of mathe­ matical computations in astronomy, being the first to make use of a table of sines for the purpose. The greatest con­ tribution of Arabic astronomy was the perfecting of spherical trigonometry. In medieval Europe he was to be the most respected of the Arabian astrono­ mers. [84] GERBERT (zhare-bare') French scholar Bom: Aurillac, Auvergne, about 945 Died: Rome, Italy, May 12, 1003 As a scholar, Gerbert tutored the son of Hugh Capet, king of France, and gained the admiration of the Holy Roman emperor, Otto II. As a churchman he reached the pinna­ cle, becoming archbishop and finally pope (the first French one), in 999, under the name of Sylvester II. (It was a ticklish time to be pope, for there was strong feeling in Europe that the world was coming to an end in 1000.) Gerbert was for his time a famous scholar, fa­ 52

ALHAZEN

[85]

mous enough to be suspected of wiz­ ardry, despite his eminence in the church. He reintroduced the use of the abacus in mathematical calculation and may have picked up the use of Arabic numerals (without the zero) from alKhwarizmi [79]. He built clocks, organs, and astronomical instruments out of his consultation of Arabic works, which he procured in translation. The rebirth of European learning may be dated from Gerbert. [85] ALHAZEN (aPha-zen); Arabic name, ABU-‘ALI AL-HASAN IBN AL-HAYTHAM Arabian physicist Born: Basra (A1 Basra, in what is now Iraq), about 965 Died: Cairo, Egypt, 1039 Alhazen, in an attempt to obtain a si­ necure for himself, put forth the claim that he could devise a machine that would regulate the flooding of the Nile. As he hoped, this attracted the atten­ tion of the Egyptian caliph, who hired him to do the job. Unfortunately for Alhazen, the Egyptian caliph was alHakim, the most dangerous crowned madman between the times of Caligula and Ivan the Terrible. It dawned on Alhazen that al-Hakim was not joking about his request that the machine should be built at once and that he would see that Alhazen was put to death in some complicated fashion if the ma­ chine was not built. There was nothing for Alhazen to do but pretend to have gone mad. He had to keep it up for years, until al-Hakim died in 1021. At the times when Alhazen could afford to be sane, he proved himself the most important physicist of the Middle Ages. His field of particular interest was optics. This science had been fumblingly begun by Hero [60] and by Ptolemy [64], who felt that men saw by means of rays of light issuing from the eye and reflecting from the objects seen. Alhazen held the correct view that light issued from the sun or from some other lumi­

[8 6 ]

AVICENNA

OMAR KHAYYAM

[87]

nous source and was reflected from the object seen into the eye. He also explained, correctly, how a lens worked, attributing its magnifying effect to the curvature of the surface and not to any inherent property of the sub­ stance making it up. He was interested in the reflection and refraction of light, discussed the rain­ bow, studied the focusing of light through lenses and constructed a pinhole camera. He also constructed parabolic mirrors, a type now used in telescopes. Like Ptolemy he assumed the atmo­ sphere had a finite depth, and estimated that depth to be about ten miles. His work was published in Latin trans­ lation in the sixteenth century and ex­ erted an important influence on such men as Kepler [169]. It was not until Kepler, six centuries later, in fact, that work on optics progressed beyond the point to which Alhazen had brought it.

mained in hiding until a medical emer­ gency on the part of the shah made his presence necessary and his person safe. When Hamadan fell to a neighboring ruler, Avicenna was one of the spoils of war and served a new master. In the end he died on the march with the army of that new master when it was heading for another attack on Hamadan. Avicenna apparently had a tendency to work hard at his pleasures as well as his studies, for it was of indigestion (or colic) that he died. More than two hundred and fifty books are attributed to Avicenna (many are probably really his) and of these the most important are his works on medi­ cine. His theories were based on those of Hippocrates [22] and Galen [65], and once his books were translated into Latin in the twelfth century, they became Europe’s most important medical text­ books, remaining so until the time of Harvey [174], Avicenna also dealt with alchemy, and he was unusual in being one of the few [86] AVICENNA (av-ih-sen'uh); Ara­ who intuitively felt that transmutation bic name, ABU-ALI AL-HUSAIN was impossible. In his philosophical IBN ABDULLAH IBN SINA works he helped preserve the views of Persian physician Aristotle [29] for western Europe, but Born: Kharmaithen, near his importance in this respect is less than Bukhara (in what is now the that of Averroës [91]. Uzbek SSR of the Soviet Union), 980 Died: Hamadan (in what is now northwest Iran), June 1037 [87] OMAR KHAYYAM (oh'mar kyahm') Avicenna, the son of a tax collector, Persian astronomer was an infant prodigy able to recite the Born: Nishapur (in what is now entire Koran at the age of ten. He re­ Iran), May 15, 1048 ceived all the education the cultivated Died: Nishapur, December 4, Arab world of the time could offer. Un­ 1131 fortunately the once-great Arabian em­ pire, although still highly cultured, had The two things known about Omar fallen apart into warring pieces and there Khayyam to the average well-educated was no safe place even for the greatest modern are that he was a tentmaker, physician of medieval times, which Avi­ which is what “Khayyam” means, and cenna was. Avicenna was in the employ that he wrote clever quatrains. His fa­ of several Muslim rulers but political in­ ther was a tentmaker, and he himself stability was such that although this was a tentmaker in early life, it is true, brought him fame, money, and a chance but he was recognized as a gifted scholar to do research, it also placed his life in and spent most of his life pensioned by, danger more than once. first, the vizier of the Seljuk sultan, Alp In Hamadan, he served as vizier for a Arslan, and then by the sultan’s succes­ while and for his pains was nearly put to sor, Malik Shah. (Under these two rul­ death during a military coup. He re­ ers, the Seljuk Turkish Empire reached 53

[8 8 ]

ABELARD

its height.) Omar’s poetry came into prominence in English only in 1859 when Edward FitzGerald produced his translation of the Rubaiydt. However, the lines we admire are far more the work of FitzGerald than of Omar. Omar Khayyam wrote a book on alge­ bra that was the best of its time, and he also prepared improved astronomical tables. His most spectacular feat was that of reforming the Muslim calendar in 1074 and producing one that would bet­ ter fit the astronomical facts of life. This was comparable with the Gregorian re­ form in Europe five centuries later. He could handle quadratic equations neatly but was stumped by cubic equations. He suspected that a general solution for the cubic equation did not exist, but Car­ dano [137] was to publish one four and a half centuries later. After the death of Malik Shah and the assassination of his vizier, Omar Khay­ yam fell into disfavor in 1092, partly be­ cause of his free-thinking attitudes (which show up in his quatrains). How­ ever, he was allowed to live out his life in peace.

ADELARD OF BATH

[89]

gans for it. What is more, in his most fa­ mous book, Sic et Non (“Yes and No”) he carefully quoted the most respected authorities on a variety of important theological questions and showed them, in every case, to be hopelessly at odds with each other. It needed no comment from Abelard to show the bankruptcy of appeals to authority. Naturally, Abelard, who was a magnificent and popular lecturer, (and is usually considered the founder of the University of Paris) incurred the wrath of less intelligent, but more orthodox, scholars (particularly the wrathful Ber­ nard of Clairvaux, an abbot more power­ ful than the pope) and he was in con­ stant danger of condemnation for heresy. Indeed, when he died he was preparing his defense against such a charge. The best-known aspect of Abelard’s life, however, is his affair with his beau­ tiful and intelligent student Heloise. It was apparently a case of deep love on both sides. They were secretly married (It had to be secret or Abelard’s career in the church would have come to an end.) and a son was born to them. Heloise’s uncle, Fulbert, the powerful canon of Notre Dame, was furious at all [88] ABELARD, Peter (ab'uh-lahrd, or this, and hired thugs to castrate Abelard a-bay-lahr in French) in 1121. That prevented any advance­ French scholar, French name, ment in the church just as surely as mar­ riage would, since no eunuch could be a PIERRE ABÉLARD Born: Le Pallet or Palais, Brit­ priest. He continued his studies and his writings, however. tany, 1079 Died: near Chalon-sur-Saône, April 21, 1142 [89] ADELARD OF BATH Abelard was the son of a landowner, English scholar and it would have been natural for him Born: Bath, about 1090 to train for a military career; but he en­ Died: about 1150 tered the field of scholarship and theol­ ogy, although his attitude toward it was Adelard was a tutor of the English that of a fighter and polemicist. prince who later became Henry II. He is He studied with competing masters supposed to have traveled widely during and developed contempt, to a greater or his youth through the lands of ancient lesser degree, for all, since they taught learning, Greece, Asia Minor, northern on the basis of what authorities had said Africa. He learned Arabic and upon his and did not use reason—or, rather, they return to England translated Euclid [40] distrusted it as leading to pitfall and from Arabic into Latin. This was the error. first time Euclid became available to It was Abelard’s service to the cause Europe. He also translated al-Khwarizmi of science that he fought hard for the [79], and made use of “Arabic nu­ use of reason and praised the ancient pa­ merals,” something that Fibonacci [95] 54

[90]

GERARD OF CREMONA

was to establish firmly a century later. For popular consumption Adelard also wrote a book called Natural Questions which contained a summary of all he had learned of Arabic science.

MAIMONIDES

[92]

Alhazen [85], both the benefit and the difficulties involved in being patronized by powerful Muhammadan rulers. The rulers of those portions of Spain still under Muhammadan control set him up as a judge, first in Seville and then, like his father, in Cordoba. He was sent on diplomatic missions. Because (ap­ parently) he was suspected of being a scholar, he was imprisoned for a while in 1195. Finally he retired to Morocco for his own safety. Averroës’ importance is not due to any original work, but to his lengthy and thoughtful commentaries on the work of Aristotle [29], In this only his younger contemporary Maimonides [92] is to be compared to him. Averroës was at once the peak and the end of Arabic philosophy, for the gather­ ing woes of Muslim disunity were com­ ing to a head. After Averroës’ time, the Muhammadans were to feel the blows of the Christians in Spain and the Mongols and Turks in the east. The Muslim world entered a Dark Age, where scientific in­ quiry was lost, just as the Christian world was emerging from one. It followed, then, that Averroës’ im­ portance was not felt by the Muslims as much as by the Christians of Europe, who read his work in Latin translation and who built on it, this reaching a cli­ max with Thomas Aquinas [102]. In fact, some of Averroës’ books are lost in their Arabic original and exist only in their Latin translations.

[90] GERARD OF CREMONA (jerard') Italian scholar Born: Cremona, about 1114 Died: Toledo, Spain, 1187 The twelfth century is unique in the history of science as being the time when it was possible for translation to be the most important scientific work. The books of the Arabic scholars, who for centuries had preserved the works of the Greek philosophers by translation and commentary, began to be rendered into Latin. One of the earliest men to encour­ age the task was Gerbert [84], an impor­ tant churchman. Over the space of three centuries, however, the most important translator was Gerard of Cremona. He spent much of his life in Toledo, Spain, working under church auspices. Toledo had been a center of Muslim learning and had been reconquered by the Spaniards in 1085. It was a good place to find learned Arabic works, and learned Arabs too, who could help with the translation and with clearing up uncertain points. Gerard translated (or supervised the translation of) ninety-two Arabic works, some extremely long. These included portions of Aristotle [29] and all of the Almagest of Ptolemy [64], as well as the [92] MAIMONIDES (my-mon'ih-deez); Hebrew name, MOSES BEN works of Hippocrates [22], Euclid [40] MAIMON and Galen [65], Jewish philosopher Born: Cordoba, Spain, March 30, 1135 [91] AVERROËS (uh-ver'oh-eez); Ara­ Died: Cairo, Egypt, December 13, bic name: ABU-AL-WALID 1204 MUHAMMAD IBN AHMAD IBN RUSHD As a child, Maimonides left Spain with Arabian philosopher his family. Cordoba had been taken by a Born: Cordoba, Spain, 1126 Died: Marrakesh, Morocco, De­ new and barbaric line of rulers from North Africa and Maimonides’ family cember 10, 1198 no longer felt comfortable there. He Averroës, the son of a judge in traveled eastward and finally settled in Cordoba, had, like Avicenna [86] and Egypt in 1165. There he served as physi­ 55

[93]

NECKAM

cian to Saladin himself, the famous ruler who opposed Richard the LionHeart during the third Crusade. Indeed, Richard invited Maimonides to come to England but the philosopher preferred to remain in Egypt, then by far the more civilized of the two nations. Maimonides in his book Guide for the Perplexed disdains astrology, tries to rec­ oncile the teachings of Aristotle [29] with the teachings of the Old Testament. He has been the most influential of all Jewish philosophers.

FIBONACCI

[95]

Grosseteste’s primary fame is that of a theologian and prelate. Of a poor family, he was nevertheless educated at Oxford and rose steadily in the church, becom­ ing bishop of Lincoln in 1235. He did not fear controversy, standing firmly on principle against all authorities. He fought for the inclusion of more science in the university curriculum, defended the Jews against King Henry III and at­ tacked church abuses even against Pope Innocent IV. He was also pre-eminent in scholarship and was one of the earliest to introduce Aristotle [29] to Europe. In an age when the translation of the Arabic works of science was of crowning importance, he went even further back. Feeling that third-hand Latin translations from Ara­ bic translations of Greek originals were inevitably corrupt, he brought scholars from the remains of the Byzantine Em­ pire (sections of which were under the temporary control of the West at the time) to translate from the original Greek. Grosseteste was particularly interested in optics, using Alhazen [85] as his guide. He experimented with mirrors and with lenses and advanced an explanation for the rainbow. Indeed, he thought the primal substance of the universe was not any form of matter, but light itself. If, for light, we substitute the more general term of “energy,” Grosseteste, like Heraclitus [10] would seem curiously close to the modem conception. And yet his greatest claim to fame lies not in his own deeds, but in the fact that he was the teacher of Roger Bacon [99],

[93] NECKAM, Alexander (nek'am) English scholar Born: St. Albans, Hertfordshire, September 8, 1157 Died: Kempsey, Worcestershire, early 1217 Neckam was bom, according to leg­ end, on the same night as the prince who later became Richard I, the Lion-Heart. Neckam’s mother was wet nurse for the prince as well, but if Neckam lacked the stature, gallantry, and derring-do of the prince, he far surpassed him in intelli­ gence. Neckam traveled to Paris, and studied and later lectured at its renowned uni­ versity. In 1186 he returned to England and in 1213 became abbot of Circencester. In Paris, Neckam had learned of the mariner’s compass, which the Chi­ nese had been using for at least two cen­ turies. In a book he wrote about 1180 was the first reference to the compass as being in use among Europeans. He must have had his enemies though (as most scholars did in the ferociously polemical philosophical battles of the Middle Ages) for he was often deliber­ ately misreferred to as “Nequam,” which [95] FIBONACCI, Leonardo (fee-bohnaht'chee); also called LEO­ is Latin for “useless.” NARDO DA PISA Italian mathematician Born: Pisa, about 1170 [94] GROSSETESTE, Robert (grohs'Died: about 1240 test) English scholar Born: Stradbroke, Suffolk, about Fibonacci, the first great Western mathematician after the end of Greek 1168 Died: Buckden, Huntingdonshire, science, lived in Pisa at a time when it October 9, 1253 was one of the great mercantile centers 56

[96]

ALBERTUS MAGNUS

ALBERTUS MAGNUS

[96]

of Italy. It had strong commercial ties with Muhammadan North Africa and Fibonacci’s father was the head of a warehouse and therefore intimately con­ nected with this commerce. Fibonacci himself was tutored by a Muhammadan in Algeria and, in later life, traveled widely, remaining in North Africa for extended periods and not settling down in Pisa till 1200. He thus had ample opportunity to be­ come acquainted with Arabic mathe­ matics and, in particular, with the system of arithmetic notation that al-Khwarizmi [79] had learned from the Hindus. This notation Fibonacci considered so much more useful than any he had met with in Europe that he bent his energies to propagating its value. In his book Liber Abaci (“Book of the Abacus”), published in 1202, he explained the uses of “Arabic numerals.” He also made clear the values of positional notation, which made the numbers 213, 123, 132, 321, 231, and 312 all have different values. And, of course, he explained the use of zero. This had been anticipated by Adelard of Bath [89] a century earlier, but it was with the appearance of this book that the old system of notation by letters of the alphabet, which the Greeks and Romans had used, received its deathblow. (How­ ever, the old system took several cen­ turies to die, and we still use Roman nu­ merals for ceremonial occasions, part of their impressiveness being that few peo­ ple can make them out without some study.) Fibonacci’s learning was sufficiently recognized for him to be presented to the Emperor Frederick II [97] in 1225.

Magnus (Albert the Great) because of his learning. He was also called the Uni­ versal Doctor. It was a grandiloquent age and Thomas Aquinas [102], a pupil of Albertus Magnus, was called the An­ gelic Doctor, while Roger Bacon [99], an enemy and reluctant admirer of Al­ bertus Magnus, was called the Admira­ ble Doctor. Albertus Magnus studied at the Uni­ versity of Padua in Italy, the intellectual center of Europe in those days, and brought the new learning of the transla­ tions from the Arabic northward to Paris, where he lectured from 1245 to 1254. He labored to adapt Aristotelian philosophy into a world view fitted to the medieval mind, a work in which he was to be surpassed by Aquinas. He was, however, more concerned with science itself than Aquinas was, being particu­ larly interested in botany, bringing to that science his own observations made in his many travels on church business. (He was sometimes called the Bishop with the Boots. ) He did not consider Aristotle [29] the last word (although his enemies slight­ ingly referred to him as the Ape of Aris­ totle) and insisted on the value of per­ sonal observation. He conducted alchemical experiments and is equivocal on the possibility of the transmutation of elements. In this con­ nection he apparently found it difficult to swim against the tide; yet he shows ex­ treme skepticism concerning the possi­ bility. He describes arsenic so clearly in his writings that he is sometimes given credit for its discovery, although it was probably known to earlier alchemists in an impure form. He suspected the spots on the moon to be surface configurations and the Milky Way to be composed of myriads of stars. He compiled a list of a hundred minerals [96] AI.BERTUS MAGNUS and seems to have taken note of the ex­ German scholar Born: Lauingen (in southern istence of fossils. Germany), 1193 His learning was such that he was sus­ pected of wizardry, but his position in Died: Cologne, November 15, the church and his orthodoxy protected 1280 him. He was bishop of Regensburg from Albertus Magnus’ actual name is Al­ 1260 to 1262 after which he retired to a bert, Count von Bollstadt (an inherited monastery in Cologne to devote himself title), but he was called Albertus for the remainder of his life to his stud­ 57

[97]

FREDERICK O

BACON

[99]

ies. Pius XI proclaimed him a Doctor of in which he reported his own observa­ the Church—thus automatically canon­ tions and thrust aside conclusions based on hearsay (an uncharacteristic attitude izing him—in 1931. for a medieval scholar). In the book, he discussed hundreds of kinds of birds, with illustrations, and made numerous [97] FREDERICK II valid generalizations concerning their German Emperor Born: Iesi, central Italy, Decem­ anatomy, physiology, and behavior. It was first-rate natural history, and in it he ber 26, 1194 Died: Lucera, southern Italy, De­ did not hesitate to refute Aristotle [29]. cember 13, 1250 Frederick II was one of the remark­ SCOT able monarchs of history, a man of [98] MICHAEL Irish (?) scholar many talents and a “Renaissance man” Bom: before 1200 two centuries before the Renaissance. Died: about 1235 His reign was a romantic and turbulent one, marked by desperate battles with The surname “Scot” may indicate Irish the papacy and against his own rebel­ birth, but so little is known about the life lious son. He took over Jerusalem by ne­ of Michael that even this cannot be said gotiation, where previous monarchs had with any degree of certainty. failed through the use of force, but he He was another of those whose impor­ didn’t hold it long. He was the last tance lay in his translations. In particu­ strong ruler of the medieval Empire. translated Averroës [91] from He was unusual also in his tastes. Al­ lar, he into Latin; and in this way made though he ruled over Germany and was Arabic the teachings of Aristotle [29] available German by descent, he preferred Sicily to European scholars. for his home and under him Sicily had He was one of those scholars whom one last period of splendor, one last mo­ the learned and intellect-admiring Em­ ment when it might be recognized as the peror Frederick II [97] gathered round land of Archimedes [47]. him, and it was Frederick who en­ Frederick was unusual for his time in couraged him in his work of translation another respect too, for he possessed no and urged him to disseminate the results religious intolerance. This came easily to through the universities of Europe. him for he was a convinced and practic­ Michael was an astrologer and in­ ing atheist. He made no distinctions dulged in the mystical nonsense of the among the religions, delighted in the times, with the result that he was feared company of learned Jews and Muslims, by the superstitious, and rumors arose of as well as Christians, and even employed his great wizardry and of his dealings Muslim mercenaries in his armies. (They with demons. This was one of the haz­ were particularly useful in his battles ards of secular scholarship in those days. Albertus Magnus [96] and Roger Bacon against the pope.) Frederick II was one of those mon­ [99] were likewise suspected of wizardry, archs who, like Charlemagne [78], and that attitude of mind was eventually Alfred [81], and Alfonso X [100] were responsible for the Faust legend brought interested in learning. Frederick spoke to its highest pitch of literary excellence many languages, patronized scholars and by Goethe [349]. corresponded with them, wrote poetry, kept a zoo that, at one time or another, included monkeys, camels, a giraffe and [99] BACON, Roger an elephant, and interested himself in English scholar every branch of science. Born: Ilchester, Somerset, about His most important personal contri­ 1220 bution was an excellent book on falconry Died: Oxford, June 11, 1292 58

[99]

BACON

Roger Bacon, the son of well-to-do parents in the service of Henry IH, stud­ ied at Oxford and then traveled to Paris to teach. There he obtained his degree of master of arts by 1241, then resigned his post in 1247 to devote himself to re­ search. He returned to Oxford about 1251. Among those he studied under in the course of his education was Grosse­ teste [94]. Bacon somewhat resembles Galileo [166], Like the Italian scientist of three and a half centuries later, Bacon was a man of bold ideas and imperious self­ confidence. Like Galileo, he was unspar­ ing in expressing his contempt of those he felt worthy of it and, in so doing, made numerous important enemies. It was the influence of these enemies (one of them the general of the Franciscan order, of which Bacon was a member) that had him imprisoned for fifteen years and ordered his works suppressed. On the other hand the church did not officially condemn him, and much of his work was done at the request of Pope Clement IV, a great admirer of Bacon. Clement IV died in 1268 and Bacon in his later years no longer had papal pro­ tection. Bacon attempted to write a universal encyclopedia of knowledge, but in his time the task had already become impos­ sible. In his works, he denounced magic generally but accepted the value of as­ trology. He upheld the roundness of the earth and was the first to suggest that man could circumnavigate it (a romanti­ cally fantastic thought for his day). Co­ lumbus [121] quoted this in a letter to Ferdinand and Isabella of Spain, but it was to be nearly three centuries before Magellan [130] made reality out of the suggestion. Bacon estimated the outermost of the heavenly spheres, that of the stars, to be one hundred and thirty million miles from earth, or some five hundred times the distance of the moon. This was a daring guess for the times but Bacon’s whole universe was. by this estimate, far smaller than we now know the solar sys­ tem itself to be. Bacon pointed out that the Julian cal­ endar made the year a trifle long, so that

ALFONSO X

[100]

the equinoxes fell earlier by a day every century or so, but it was to be three cen­ turies before the defect was corrected. He followed his teacher, Grosseteste, in his interest in optics, constructing magni­ fying glasses, suggesting the use of spec­ tacles for those who were farsighted and even made remarks that sound very much like the description of a telescope (to say nothing of others that sounded like the prediction of steamships, auto­ mobiles, and airplanes). Like Grosseteste he appreciated the value of Greek and, indeed, compiled a Greek grammar. He was interested in alchemy, too, which he claimed was essential to medi­ cine, thus foreshadowing Paracelsus [131], and believed in the possibility of making gold. Because he was one of the first to mention gunpowder (in a letter written in 1247), it was long supposed that he had invented it. (How gunpow­ der came to be introduced to the West­ ern world, whether from China or through independent invention, is un­ certain.) In fact, a whole cluster of leg­ ends gathered about Bacon in later cen­ turies, most of which—like the tale that he had constructed a mechanical man— can be dismissed. Bacon’s most modern ideas involve his vehement pioneering belief in experi­ mentation and mathematics as the true routes of scientific advance. He even ap­ pealed to Pope Clement to change the educational system to allow for more ex­ perimentation and he wrote in high praise of Peter Peregrinus [104], a con­ temporary experimenter of ability. Un­ fortunately his influence was lessened by the fact that his books were condemned and therefore unread by most scholars. His greatest work, Opus Majus, was not published till 1733. It was to be three and a half centuries before experi­ mentation and quantitative measure­ ments were to become all important in science. [100] ALFONSO X of Castile Spanish monarch Born: Burgos, November 23, 1221 Died: Seville, April 24, 1284 59

[100]

ALFONSO X

Alfonso X, who became king of Cas­ tile and Leon in 1252, was victorious over the Muslims, capturing Cadiz in 1262, but was not a success as a king. His visionary schemes resulted in de­ based currency and revolts among the nobles and he wasted much effort in a futile attempt to become Holy Roman emperor. He suppressed a revolt by one son, but a second revolt, raised by a second son, forced him from the throne in 1282. He was noted for his scholarship and his encouragement of learning, for the schools he founded, and for the law codes he sponsored. This resulted in his being called Alfonso el Sabio (Alfonso the Wise), a cognomen granted very few other rulers in history. Under his patronage the first history of Spain was written and Jews of Toledo translated the Old Testament. He pre­ pared a code of laws, wrote poetry, made commentaries on alchemy, and en­ couraged further translation of scholarly Arabic books. He is most famous for encouraging the preparation of revised planetary tables. These were published in 1252, on the day of his accession to the throne. These “Alfonsine Tables” proved the best the Middle Ages had to offer and were not replaced by better ones for over three centuries. Alfonso X is famous for his remark, made during the tedious preparation of those tables on the basis of the compli­ cated Ptolemaic view of the universe, that had God asked his advice during the days of creation, he would have recom­ mended a simpler design for the uni­ verse. This touch of impatience with the sacrosanct conclusions of the Greek sci­ entists extended to physics, too, as Buri­ dan [108] was to show, and three cen­ turies after Alfonso’s time was to ex­ plode in the Scientific Revolution. An honor the monarch might never have suspected befell him several cen­ turies later when a crater on the moon was named “Alphonsus” in his honor. In 1957 this crater made headlines when possible volcanic activity was noted in it. 60

AQUINAS

[102]

[101] ALDEROTTI, Taddeo Italian physician Born: Florence, 1223 Died: Bologna, about 1295 Alderotti is the bridge between Greek and European medicine. Judging from his own writings, he was brought up in poverty and it was not until he was an adult that he could find his way to an education. He studied at Bologna, which had one of the great medical schools in western Europe, advanced quickly, and by 1260 was lecturing there. He wrote commentaries on Hip­ pocrates [22], Galen [65], and Avicenna [86] but urged his readers to go to the originals. He collected clinical cases, pre­ sented them to his readers along with ad­ vice on treatment. He became a very successful physi­ cian, numbering Pope Honorius IV among his patients. Remembering his poverty-stricken childhood, he charged high fees and, presumably, he was worth them. [102] AQUINAS, Saint Thomas (uhkwy'nus) Italian theologian Born: Roccasecca, near Aquino, about 1225 Died: Fossanuova, March 7, 1274 After an education at Monte Cassino and at the University of Naples, which he entered in 1240, Thomas Aquinas, the youngest of nine children, joined the new Dominican order in 1244. His fam­ ily objected, kidnapped him, and held him in custody. He escaped and made his way to Paris in 1245 where he studied under Albertus Magnus [96], whom he later accompanied to Cologne in Ger­ many. Eventually he began to write com­ mentaries on Aristotle and achieved great fame. He taught at various places in France and Italy but refused all ap­ pointments to high posts, including the archbishopric of Naples. Drawing on Averroes [91] and Maimonides [92] and adding his own thought, he tried to build a system that would blend and reconcile

[103]

ARNOLD OF VILLANOVA

Aristotelian philosophy and Catholic the­ ology. In this he was most successful. He was canonized in 1323, a mere half cen­ tury after his death, and his philosophic system remains the basis of Catholic teaching to this day, and he is a Doctor of the Church. His importance to science lies in the fact that he was a rationalist. He upheld reason as a respected method for extending the boundaries of human knowledge, and the result was to help make science once again respectable in Christian Europe after a long period of being considered pagan. [103] ARNOLD OF VILLANOVA Spanish alchemist Born: near Valencia, about 1235 Died: at sea, near Genoa, Sep­ tember 6, 1311 Bom in Spain of parents who may have been converted Jews, Arnold had the advantage of being physically close to the Arabic heritage. He could speak Arabic and Greek and through him the full tradition of Arabic alchemy entered the stream of European thought. Arnold traveled widely and wrote vo­ luminously. As a physician of reputation, he became wealthy. Like Alderotti [101] he helped introduce the teachings of Galen [65] and Avicenna [86] to western Europe. From the grateful royalty he treated (Pedro III of Aragon, for instance), he received castles and a professorship at the University of Montpellier in France. He was a controversialist, with strong views on theology that led him into occa­ sional conflict with the church. However, he treated Pope Boniface VIII success­ fully during a papal illness and this got him out of a particularly bad siege of trouble. Arnold was a strange mixture of mys­ ticism and science. He announced that the world would end in 1378, for in­ stance, with the appearance of the An­ tichrist. He accepted transmutation of the ele­ ments and modified the mercury-sulfur theory of Geber [76]. He thought mer­

PEREGRINUS

[104]

cury alone was sufficient, although he never proved this by actually producing gold out of it. He was apparently the first to notice that wood burning under conditions of poor ventilation gave rise to poisonous fumes. This amounts to the discovery of carbon monoxide. He was also the first to prepare pure alcohol. He, like the “false Geber” [107], was one of those later alchemists in whom genuine science was faintly reappearing. [104] PEREGRINUS, Petrus (per-uhgrine'us) French scholar Born: about 1240 Died: date unknown Little is known of Peregrinus’ personal life; he may have been a Crusader, since his cognomen, Peregrinus, means “the pilgrim.” His real name was Petrus de Maricourt. A friend of Roger Bacon [99], he was one of the few medieval scholars who practiced experimentation, centuries before Galileo [166] made it the nub of science. Peregrinus was an engineer in the army of Louis IX and interested himself in mechanics. He began by attempting to construct a motor that would keep the planetarium designed by Archimedes [47] moving for a period of time. To do so without muscular effort, he conceived of using magnetic forces for the purpose. This was the first suggestion that magne­ tism might be converted to kinetic en­ ergy. These speculations, in turn, led him to a deeper consideration of the magnet. The Greek tradition had it that Thales [3] was the first to observe and study the manner in which certain rocks (lodestone) attracted iron. It was a phenome­ non that exercised the ingenuity of phi­ losophers because it seemed to represent “action at a distance.” It was hard to un­ derstand how one object could exert a force on another without physical con­ tact. It was somehow learned (by whom is not known) that a magnet in the form of a needle if freely suspended or freely 61

[1051

POLO

floating would align itself roughly north and south. Some time before 1200, Eu­ ropean navigators began to use such a needle (a “compass”) to guide them in their voyages. Legend has it that the Chinese made the discovery centuries earlier and the Europeans picked up the knowledge via the Arabs, but this is un­ certain. In any case, in 1269, while taking part in the slow and dull siege of an Italian city. Peregrinus wrote a letter to a friend in which he described his researches on magnets. He showed how to determine the north and south poles of a magnet, pointed out that like poles repelled each other whereas unlike poles attracted. He also explained that one could not isolate one of the poles by breaking a magnet in two. because each half was then a com­ plete magnet with both a north and south pole. Most important of all, perhaps, he de­ scribed an improved compass to be formed by placing the magnetic needle on a pivot, rather than allowing it to float on a piece of cork, and surrounding it by a graduated circular scale to allow directions to be read more accurately. Undoubtedly it was this device that made the compass really practical; and it was, in turn, the use of a practical com­ pass that gave European navigators the self-confidence needed to sail into the Atlantic far out of sight of land. Pere­ grinus thus was another herald of the great Age of Exploration that was to begin in another century and a half. Where Peregrinus chiefly failed was in his explanation of the reason for the north-south alignment of the needle. He believed the needle pointed to the pole of the celestial sphere, the outermost of the spheres in the Ptolemaic heavens. A better explanation had to await Gilbert [155],

POLO

[105]

still a young boy, his father, Nicolo, and his uncle, Maffeo, set out eastward on a trading mission. They began in 1260 at an unusual time in history. A half century earlier the Mongol, Genghis Khan, had begun a remarkable career of conquest and now his grandson, Kublai Khan, acknowl­ edged as head of the various Mongol princes, ruled over an immense empire that, for the first time, placed much of Asia and Europe under a single rule and made travel over that whole area practi­ cal. Kublai Khan had the Venetians brought to his summer palace at Shangtu in China (Coleridge, in his famous poem “Kublai Khan” called it Xanadu). The Mongol ruler was fascinated by them and eventually sent them back to Europe to bring missionaries to teach him and his people Christianity. The Polos unfor­ tunately found the papacy in the turmoil of an interregnum. The missionaries were never sent and the great chance to Christianize the Far East never returned. The Polos returned to China in 1275 and this time Marco was with them. Marco in particular rose to high place and was a trusted diplomat in Kublai Khan’s service. In the khan’s old age, however, the Polos felt they could not trust in the favor of his successor and, when they were given the mission of es­ corting a Mongol princess to Persia, they seized the opportunity to continue on­ ward toward home. They finally reached Venice again in 1295. Central Asia was not to be observed by Europeans in such detail for five more centuries. Marco Polo’s stories of the wonders he had seen and of the high civilization of the Far East in the midsummer of Mon­ gol domination was greeted with derision and he was named Marco Milioni (Marco Millions) because he dealt with such large numbers in his descriptions. In 1298 Venice and Genoa renewed [105] POLO, Marco their naval wars and Marco Polo held a Italian explorer command in the Venetian fleet. He was Born: Venice, about 1254 captured. While in a Genoese prison he Died: Venice, January 9, 1324 dictated the story of his travels. He did not deal so much with personal matters Marco Polo came of a family of well- as with a description of the portions of to-do Venetian merchants. While he was Asia and Africa with which he was rea-

62

[106]

d ’abano

sonably familiar. A year later he was released and allowed to return to Venice. The book was popular, but it was largely disbelieved and considered an en­ tertaining but implausible tissue of tall tales. It was not until five and a half cen­ turies later that European explorers finally penetrated the interior of Asia and found that, on the whole, and bar­ ring a few wonder stories, Marco Polo was accurate in his description of such matters as coal, asbestos, and paper cur­ rency. The importance of the book lay in its portrayal of the wealth of the “Indies.” Columbus [121] owned a copy of Polo’s book and scribbled enthusiastic marginal notes in it. It was Marco Polo’s great trek east that drove Columbus west in the hope of arriving at the same destina­ tion. Marco Polo therefore contributed his bit toward the intellectual ferment that was to break over Europe within two centuries, broadening horizons both geographically and intellectually. [106] D’ABANO, Pietro (dalTbah-noh) Italian physician Born: Abano, near Padua, 1257 Died: Padua, about 1315 D’Abano, after studying at Padua, traveled through Greece and the Near East, visiting Constantinople, absorbing knowledge of Arabic medicine, then completed his formal Western training at Paris. He had apparently met Marco Polo [105] and caught a breath of the world that was still beyond the medieval horizon. As Marco Polo foreshadowed the great Age of Exploration soon to come, so D’Abano foreshadowed the great Age of Science. He wrote a book entitled Conciliator in which he tried to weave together the Greek and Arabic schools of medicine and in which he ex­ pressed some ideas that were well ahead of his time. For instance, he maintained that the brain was the source of the nerves, and the heart of the blood ves­ sels. He also stated that air had weight, and he made an unusually accurate esti­ mate of the year. He was, however, convinced of the

BURIDAN

[108]

usefulness of astrology and, like so many of the scholars of the period was sus­ pected of magical practices (particularly by competing physicians less successful in their practice). He was brought up twice for heresy before the Inquisition because he re­ jected the miraculous aspects of the gos­ pel tales. He was acquitted the first time and died during the course of the second trial. [107] FALSE GEBER Born: Perhaps about 1270 Died: Date unknown Nothing is known of him, not even his name (for he wrote under the pseud­ onym of Geber [76]), except that he was probably a Spaniard, like Arnold of Vil­ lanova [103], and that he wrote about 1300. He was the first to describe sul­ furic acid, the most important single in­ dustrial chemical used today. The al­ chemical discovery of sulfuric acid and the other strong acids is, by all odds, the greatest chemical achievement of the Middle Ages. It made possible all sorts of changes that could not be brought about by vinegar, the strongest acid known to the ancients. The discovery was infinitely more important than the preparation of gold would have been, for even if gold could be prepared, the mere fact that it could, would erase its value. Gold, after all, is a comparatively useless metal (although admittedly the most beautiful) and has few values that do not stem from its rarity. [108] BURIDAN, Jean (byoo-ree-dahn") French philosopher Born: Béthune, Artois, about 1295 Died: Paris, about 1358 Buridan studied under Ockham [109] and became himself a professor at the University of Paris. He rejected impor­ tant sections of Aristotle’s [29] theories of physics, then in full sway over the minds of Europe’s scholars. Aristotle had felt that an object in mo­ 63

[1 0 9 ]

OCKHAM, WILLIAM OF

tion required a continuous force and reasoned that the air supplied that con­ tinuing force after the initial impetus (that of a catapult, for instance) had been spent. Buridan maintained that the initial impetus was sufficient; and that once it was supplied, motion continued indefinitely. The spheres of heaven, for instance, having been put in motion by God, continued so and required no con­ stantly working angels to keep them moving. This was an anticipation of Newton’s [231] first law of motion (pro­ pounded three centuries later). More generally, he believed the same laws of motion prevailed in the heavens as on earth. Buridan is most famous for a point he is supposed to have made concerning the impossibility of action by free will under two opposite and exactly balanced im­ pulses. His example was the case of an ass poised exactly between two exactly equivalent bales of hay. Since there would be no reason to choose one bale over the other, the ass would remain in perpetual indecision and would starve to death. However, “Buridan’s ass” is no­ where to be found in Buridan’s writings, so it is doubtful that he is really the au­ thor of it. [109] OCKHAM, WILLIAM OF (ok'um) English scholar Born: Ockham, Surrey, about 1285 Died: Munich, Germany, 1349 William of Ockham (called the Invin­ cible Doctor) joined the Franciscan order, studied at Oxford, and lectured there from 1315 to 1319. He was among the last of the medieval scholars and led the battle against the views of Thomas Aquinas [102]. Ockham held that much of theology was a matter of faith, not amenable to reason. For this and, even more so, because he was an opponent of papal supremacy, he was tried for heresy in 1324 by Pope John XXII. He fled and was protected by Holy Roman Emperor Louis IV, who as a strong political oppo­ nent of the pope automatically favored 64

MONDINO DE’ LUZZI

[HO]

any antipapal scholar. After Louis’ death, Ockham cautiously made his peace with the church. Ockham battled against the universals that had been introduced by Plato [24], the notion that the only true realities were the ideal objects of which the earthly objects sensible to perception were only imperfect copies. These ideals Ockham considered abstractions, mere names (hence the expression “nomi­ nalism” for this philosophy), and held that only the objects perceived were real. Since the universalists kept adding more and more items to their ideals in order to make their theories work, Ock­ ham laid down the rule that: “Entities must not needlessly be multiplied.” This has been interpreted in modern times to mean that of two theories equally fitting all observed facts, that theory requiring the fewer or simpler assumptions is to be accepted as more nearly valid. The rule, now called “Ockham’s razor,” is of vital importance in the philosophy of science. [110] MONDINO DE’ LUZZI (mondee'noh day loot'tsee) Italian anatomist Born: Bologna, about 1275 Died: Bologna, 1326 The thirteenth century marked the height of the Middle Ages and thereafter there was a stirring of new viewpoints, particularly in Italy, as was exemplified by Pietro d’Abano [106], The transla­ tions from the Arabic had aroused an in­ terest in the nonscientific works of the Greeks and Romans, which were read anew with great appreciation. They in­ spired imitation and a resurgence of in­ terest in man and the world (humanism) after the long preoccupation with theol­ ogy and the afterworld. This was the Re­ naissance. Scientifically, an interest in man meant the faint stirrings of biology and medi­ cine. Famous Italian schools of medicine sprang up at Salerno in the ninth century and Bologna in the thirteenth. At Bo­ logna the art of dissection was revived, not specifically for research but for utili­ tarian work in connection with legal

[I ll]

HENRY THE NAVIGATOR

cases or medical postmortems and for demonstrations to confirm the views of Galen [65] and Avicenna [86]. The greatest of the Renaissance anato­ mists was Mondino de’ Luzzi, the son of an apothecary, who studied at the medi­ cal school at Bologna, under Alderotti [101] graduating about 1290 and joining its teaching staff in 1306. He taught anatomy in a very unusual way for the times. Ordinarily the lec­ turer, mounted on a high platform, lec­ tured loftily from the ancient writers while a menial conducted the actual il­ lustrative dissection. This perpetuated er­ rors, since the lecturer did not himself see what he was talking about, and the anatomist could not understand the talk concerning what he saw. Mondino, however, did his own dissec­ tions, and on the basis thereof wrote, in 1316, the first book in history to be devoted entirely to anatomy. (He is therefore called the Restorer of Anat­ omy.) Much of Mondino’s terminology is taken from the Arabic and is rather disorderly. The book contains many er­ rors where Mondino remains too much under the influence of the ancients. He describes the stomach as spherical, gives the liver five lobes instead of three, and sticks to Avicenna’s description of the heart. However, he made some advances, notably in his description of the organs of the reproductive system. In any case, Mondino’s book was to be the best available until the time of Vesalius [146], over two centuries later, for Mondino’s successors reverted to the practice of having somebody else do the dissecting. [Ill] HENRY THE NAVIGATOR Portuguese prince Born: Oporto (now Porto), March 4, 1394 Died: Sagres, November 13, 1460 Henry, a younger son of King John 1 of Portugal, was part English, for his mother’s father was John of Gaunt. Henry was thus the great-grandson of Edward III of England.

ULUGH BEG

[112]

In Henry’s day the tide had turned and the Christians of Portugal were finally recrossing the Strait of Gibraltar to fight the Muslims on African soil. In 1415 Henry took part in a battle at Ceuta, on the northwestern tip of Africa and was knighted for heroism. Although he himself never penetrated deeper into Africa, he fell in love with the continent, or rather with the project of exploring its coasts. He dedicated himself to that sole pur­ pose, establishing an observatory and school for navigation at Sagres on Cape St. Vincent in 1418. This was in south­ ernmost Portugal, the southwestern tip of Europe. Year after year he outfitted and sent out ships that inched their way farther and farther down the African coast. He even supervised the collection of astronomic data to ensure the greater safety and success of the ships. It was Henry’s ultimate aim to circum­ navigate Africa as Hanno [12] had sup­ posedly done two thousand years before, but in his lifetime his ships only reached the area now marked by Dakar, the west­ ernmost point on the western bulge of Africa. He died a full generation before the continent was successfully rounded. The light he lit did not go out. Portu­ guese successes inspired other west Euro­ pean nations to send expeditions of their own and the great Age of Exploration was under way, reaching its climax with Columbus [121] and Magellan [130]. [112] ULUGH BEG (oo'loog begO Mongol astronomer Born: Soltaniyeh, Persia, March 22, 1394 Died: Samarkand (now part of the Uzbek S.S.R.), October 27, 1449 Ulugh Beg (“great prince”) is the name by which Muhammad Taragay is known. He was a grandson of the Mon­ gol warrior Tamerlane, last of the great barbarian conquerors. He himself gov­ erned a portion of the central Asian realm in the lifetime of his father and succeeded to the throne in 1447. His real fame, however, is as the only 65

[113]

TOSCANELLI

important scientist to be found among the Mongols. In 1420 he founded a uni­ versity in Samarkand, and in 1424 he built an astronomic observatory there, the best in the world at that time. Furthermore, he did more than merely fiddle with Ptolemy’s [64] tables, as Eu­ ropean astronomers were doing through­ out the Middle Ages. Ulugh Beg pub­ lished new tables in the Tadzhik lan­ guage based on his own observations. They were superior to those of Ptolemy. His star map, containing 994 stars, was the first new one since Hipparchus [50], Ulugh Beg, however, was doomed to obscurity by the accident of space and time. He had no followers and when he was assassinated by his son in 1449, Mongolian astronomy died with him. His observatory was reduced to ruins by 1500 and it was only in 1908 that its remains were found. His writings appeared in Arabic and Persian, but the nations of Europe where astronomy was soon to burst into new and gigantic growth did not hear of him. It was not until 1665 that his tables were translated into Latin and by that time Ulugh Beg had been surpassed by Tycho Brahe [156] and had been made obsolete by the coming of the telescope. Few even today realize that a Mongol prince had once been the greatest astron­ omer of his time. [113] TOSCANELLI, Paolo (tos-kuhnel'lee) Italian physician and mapmaker Born: Florence, 1397 Died: Florence, May 15, 1482 Toscanelli, the son of a physician, studied medicine and was a friend of Nicholas of Cusa [115]. He was inter­ ested in astronomy and made creditable observations of comets. His lone claim to fame, however, and his chief service to science, consisted of a mistake firmly held. He believed that Asia lay three thousand miles west of Europe and drew up a map of the Atlan­ tic Ocean with Europe on the east and Asia on the west. He showed this to 66

GUTENBERG

[114]

Columbus [121], and that was all Co­ lumbus needed. [114] GUTENBERG, Johann (goo'tenberg) German inventor Born: Mainz, Hesse, about 1398 Died: Mainz, about 1468 Little is known of Gutenberg’s early life, except that he used his mother’s maiden name. (His father’s name was Ganzfleisch—“goose meat”—and the change seems an improvement.) About 1430 he had to leave Mainz as a result of being on the losing side of a civic squabble. He went to Strasbourg, a hun­ dred miles to the south. By 1435 he was involved in a lawsuit, and in that suit the word drucken (printing) was used. Gu­ tenberg’s attempt to make printing prac­ tical may have begun as early as that. Until Gutenberg’s time, books were laboriously copied by hand. This meant that they were few and expensive, that only rich men, monasteries, and universi­ ties could have libraries of dozens of books, that entire cultures had to be satisfied with only one or two really large libraries. (The one at Alexandria was the most famous in all the centuries before Gutenberg.) Furthermore, errors were bound to infiltrate hand-copied books unless the most heroic precautions were taken. (The Jewish copyists of the Bible counted every letter in an effort to guard against error.) The mechanical reproduction of letter­ ing—incising it in reverse on wood or metal and then pressing the surface against a soft medium or (after inking) on a blank sheet—was known in ancient times. The Sumerians and Babylonians used small intaglios to serve as signatures when impressed in clay, much as we use inked stamps. What Gutenberg conceived, however, was not a one-shot stamp, good only for one purpose, but a series of small stamps, each representing a single letter, which could be assembled to form a page of lettering, then broken down and reassembled to form another page. A limited number of such movable type

[114]

GUTENBERG

could then be used to print an unlimited number of different books, and, what is more, an unlimited number of identical copies of a particular book could be printed in very little time. By 1450 Gutenberg was back in Mainz and definitely engaged in working on his invention. Like most crucial in­ ventions, the practical development de­ pended on the concurrent success of other developments. The production of many books required the existence of a cheap and plentiful supply of something on which the printing could be impressed. Fortunately paper, which had been invented by Tsai Lun [63] fourteen centuries earlier, had reached Europe. Proper inks had to be developed and also proper techniques for forming tiny metal letters all of the same measure­ ments so that they could be interchanged without trouble and so that all would impress themselves on the paper equally. Gutenberg also designed a printing press to make the impression more firmly than could be managed by the unaided biceps. It was not easy; although the concept of printing probably took no more than an instant of time to enter Gutenberg’s head, the practical development took at least twenty years. By 1454 Gutenberg was ready for the big task. He began to put out a Bible, in double columns, with forty-two lines in Latin to the page. He produced three hundred copies of each of 1282 pages and thus produced the three hundred Gutenberg Bibles. It was the first printed book, and many people consider it the most beautiful ever produced—so that the art was born at its height. The Gu­ tenberg Bibles that remain are the most valued books in the world. Unfortunately, Gutenberg had gone into debt to produce the Bible and was sued for the money. He lost (he was a chronic loser) and was forced to hand over his tools and presses. He did not even get a chance actually to publish his Bible. The winners of the suit, including his ex-partner, did so. Gutenberg, who never married, died in debt and, apparently, a failure, but print­ ing proved a phenomenal success. It swept Europe and introduced a new

NICHOLAS OF CUSA

[115]

method by which propagandists could spread their views. It is probable that Luther’s rebellion against the church suc­ ceeded where previous rebellions had failed because Luther harnessed the printing press and fought his battle with broadsides of intensely styled pamphlets. Printing meant cheap books, and cheap books made literacy worthwhile. By 1500 up to nine million printed cop­ ies of thirty thousand different works were in circulation. The base of scholar­ ship broadened and the educated com­ munity grew in numbers. Furthermore, the views and discoveries of scholars could be made known quickly to other scholars. Scholars began to act as a team, instead of as isolated individuals. The realm of the unknown could more and more be assaulted by concerted blows. Scientists were no longer fists, but arms moving a battering ram. Printing did not immediately bring on the Scientific Revolution. A century was yet to pass. However, it made the revolu­ tion inevitable. And, taken in reverse, the revolution would probably have been impossible without printing. [115] NICHOLAS OF CUSA German scholar Bom: Kues, near Treves, Rhine­ land, 1401 Died: Lodi, Italy, August 11, 1464 Nicholas Krebs, usually known as Nicholas of Cusa from his birthplace, was the son of a fisherman. He studied law at Heidelberg, then at the University of Padua, where he met Toscanelli [113] and where he received his degree in 1423. He abandoned law, however, to enter the church in 1430. He was pri­ marily a philosopher and had the un­ canny knack of coming upon notions that are close to those now held. In opposition to the practical Regio­ montanus [119], Nicholas, in a book published in 1440, held that the earth turned on its axis and moved about the sun, that there was neither “up” nor “down” in space, that space was infinite, that the stars were other suns and bore 67

[116]

BESSARION

in their grasp other inhabited worlds. These beliefs, however, were not backed by detailed observation, calculation, or theory. They did not affect the course of science, and it is doubtful that Coper­ nicus [121] even heard of them. In other fields, Nicholas was equally intuitive. He constructed spectacles with concave lenses for the nearsighted, where earlier spectacles had made use only of the more easily ground convex lenses and served only the farsighted. He con­ sidered that plants drew their sustenance in part from the air, and he advocated counting the pulse as a diagnostic aid in medicine. In general, he was anxious to measure physical phenomena, a point of view Galileo [166] was to make popular a century and a half later. Far from get­ ting into trouble for his radical views, Nicholas was appointed a cardinal in 1448. Bruno [157], who shared many of his views in a later and more troubled time, was not to be so fortunate. [116] BESSARION, John (beh-saCee-on) Greek scholar Born: Trebizond (now Trabzon, Turkey), January 2, 1403 Died: Ravenna, Italy, November 18, 1472 Constantinople, after having been the great Roman capital of the East, had grown weaker and weaker and was in imminent danger of falling to the waxing power of the Ottoman Turks. Repeat­ edly, the Byzantine Emperors appealed for help to the West. The West wasn’t strong enough to help and, in any case, wanted the Eastern Christians to ac­ knowledge the primacy of the pope, which the Eastern Christians would not do even if it meant subjection to the Turks. In 1437, Emperor John VIII came to Italy, pleading for help. With him was Basil Bessarion, archbishop of Nicaea. Bessarion, at least, favored accepting the pope’s terms and when the emperor re­ turned with nothing accomplished, Bes­ sarion stayed on in Italy, took the name 68

ALBERTI

[117]

John, and was made a cardinal in 1439 by Pope Eugene IV. Bessarion was a great scholar who had accumulated many manuscripts of the great Greek books. He spread the knowl­ edge of Greek to western scholars; trans­ lated the works of Aristotle [29], which thus reached the West for the first time without having been filtered through the Arabic first. On his death, he left his library to the Senate of Venice. By that time, Constan­ tinople had fallen to the Turks (in 1453) but, thanks to Bessarion, Greek knowledge was not utterly lost to the West. [117] ALBERTI, Leone Battista (al-ber'tee) Italian artist Born: Genoa, February 18, 1404 Died: Rome, April 25, 1472 In their almost uncritical appreciation of the achievements of the ancients the humanists of the Renaissance failed to see that after those ancients a number of advances had been made in technology, and those later centuries were not simply to be dismissed as “dark.” The Dark Ages (a term invented in the Renais­ sance as a derogatory reference) saw the introduction of the compass, of gunpow­ der, of windmills, of horseshoes, and horse collars. Nor was the literature, ar­ chitecture, art, and philosophy of the Dark or Middle Ages to be too easily dismissed. In comparison the men of the Renaissance, who exalted art and litera­ ture (the “humanities”), tended to ne­ glect science. The neglect was not, of course, com­ plete. Even the finest of the fine arts will, in some measure, lead thought in the di­ rection of science, because, in the final analysis, all knowledge is one. Alberti, the illegitimate son of a wealthy Florentine exile, is an example. He was educated in law at the University of Bologna, receiving his doctorate in 1428, but law did not hold him and could not. He was a “Renaissance man” in the sense of having a broad range of

[118]

PEURBACH

interests, of excelling in many fields and scorning narrow specialization. Arriving in Rome in 1432, where his talents had full scope, he was prominent in nearly all the arts, in painting and in sculpture. He was an excellent architect (the best since Vitruvius [55]) and de­ signed some notable churches in Mantua and Rimini. He wrote a treatise on ar­ chitecture that remained authoritative for centuries. He was a musician and or­ ganist as well, a writer of tragedies in Latin, and also a mathematician. Alberti was a developer of the laws of perspective in a book published in 1434 and thus the forerunner of what is today called “projective geometry,” a science properly developed by Poncelet [456] four centuries later. He used mechanical aids, such as pinhole cameras, to guide him. The laws of perspective gave Re­ naissance art its naturalism and distin­ guished it from the solemn two-dimen­ sionality of medieval art. In the hands of later Renaissance masters, such as Leo­ nardo da Vinci [122], considerations of perspective grew so detailed that art be­ came almost a branch of geometry. The vogue for such “real looking” art has long passed among most artists, but it is still the kind of art most easily appreci­ ated by the untrained eye. [118] PEURBACH, Georg von (poir'bahkh) Austrian mathematician and as­ tronomer Born: Peurbach (near Vienna), May 30, 1423 Died: April 8, 1461 Peurbach studied at the University of Vienna, then traveled to Italy, the intel­ lectual center of Europe at the time. There he met Nicholas of Cusa [115]. He returned to Vienna in 1453 and lec­ tured there on astronomy and mathe­ matics, and was appointed astrologer to King Ladislas V of Hungary and later to the Emperor Frederick III. Peurbach was an ardent advocate of the use of Arabic numerals, an innova­ tion that was already two hundred and

REGIOMONTANUS

[1 1 9 ]

fifty years old, having been introduced that long ago by Fibonacci [95], Even so, the infinitely inferior Roman nu­ merals were still doggedly retained by many, a remarkable example of self­ damaging conservatism. Peurbach’s use of Arabic numerals to prepare a table of sines of unprecedented accuracy, ad­ vancing the mechanics of trigonometry past the Greek and Arabic mark, made it very difficult for the reactionaries. He died, however, before he could finish. His pupil Regiomontanus [119] labored at the table too, and also died before he could finish. Peurbach attempted to polish the Ptole­ maic system, but he did not dare change it in essentials. He took a backward step in fact by insisting on the solid reality of the crystalline spheres of the planets, something which Ptolemy [64] had not quite insisted upon in the Almagest. These solid spheres only lasted a cen­ tury, however, and then Tycho Brahe [156] destroyed them once and for all. [119] REGIOMONTANUS (ree-jee-ohmon-tayffius) German astronomer Born: Königsberg, Franconia, June 6, 1436 Died: Rome, Italy, July 8, 1476 Regiomontanus was the son of a miller and his real name was, appropriately enough, Johann Müller. His high-sound­ ing pseudonym (“king’s mountain” in English) is the Latin name of his birth­ place, which is not, by the way, the more famous Königsberg (now Kaliningrad), East Prussia. Regiomontanus was admitted to the University of Leipzig at the age of eleven. In 1450, he was at the Univer­ sity of Vienna, where he gained his bachelor’s degree in 1452 and was on the faculty in 1457. He was a thoroughgoing follower of Ptolemy’s [64] astronomy, and learned Greek in order to probe back beyond the Arabs. He studied with Peurbach [118] and labored with him in joint endeavors. Regiomontanus published a revised 69

[119]

REGIOMONTANUS

and corrected version of Almagest, mak­ ing use of the Greek copies Bessarion [116] had brought from Constantinople. However, it was not as good a version as, unknown to him or anyone in Europe, Ulugh Beg [112] was preparing a continent away. Regiomontanus also discovered an uncopied manuscript of Diophantus [66], the only portion of his work ever recovered. Regiomontanus was conservative in his outlook. He went out of his way to deride the possibility that the earth moved. He insisted that rotation on its axis was a foolish concept and pointed out that the earth’s rotation would mean that birds would be blown away, clouds would be left behind, buildings would tumble. This argument had been used before and would continue to be used with powerful effect until the time of Galileo [166], Regiomontanus made important obser­ vations of the heavens and prepared new tables of planetary motions that brought those prepared under Alfonso X [100] up to date. The new tables were widely used by the navigators of the Age of Ex­ ploration, which was now in full swing, and were, for instance, used by Colum­ bus [121], Regiomontanus introduced Germany to the use of Arabic algebraic and trigonometric methods, reproducing the tables by the use of Gutenberg’s [114] then newfangled technique of printing. As might be expected of a Renaissance man, Regiomontanus also lectured on Vergil and Cicero. And, on the other hand, he published books on astrology, of which he was an ardent practitioner. In 1472 Regiomontanus made obser­ vations of a comet (later known as Hal­ ley’s) and this was the first time that comets were made the object of a scientific study, instead of serving merely to stir up superstitious terror. By 1475 his fame had grown so that he was sum­ moned to Rome by Pope Sixtus IV to help reform the Julian calendar, a proj­ ect that had been hanging fire for cen­ turies. However, Regiomontanus died in Rome the following year of the plague, and the project dragged on for nearly another century. 70

COLUMBUS

[121]

[120] PACIOLI, Luca (pah-choh'lee) Italian mathematician Born: Sansepolcro, Tuscany, about 1445 Died: Sansepolcro, 1517 Pacioli studied mathematics when he was in the service of a rich Venetian merchant. He became a Franciscan friar about 1470 and wandered from place to place, teaching mathematics and writing books on arithmetic sufficiently success­ ful to net him positions as lecturer at such universities as those at Perugia, Naples, and Rome. At the court of Lu­ dovico Sforza, Duke of Milan, Pacioli met Leonardo da Vinci [122]. Pacioli taught Leonardo mathematics and in re­ turn, Leonardo helped illustrate one of Pacioli’s books. (Lucky Pacioli!) Pacioli also prepared both Latin and Italian ver­ sions of Euclid. Pacioli’s work on mathematics was of minor importance, but there are humble ways, too, in which it can be of use. In 1494, he had published his major work on arithmetic and geometry and it in­ cluded the first appearance in print of a detailed description of the method of double-entry bookkeeping. It may not seem much but such a device greatly fa­ cilitates the ease and accuracy with which business can be conducted and did its bit to contribute to the growth of the merchant states of western Europe on their way to world domination. [121] COLUMBUS, Christopher Italian explorer Born: probably Genoa, 1451 Died: Valladolid, Spain, May 20, 1506 Not much is known of Columbus’ early life. Although it is generally thought he was born in Italy, there is nothing in his later life to make him seem an Italian. His writing was always in Spanish or Spanish-tinged Latin; he used a Spanish version of his name; and he showed no signs of any Italian sympa­ thies. There is a persistent, but un­ verified, rumor that he was born of a

[121]

COLUMBUS

Spanish-Jewish family residing in Genoa at the time of his birth. The son of a weaver, Columbus re­ ceived an education, though this may have been from reading rather than for­ mal training. About 1465, rather than work as a wool comber like his father, he ran away to sea. While still young he sailed through the Mediterranean and is supposed to have made a trip to Iceland. In 1479 he married the daughter of a distinguished Italian navigator in the Portuguese service and this intensified his interest in navigation generally. He gained a knowledge of mapmaking and, very fortunately, gained just enough misinformation to believe with Poseidonius [52] that the earth was no more than eighteen thousand miles in circum­ ference. This was reinforced by a map by Toscanelli [113], with whom he was in contact in 1481. He had read eagerly of the wonders of the Indies in the book by Marco Polo [105] and it seemed to him that a voyage of only three thou­ sand miles west of Europe would bring him to those same Indies. (It is a common myth that Columbus believed the earth was round while ev­ eryone else thought it was flat. The fact is that the earth’s rotundity was accepted by all European scholars of the time. The only points of disagreement lay in the distance from Europe to Asia—that is, in the circumference of the earth— and in the feasibility of traveling that distance in the boats of the day.) In the early 1480s Columbus was, like his father-in-law, sailing in the service of Portugal and his passion for a westward trip finally goaded him into placing the project before the Portuguese king, John II. The king, in turn, referred it to the Portuguese geographers who, very prop­ erly, rejected it, for they were sure that Columbus’ claim of three thousand miles to Asia was a gross underestimate and that the surest route to Asia was around Africa. In this the experienced Portuguese were quite correct (Africa was successfully circumnavigated fifteen years later) and the Italian dreamer completely wrong. What neither of them knew, however, was that between Europe and Asia lay unknown continents

COLUMBUS

[121]

and that these unknown continents did lie three thousand miles distant. (This is one of the more fortunate coincidences of history.) Columbus then tried to interest the city of Genoa, other Italian city-states, England, and Spain in his visionary plan and, for a while, met failure all around. In 1492, however, the monarchs of Spain, Ferdinand and Isabella, had just wiped out the last remnant of Muslim rule over the peninsula, and in the glow of triumph they agreed to subsidize Co­ lumbus. The subsidy was not a generous one, but on August 3, 1492, Columbus set sail with three small ships and 120 men (mostly from the prisons). On October 12 he landed on a small island of what he thought were the Indies. He explored various regions and returned to Spain and the sort of wild acclamation that these days is accorded an astronaut safely returned to earth. In the next ten years he made three more voyages to the Indies. He was given office in the new lands, but was as poor an administrator as he was coura­ geous a navigator, and that is very poor indeed. He died in eclipse, still believing that he had reached Asia. King Ferdinand, having watched with indifference while Columbus ended his life in misery, gave him a splendid fu­ neral. His body was eventually moved to the New World and now rests in the Dominican Republic. His voyage caught the imagination of Europe far more strongly than any pre­ vious ones. There were great explorers before Columbus, but Columbus drama­ tized exploration and did for ocean-going what Lindbergh [1249] was to do for air­ going more than four centuries later. It was impossible to make a trip of this sort without adding to man’s knowl­ edge. Columbus discovered new races of men, new plants, and new phenomena. He was the first to note, on September 13, 1492, the shifting of the direction in which the compass needle pointed as one traveled from place to place on the earth’s surface. (He kept this from his men lest they panic at the thought that they were heading into strange regions 71

[1 2 2 ]

LEONARDO DA VINCI

where the laws of nature were no longer observed.) The new picture of the globe that fol­ lowed on Columbus’ voyage seemed to emphasize the littleness and insufficiency of ancient knowledge. The fact that huge lands existed of which Aristotle [29] and Ptolemy [64] knew nothing, seemed to lift some of the psychological restraint of intellectual rebellion. The birthpangs of the imminent Scientific Revolution (Co­ pernicus [127] was nineteen when Co­ lumbus made his great voyage) were made that much easier. [122] LEONARDO DA VINCI (veen'chee) Italian artist Born: Vinci, near Florence, April 15, 1452 Died: Castle Cloux, near Amboise, France, May 2, 1519 Leonardo was of illegitimate birth, but was acknowledged and raised by his fa­ ther, a notary. Most of us think of him as an artist, particularly as the painter of the “Mona Lisa” and the “Last Supper,” but he was much more than that. Even more than Alberti [117] he was a “Re­ naissance man,” though he lacked a clas­ sical education and knew neither Latin nor Greek. He was a military engineer who visual­ ized devices beyond the scope of his time and drew sketches of primitive tanks and airplanes, using all sorts of elaborate gears, chains, ratchets, et cetera. He was endlessly ingenious in the mechanical gadgetry possible to the level of technol­ ogy of the time. He is supposed to have designed the first parachute and to have constructed the first elevator, one for the Milan cathedral. In order to design air­ planes he studied the flight of birds, and for submarine designs he studied the manner in which fish swam. He also ad­ vertised his abilities as flamboyantly as Alhazen [85] five centuries earlier, but more honestly and with better results. Despite the seeming bloodthirstiness of his war engines, he was a humanitarian who denied himself meat out of an aver­ sion to the killing of animals. Moreover, the combination of military 72

VESPUCIUS

[123]

engineering ability and superlative artis­ tic skill brought Leonardo a succession of powerful patrons in an age that val­ ued war and art equally. These included Lorenzo the Magnificent of Florence, Ludovico Sforza of Milan, Cesare Bor­ gia, the son of Pope Alexander VI, Louis XII of France, Giulio de Medici, brother of Pope Leo X, and, finally, Francis I of France. In science Leonardo had amazing in­ sight. He had a notion of the principle of inertia, and nearly a century before Gali­ leo [166] he understood that falling bod­ ies accelerated as they fell. He grasped the impossibility of perpetual motion decades before Stevinus [158], As an artist, he studied the structure of the muscles and bones of the human body, dissecting some thirty cadavers. (This brought on some difficulties with authorities in Rome.) He also studied the structure and working of the heart and its valves and speculated on the cir­ culation of the blood a century before Harvey [174], He considered the moon to be earthy in nature and to shine by reflected sun­ light; and the earth not to be the center of the universe, and to be spinning on its own axis. He even considered the possi­ bility of long-continued changes in the structure of the earth two centuries ahead of Hutton [297] and had correct opinions as to the nature of fossils. His close observation and his amazing skill at drawing were such that his pictures of waves and bubbles in water could not be improved on till the coming of the slow­ motion camera. Unfortunately he kept his ideas to himself, writing them in code in volumi­ nous notebooks so that his contem­ poraries knew nothing of his ideas and remained uninfluenced by them. It is only we modems who have learned of them, and that only long after the fact. [123] VESPUCIUS, Americus (vespyoo'shus) Italian navigator Born: Florence, March 1454 Died: Seville, Spain, February 22, 1512

[124]

CANO

Americus Vespucius is the Latinized version of Amerigo Vespucci. Vespucius was the son of a notary, who worked for Florentine bankers and was sent by them on missions to Spain. The voyages of Columbus [121] had shaken the world; Asia had presumably been reached, and yet the wealth and civilization of Asia had not become ap­ parent. Between 1497 and 1504, Vespu­ cius took part in voyages to the western shores of the Atlantic to consider the matter. Vespucius did not make any funda­ mental physical discoveries, but he did something more important. He had a keen flash of insight. To his dying day, Columbus had been convinced he had reached Asia; but to Vespucius, this was impossible. The new lands extended too far to the south. In 1504, Vespucius said that the new lands were not Asia but represented a new continent totally un­ known to the ancients; and that between that continent and Asia there must stretch a second ocean. (Actually, Co­ lumbus, too, would have believed this, were it not that he was convinced earth was considerably smaller than it really was.) It was this concept which really marked the break with the ancient world. If Columbus had simply reached Asia, this was after all in accordance with the Greek notions of the world. It was a new continent unknown to them that turned everything topsy-turvy, and it is only justice that the new continents were named America after Vespucius and not Columbia after Columbus. Vespucius ended his life as official as­ tronomer to Ferdinand II of Spain. Ves­ pucius met Columbus toward the end of the latter’s life and their relationship was friendly.

DÜRER

[126]

The great moment of Cano’s life was his return to Spain with one ship carry­ ing a crew who had circumnavigated the earth. It is he, not Magellan [130], who deserves the title of first circum­ navigator. However, it was Magellan whose grit kept the expedition together during the terrible months in the Pacific. Cano died four years later on a second expedition to the far Pacific. The pitcher went to the well once too often. [125] WALDSEEMOLLER, Martin (vahlt'zay-myool-er) German cartographer Born: Radolfzell or Freiburg, Baden, about 1470 Died: St. Die, Alsace (now in France), about 1518 Were it not for one thing, Waldseemiiller and his maps (competent though they were) would have sunk without a trace as far as the history books were concerned. In 1507, however, he printed one thousand copies of one particular map in which he decided that Columbus’ [121] discovery was indeed a new continent as Americus Vespucius [123] claimed it was, and in the excitement of his sudden conviction, he named that new continent “America” and inscribed the name on the map. It was the first time the name had ap­ peared in print on a map, and it caught on at once. All but one of the maps of that printing were lost with time. The ex­ ceptional one was uncovered in 1901 in the private library of a German noble­ man. Waldseemiiller was canon of St. Die at the time of his death.

[126] DÜRER, Albrecht (dyoo'rer) German artist Born: Nürnberg, May 21, 1471 [124] CANO, Juan Sebastian del (kah'Died: Nürnberg, April 6, 1528 noh) Spanish navigator Dürer, the son of a goldsmith, worked Bom: Guetaria, about 1460 as his father’s apprentice in early life. He Died: somewhere in the Pacific is pre-eminently known as one of the Ocean, August 4, 1526 great artists of history. He was per­ 73

[127]

COPERNICUS

COPERNICUS

[127]

when he attended a conference in Rome that dealt with calendar reform, under­ stood to be necessary since the time of Roger Bacon [99] two centuries before but not to come for another seventy years. The intellectual ferment in Italy was not above questioning established ways. The system of the universe as pro­ pounded by Hipparchus [50] and Ptol­ emy [64], in which all heavenly bodies were considered rotating about the earth, was almost indecently complex and de­ spite all the careful mathematics in­ volved was not very useful for predicting the positions of the planets over long pe­ riods. The Alfonsine Tables, of Alfonso X [100], the best the previous centuries had produced, were already far off the mark, and the corrections of Regiomon­ tanus were only of temporary value. It occurred to Copernicus as early as 1507 that tables of planetary positions could be calculated more easily if it were assumed that the sun, rather than the earth, were the center of the universe. This would mean that the earth itself, along with the other planets, would have to be considered as moving through space and revolving about the sun. This was not a new idea. Among the ancients, Aristarchus [41] had suggested the notion, and not many years before [127] COPERNICUS, Nicolas (co-peri- the time of Copernicus, Nicholas of Cusa [115] had made a similar sugges­ nuh-cus) tion. Polish astronomer Copernicus was to do more than sug­ Born: Torun, February 19, 1473 gest, however. Beginning in 1512, he set Died: Frombork, May 24, 1543 about working out the system in full Copernicus was the son of a well-to-do mathematical detail in order to demon­ copper merchant and, after his father’s strate how planetary positions could be early death in 1483, was brought up by calculated on this new basis. In doing his uncle, a prince-bishop, so he had the this, he made little use of his own obser­ advantage of being able to get a first- vations, for astronomical observation was not his forte, apparently. He is sup­ class education. Beginning in 1491, he studied mathe­ posed never to have seen the planet Mer­ matics and painting at Cracow, then and cury (which is, however, the most dif­ for many years afterward the intellectual ficult of the planets to observe because center of Poland. In 1496 he traveled to of its nearness to the sun). Still, his ob­ Italy for a decade’s stay, during which servations were good enough to enable time he studied medicine and canon law, him to determine the length of the year and after reading the works of Regio­ to within twenty-eight seconds. montanus [119], interested himself in as­ As it turned out, the Copernican sys­ tem explained some of the puzzling mo­ tronomy. In 1500 this interest wax intensified tions of the planets rather neatly. The

haps the greatest to express himself in the field of engraving and woodcuts, and as the inventor of the art of etching. Like Leonardo da Vinci [122], Dtirer’s interest in art drove him to science. In 1525 he published a book on geometrical constructions, using the straightedge and compass. Essentially, it was for use by artists, for this was at the height of the move for naturalism in art, a time when artists strove to present a perfect three­ dimensional illusion on a two-dimen­ sional surface. It might, from this stand­ point, be considered the first surviving text on applied mathematics. However, Dürer was not content merely to supply artists with mathe­ matical recipes; he supplied careful proofs to show the validity of his con­ structions, which included complex curves. The book was published in Ger­ man (it was unusual in those days to publish learned material in the “vulgar tongue”), but it was quickly translated into Latin so that it might serve the needs of artists and scholars outside Ger­ many. Dürer also wrote on the propor­ tions of the human body. Dürer was court painter to Emperor Maximilian I and to his successor, Charles V.

74

[127]

COPERNICUS

orbits of Mercury and Venus, according to the new system, would naturally never take those planets farther than a certain distance from the sun, as viewed from the earth, because the orbits of those two planets lay closer to the sun than did the orbit of the earth. On the other hand, since the earth would have to be consid­ ered as traveling in a smaller orbit than those of Mars, Jupiter, and Saturn, it would periodically overtake those planets and cause them to appear to be moving backward in the sky. Both the limited motion of Mercury and Venus and the backward (“retro­ grade”) motions of Mars, Jupiter, and Saturn had been thorns in the side of the Ptolemaic theory and vast complications had been introduced to account for them. Now they were easily and simply explained. Furthermore, the phenome­ non of the precession of the equinoxes, discovered by Hipparchus, could be ex­ plained not by a twisting of the entire celestial sphere, but by a wobbling of the earth as it rotated on its axis. As for the celestial sphere of the stars, Copernicus held it to be a vast distance from the earth, at least a thousand times as distant as the sun, so that the positions of the stars did not reflect the motion of the earth. (The fact that they did not was used as an argument against Copernicus, an argument that was not fully laid to rest until the time of Bessel [439] three centuries later.) So much was explained so well by the new Copernican system that it grew tempting to consider that system as more than a mere device to calculate planetary positions. Perhaps it described the actual situation, moving earth and all. Coper­ nicus, however, still kept the notion of perfectly circular orbits and had to re­ tain thirty-four of the epicycles and ec­ centrics associated with the older theory. This was not corrected until the time of Kepler [169] a half century later. Copernicus described his system in a book, but for years he hesitated to pub­ lish it, believing that any suggestion that the earth moved would be considered heretical and might get him into trouble. This view was a natural and perhaps a

COPERNICUS

[127]

prudent one in the light of the later trou­ bles of Galileo [166] and Bruno [157]. In 1505 Copernicus returned to Po­ land, where he served as canon, under his uncle, at the cathedral at Frombork (Frauenberg, in German), though he never became a priest. (He never mar­ ried, just the same.) He also served as his uncle’s doctor and fulfilled a variety of administrative duties, especially after his uncle’s death. He was involved in diplomatic negotiations between the Poles and the Teutonic Knights of Prus­ sia, for instance. Then, too, in working on currency reform, he came up with the notion that the appearance of debased currency drives good coins into hiding— something later called “Gresham’s law” after an economist who was a younger contemporary of Copernicus. Meanwhile, by 1530, he had prepared a summary of his notions in manuscript and this circulated among Europe’s scholars, creating considerable interest and enthusiasm. Finally, at the urging of the mathematician Rheticus [145], Co­ pernicus permitted publication of his en­ tire book, carefully dedicating it to Pope Paul III. Rheticus volunteered to oversee its publication. Unfortunately, Rheticus had to leave town since he was involved in some rather uncomfortable doctrinal disputes and since he had a chance to accept a better position at Leipzig. He left a Lutheran minister, Andreas Osiander, in charge. Luther had expressed himself firmly against the Copernican theory, and Osiander played it safe by adding an unauthorized preface to the effect that the Copernican theory was not advanced as a description of the actual facts but only as a device to facilitate computation of planetary tables. This weakened the book and for many years compromised Copernicus’ reputation, for it was long thought that he was responsible for the preface. It wasn’t until 1609 that Kepler discovered and published the truth. The book was published in 1543 and the story has long persisted that the first copy reached Copernicus as he lay on his deathbed, suffering from a stroke. A copy of the book, dated four weeks be­ fore his death has recently come to light 75

[128]

BALBOA

SCHÖNER

[129]

and it may be that Copernicus had a chance to see it. Only a few hundred copies of this original edition were printed. About two hundred of them still exist, forty-four of them in various American collections. The Vatican Library, ironically enough, has three. The original hand-written draft also exists and we can see in it that Copernicus crossed out an original refer­ ence to Aristarchus (in order not to have some suppose, it may be, that his ideas were derivative). The book began to win converts at once, Reinhold [143] using it within a few years to publish new tables of plane­ tary motion. Nevertheless it was not a financial suc­ cess. It was overpriced and was allowed to go out of print. A second edition was not printed till 1566 (in Basel, Swit­ zerland) and a third not until 1617 (in Amsterdam). With Copernicus began the Scientific Revolution, which was to dethrone Greek science and set man on a new and far more fruitful path. It reached a cli­ max and fulfillment with Newton [231] a century and a half later. Yet it was not until 1835 that Copernicus’ book was re­ moved from the list of those banned by the Roman Catholic Church. In 1807 Napoleon’s conquering career had brought him to Poland. He visited the house in which Copernicus was born and expressed his surprise that no statue had been raised in his honor. In 1839 this omission was rectified, but when the statue to Copernicus was unveiled in Warsaw, no Catholic priest would officiate on the occasion.

creditors. He went to America in 1500 for a new start. In what is now Haiti, he tried to be a planter, went into debt as usual, man­ aged to get onto a ship by hiding in a large barrel that was supposed to be full of provisions, and ended up on the northern coast of South America. When conditions grew bad there, he suggested in 1510 that the colony be transferred to Darien (what is now Pan­ ama). There, in 1513, he received a let­ ter indicating he would be summoned back to Spain to answer certain charges. He decided that the charges would surely be dismissed if he could find gold. He outfitted an expedition of 190 Spanish soldiers and a thousand Indian warriors and headed inland from the Panama coast to find the gold. He didn’t realize he was on a narrow isthmus. On September 7, 1513, he found himself on the other side of the isthmus, facing what seemed to be a huge body of water. Since Panama runs east and west and the Atlantic was on the north shore; Balboa called this new body of water the South Sea. He didn’t quite realize it but for once he had had an amazing stroke of good fortune. He was the first European ever to see the eastern end of the Pacific Ocean. He was standing on the shore of the second ocean that Americus Vespucius [123] had talked of nine years be­ fore as lying between Europe and Asia. But the good fortune wasn’t enough; for it wasn’t gold. Balboa was replaced as head of the colony and eventually was falsely accused by his enemies, convicted on trumped up charges and perjured tes­ timony, and beheaded.

[128] BALBOA, Vasco Nünez de (balboh'uh) Spanish explorer Born: Jerez de los Caballeros, Ba­ dajoz, 1475 Died: Panama, 1517 Balboa was a man for whom misfor­ tune seemed to be a constant companion. He was forever getting into debt and having to go to extremes to elude his

[129] SCHÖNER, Johannes (shoi'ner) German geographer Born: Karlstadt (now Karlovac, Yugoslavia), January 16, 1477 Died: Nuremberg, Bavaria, January 16, 1547 Schöner studied theology in the Uni­ versity of Erfurt. He did not take a de­ gree but was ordained a Roman Catholic priest.

76

[130]

MAGELLAN

He was a professor of mathematics at the University of Nuremberg, and is best remembered for the globes he made. The one he constructed in 1515 was the first globe to include the new lands discov­ ered by Columbus [121] and to name those lands “America,” as Waldseemiiller [125] had suggested. In later life, Schoner abandoned the priesthood and became a Lutheran. [130] MAGELLAN, Ferdinand (majel'an) Portuguese explorer Born: Sabrosa, Tras-os-Montes, about 1480 Died: Philippine Islands, April 27, 1521 Through most of his life, Magellan was a loyal son of Portugal. He served as page at the court of John II, the king who turned down Columbus [121]. He was on expeditions to the East Indies and fought in Morocco, where he was wounded in action and permanently lamed. He was denied a pension, accused of trading with the Moroccans—tan­ tamount to treason—and was dismissed from the armed forces in 1517. Magellan, bitter at this treatment, joined the Spanish service and offered to show the Spaniards a way to poach on Portuguese preserves. It seems that shortly after the voyage of Columbus, a north-south line had been drawn down the Atlantic under the auspices of Pope Alexander VI. All heathen lands west of the line were to belong to Spain, all east to Portugal. However, the line was not drawn completely around the earth and Magellan pointed out to Emperor Charles V that if the Spaniards contin­ ued to sail westward, they would stay on their side of the line and yet find them­ selves in the East Indies, which the Por­ tuguese were then exploiting. In other words, Magellan was proposing to do what Columbus had intended, but to do it right. He was placed in command of an ex­ pedition, therefore, and set sail on Au­ gust 10, 1519, with five ships. The ships crossed the Atlantic and sailed down the

MAGELLAN

[130]

eastern coast of South America, search­ ing for a sea passage through the conti­ nent. They found it finally far to the south, a passage still called the Strait of Magellan. (He called it the Strait of All Saints.) On this portion of the voyage they also sighted dim luminous clouds in the night sky that looked like detached pieces of the Milky Way. Visible only in the southern hemisphere, they are still called the Magellanic Clouds. Four cen­ turies later, Leavitt [975] was to forge of them a mighty measuring rod for the heavens. After a stormy and hellish voyage through the strait, Magellan burst into the calm of a great ocean, doing in real life (for a European) what Coleridge’s Ancient Mariner was to do in the poem. (“We were the first that ever burst into that silent sea.”) The ocean had been discovered at Panama by Balboa [128] seven years before and named the South Sea, but Magellan, because of its calm­ ness after the storms of the strait, called it the Pacific Ocean. Actually it is no more pacific than the Atlantic is. For ninety-eight days Magellan crossed the Pacific with no sign of land. He seized the occasion to try an ocean sounding, the first on record. He paid out nearly half a mile of rope in the mid-Pacific and did not reach bottom. The empty wastes of waters, calm but terribly blank, reduced the crew to des­ peration and starvation. On the brink of disaster they reached Guam on March 6, 1521, and were able to take on food and water. They then sailed to the Philip­ pines, where Magellan was killed in a squabble with the natives. Magellan’s expedition was the first to circumnavigate the earth, for one last ship, the Victoria, under Cano [124], managed to make its way across the In­ dian Ocean, around the southern tip of Africa and back to Spain, arriving Sep­ tember 8, 1522. The voyage had lasted three years and cost four ships, but the spices and other merchandise brought back by the surviving vessel were enough to allow a handsome profit. Magellan’s ships had accomplished a heroic task—for the technology of the 77

[131]

PARACELSUS

day—equivalent to the orbital flight of Gagarin [1502], It proved once and for all that the estimate of Eratosthenes [48] as to the size of the earth was correct and that of Poseidonius [52] and Ptol­ emy [64] was wrong. It also proved that a single stretch of water girdles the earth. There was one sea, not seven. [131] PARACELSUS (par-uh-sel'sus), Philippus Aureolus Swiss physician and alchemist Born: Einsiedeln, Schwyz, May 1, 1493 Died: Salzburg, Austria, Septem­ ber 24, 1541 Paracelsus’ real name was Theo­ phrastus Bombastus von Hohenheim, but in a fit of vainglory he named him­ self Paracelsus, meaning “better than Celsus” [57], the Roman physician whose works had recently been trans­ lated into Latin and had made a great impression on Paracelsus’ contem­ poraries. His father, a professor at a school of mines, taught him medicine and he him­ self studied everywhere he could, at the University of Basel which he entered in 1510, in Austrian mines, and wherever his feet carried him. He had to do much wandering (from Ireland to Russia to Turkey, according to his own account), part of it not altogether voluntary, for his life was marked by eccentricity, quarrelsomeness, and a vast army of en­ emies lovingly manufactured by himself. Despite a mystical obscurity of state­ ment, he marks the beginning of the transition from alchemy to chemistry. Paracelsus came to one crucial deci­ sion about the purpose of alchemy. The purpose of alchemy, he decided, was not to discover methods for manufacturing gold but to prepare medicines with which to treat disease. (These views of his were eventually developed into a sys­ tem called iatrochemistry.) It was a point of view then coming into fashion, as in the case of Paracelsus’ contem­ porary and fellow physician Agricola [132] , but it was Paracelsus’ loud mouth 78

PARACELSUS

[131]

that did most to bring it to general no­ tice. Before Paracelsus’ time, such medi­ cines as were used were from plant sources, but Paracelsus stressed the im­ portance of minerals, although he was the first to use the plant-derived tincture of opium in medical treatment (naming it laudanum). He did not always achieve happy results, for his almost psychotic cocksureness led him to use such medi­ cines as compounds of mercury and an­ timony even after practice had shown them to be toxic. Nor did Paracelsus in any way give up the mysticism of alchemy and astrology. He believed wholeheartedly in the four elements of the Greeks and the three principles (mercury, sulfur, and salt) of the Arabs as well as the influence of stars on disease. He sought unceasingly for the philosopher’s stone, which he believed to be an elixir of life, and even claimed to have found it, insisting that he would live forever. (To be sure, he died before he was fifty, but that was no real test: He drank heavily and his death was apparently brought about by an ac­ cidental fall.) He had the courage of his convictions. As town physician at Basel, he burned the works of Galen [65] and Avicenna [86] in public in 1527 and found no terms too harsh to denounce the an­ cients, whose theory of humors he would not accept. He also insisted on lecturing in Ger­ man, not Latin, and admitted barber-sur­ geons to his courses even though they sullied their hands with actual dissec­ tions. The result was that he was kicked out of Basel in 1528. That, however, didn’t stop him and for the rest of his life he kept furiously inveighing against his enemies and predecessors. He seized medicine by the scruff of its neck, so to speak, and if it wasn’t entirely sense that he shook into it, the shaking was beneficial just the same. He wrote intelli­ gently on the problems of mental dis­ ease, for instance, scoffing at theories of demonic possession. He studied lung diseases of miners and associated them with mining. He cor­ rectly diagnosed congenital syphilis. He

[132]

AGRICOLA

also correctly associated head injury with paralysis, and cretinism (a form of men­ tal and physical retardation) with goiter. Paracelsus was the first to describe zinc, and he is sometimes considered its discoverer, though zinc, at least in alloy form as brass, was known even in an­ cient times. * [132] AGRICOLA, Georgius (a-grik'oh-luh) German mineralogist Born: Glauchau, Saxony, March 24, 1494 Died: Chemnitz (modern Karl Marx Stadt), Saxony, November 21, 1555 Agricola was the son of a draper and his real name was Georg Bauer but, as was rather the fashion of his time, he Latinized it. Agricola in Latin and Bauer in German both mean “farmer.” Agricola was a physician by profes­ sion, having graduated from the Univer­ sity of Leipzig about 1518, then having studied medicine at the University of Ferrara in Italy. In the fashion of his contemporary Paracelsus [131] he be­ came interested in mineralogy through its possible connection with medicines and through the miners’ diseases he stud­ ied. In fact, the connection between medicine and minerals and the combina­ tion of the physician-mineralogist was to remain a prominent feature in the devel­ opment of chemistry for two and a half centuries. Agricola began his medical practice in 1527 in Joachimsthal, a mining center where he grew well-to-do through clever mining investments. Later, as his fame grew, he was subsidized by Prince Maurice of Saxony. In 1531 he traveled to Chemnitz where mining was even more important. Here he served as town physician and in 1546 became its mayor. His most important work, De Re Me­ tallica, wasn’t published till a year after his death, but in it he summarized all the practical knowledge gained by the Saxon miners. It was clearly written and had excellent illustrations of mining machin­ ery, so that it became popular at once

FERNEL

[134]

and indeed remains a worthy classic of science even today. It has been trans­ lated into English by Herbert and Lou Henry Hoover. Through this book Agric­ ola earned his title of father of mineral­ ogy. And, incidentally, it is he who may have coined the word “petroleum.” [133] APIAN, Peter (ay'pee-an) German astronomer Born: Leisnig, April 16, 1495 Died: Ingolstadt, April 21, 1552 Apian, who was also known as Petrus Apianus and Peter Bienewitz, studied mathematics and astronomy at Leipzig and Vienna and prepared maps that were based on the work of Waldseemiiller [125]. He wrote books populariz­ ing both mathematics and astronomy and served as professor of mathematics at the University of Ingolstadt, where he remained to his death. He was knighted by Emperor Charles V. His importance to science rests on a single observation. In 1540, he published a book in which he describes his obser­ vations of comets, and in which he de­ scribes the appearances of five different comets including the one that was later to be known as Halley’s comet. In the course of these descriptions, he mentions the fact that comets have their tails al­ ways pointing away from the sun. This was the first scientific observation concerning comets other than their posi­ tion in the sky. [134] FERNEL, Jean François (fer-nel') French physician Born: Montdidier, Somme, 1497 Died: Fontainbleu, Seine-etMame, April 26, 1558. Femel, the son of an innkeeper, grad­ uated from the University of Paris in 1519. He went on to obtain his medical degree in 1530 and in 1534 became pro­ fessor of medicine there. About 1547, after having successfully treated Diane de Poitiers, the king’s mistress, he be­ came physician to the king himself, Henry II of France, even though he had failed to prevent the king’s father, 79

[135]

TARTAGLIA

Francis I, from dying of syphilis earlier that year. (But then, no one in those days could have.) Femel’s reputation grew high enough to earn for him the sobriquet of the Modern Galen [65]. Femel was the first modern physician to make dissection an important part of his clinical duties. He wrote a book on the subject in 1542 and in it did not hes­ itate to correct Galen’s errors. He was the first to describe appendicitis. He also described peristalsis (the waves of con­ traction of the alimentary canal) and noted the central canal of the spinal cord. He introduced the terms “physiol­ ogy” and “pathology.” He wrote also on astronomy and mathematics and rejected astrology as possessing no relevance whatever to medicine.

FUCHS

[136]

volving cubic equations and could pose problems of that sort, which others found insoluble. Naturally, he kept his methods secret. Cardano [137] wheedled the method from, him under a promise of secrecy and eventually published it, something Tartaglia undoubtedly felt more deeply than ever he did the child­ hood slash. In 1537 Tartaglia published the first book on the theory of projectiles. (Leo­ nardo da Vinci [122] had written one that had not been published.) Tartaglia thought the ball began with “violent mo­ tion,” traveling straight from the can­ non’s mouth, and ended with “natural motion,” falling straight downward, with a region of “mixed motion” between. This did not agree, of course, with the practical experience of gunners, who could not, however, match Tartaglia’s theoretical arguments. Ballistics did not receive an accurate foundation until [135] TARTAGLIA, Niccold (tahr-tal'- Galileo’s [166] time nearly a century yah) later. Italian mathematician Born: Brescia, 1499 Died: Venice, December 13, 1557 [136] FUCHS, Leonhard (fyooks) German botanist Tartaglia was brought up in poverty Born: Wemding, Bavaria, January and was largely self-educated. His true 17, 1501 name was Fontana and the nickname by Died: Tübingen, May 10, 1566 which he is now universally known was born of a tragic incident in his child­ Fuchs obtained his medical degree at hood. Italy, after several centuries of the University of Ingolstadt in 1524. In high civilization, was made the victim of 1528 he became private physician to the invading armies and was reduced to margrave of Brandenberg and in 1535, some centuries of beggary. When Tar­ he became professor of medicine at the taglia was about twelve his native town University of Tübingen. He remained was sacked and a French soldier slashed there the rest of his life. his face. He recovered only through the Like Gesner [147], Fuchs interested loving care of his mother, and the himself in natural history and wrote wound left him with a speech defect and books such as History of Plants (1542) the name Tartaglia (“stutterer”). His in which numerous plant species were mind, however, did not stutter and, as a described in detail. There is a genus of mature man, he taught mathematics in shrubs that was eventually named in his various universities of northern Italy, honor because he described them, and coming to Venice at last in 1534. the color of its flower has given him a Tartaglia was the first to work out a kind of immortality. Not only the genus, general solution for equations of the but that particular color, a bluish red, is third degree (cubic equations). In those called fuchsia. days, mathematicians posed problems for Fuchs prepared the first important each other, and upon their ability to modern glossary of botanical terms. This solve those problems rested their reputa­ represented a clear break from Diostions. Tartaglia could solve problems in­ corides [59] and helped pave the way for 80

[137]

CARDANO

GEMMA FRISIUS

[138]

modern botany. Fuchs was an active 1539, then published the method six supporter of Vesalius [146], years later despite having solemnly vowed to keep it secret—an act that has placed a permanent blot on his memory. [137] CARDANO, Girolamo or Ge- He did give Tartaglia credit, but the ronimo (kahr-dah'noh) method is still called “Cardano’s rule.” Italian mathematician The importance of this incident lay in Born: Pavia, September 24, 1501 the fact that it aroused controversy on Died: Rome, September 21, 1576 the ethics of scientific secrecy. Eventu­ ally the decision was made that secrecy Cardano was the illegitimate son of a is of great harm to science and that the learned lawyer-mathematician who was a credit for any finding must go not to the friend of Leonardo da Vinci [122], The man who first makes the discovery, but young Cardano was nearly dead when he to the one who first publishes it. This is was born and passed a sickly and very now universally accepted. It has led to unhappy childhood. The illegitimacy em­ some injustices, as in the case of Scheele bittered his adult life, too, for after hav­ [329] and John Couch Adams [615], but ing attained his medical degree, he was on the whole the rule has served the denied admittance to the College of Phy­ cause of science well. sicians until he had earned that right by In his two hundred works, Cardano a clear demonstration of his excellence contributed useful ideas to science. He in the field. Eventually, his fame as a was the first to grasp the water cycle: physician came to be second only to that the seas are evaporated, that the Vesalius [146] and he was admitted in vapor turns to rain, that the rain flows 1539. In 1546, he was appointed profes­ back to the ocean via the rivers. sor of medicine at the University of Cardano’s later life was tragic. His fa­ Pavia. vorite son married a worthless woman He was the first to write a clinical de­ who was repeatedly unfaithful. The son scription of the disease we now know as overreacted by murdering his wife and, typhus fever. In 1552 he cured a Scottish despite Cardano’s efforts in the defense, cardinal of asthma by forbidding him to was executed in 1560 for the murder. use feathers in his bed, and this showed Cardano was brokenhearted over this an intuitive understanding of the phe­ and the fact that another son was con­ nomenon of allergy. He had vague no­ stantly being jailed for various crimes tions of evolution, believing all animals did not help. Cardano himself did not al­ were originally worms. He was also an ways escape punishment for his knav­ astrologer, convinced of the validity of eries. In 1570 he himself spent some the “science” no matter how many times time in prison for debt or heresy or, pos­ his predictions failed. He even attempted sibly, both. (so some said) to cast the horoscope of There is a persistent story that in old Jesus, a deed that resulted in his impris­ age Cardano predicted (astrologically) onment for a time. the day of his own death. When the day He was a thoroughgoing knave and came and found him in good health, he rascal, a gambler, cheat, given to mur­ killed himself. This sounds too dramatic derous rage, insufferably conceited and to be true. yet, withal, a first-class mathematician. He was the first, for instance, to recog­ nize the value of negative numbers and [138] GEMMA FRISIUS, Reiner imaginary numbers. He also put his Dutch geographer gambling to use by writing a book on Born: Dokkurn, Friesland, 1508 the mathematics of chance—a prelude to Died: Louvain, Brabant, 1555 the complete opening of the subject by Pascal [207] and Fermat [188]. The surname “Frisius” refers to He obtained the method of solving Gemma’s birth in Frisia (Friesland). He cubic equations from Tartaglia [135] in received his medical degree at the Uni­ 81

[139]

PARÉ

versity of Louvain and practiced medi­ cine there. His interest was in geography, how­ ever, and his importance to science rests on an observation he made concerning longitude. The latitude of a particular spot on earth is easily measured by the height of the noonday sun. The longi­ tude is another matter altogether; no measurement of any object in the sky will suffice. Gemma Frisius pointed out in 1533 that if one had an accurate way of keep­ ing time, it would then be possible to de­ termine longitude. He was perfectly cor­ rect; but considering that no accurate timepiece existed or could, at the time, even be conceived as existing, the sug­ gestion has a certain imaginatively science-fictionish air about it. Nevertheless, the time was to come when Harrison [259] was to convert Gemma Frisius’ suggestion into reality two centuries later. [139] PARÉ, Ambroise (pa-rayO French surgeon Born: Bourg Hersent, near Laval, Mayenne, 1510 Died: Paris, December 20, 1590 Pare belonged to an era in which phy­ sicians removed themselves from sur­ gery, considering it to be fit for manual laborers but not for professional men of intellect. In those days, and for two cen­ turies later, surgery was merely one of the specializations of the barbering pro­ fession; the flesh was cut as well as the hair. And, indeed, Paré was only a bar­ ber’s apprentice when he came to Paris as a boy in 1519. He attained the rank of master barber-surgeon in 1536. Paré attached himself to the army as barber-surgeon, a post for which he qual­ ified in 1541, and his fame grew rap­ idly. He rose to higher and higher posts until he was surgeon to a series of four kings, Henry II and his three sons, who ruled successively as Francis II, Charles IX, and Henry III. There is a story, pos­ sibly a fable, that he turned Protestant and that he was saved during the St. Bartholomew’s Day massacre only be­ 82

COLOMBO

[140]

cause Charles IX needed his services and hid him in his own bedchamber. Paré’s fame was securely founded, for he introduced several important changes in the surgery of the day that could not help but make him popular with any man who felt he might someday be a candi­ date for surgery. Most surgeons of the time practiced searing heavily. They dis­ infected gunshot wounds with boiling oil and stopped bleeding by cauterizing the arteries (without anesthetics). Paré fol­ lowed Hippocrates’ [22] principle of in­ terfering as little as possible with nature. He practiced cleanliness and he used soothing ointments for gunshot wounds. (One story is that once, in camp, he ran out of boiling oil and quickly discovered he was better off without it—to say nothing of the poor wounded soldiers.) He also tied off arteries to stop bleeding. With an infinitesimal fraction of the pain he brought off far more cures. It is no wonder that he is often considered the father of modern surgery. He wrote a report of his findings in this area in 1545. His lack of education forced him to write it in French rather than Latin. For this, he was scorned by the learned ignoramuses of the day. He also wrote French summaries of the works of Vesalius [146], so that barber-surgeons might learn something of the structure of the human body be­ fore hacking away. He devised clever artificial limbs and improved obstetrical methods. [140] COLOMBO, Realdo (koh-lohm' boh) Italian anatomist Born: Cremona, about 1510 Died: Rome, 1559 Colombo, the son of an apothecary, was educated at Milan and was himself an apothecary until he was apprenticed to a leading Venetian surgeon. He went on to study medicine at Padua and ob­ tained his degree in 1541. He was appointed professor of anat­ omy at Padua, replacing Vesalius [146], then went on to teach at Pisa. Although friendly to Vesalius at first, Colombo

[141]

EUSTACHIO

found he could not make the break with ancient anatomy that Vesalius’ teach­ ings required and he became a violent critic of the new anatomy. He went to Rome in 1548 in an effort to enlist Michelangelo as illustrator for a book that would surpass Vesalius’. But Mi­ chelangelo was in his seventies and could not take on the task. (Pity!). Nevertheless, Colombo was not merely a spoiler. He departed from Galen [65] himself by clearly showing in 1559 that blood leaves the heart on its way to the lungs by means of the pulmonary artery and returns by the pulmonary vein, with­ out ever passing through the wall sepa­ rating the two ventricles (as Galen claimed). He had thus demonstrated the pulmonary circulation of the blood though he stopped short of grasping the general circulation. That was left for Harvey [174] seven decades later, but Colombo was an important forerunner as Harvey himself recognized. Colombo remained in Rome the rest of his life, serving as papal surgeon. [141] EUSTACHIO, Bartolemeo (ayoo-stah'kee-oh) Italian anatomist Born: San Severino, about 1510 Died: Fossombrone, Urbino, Au­ gust 27, 1574 Eustachio, the son of a physician, and a physician himself from 1540, was an adversary of Vesalius [146] and an upholder of Galen [65], yet his ana­ tomical studies paralleled those of the former and not those of the latter. Eustachio’s work was completed in 1552 but was not published until rediscovered in 1714. For this reason he scarcely influenced his contemporaries. His illustrations were in some respects even more accurate than those of Ve­ salius, but they were stiff and clumsy and unworthy, as far as sheer beauty is con­ cerned, to be mentioned in the same breath. Eustachio’s most successful work was done on the sympathetic nervous system, the kidney, and the ear. His name has been given to the Eustachian tube, a narrow canal connecting the ear

[142] and throat, although this had been dis­ covered by Alcmaeon [11] two thousand years before. He was also the first to describe the adrenal glands and he pio­ neered in the study of the detailed struc­ ture of the teeth. In 1562 he was appointed professor of medicine in the Collegio della Sapienza in Rome, a post he held till his death. SERVETUS

[142] SERVETUS, Michael (sur'vee'tus) Spanish physician Born: Villanueva de Sixena, Sep­ tember 29, 1511 Died: Geneva, Switzerland, Octo­ ber 27, 1553 Servetus, the son of a notary, was in­ tended for the law, but his interests were much wider. He lectured on astrology (in which he firmly believed) and de­ fended the botanical views of his friend Fuchs [136], These, however, were the days of the Protestant Reformation and all Europe was convulsed with theological discus­ sions. Servetus developed radical notions that would today be described as Unitar­ ian. He advanced them tactlessly, anger­ ing both the Catholics and the Protes­ tants. He went to Paris in 1536 and studied medicine there, meeting his even­ tual nemesis, John Calvin, one of the most noted and powerful of the early Protestants. Servetus quarreled with the physicians in Paris, went elsewhere, and finally settled down to practice in Vienne, in southeast France. In 1553 Servetus published his theological views anonymously and some years previously he had sent a manuscript version to Calvin, with whom he was carrying on a correspondence. Calvin, however, quickly broke off the correspondence on reading those views. He was not one to appreciate—or forget—Servetus’ views. In the book, Servetus also described the circulation of that part of the blood that went through the lungs. The blood, he held, traveled out of the heart through the pulmonary artery and back through the pulmonary vein; it did not go through the heart muscle itself. This 83

[144] MERCATOR REINHOLD [143] were, and in three quarters of a was a good start at breaking with Galen, they century they were to be superseded by though it got nowhere until Harvey the better tables published by Kepler [174] generalized the matter for all the [169]. body, three quarters of a century later. Reinhold’s acceptance of the Coper­ Servetus’ physiological heresy was dis­ nican theory was not wholehearted. He regarded, but his theological heresy was recognized a mathematical device not. His authorship was discovered, he for preparingit as planetary tables more ac­ was arrested and escaped, making for curately but did not consider it a repre­ Italy. Foolishly he went by way of sentation of reality. nearby Geneva, then under control of the dark and bitter Calvin. Servetus was not a subject or resident of Geneva and [144] MERCATOR, Gerardus (merhad committed no crime in Geneva for kay'ter) which he could be held. Nevertheless, Flemish geographer Calvin insisted on having him con­ Bom: Rupelmonde (in what is demned to death (a deed that has black­ now Belgium), March 5, 1512 ened Calvin’s name in the eyes of poster­ Died: Duisburg, Germany, De­ ity) and Servetus was burned at the cember 2, 1594 stake, crying out his Unitarian views to the last. Mercator’s real name was Gerhard Kremer, but he shared in the sixteenthcentury predilection for Latinized pen [143] REINHOLD, Erasmus (rine'names, and adapted the Latin version hold) (meaning “merchant”) when he entered German mathematician the University of Louvain in 1530, Born: Saalfeld, Thuringia, Octo­ emerging with a master’s degree in 1532. ber 22, 1511 Young Mercator’s interest in geogra­ Died: Saalfeld, February 19, 1553 phy was dictated by both time and place. The great voyages of the Age of Explo­ Reinhold studied at the University of filled the air in his youth, and the Wittenberg and was appointed professor ration of the Netherlands were not back­ of mathematics there in 1536. Although ships in the exploration of distant is­ the University was the very center of ward lands. maps were necessary if nav­ Lutheran doctrine, and although Lu­ igationGood was to be more than hit or miss theranism was profoundly anti-Copemi- (with lives very likely sacrificed if it was can at the start, Reinhold was neverthe­ less one of the first converts to the new miss). In 1534, therefore, Mercator, who had astronomical theory even before Coper­ studied Gemma Frisius [138], nicus’ [127] book was published for he founded under a geographical establishment at had studied it in manuscript. from whose university he had Reinhold made the practical contri­ Louvain, four years earlier, and began bution of calculating the first set of plan­ graduated preparation of a long series of maps, etary tables based on Copernican theory, the use of instruments designed by and, for the purpose, he went over Co­ making and bringing to his task more pernicus’ calculations from stem to stem, himself than a bit of mathematical knowledge. correcting where necessary. also prepared a set of such instru­ The tables were subsidized by Albert, He for Emperor Charles V. Duke of Prussia, and were therefore ments The religious unrest of the time placed called Tabulae Prutenicae (Prussian Mercator, a Protestant in a Catholic re­ Tables). Published in 1551, they were gion, in some In 1544 he was rather better than the Alfonsine Tables, prosecuted for danger. heresy and he and their mere existence was a strong ar­ got off with a whole skin, healthough eventually gument in favor of Copernicus. They decided to play it safe and emigrated to were not, however, quite as good as the Protestant Germany in 1552. In 1559 he partiality of the author led him to claim 84

[144]

MERCATOR

was appointed cartographer to the Duke of Cleves. At first he remained under the domi­ nation of Ptolemy [64], whose redis­ covery in the late Middle Ages had had a cramping effect on cartography. So revered was the old Greek that maps built on observation, and therefore show­ ing the Mediterranean Sea at its correct length, were deliberately altered into error in order to make them match Ptol­ emy’s version, which had the Mediter­ ranean several hundred miles too long. Gradually Mercator adjusted Ptolemy to the facts and then, in 1568, he made his great advance. It had always been a problem to depict a spherical surface on a flat piece of paper. In ancient days the area of immediate geographical interest formed so small a portion of the globe that it could be presented as flat without serious trouble to the coast-hugging mar­ iners. By the sixteenth century, however, the whole world had to be depicted and the change from sphere to plane meant inevitable distortion. The problem was to obtain the least damaging distortion for mariners sailing thousands of miles across the open ocean. It occurred to Mercator to make use of a “cylindrical projection.” Imagine a hollow cylinder encircling the earth and touching it at the equator. A light at the earth’s center can then be imagined as casting the shadow of the surface fea­ tures on the cylinder, and the cylinder when unwrapped carries a map of the world by “Mercator projection.” In this map the meridians of longitude are vertical and parallel. Since on the sphere the meridians of longitude ap­ proach each other and meet at the poles, this means that east-west distances are increasingly exaggerated as one travels north and south from the equator. The parallels of latitude run horizontal and parallel. As one goes north and south from the equator, they spread out more widely. On such a map Greenland and Ant­ arctica are enormously enlarged and nei­ ther the North Pole nor the South Pole can be shown. Nevertheless, it was a par­ ticularly useful map for navigators (who generally avoided both Arctic and Ant­

RHETICUS

[145]

arctic) because a ship traveling in a con­ stant compass direction followed a route that appeared as a straight line on the Mercator projection, but a curved line on all other projections. The world map most familiar to us even today is drawn according to the Mercator projection. The last few years of Mercator’s life were devoted to preparing a detailed series of maps of various portions of Europe. It was not published till the year after his death. Because the cover of the book of these maps showed a picture of the Greek Titan, Atlas, holding th'e world on his shoulders, the book (and all future books of maps) was called an atlas. With Mercator the influence of Greek geography comes to an end, and the era of modem geography begins. [145] RHETICUS (ray'tih-koos) German mathematician Born: Feldkirch, Austria, Febru­ ary 16, 1514 Died: Cassovia, Hungary, now Kosice, Czechoslovakia, Decem­ ber 4, 1574 The real name of Rheticus was Georg Joachim von Lauchen, but he named himself after the ancient name (Rhaetia) of the province in which he was bom. (His father had been a physician who was beheaded for sorcery when Rheticus was fourteen so that may have made the change of name advisable.) Rheticus studied at Zürich, where Gesner [147] was a schoolmate and where he met Paracelsus [131]. He went on to Wittenberg and obtained his master’s degree in 1536; then began to teach mathematics there. He was a rea­ sonably important mathematician, being the first to relate the trigonometric func­ tions to angles rather than to the arcs of circles and preparing the best trig­ onometric tables up to his time. He is best known, however, as Coper­ nicus’ [127] first disciple. In 1539 he traveled to Frombork to study Coper­ nicus’ manuscript, and received an in­ tense ten-week course in the new view. 85

[146]

VESALIUS

He published a summary of its contents in 1540, but was careful not to mention Copernicus by name. He then persuaded the older man to publish his great book. He wrote a biography of Copernicus but that, unfortunately, is lost. He also drew the first map of East Prussia and that too is lost. [146] VESALIUS, Andreas (veh-say'lee-us) Flemish anatomist Born: Brussels, December 31, 1514 Died: Zante (now Zakinthos), west of Greece, October 15, 1564 Vesalius’ mother was English and his father was court pharmacist to Emperor Charles V. He came, in fact, of a long line of physicians who originally dwelt in Wesel—hence his surname. He studied medicine at Louvain (in what is now Belgium) and in Paris, both very conser­ vative centers saturated with the teach­ ings of Galen [65], He quarreled bitterly with his teacher in Paris, but learned his Galen thoroughly, wrote a graduation dissertation on Rhazes [82], and, as late as 1538, was publishing material largely Galenian in nature. He was always eager to dissect for himself but found this difficult to arrange in northern Europe where he served for a while as a military surgeon. He there­ fore traveled to Italy, where in the light of the late Renaissance there was more intellectual freedom than in other parts of Europe. Dissection was improper, to be sure, but the authorities were readier to look the other way and men such as Mondino de’ Luzzi [110] had made it al­ most respectable two and a half cen­ turies earlier. He obtained his medical degree at Padua in 1537. In Italy, Vesalius taught anatomy at the universities of Pavia, Bologna, and Pisa. Disgusted with slipshod, hacking dissections by assistants, he reintroduced Mondino’s important but forgotten habit of conducting anatomical demonstrations in person. He became a popular lecturer, and students, of whom the most impor­ tant was Fallopius [149], flocked to him. 86

VESALIUS

[146]

He managed to make a sensation with something as simple as a demonstration that men and women have equal num­ bers of ribs. (Because of the story in Genesis that Eve had been created out of Adam’s rib, it was widely believed during the Middle Ages that men had one rib fewer than women.) He put together the result of his re­ searches in one of the great books of scientific history, De Corporis Humani Fabrica (“On the Structure of the Human Body”). This was the first accu­ rate book on human anatomy; its great advantage over the ancient books was that it had illustrations which, being printed, could be reproduced exactly in any number of copies. (Before the time of printing, even where words were cop­ ied accurately, illustrations degenerated of necessity.) This alone allowed print­ ing to revolutionize biology. Illustrations in themselves would have been enough, but those in Vesalius’ books were outstanding in beauty. Jan Stephen van Calcar, a pupil of the artist Titian, did many of them, and it was chiefly in the illustrations that Vesalius was superior to his rival, Eustachio [141]. The human body was shown in natural positions and the illustrations of the muscles in particular are so exact that nothing since has surpassed them. The book, an astonishing achievement for a man not yet thirty, met with fierce oppo­ sition from such anatomists as Colombo [140], but it was the end of Galen. Vesalius’ work was not a false dawn, as Mondino’s had been. It marked at one stroke the beginning of modern anatomy. By an interesting coincidence it was pub­ lished in the same year as Copernicus’ [127] book, a simultaneous end and be­ ginning in the biological and physical sciences. Together, they were the birth of the Scientific Revolution. Though he was accurate as an anato­ mist, Vesalius clung to some of the old ideas in physiology. (Whereas anatomy deals with the structure of the living or­ ganism. physiology deals with its func­ tioning.) Vesalius accepted Galen’s views on the circulation of the blood and believed that blood must pass from one

[147]

GESNER

ventricle of the heart to the other through invisible pores in the wall of muscle separating those ventricles. How­ ever, the truth of the matter was begin­ ning to dawn on Servetus [142]. Toward the end of Vesalius’ life, he too grew to doubt Galen in this respect. Vesalius was opposed to the view of Aristotle [29] that the heart was the seat of life, mind, and emotion. Vesalius believed that the brain and nervous sys­ tem represented that seat, and no one has doubted it since. Vesalius’ work came to a halt with the publication of his book. Perhaps an­ noyed at the furore it aroused and the opposition to it (led by his old teacher at Paris), he quit research. It had made him enough of a reputation, however, to earn him the post of court physician to Charles V, and later to Charles’s son, the Spanish king Philip II. When Henry II of France was fatally wounded in a tour­ nament in 1559, Vesalius attended him, taking precedence over Paré [139]. As he became more prominent his en­ emies accused him of heresy, body snatching, and dissection, and for a while it looked as though he might be executed. But his royal connections stood him in good stead, and the sentence was commuted to a pilgrimage to the Holy Land. This, however, represented but a short reprieve. On the way back from his pilgrimage, his ship was battered by storms off the coast of Greece and Vesa­ lius died shortly after the ship managed to land at Zante. [147] GESNER, Konrad von (guess'ner) Swiss naturalist Born: Zürich, March 26, 1516 Died: Zürich, December 13, 1565 The late Middle Ages brought to the attention of Europeans the zoological and botanical works of Aristotle [29] and Theophrastus [31]. In addition, the explorations of the fifteenth century in­ troduced Europe to hordes of plants and animals of which the ancients had been ignorant. A new group of writers on nat­ ural history arose, and among these the

GESNER

[147]

most prominent were Gesner and Fuchs [136]. Gesner, the son of a furrier killed in the religious wars, and the protegé of the Protestant reformer, Ulrich Zwingli, was a physician by profession. He obtained his medical degree at the University of Basel in 1541 and served as town physi­ cian in Zürich during the last decade of his life. However, he was a Renaissance man with interests ranging from Greek through comparative phüology to natural history. He used the collection of rare mountain species of plants as an excuse for indulging in the then newfangled hobby of mountain climbing and it is difficult to say which interested him more. He was the first to present ülustrations of fossils, but he had no suspi­ cion that they represented remnants of past life. He considered them simply stony concretions. In his wide-ranging interests, his cre­ dulity, and his absolute compulsion to work, he resembled Pliny [61] and, in­ deed, has been known as the German Pliny and as a “monster of erudition.” He wrote a “Universal Library,” for in­ stance, in which he listed all known books in Hebrew, Greek, and Latin, with summaries of each. Between 1551 and 1558 he wrote similarly exhaustive vol­ umes designed to describe all known ani­ mals and replace the earlier and less complete work of Aristotle. He also col­ lected at least five hundred plants not known to the ancients. Gesner was still working feverishly when in 1565 a plague struck Zürich. He refused to abandon his patients and died of plague. Although there is some attempt at classification in his works, Gesner be­ longs, by and large, to the old school of purely descriptive natural history. Other naturalists, of a more analytical turn of mind, such as Alpini [160] and Belon [148], were oriented more in the direc­ tion of the future, but they were less influential in their own time. The attempt to make deeper sense out of the realm of life through rational classification had to wait another century for Ray [213] and, above all, Linnaeus [276]. 87

[149]

FALLOPIUS

[148] BELON, Pierre (be-lohn') French naturalist Born: Soultiere, 1517 Died: Paris, April, 1564 Belon, the son of poor parents, was recognized as a promising youth by the local bishop, who made it possible for him to study medicine. Belon obtained his medical degree at the University of Paris and had King Francis I as patron. He was sent east in 1546, accompanying diplomatic missions. This gave him a chance to study plant and animal life in countries bordering the eastern Mediter­ ranean and he was the first to notice the similarities of basic plan in the skeletons of the various vertebrates from mammals to fish. These homologies (a first step to­ ward comparative anatomy) were an im­ portant impulse in the slow development of evolutionary theories over the next three centuries. He also studied the por­ poise embryo and initiated researches, in this way, that were to lead to the science of embryology. Belon introduced the cedar tree to France and founded two botanical gar­ dens. Having survived his travels without trouble, he was so indiscreet as to go out to gather herbs in the Bois de Boulogne, in the heart of Paris, and there he was waylaid by robbers and killed. [149] FALLOPIUS, Gabriel (fa-loh'pee-us) Italian anatomist Born: Modena, 1523 Died: Padua, October 9, 1562 Fallopius entered the church when his father died, leaving the family impover­ ished. He was canon in the cathedral of Modena for a time, but when the finan­ cial situation took a turn for the better, he abandoned the religious life to prac­ tice science. He succeeded his teacher Vesalius [146] as the most important anatomist, rising eventually to a professorship at Padua in 1551 as successor to Colombo [140]. He is best known today for his de­ scriptions of the inner ear and of the or­ gans of generation. He described the 88

PORTA

[150]

tubes that lead the human ovum from the ovary, where it is formed, to the uterus where, if the ovum is fertilized, the embryo develops. It is in these tubes that fertilization takes place. Fallopius did not know the function of the tubes because the mammalian ova, or egg cells, were not discovered for nearly three centuries after his time. Nevertheless, the organs today are known as the Fallopian tubes. He coined the term “vagina” and de­ scribed the clitoris. He died before his fortieth birthday of that great killer of young people in those days—tuberculosis. [150] PORTA, Giambattista della (pawr'tah) Italian physicist Born: Vico Equense, near Naples, October 1535 Died: Naples, February 4, 1615 Porta was the son of a small govern­ ment official and may have been largely self-taught. His most important work was a quite serious discussion of magic and how it could be used to control the environment —all quite worthless, of course. Yet he cannot be dismissed. He founded the first of the modem scientific “academies,” those associations for the intercommunications of scientific re­ search. This was the Academia Secretorum Naturae in 1560. It was suppressed by the Inquisition, but he then reconstituted it as the Accademia dei Lincei in 1610 and that remained. (Perhaps lynxes, for all their legendary sharpness of sight didn’t seem as threat­ ening to the clerics as investigating the secrets of nature would.) Porta also worked with the camera obscura or pinhole camera, in which light entering an enclosed box through a small hole forms an inverted image in­ side. It lacked the essentials of a modern camera—the lens and the photosensitive film; but that would come eventually with the work of Niepce [384] and Da­ guerre [467] a little over two centuries later.

[151]

FABRICIUS AB AQUAPENDENTE

Most important, Porta was the first to demonstrate the heating effect of light. It was a small step, but a step, toward the recognition of the unity of energy. [151] FABRICIUS AB AQUAPEN­ DENTE, Hieronymus (fa-brish'ee-us) . Italian physician Born: Aquapendente, Papal States, May 20, 1537 Died: Padua, May 21, 1619 Fabricius obtained his M.D. at Padua in 1559 and in 1565 became a professor of surgery there. He has two chief claims to fame. First, he was the teacher of Harvey [174]. Second, he discovered the one-way valves in the veins and de­ scribed them accurately in a book pub­ lished in 1603. However, he failed to see their significance. Fabricius was a pupil of Fallopius [149], whom he had succeeded at Padua, in 1565 so that the line from Vesalius [146] to Harvey, via Fallopius and Fa­ bricius, covers four student generations. Fabricius corrected Vesalius in one re­ spect. Vesalius, for some reason, placed the lens in the center of the eyeball. Fabricius correctly described its location near the forward rim. Fabricius also published an exhaustive study of the chick embryo in 1612, re­ storing the subject to the point where Aristotle [29] had left it and paving the way for future advance. [152] CLAVIUS, Christoph (klah'veeoos) German astonomer Born: Bamberg, Bavaria, 1537 Died: Rome, Italy, February 6, 1612 Clavius entered the Jesuit order in 1555 and attended lectures at the Uni­ versity of Coimbra in Portugal. He lec­ tured at the Collegio Romano in Rome beginning in 1565 and remained there for the rest of his life with incon­ siderable exceptions. His contribution to astronomy is the

VIETA

[153]

rather negative one of being one of the last important astronomers to be a die­ hard opponent of Copernicus’ [127] doc­ trine. He very carefully pointed out the various Biblical quotations that showed that God himself declared Copernicus to be absurd. Somehow that didn’t stop the steady shift of scholarly opinion toward Copernicus. On the other hand, Clavius was the first astronomer since Sosigenes [54] to reform the calendar. The Julian calendar set up by Sosigenes had been gaining three days on the sun every four hun­ dred years, as had been pointed out by Roger Bacon [99]. By Clavius’ time, the calendar was eleven days ahead of the sun and it marked the vernal equinox eleven days after the sun did—with seri­ ous effects on the calculation of Easter. An astronomical conference was held in Rome and Clavius’ proposal was ac­ cepted. Eleven days were dropped so that the day after October 4, 1582, was October 15, 1582, and thereafter, the century years not divisible by 400 were not leap years. Pope Gregory XIII es­ tablished this, so Clavius’ reform is the “Gregorian calendar” that is used virtu­ ally throughout the world today. Naturally, the Protestant nations ob­ jected and refused for quite a while to accept the reform. Surprisingly, there was opposition from some scientists (Protestant, to be sure) such as Vieta [153] and Scaliger [154], [153] VIETA, Franciscus (vyay'tuh) French mathematician Born: Fontenay-le-Comte, Poitou, 1540 Died: Paris, February 23, 1603 Vieta (François Viete), the son of a lawyer, was educated in law at Poitiers and received his degree in 1560. He oc­ cupied high administrative office under Henry IV. This may have come about because for a time he was a Protestant as Henry had been before he became king. When Henry turned Catholic, Vieta did likewise. Perhaps the most dramatic of Vieta’s 89

[154]

SCALIGER

feats involved his capacity as a skilled cryptanalyst. Working for the French government in 1589, he deciphered the code that Philip II of Spain was using. This worked to the great disadvantage of the Spanish armies then at war with France. Philip II could explain the leak­ age of what he thought were inviolable secrets by no means other than sorcery and he accused the French of that crime to the pope. Vieta engaged himself in mathematics only as a hobby and yet accomplished great work in algebra and trigonometry. In fact, it was he who first used letters to symbolize unknowns and constants (vowels for the former and consonants for the latter) in algebraic equations, so that a book he wrote in 1591, lsagoge in artem analyticam, is the first that a mod­ ern high-school student could look at and recognize at once as a book on alge­ bra. For this reason, he is called the fa­ ther of modern algebra, although great men in the field such as Cardano [137] preceded him. Oddly enough Vieta repudiated the word “algebra,” which was Arabic and not Latin, and preferred the term “analy­ sis.” In fact, the title of his book, in En­ glish, is Introduction to the Analytic Art. As a result, the term “analysis” is now used for algebraic methods of solving problems, though the term “algebra” is still retained for that branch of mathe­ matics that deals with the rules govern­ ing the manipulation of equations. In one respect, Vieta was formidably geometric. He made use of Archimedes’ [47] method for calculating pi through polygons of many sides. Vieta used poly­ gons of 393,216 sides in his calculation and obtained a value of pi accurate to ten decimal places—the best value up to that time.

GILBERT

[155]

Scaliger was a monumental scholar who had been inhumanly driven by his scholarly father into an encyclopedic knowledge of Latin and Greek authors at an early age. Young Scaliger took to the task with avidity, but his proficiency in the classics did not blind him to other matters. He studied at Bordeaux first and then, in 1559, traveled to Paris. He was converted to Protestantism in 1562 and had the good sense to leave France for Geneva in 1572, just before the dreadful St. Batholomew’s Day Mas­ sacre of Protestants. In 1593 he took a professorial position with the safely Prot­ estant University of Leiden and re­ mained there the rest of his life. He did not consider Greek and Roman history the only history that counted but urged that the records of the various Oriental empires be studied. In a book published in 1606, he studied every scrap of record he could find and care­ fully compared the various chronologies in the light of the astronomic learning of the day. His hope was to bring them all into some agreement and to deduce a single line of history. He is the founder of modern chronology. In addition he founded the system of the Julian Day. He set January 1, 4713 b .c ., equal to Day 1 and numbered all the days from that. (Thus, January 1, 1982, is Julian Day, 2,444,970.) This freed astronomers from the vagaries of changing calendars, and the system is still used to this day. The word “Julian” is Scaliger’s hom­ age to his intellectually slave-driving fa­ ther, Julius Caesar Scaliger. It was an undeserved homage, for the father had filled his son’s ears with tales of noble birth that the son innocently boasted about. When the stories were proved lies, Scaliger was utterly humiliated. He wilted and died.

[154] SCALIGER, Joseph Justus (skal'ih-jer) French scholar [155] GILBERT, William Born: Agen, Lot-et-Garonne, Au­ English physician and physicist gust 5, 1540 Born: Colchester, Essex. May 24, Died: Leiden, Netherlands, Janu­ 1544 ary 21, 1609 Died: London, November 30, 1603 90

[155]

GILBERT

Gilbert took his medical degree at Cambridge in 1569, then traveled through Europe, unhampered by family, since he remained a lifelong bachelor. He settled in London about 1573 and gained considerable renown as a physi­ cian, becoming president of the College of Physicians in 1600. In 1601 he was appointed court physician to Queen Eliz­ abeth I, at the usual salary of £100 per year. The year before, he had published a book, De Magnete (“Concerning Mag­ nets”), which established his reputation as a physicist. Gilbert might be viewed as merely re­ peating the work done earlier by Peter Peregrinus [104]. Peregrinus’ work, how­ ever, had been mostly forgotten. Also, Gilbert went much further than Pere­ grinus. Gilbert, like Galileo [166], was a pioneer of experimentation and refuted many superstitions by direct testing. In­ deed, Galileo considered Gilbert the chief founder of experimentalism. Gil­ bert showed that garlic did not destroy magnetism, as it was believed to do, by smearing a magnet with it and demon­ strating that the magnet’s powers re­ mained unimpaired. Gilbert further showed not only that a compass needle points roughly north and south, but also that if it is suspended to allow vertical movement it points down­ ward toward the earth (“magnetic dip”). A compass needle also shows a dip in the neighborhood of a spherical magnet, and at the magnetic poles of the sphere it points vertically. Gilbert’s great contri­ bution was to suggest that the earth itself is a great spherical magnet and that the compass needle points not to the heavens (as Peregrinus believed) but to the mag­ netic poles of the planet. Gilbert believed this situation was fixed—that at any point on the earth the magnetic needle held constant. This idea was corrected a generation later by Gellibrand [184], (Because Gilbert was a pioneer in the study of magnetism, magnetomotive force is measured now in units called “gilberts.”) Gilbert studied other attractive forces in the universe. It had been known since ancient times that amber, when rubbed,

BRAHE

[156]

acquired the power of attracting light objects. This differed from magnetism in that magnetism involved iron only, whereas the amber attraction could be felt by any light object and Gilbert was the first to point out this difference clearly. (According to the Greeks it was Thales [3] who first studied this effect of rubbed amber.) Gilbert extended knowledge in this field by discovering that substances other than amber, as, for example, rock crystal and a variety of gems, showed the same attractive force when rubbed. He grouped all such substances under the name of “electrics,” from the Greek word for amber (elektron). He also elaborated notions on the structure of the universe that were both advanced and daring for his time. He ac­ cepted the views of Copernicus [127] and was the first important Englishman to do so. Also, he followed Nicholas of Cusa [115] in believing that the stars were at varying, but enormously large, distances from the earth and that they might themselves be circled by habitable planets. Finally, he was the first to spec­ ulate on what might keep the planets in their paths if the celestial spheres first in­ vented by Pythagoras [7] two thousand years before his time proved, after all, not to exist. Coming down heavily on his own specialty, Gilbert decided it was a form of magnetic attraction. Galileo and Kepler [169] came to no better conclu­ sion. When Elizabeth I died, Gilbert was reappointed court physician by James I. He died within the year. Gilbert left his books, instruments, and other memorabilia to the College of Phy­ sicians, but they were destroyed in the Great Fire of London sixty years later. [156] BRAHE, Tycho (ty-ko brah'uh) Danish astronomer Born: Knudstrup, Scania (south Sweden, then part of Denmark), December 14, 1546 Died: Prague (in what is now Czechoslovakia), October 24, 1601 91

[156]

BRAHE

Tycho Brahe, the son of a Danish nobleman of Swedish descent, is sup­ posed to have been one of twins. His brother, however, was either stillborn or died soon after birth. When one year old, Tycho was kidnapped by his child­ less uncle, and Tycho’s father accepted the situation. Tycho (usually known by his first name only, a Latinized version of the Danish, Tyge) was the last and, with the possible exception of Hipparchus [50], the greatest of the naked-eye astrono­ mers. In early life he studied law and philosophy at the University of Copen­ hagen, which he entered at the age of thirteen. He originally intended to go into politics, but in 1560 he observed an eclipse of the sun and switched to as­ tronomy and mathematics. Later he went to Germany for more training. In observing a close approach of Ju­ piter and Saturn in 1563, Tycho noticed that it came a month away from the time predicted for it by the tables pre­ pared under Alfonso X [100]. Conse­ quently he began to buy instruments with which to make observations for the preparation of new tables. He also began to cast horoscopes, and retained a life­ long interest in astrology, as did many astronomers of early modern times. (As­ trology was a far more lucrative pursuit than was genuine astronomy, and pa­ trons would far more willingly pay for horoscopes than for scientific findings.) In 1572, after a period in which al­ chemy temporarily claimed Tycho’s at­ tention, he finally made his mark, on the occasion of the flaring out (on Novem­ ber 11) of a new star. Hipparchus had noted one and used it as an occasion to prepare the first star map of importance. Another appeared in 1054, but it was observed only by Chinese and Japanese astronomers. These are not new stars but existing ones that explode and increase enor­ mously in brightness. Prior to the explo­ sion they may be too faint to be seen with the naked eye. Before the days of the telescope, they did indeed seem new stars. Tycho, observing the new star of 1572 (now sometimes called “Tycho’s 92

BRAHE

[156]

star”), described it—and its astrological significance—in a fifty-two-page book of which a short version of the title is De Nova Stella (“Concerning the New Star”). Tycho’s star grew to be brighter than Venus and remained visible for a year and a half before fading out. Tycho had at first hesitated to publish the book, for he felt it beneath the dig­ nity of a nobleman to write books, but, fortunately, he overcame this snobbish impulse. Tycho’s book did three things. It es­ tablished the name “nova” for all ex­ ploding stars. It made the young man’s reputation as an astronomer. And, finally, since Tycho showed by parallax measurements, using the observations of other astronomers from distant places such as England, that the new star was too far for its distance to be measured, but certainly much farther than the moon, it struck a telling blow against the notion of Aristotle [29] that the heavens were perfect and unchanging. Tycho stretched his mind to the limit to imagine the size of the universe but, of course, he fell short. He thought the nova was three billion miles from earth, and the farthest star only four million miles beyond the nova. The stars, in other words, only occupied a comparatively thin shell just beyond the planetary system. The whole universe, by Tycho’s scheme, was only 6,100,000,000 miles in diameter—which is less than we now know the diameter of the planetary system to be. The king of Denmark, Frederick II, decided to serve as patron for his re­ markable young subject, who had flashed into prominence like a living nova, and to keep him from emigrating to Ger­ many, then the center of astronomical research. (The brain drain is by no means a modern phenomenon only.) To do this, he sponsored astronomical lec­ tures by the young man and, more im­ portant still, he subsidized the building of an observatory for Tycho on the is­ land of Hveen (now Ven), three square miles in area between Denmark and Sweden. Tycho built elegant buildings

[156]

BRAHE

and outfitted them with the best instru­ ments he could make. Completed in 1580, it was the first real astronomical observatory in history and cost, it is es­ timated, about a million and a half dol­ lars of today’s money. He spared no ex­ pense, even building a five-foot spherical celestial globe. Here his reputation continued to grow and scholars from all over Europe visited him. So did rulers who fancied them­ selves scholars, such as James VI of Scotland, who visited Denmark in 1590 to marry a Danish princess. (Later, he succeeded to the English throne as James I.) In 1577 a great comet appeared in the sky and Tycho observed it carefully. Parallax studies showed that this object also was farther than the moon—an even worse blow against the perfection of the heavens. Aristotle, recognizing that the erratic comings and goings of comets could not be harmonized with the permanence and regularity of motion of other bodies, had insisted that comets were atmospheric phenomena. He was wrong. Galileo [166] in this respect agreed with Aristotle and was therefore behind Tycho here. Tycho, in studying the apparent mo­ tion of the comet, reluctantly came to the conclusion that its orbit could not be circular but must be rather elongated. This was a daring suggestion because in that case it must be passing through the various planetary spheres, and it could scarcely do that unless the planetary spheres did not exist. Such a possibility went much against Tycho’s personal leanings, for he was a conservative astronomer who would not abandon the notion of Ptolemy [64] and his Greek predecessors that the earth was the center of the universe. He was the last great astronomer to insist on it and to reject the heliocentric theory of Copernicus [127]. His great argument against it was the lack of stellar parallax, and he used this argument in his correspondence with Galileo to wean away the latter from Copernicanism. In this he failed. In his book on the comet, published in

BRAHE

[156]

1583, Tycho tried to strike a compro­ mise. He was willing to go so far as to suggest that all the planets but the earth revolved about the sun. Then, he insisted, the sun with its train of atten­ dant planets revolved about the earth. This would explain everything Coper­ nicus’ theory explained, but it did away with the celestial spheres of the Greeks, something Copernicus had not done. That was bothersome for if the spheres did not exist, what kept the planets in their orbits? This “Tychonic theory” was proposed, in part, to emphasize Tycho’s orthodoxy against his enemies at the Danish court —of whom he had many. Reminiscent of the views of Heracleides [28], it shared the fate of all halfhearted com­ promises in an age of desperate antago­ nism. It went almost entirely dis­ regarded. (Nevertheless, a half century later, Riccioli [185] was to give names to the craters on the moon, which the telescope of Galileo revealed. Riccioli, at least, ad­ mired the Tychonic theory, and so he gave Tycho’s name to the most promi­ nent and spectacular of all the craters visible from earth. Since he was an ad­ mirer of Greek astronomy, the book in which he did this was named the New Almagest, and he gave the names of Hipparchus and Ptolemy to two large craters, centrally located on the moon’s surface. The name of Copernicus was given to a lesser crater and that of Aris­ tarchus [41] to quite a small one. The face of the moon still bears these names —a mark of the reluctance with which Greek astronomy was abandoned.) All through the years Tycho kept making magnificently accurate observa­ tions, reaching the limits that could be expected of the unaided eye. He was one of those who allowed for changes in the apparent position of heavenly bodies be­ cause of atmospheric refraction, and he corrected for instrumental errors as well. Nobody has ever observed more accu­ rately without a telescope. Where Ptol­ emy’s observations were correct to ten minutes of arc, Tycho’s were correct to two, which is about the theoretical limit 93

[156]

BRAHE

for naked-eye observation. Tycho cor­ rected almost every important astro­ nomical measurement for the better. He observed the motions of the planets, par­ ticularly of Mars, with unprecedented accuracy. He prepared tables of the mo­ tion of the sun that were far better than anything previously done. He determined the length of the year to less than a sec­ ond. Even Tycho, however, could not free himself from his times altogether. He estimated the distance of Saturn, then the farthest known planet, at fortyfive million miles, which seemed an enormous distance to the astronomers of the age, but was only one-eighteenth the real figure. The new accuracy in astronomy made calendar reform inevitable, and in 1582, under the sponsorship of Clavius [152] and of Pope Gregory XIII, it finally came to pass. Ten days were dropped, these having accumulated since the time of the Roman Empire because the lulian year was some minutes longer than the real year. To prevent further accumu­ lations in the future, every cycle of four hundred years was to see only ninetyseven leap years rather than one hun­ dred. The even-century years, such as 1700. 1800, and 1900, were not to be leap years, even though divisible by four, unless (like 1600 and 2000) they were also divisible by four hundred. This “Gregorian calendar” was quickly accepted by the Catholic nations, but only slowly accepted by the Protes­ tant and Greek Orthodox countries. (They preferred to be wrong with Sosig­ enes [54] than right with the pope.) It is now universally used throughout the civilized world, except where religious ritual demands the use of another. At about the time of the reform, chronology generally was being put on a scientific basis by Scaliger [154], But troubles were gathering about Ty­ cho’s head, mostly of his own making. Tycho simply could not forget he was a Danish nobleman and insisted on being an extraordinarily quarrelsome and arro­ gant one. He was harsh to his underlings and fought with everyone. In a foolish midnight duel at Rostock over some point in mathematics (it was 1565 and 94

BRAHE

[156]

he was still only nineteen) his nose was cut off and he wore a false nose of metal for the rest of his life. Some have doubted the story, but a recent exhuma­ tion of his skeleton has confirmed it. Tycho’s vision of himself as a nobleman even led him to the rather humorous ex­ treme (according to tradition) of mak­ ing his astronomical observations in court dress. His patron, Frederick II, had the pa­ tience of a saint and endured it all, but he died in 1588 and his successor, Chris­ tian IV (who was to rule Denmark for sixty years), had a bit of a temper him­ self. After a few years he had had enough of the cantankerous and expen­ sive astronomer. He stopped the subsidy and forced Tycho out. (It should be mentioned that despite his haughty aris­ tocratic ways, Tycho married a peasant girl for love and made a good life with her.) Tycho left for Germany in 1597 and, at the invitation of the Emperor Rudolf II (whose coronation Tycho had witnessed years before), settled in new quarters in Prague. There he made his greatest discovery, for he found an assis­ tant in a young German named lohann Kepler [169], Tycho gave Kepler his painstakingly gathered observations and set him to working on the preparation of tables of planetary motions. That was the crown­ ing act of his life. When he died in 1601, after a short illness due, perhaps, to a ruptured bladder, he moaned, “Oh, that it may not appear I have lived in vain.” Kepler kept control of the data and con­ tinued to work with what were to prove to be results of the first importance. Tycho received an elaborate state funeral and Kepler saw to it, in fact, that Tycho had not lived in vain. He even loyally worked on Tycho’s scheme of the uni­ verse as he promised his teacher he would. Even Kepler, however, could not keep that alive. As for Tycho’s instruments—the glori­ ous equipment with which he had outfitted his Danish observatories—they were never used again. Within a decade of his death, Galileo’s telescope had made all of Tycho’s instruments obso­

[157]

BRUNO

STEVINUS

[158]

lete. They gathered dust and were finally accept the cross held out to him at the burned during the first years of the last moment. Thirty Years’ War. [158] STEVINUS, Simon (steh-vee'nus) Belgian-Dutch mathematician Born: Bruges, 1548 [157] BRUNO, Giordano Died: The Hague, Netherlands, Italian philosopher about March 1620 Born: Nola (near Naples), Janu­ ary 1548 Stevinus was of illegitimate birth. His Died: Rome, February 17, 1600 first position was as tax collector at Bruno, the son of a soldier, was bom Bruges, but he left this for broader fields of very poor parents, was educated at in 1583, when he entered the University the University of Naples, and entered a of Leiden. As quartermaster in the Dominican monastery in 1563. He held Dutch army under Maurice of Nassau, unpopular opinions with fearlessness and Stevinus worked out a system of sluices had the ability to attract huge audiences in the dikes that made it possible to by his speaking and writing. (He had flood the country quickly in case that also developed a system of mnemonics— were needed to stop an enemy. In math­ a memory course, so to speak—which ematics he introduced the use of decimal fractions and was the first to translate proved most popular.) Bruno developed mystical religious no­ Diophantus [66] into a modern language. tions that fit in with the opinions of He was also a firm partisan of the CoNicholas of Cusa [115] concerning the pemican view of the planetary system. infinity of space, the inhabitability of His main contributions to science are other worlds, the motions of earth, and three: so on. He was also an atomist, and a First, he showed in 1586 that the pres­ believer in the circulation of the blood sure of a liquid upon a given surface but everything was in the service of his depends on the height of the liquid dark and obscure mysticism; and it was above the surface and upon the area of his obvious and extreme religious heresy the surface but does not depend on the that made him persona non grata to all shape of the vessel containing the liquid. He may be said to have founded the sci­ sides. Changing his name to Filippo Gior­ ence of hydrostatics. dano for safety, he fled first to Rome, Second, he demonstrated the impossi­ then to Geneva. In Geneva, the Cal­ bility of at least one variety of perpetual vinists ejected him and he went to Paris motion. He used for this purpose an end­ where he was patronized by Henry III, less chain about two inclined planes but where the Aristotelians also ejected joined in a triangle and showed geomet­ him. He wandered over Europe, lectur­ rically that the chain would have to ing at Oxford, England, in 1582 and in remain motionless. In this manner he Germany for some years after 1586. In continued the study of statics where the 1592 he was arrested in Venice by the recently translated Archimedes [47] had left off. Inquisition and charged with heresy. He might have gotten off by recanting Third, in 1586 he performed the key as Galileo [166] was to do a generation experiment of dropping two different later. However, no one since the days of weights simultaneously and observed that Socrates [21] worked quite so hard and they struck the ground at the same time with such determination to secure his —the experiment that seems indissolu­ own conviction. As he said, his judges bly, if incorrectly, wedded to the name were more afraid of him than he was of of his younger contemporary Galileo his judges. After a seven-year trial he [166], Stevinus was also the first (in 1599) was burned alive at the stake. Intransigent to the last, he refused to to give values of magnetic declination 95

[159]

NAPIER

for specific spots on earth—forty-three of them. In that same year, he published a de­ sign for a sail-propelled cart with front wheels that could be used to steer—a novelty. He also worked out the theory of navigating a ship according to a Mercator [144] map. The fact that Stevinus wrote in Dutch —and did so charmingly—helped mark the beginning of the end of Latin as the universal European language of learning. Other scholars of the era were beginning to use the “vulgar tongue,” Alberti [117] and Galileo for instance using Italian and Descartes [183] using French. The change was slow, however. Even a cen­ tury after Stevinus’ time Newton [231] was writing his great works in Latin. Stevinus married late in life, at sixtyfour, but managed to have four children, two of each sex, before dying. [159] NAPIER, John (nay'pee-ur) Scottish mathematician Born: Merchiston Castle, near Edinburgh, 1550 Died: Merchiston Castle, near Edinburgh, April 4, 1617 Napier was born into the Scottish aris­ tocracy and was the eighth Laird of Merchiston. During his youth, he trav­ eled through a Europe split into warring camps by the Protestant Reformation. His native Scotland was itself in the pro­ cess of turning Calvinist. Napier was a wholehearted Protestant and in 1593 he published a bitterly anti-Catholic com­ mentary on the Revelation of St. John, the first Scottish work on biblical inter­ pretation. As a further sign of the hot passions aroused in those times, Napier spent considerable energy thinking out devices for destroying an invasion by Philip II of Spain, in case it should come. He planned a burning mirror like that ascribed to Archimedes [47], artillery that would destroy almost all life within a radius of over a mile, and armored war chariots and submarines. He did not pro­ duce any of these inventions and the 96

NAPIER

[159]

only attempt made by the Spanish Ar­ mada anywhere near Scotland was de­ stroyed in 1588 by the small, maneu­ verable English vessels. No new inven­ tions were needed. It is no wonder, though, that Napier gained the reputation among the com­ mon folk of being a black magician. Some considered him unbalanced. Na­ pier’s firm belief in astrology and divina­ tion certainly did nothing to discourage such beliefs. Napier’s solid reputation rests upon a new method of calculation that first oc­ curred to him in 1594, the year after he wrote on the Bible. The result was a much more fruitful and memorable work. It occurred to Napier that all numbers could be expressed in exponen­ tial form. That is, 4 can be written as 22, while 8 can be written as 2s, and 5, 6, and 7 can be written as 2 to some frac­ tional power between 2 and 3. Once numbers were written in such exponen­ tial form, multiplication could be carried out by adding exponents, and division by subtracting exponents. Multiplication and division would at once become no more complicated than addition and sub­ traction. Napier spent twenty years working out rather complicated formulas for obtain­ ing exponential expressions for various numbers. He was particularly interested in the exponential forms of the trig­ onometric functions, for these were used in astronomical calculations and it was these which Napier wanted to simplify. His process of computing the exponen­ tial expressions led him to call them logarithms (“proportionate numbers”) and that is the word still used. Finally, in 1614, Napier published his tables of logarithms, which were not im­ proved on for a century, and they were seized on with avidity. Their impact on the science of the day was something like that of computers on the science of our own time. Logarithms then, like the computers now, simplified routine calcu­ lations to an amazing extent and relieved working scientists of a large part of the noncreative mental drudgery to which they were subjected. This relief was in­ tensified by a slight modification of log-

[160]

ALPINI

arithms introduced almost at once by Briggs [164]. Napier tried to mechanize the use of logarithms by the manipulation of calcu­ lating rods. These were called “Napier’s bones” and achieved a certain fame but were completely outclassed and replaced by a much more practical device first constructed by Oughtred [172]. Lost in the colossal structure of log­ arithms is another advance made by Napier, much smaller, almost invisible in fact but familiar to every grammar school student. Napier completed the present form of the decimal fraction, first used by Stevinus [158], by inventing the decimal point. [160] ALPINI, Prospero (ahl-pee'nee) Italian botanist Born: Marostica, Venice, Novem­ ber 23, 1553 Died: Padua, November 23, 1616 Alpini earned his medical degree at the University of Padua in 1578. He served as physician to the Venetian con­ sul in Cairo, Egypt. There he was able to study the date palm and to detect, for the first time, that plants, like animals, could exist as male and female. It was the sexual differences among plants that Linnaeus [276], a century and a half later, was to use as the basis for his classification of the plant kingdom. Alpini was also the first European to describe the coffee plant and the banana. In 1593 he became professor of botany at the University of Padua. He died of a kidney infection con­ tracted while in Egypt. [161] NORMAN, Robert English navigator Born: Bristol, about 1560 Died: date unknown Norman, a navigator, would naturally be interested in the compass and its workings. He was the first to note that steel did not alter its weight when it was magnetized. This argued against magne­

LIBAVIUS

[162]

tism being a fluid which was somehow poured into the steel. He was also the first, apparently, who allowed a compass needle to swing up and down, showing, in 1576, that its north-seeking end would then point below the horizon. This is “magnetic dip” and was used to good effect by Nor­ man’s contemporary, Gilbert [155]. [162] LIBAVIUS (lih-bay'vee-us) German alchemist Born: Halle, Saxony, 1560 Died: Coburg, Bavaria, July 25, 1616 Libavius is the Latinized name of An­ dreas Libau, the son of a weaver, who is known almost entirely for the book he wrote. Like Zosimus [67], his contri­ bution to science is that he summarizes an epoch of alchemy. Libavius obtained his medical degree at the University of Jena in 1581 and was then town physician at Rothenburg from 1591 to 1596. After quarreling with the rector at Jena, where he was lecturing, he founded a school of his own in Coburg in 1605, remaining there till his death. In 1597 Libavius published Alchemia, a summary of the medieval achievements of alchemy that could be considered the first chemical textbook worthy of the name. He was a follower of Paracelsus [131] in that he believed in the impor­ tance of the medical applications of al­ chemy. He differed from Paracelsus, however, in largely eschewing mysticism. He bit­ terly attacked the mumbo-jumbo of those he called Paracelsians and also argued against the doctrines of the Rosicrucians. In fact, his writing is quite clear. He was the first to describe the preparation of hydrochloric acid, tin tet­ rachloride, and ammonium sulfate. He gave clear directions for preparing strong acids such as sulfuric acid and aqua regia. He suggested that mineral sub­ stances could be identified from the shape of the crystals produced when a solution is evaporated. More clearly than Paracelsus a half 97

[163]

BACON

century earlier, Libavius foreshadowed the chemistry of the future. And yet, for all the foreshadowing, Libavius remained firmly immersed in al­ chemy. He believed in the possibility of transmutation and considered the discov­ ery of practical methods of making gold to be an important end of alchemical study. [163] BACON, Francis English philosopher Born: London, January 22, 1561 Died: London, April 9, 1626 Bacon was born of a family prominent at the English court, and he himself took up the court as a career. He was a great success as a courtier, for he had a re­ markable facility for choosing the win­ ning side and abandoning it just before it stopped winning. He studied law at Cambridge where he gained a distaste for Aristotle’s [29] phi­ losophy. He entered practice in 1576. After a stay in France with the English ambassador, he entered Parliament in 1584. He became confidential aide to the earl of Essex, Queen Elizabeth I’s favor­ ite, but carefully judged the moment when Essex fell out of favor. By 1601 he was one of the judges who tried and con­ victed Essex for treason, and with Essex executed, he remained in favor with Eliz­ abeth. Elizabeth died two years later, but Bacon, in ample time, had won the favor of her successor, and under James I his star rose higher than ever, especially since he courted the patronage of the duke of Buckingham, James’s favorite. Bacon was knighted in 1603, shortly after James’s accession, became solicitor general in 1607, attorney general in 1613, lord chancellor in 1618. In 1618, also, he was raised to the peerage, being made Baron Verulam. Throughout, he bought his preferment by a disgraceful display of obsequiousness to people in authority and an unprincipled willingness to do any dirty work that needed doing. In 1621 he was made viscount of St. Albans, and at that moment, at the height of his career, he was suddenly 98

BACON

[163]

dashed down. He was accused of taking bribes in his capacity as judge, and the evidence was overwhelming. Bacon’s only defense was that the bribes, al­ though accepted, did not influence his judgment, and that he judged against the bribe-giver when that seemed the just thing to do. (It did not seem to occur to him that to accept a bribe and then cheat the briber was to be doubly dis­ honest. ) He was not punished severely, as he might have been, because the king inter­ vened to spare him the worst However, his political career was over. (There are enthusiasts who think Francis Bacon wrote Shakespeare’s plays, largely be­ cause Bacon was very educated and wrote, as a matter of course, in Latin, while Shakespeare was, apparently, poorly educated.) Despite his mean character, Bacon was an effective and influential philosopher. In early life he wrote to his uncle that he was taking “all knowledge to be my province,” something that in his day, could still reasonably be attempted. And he was the first, perhaps, to see history as the story of developing ideas rather than of conquering kings. Bacon’s great contribution to experi­ mental science was the glow of respect­ ability he gave it. (He was no relation to Roger Bacon [99], however, who had at­ tempted the same thing three and a half centuries before.) In 1605 Francis Bacon published a book called Advancement of Learning in which he argued against mysticism and characterized the dead hand of tradition as the true devil threatening mankind. There was no use, he said, in studying magic and trying to work through spirits. Science should concern itself with the ac­ tual world that was apparent to the senses, for its true purpose was not that of bolstering religious faith, but of im­ proving the human condition. (Never­ theless, he accepted astrology, as indeed nearly everyone did up to the time of Newton [231].) In 1620 came the Novum Organum, that is, the “New Organon,” the refer­ ence being to the Organon of Aristotle in which the Greek philosopher had dem­

[163]

BACON

onstrated the proper method of logic—of reasoning by deduction. Bacon’s book, as the title implies, contains a new method of reasoning. Bacon argued strenuously that deduc­ tion might do for mathematics but that it could not do for science. The laws of sci­ ence had to be induced, to be established as generalizations drawn out of a vast mass of specific observations. Bacon, however, was no experi­ mentalist himself and, ironically, one of his few attempts to be one brought on his death. In March 1626 he suddenly began to wonder if snow would delay the putrefaction of living tissue. (Substitute “cold” for “snow” and this is an excel­ lent stroke of intuition.) He was in his carriage at the time, staring at heaps of snow outside, and no doubt that set up the train of thought. He jumped out of the carriage, bought a chicken, and then, with his own hands, stuffed it with snow. He caught a chill almost at once, which turned to bronchitis and brought him to his death. Bacon’s concern with theory blinded him to the men who in his generation were practicing experimental science. Two of them, Gilbert [155] and Harvey [174], were in his own country and time. Moreover, his views remained (perhaps due to his intensively classical educa­ tion) medieval in some respects. For in­ stance, he could not bring himself to ac­ cept the views of Copernicus [127], for he could not swallow the notion of the great, solid earth flying through space. Harvey, unblinded by Bacon’s fine words, and seeing the backwardness of some of the thought, stated dryly that Bacon wrote of science “like a lord chancellor.” Nevertheless, Bacon put the theory of experimental science in the most refined of scholarly terms and made it possible for other scholars to accept it. The world of philosophy might easily ignore a Gil­ bert or even a Galileo [166] as a mere tinkerer and mechanic. (That is un­ doubtedly the way in which the Greek philosophers of the Alexandrian period viewed Hero [60], for instance.) But when Bacon placed the stamp of philo­

BRIGGS

[164]

sophic approval on such “tinkering,” it became a different matter. Largely because of Bacon’s influence, experimental science became fashionable among English gentlemen. A group of them began to gather to discuss and practice the new intellectual fad, in imi­ tation of the “House of Solomon,” a community of investigators and philoso­ phers described by Bacon in his book The New Atlantis. This finally developed into the Royal Society, perhaps the most unusual collection of brilliant scientists to forgather in a single city since the great days of Alexandria. Yet Bacon had had a real-life model to draw on, too; for a similar group, “Accademia dei Lincei,” had been es­ tablished in Rome earlier by Porta [150]. Its membership had included Galileo. [164] BRIGGS, Henry English mathematician Born: Warley Wood, Yorkshire, February 1561 Died: Oxford, January 26, 1630 Briggs obtained his master’s degree in Cambridge in 1585 and lectured there in 1592. In 1596, he became professor of geometry at Gresham College in Lon­ don. He is remembered chiefly for his re­ action to Napier’s [159] publication of logarithms. He was lost in admiration for the beauty of the system and its sim­ plicity (and aghast at his own stupidity in not seeing it until it was shown him). He went to the considerable trouble of making a trip to Edinburgh to see Na­ pier and talk to him. Napier had written his exponential numbers as e2, e2-32, e 3.®7, and so on, where e is an unend­ ing decimal fraction that starts 2.7182818284 . . . There are good mathematical reasons for doing this and such Napierian or “natural” logarithms are still used in calculus. However, Briggs pointed out during his conver­ sation with Napier the convenience of using exponential numbers such as 102, 102-32, 103-97, and so on. Log­ arithms in this fashion are called Briggs­ ian or “common” logarithms and are al­ 99

[165]

SANCTORIUS

most invariably used for ordinary calcu­ lations. Briggs worked out the first logarithm tables for numbers from 1 to 20,000 and from 90,000 to 100,000 (to fourteen places!) in 1624. Briggs also invented the modern method of long division. In 1619 he had reached the peak of his academic career when he became professor of astronomy at Oxford. Unlike Napier, Briggs scorned astrol­ ogy. [165] SANCTORIUS, Sanctorius (sanktoh'ree-us) Italian physician Born: Justinopolis, Venice (now Koper, Yugoslavia), March 29, 1561 Died: Venice, March 6, 1636 Sanctorius obtained his medical degree at the University of Padua in 1582 and later is supposed to have spent fourteen years as physician to King Sigismund III of Poland and then to have returned to Italy. Along with Harvey [174], Sanctorius subjected the human body to its first quantitative measurements. As a profes­ sor of medicine at Padua, a post he took in 1611, he weighed human beings from day to day on a balance he had con­ structed himself and proved that they lost weight through “insensible perspi­ ration” (perspiration that evaporated as it formed). This marked the beginning of the modem study of metabolism. Galileo [166] had invented the first thermometer, a rather bulky and clumsy device in which a trapped volume of air changed the level of water in a tube as it expanded with a rise in temperature or contracted with a drop. Scantorius ap­ plied this device to measuring the warmth of the body by placing the bulb of air in the mouth. This was the first clinical thermometer. Sanctorius also in­ vented a device to measure the pulse rate. Sanctorius, who never married, died of a disease of the urinary tract, one, no doubt, of the eighty thousand different 100

GALILEO

[166]

diseases which, in a moment of mis­ guided theory, he at one time calculated were possible in human beings. [166] GALILEO (gahl-ih-lay'oh) Italian astronomer and physicist Born: Pisa, February 15, 1564 Died: Arcetri (near Florence), January 8, 1642 Galileo is universally known by his first name only, his full name being Galileo Galilei. The form of the name arose from a Tuscan habit of using a variation of the last name for the first name of the oldest son. He was bom three days before Michelangelo died; a kind of symbolic passing of the palm of learning from the fine arts to science. Galileo was destined by his father, a mathematician of a onetime wealthy but now rather run-down family, to the study of medicine and was deliberately kept away from mathematics. In those days (and perhaps in these) a physician earned thirty times a mathematician’s salary. Galileo would undoubtedly have made a good physician, as he might also have made a good artist or musician, for he was a true Renaissance man, with many talents. However, fate took its own turning and the elder Galilei might as well have saved himself the trouble. The young student, through accident, happened to hear a lecture on geometry and then, pursuing the subject further, came upon the works of Archimedes [47]. He promptly talked his reluctant father into letting him study mathematics and sci­ ence. This was fortunate for the world, for Galileo’s career was a major turning point in science. He was not content merely to observe; he searched for a cru­ cial experiment that would demonstrate his theories. He began to measure, to re­ duce things to quantity, to see if he could not derive some mathematical rela­ tionship that would describe a phenome­ non with simplicity and generality. He was not the first to do this, for it had been done even by Archimedes (whom

[166]

GALILEO

Galileo extravagantly admired) eighteen centuries before. What’s more, Galileo was not really a thoroughgoing experi­ menter compared with those who were to follow, and he still retained a great deal of the Greek tendency to theorize. Nevertheless, Galileo made experi­ mentation attractive. For one thing, he had the literary ability (another talent) to describe his experiments and theories so clearly and beautifully that he made his quantitative method famous and fashionable. The first of his startling discoveries took place in 1581, when he was a teen­ ager studying medicine at the University of Pisa. Attending services at the cathe­ dral of Pisa, he found himself watching a swinging chandelier, which air currents shifted now in wide arcs, now in small ones. To Galileo’s quantitative mind, it seemed that the time of swing was the same, regardless of the amplitude. He tested this by his pulsebeat. Then, upon returning home, he set up two pendu­ lums of equal length and swung one in larger, one in smaller sweeps. They kept together and he found he was correct. (In later experiments, Galileo was to find that the difficulty of accurately mea­ suring small intervals of time was his greatest problem. He had to continue using his pulse, or to use the rate at which water trickled through a small orifice and accumulated in a receiver. It is ironic then, that after Galileo’s death Huygens [215] was to use the principle of the pendulum, discovered by Galileo, as the means by which to regulate a clock, thus solving the problem Galileo himself could not. Galileo also attempted to measure temperature, devising a ther­ moscope for the purpose in 1593. This was a gas thermometer which measured temperature by the expansion and con­ traction of gas. It was grossly inaccurate and not until the time of Amontons [244] a century later was a reasonable beginning made in thermometry. (It should never be forgotten that the rate of advance of science depends a great deal on advances in techniques of mea­ surement.) In 1586 Galileo published a small booklet on the design of a hydrostatic

GALILEO

[166]

balance he had invented and this first brought him to the attention of the scholarly world. Galileo began to study the behavior of falling bodies. Virtually all scholars still followed the belief of Aristotle [29] that the rate of fall was proportional to the weight of the body. This, Galileo showed, was a conclusion erroneously drawn from the fact that air resistance slowed the fall of light objects that offered comparatively large areas to the air. (Leaves, feathers, and snowflakes are examples.) Objects that were heavy enough and compact enough to reduce the effect of air resistance to a quantity small enough to be neglected, fell at the same rate. Galileo conjectured that in a vacuum all objects would fall at the same rate. (A good vacuum could not be produced in his day, but when it finally was, Galileo was proved to be right.) Legend has it that Galileo demon­ strated his views by simultaneously drop­ ping two cannon balls, one ten times heavier than the other, from the Leaning Tower of Pisa. Both were seen and heard to strike the ground simultaneously. This seems to be nothing more than a legend, but a similar experiment was actually performed, or at least described, some years earlier by Stevinus [158], Nevertheless, the experiments that Galileo did indeed perform were quite sufficient to upset Aristotelian physics. Since his methods for measuring time weren’t accurate enough to follow the rate of motion of a body in free fall, he “diluted” gravity by allowing a body to roll down an inclined plane. By making the slope of the inclined plane a gentle one, he could slow the motion as much as he wished. It was then quite easy to show that the rate of fall of a body was quite independent of its weight. He was also able to show that a body moved along an inclined plane at a con­ stantly accelerating velocity; that is, it moved more and more quickly. Leo­ nardo da Vinci [122] had noted this a century earlier but had kept it to him­ self. This settled an important philosophic point. Aristotle had held that in order to keep a body moving, a force had to be 101

[166]

GALILEO

continually applied. From this it fol­ lowed, according to some medieval phi­ losophers, that the heavenly bodies, which were continually moving, had to be pushed along by the eternal labors of angels. A few even used such arguments to deduce the existence of God. On the other hand, some philosophers of the late Middle Ages, such as Buridan [108], held that constant motion required no force after the initial impulse. By that view God in creating the world could have given it a start and then let it run by itself forever after. If a continuous force were applied, said these philoso­ phers, the resulting motion would be­ come ever more rapid. Galileo’s experiments decided in favor of this second view and against Aristotle. Not only did the velocity of a falling ball increase steadily with time under the continuous pull of the earth, but the total distance it covered increased as the square of the time. He also showed that a body could move under the influence of two forces at one time. One force, applying an ini­ tial force horizontally (as the explosion of a gun), could keep a body moving horizontally at a constant velocity. An­ other force, applied constantly in a verti­ cal direction, could make the same body drop downward at an accelerated veloc­ ity. The two motions superimposed would cause the body to follow a para­ bolic curve. In this way Galileo was able to make a science out of gunnery. This concept of one body influenced by more than one force also explained how it was that everything on the sur­ face of the earth, including the atmo­ sphere, birds in flight, and falling stones, could share in the earth’s rotation and yet maintain their superimposed motions. This disposed of one of the most effec­ tive arguments against the theories of Copernicus [127] and showed that one need not fear that the turning and re­ volving earth would leave behind those objects not firmly attached to it. (Galileo’s proofs were all reached by the geometric methods of the Greeks. The application of algebra to geometry and the discovery of infinitely more pow­ erful methods of mathematical analysis 102

GALILEO

[166]

than those at Galileo’s disposal had to await Descartes [183] and Newton [231]. Yet Galileo made do with what he had and his discoveries marked the beginning of the science of mechanics and served as the basis a century later for the three laws of motion propounded by Newton.) In his book on mechanics Galileo also dealt with the strength of materials, founding that branch of science as well. He was the first to show that if a struc­ ture increased in all dimensions equally it would grow weaker—at least he was the first to explain the theoretical basis for this. This is what is now known as the square-cube law. The volume in­ creases as the cube of linear dimensions but the strength only as the square. For that reason larger animals require pro­ portionately sturdier supports than small ones. A deer expanded to the size of an elephant and kept in exact proportion would collapse. Its legs would have to be thickened out of proportion for proper support. The success of Galileo and his succes­ sors, particularly Newton, in accounting for motion by pushes and pulls (“forces”) gave rise to the thought that everything in the universe capable of measurement could be explained on the basis of pushes and pulls no more com­ plicated in essence than the pushes and pulls of levers and gears within a ma­ chine. This mechanistic view of the uni­ verse was to gain favor until a new revo­ lution in science three centuries after Galileo showed matters to be rather more complicated than the mechanists had assumed. Yet Galileo was reluctant to de­ nounce Aristotelian physics too publicly. He waited for a safe opportunity to do so and this came with the nova of 1604 (the one usually associated with Kepler [169]). Galileo used the nova to argue against the Aristotelian notion of the im­ mutability of the heavens and, by impli­ cation, against the Aristotelian view gen­ erally. Galileo’s work made him unpopular at Pisa and he moved to a better position at Padua, in Venetian territory. (Venice was a region of considerable intellectual freedom at that time.) The new position

[166]

GALILEO

paid three times the salary of the old one —though Galileo lived gaily and gen­ erously and was always in debt anyway. He was always in trouble, too, for he made himself unpopular with influential people. He had a brilliant and caustic wit and he could not resist using that wit to make jackasses—and therefore bitter enemies—of those who disagreed with him. Even as a college student, he had been nicknamed “the wrangler” because of his argumentativeness and noncon­ formity. He even refused to wear aca­ demic robes, though this cost him several fines. Besides he was so brilliant a lec­ turer that students flocked to hear him, coming in numbers as high as two thou­ sand, according to a possibly exaggerated report, while his colleagues mumbled away in empty halls, and nothing will in­ furiate colleagues more than that. In Padua, Galileo was corresponding with Kepler, and in this correspondence he admitted, as early as 1597, that he had come to believe in the theories of Copernicus, though he prudently re­ frained for a while from saying so pub­ licly. The execution of Bruno [157] in 1600 must have encouraged Galileo to continue refraining. In 1609, however, he heard that a mag­ nifying tube, making use of lenses, had been invented in Holland. Before six months had passed, Galileo had devised his own version of the instrument, one that had a magnifying power of thirtytwo. He could adjust it in reverse, to serve as a microscope, and he observed insects by this means. However, it was as a telescope that he made best use of it. He turned it on the heavens. Thus began the age of telescopic astronomy. Using his telescope Galileo found that the moon had mountains and the sun had spots, which showed once again that Aristotle was wrong in his thesis that the heavens were perfect and that only on earth was there irregularity and disorder. Tycho Brahe [156] had already done that in his studies on his nova and his comet, and Fabricius [167] had done it in his studies of a variable star, but Galileo’s findings attacked the sun itself. (Other astronomers discovered the sun­ spots at almost the same time as Galileo

GALILEO

[166]

—for indeed, very large spots can some­ times be made out with the naked eyes, when the sun’s brilliance is dimmed at the horizon, or by mist—and there was wrangling over priority, which made Galileo additional enemies. Galileo, how­ ever, whether he had priority in the dis­ covery or not, did more than merely see the spots. He used them to show that the sun rotated about its axis in twenty-seven days, by following individual spots around the sun. He even determined the orientation of the sun’s axis in that fash­ ion. (Nor did Galileo get off scot-free. His studies of the sun damaged his eyes, which had already suffered from infec­ tions in his youth, and in old age he went blind.) The stars, even the bright ones, re­ mained mere dots of light in the tele­ scope, while the planets showed as little globes. Galileo deduced from this that the stars must be much farther away than the planets and that the universe might be indefinitely large. Galileo also found that there were many stars in existence that could be seen by telescope but not by naked eye. The Milky Way itself owed its luminos­ ity to the fact that it was composed of myriads of such stars. More dramatically, he found that Ju­ piter was attended by four subsidiary bodies, visible only by telescope, that circled it regularly. Within a few weeks of observation he was able to work out the periods of each. Kepler gave these latter bodies the name of satellites and they are still known as the Galilean sat­ ellites. They are known singly by the mythological names of Io, Europa, Gan­ ymede, and Callisto. Jupiter with its sat­ ellites was a model of a Copemican sys­ tem—small bodies circling a large one. It was definite proof that not all astro­ nomical bodies circled the earth. Galileo observed that Venus showed phases entirely like those of the moon, from full to crescent, which it must do if the Copemican theory was correct. Ac­ cording to the Ptolemaic theory Venus would have to be a perpetual crescent. The discovery of the phases of Venus definitely demonstrated, by the way, the fact that planets shine by reflected sun­ 103

[166]

GALILEO

light. Galileo discovered that the night side (that is, the dark portion) of the moon when the moon was less than full had a dim glow, which he explained as caused by light shining upon it from the earth (earthshine). It had been seen be­ fore but had been explained otherwise. Poseidonius [52] thought it was sunlight shining through a partly transparent moon. Reinhold [143] thought the moon’s surface was phosphorescent. Earthshine showed that earth, like the planets, gleamed in the sun, and re­ moved one more point of difference be­ tween the earth and the heavenly bodies. All these telescopic discoveries meant the final establishment of Copernicanism more than half a century after Coper­ nicus had published his book. Galileo announced his discoveries in special numbers of a periodical he called Sidereus Nuncius (“Starry Messenger”) and these aroused both great enthusiasm and profound anger. Aged Venetian aris­ tocrats clambered to the top of a tower in order to look through one of his tele­ scopes and see ships, otherwise invisible, far out at sea. He was the best lensmaker in Europe at the time and built a num­ ber of telescopes. He sent them all over Europe (one reaching Kepler) so that others might confirm his findings. Both Venice and Florence offered him lucra­ tive positions. To the annoyance of the Venetians, Galileo chose to travel to his beloved Florence. Galileo visited Rome in 1611, where he was greeted with honor and delight, though not everyone was happy. The thought of imperfect heavens, of invisi­ ble objects shining there, and, worst of all, of the Copemican system enthroned and the earth demoted from its position as center of the universe was most un­ settling. Galileo also rather unwisely ven­ tured to write a book giving his views on the Bible and generally discussing theo­ logical subjects to the offense of theolo­ gians. Galileo’s conservative opponents persuaded Pope Pius V to declare Coper­ nicanism a heresy, and Galileo was forced into silence in 1616. Intrigue continued. Now Galileo’s friends, now his enemies seemed to have gained predominance. In 1632 Galileo 104

GALILEO

[166]

was somehow persuaded that the pope then reigning (Urban VIII) was friendly and would let him speak out. He there­ fore published his masterpiece, Dialogue on the Two Chief World Systems, in which he had two people, one represent­ ing the view of Ptolemy [64] and the other the view of Copernicus, present their arguments before an intelligent lay­ man. (Amazingly enough, despite his long friendship with Kepler, Galileo did not mention Kepler’s modification of Co­ pernicus’ theory, a modification that improved it beyond measure—but then, Kepler’s work was appreciated by virtu­ ally no one at the time.) Galileo of course gave the Copemican the brilliant best of the battle. The pope was persuaded that Simplicio, the char­ acter who upheld the views of Ptolemy in the book, was a deliberate and insult­ ing caricature of himself. The book was all the more damaging to those who felt themselves insulted, because it was writ­ ten in vigorous Italian for the general public (and not merely for the Latinlearned scholars) and was quickly trans­ lated into other languages—even Chi­ nese! Galileo was brought before the Inqui­ sition on charges of heresy (his indis­ creet public statements made it easy to substantiate the charge) and on June 22, 1633, was forced to renounce any views that were at variance with the Ptolemaic system. Romance might have required a heroic refusal to capitulate, but Galileo was nearly seventy and he had the exam­ ple of Bruno to urge him to caution. He recanted and was condemned to a pen­ ance of psalm recitations each week for three years—and, of course, to refrain from further heresy. Legend has it that when he rose from his knees, having completed his renunci­ ation, he muttered, “Eppur si muove!” (“And yet it moves,” referring to the earth.) This was indeed the verdict given by the world of scholarship, and the silencing of Galileo for the remaining few years of his old age (during which —in 1637—he made his last astro­ nomical discovery, that of the slow sway­ ing or “libration” of the moon as it revolves) was an empty victory for the

[167]

FÀBRICIUS

conservatives. When he died they won an even shallower victory by refusing him burial in consecrated ground. The Scientific Revolution begun with Copernicus had been opposed for nearly a century at the time of Galileo’s trial, but by then the fight was lost. The revo­ lution not only existed, but had pre­ vailed, although, to be sure, there re­ mained pockets of resistance. Harvard, in the year of its founding (1636), re­ mained firmly committed to the Ptole­ maic theory. Galileo’s Dialogue was not removed from the Roman Catholic Index of pro­ hibited books until 1835. In 1965, Pope Paul VI, on a visit to Pisa, spoke highly of Galileo— an even clearer admission that on this issue the church had been in the wrong. [167] FABRICIUS, David (fa-brish'ee-us) German astronomer Born: Esens, Ostfriesland, March 9, 1564 Died: Osteel, Ostfriesland, May 7, 1617 The surname is a Latinized version of Goldschmidt. Fabricius, a Protestant minister, was a friend of Tycho Brahe [156] and Kepler [169], He was one of the first to join Galileo [166] in using the telescope for astronomical research but he could never bring himself to accept Kepler’s elliptical orbits. He insisted on Plato’s [24] circles. His best-known discovery came in the time of naked-eye astronomy, for in 1596 he observed a star that Bayer [170] later named Omicron Ceti and found to show periodic variations in brightness. Hevelius [194], a half century later, named it Mira (“wonderful”). It was the first variable star to be discovered. The mere existence of a star varying in brightness was another blow to the or­ thodox Aristotelian view that the heavens were perfect and unchanging. Fabricius was murdered by one of his parishioners, who was apparently a thief and whom Fabricius had threatened to expose.

KEPLER

[169]

[168] LIPPERSHEY, Hans (lip'er-shee) German-Dutch optician Born: Wesel, Germany, about 1570 Died: Middelburg, Netherlands, about 1619 Lippershey was a lens grinder who sold spectacles, the one device for which lenses were commonly used in those days. One of his apprentices, while pass­ ing away an idle moment in 1608, adjusted two lenses before his eyes and found that distant objects seemed closer. Startled, he told Lippershey, who mounted such lenses in tubes and at­ tempted to sell them (the first tele­ scopes) to the Dutch government. Rec­ ognizing the use of the instrument in warfare, the government tried to keep it secret. Hearing rumors of such a device, however, Galileo [166] in Italy quickly constructed one and turned it upon the heavens, revolutionizing astronomy rather than warfare. [169] KEPLER, Johann German astronomer Born: Weil der Stadt, Württem­ berg, December 27, 1571 Died: Regensburg, Bavaria, No­ vember 15, 1630 In his youth, Kepler, the son of a pro­ fessional soldier (who deserted his fam­ ily) and grandson of a man who had served as mayor of the family’s home­ town, was cursed with a sickly consti­ tution. An attack of smallpox, when he was three, crippled his hands and weak­ ened his eyes. This made it necessary for him to have a religious education, for he seemed fit for no post more strenuous than that of minister. He studied at the University of Tü­ bingen, where he was scapegoated by the other students, and where he was con­ verted to Copernicanism. He graduated in 1588 and earned a master’s degree in 1591. His brilliance in mathematics was soon recognized, and by 1594 all thought of the ministry was abandoned and he was teaching science at the Uni­ versity of Graz in Austria. In 1597, he 105

[169]

KEPLER

married and in this way eventually gained five children and fourteen years of unhappiness. There was a strong strain of mysticism in Kepler. An astronomy professor in those days was expected to cast horo­ scopes, and Kepler threw himself into that form of work. He was no faker but studied the Greek astronomers carefully in an attempt to make a real science out of astrology as Cardano [137] had done nearly a century before. In this he failed, as Cardano had. Again like Cardano, Kepler attempted to use astrological techniques to solve biblical mysteries. He tried to work out the date of creation, for instance, and found it to be 3992 b .c . In later life Kepler seemed rather apologetic about his ability as an astrolo­ ger, but there is no question that it was more valued by his patrons than his achievements in science. He cast horo­ scopes for Emperor Rudolf and in later years for the imperial general, Albrecht von Wallenstein, earning him their pro­ tection, although he was a Protestant and the times were those of the Thirty Years’ War, during which religious ha­ treds were strong. In 1598 religious disputes (well in ad­ vance of the climactic quarrel of the Thirty Years’ War) were intense in Graz, and Kepler felt it advisable to leave. He accepted a position at Prague with the aged Tycho Brahe [156], with whom he had been in correspondence for some time. On Tycho’s death in 1601 Kepler inherited the invaluable data that the older man had collected over the years, including his careful observations of the apparent motion of the planet Mars. Kepler set about trying to devise a sys­ tem of the heavens based on these obser­ vations. He was spurred on by the ap­ pearance of another nova (“Kepler’s star”) on September 30, 1604, not quite as bright as Tycho’s star, but spectacular enough. In his work, however, Kepler was side­ tracked by his interest in mystic notions dating back to the Greeks. He believed firmly in the “music of the spheres” first propounded by Pythagoras [7] and his 106

KEPLER

[169]

followers and even tried to work out the exact notes sounded by each planet in its motions. (Earth, he said, sounded the notes “mi,” “fa,” “mi,” indicating it to be the abode of misery, /amine and misery.) He also felt the influence of Plato [24], for he tried to fit the five Platonic solids into the planetary scheme of things. The book in which he advanced this notion, published in 1596, was what first inter­ ested Tycho Brahe in Kepler. In working out his regular-solid theory of the planets, he circumscribed an octa­ hedron about the sphere of Mercury and placed the sphere of Venus through its vertices. An icosahedron was circum­ scribed about the sphere of Venus and the sphere of earth was placed through its vertices. And so on. He spent a tremendous amount of time working it all out in the hope of ac­ counting exactly for the relative dis­ tances from the sun of the various planets. He finally realized by 1595 he couldn’t adjust the various solids and spheres properly. Nevertheless, he did not give up. It oc­ curred to him at last that nothing he could do with spheres would fit Tycho’s data, and he began to search for some noncircular curve that would fit. First, he tried an egg-shaped oval without suc­ cess, and then he settled on the ellipse. The ellipse, a curve first studied by Apollonius [49], resembles a flattened circle. A circle has a diameter that is fixed in length however it is drawn, but an ellipse’s diameter (a straight line drawn through its center) varies in length according to its position. The longest diameter is the major axis, the shortest the minor axis. The flatter the ellipse, the greater the proportionate difference in length between major and minor axis and the greater its “eccen­ tricity.” (The eccentricity of a circle is zero; it is not flattened at all.) Along the major axis are two points called foci at equal distances from the center. The foci have this property: if from each focus a straight line is drawn to the same point on the curve of the el­ lipse, the sum of the two lines is always equal to the length of the major axis.

[169]

KEPLER

This is true no matter to which point on the curve the two lines are drawn. Kepler found that the positions of Mars, as observed by Tycho, fitted into an elliptical orbit with a high degree of accuracy. It wasn’t a very flattened el­ lipse, but it was most definitely not a cir­ cle. Furthermore, the sun was located at one focus of the ellipse. Kepler found that the orbits of the other planets could also be drawn as el­ lipses with the sun always at one of the foci. He announced this in Astronomia Nova, a book published in 1609, and this is now known as Kepler’s first law. The book also contained his second law: “A line connecting the planet and the sun will sweep over equal areas in equal times as the planet moves about its orbit.” This meant that the closer a planet was to the sun the faster it would move according to a fixed and calculable rule. Kepler went on later to apply these laws to the satellites of Jupiter as well. However, he was unable to handle earth’s own moon. Its motions were too complicated. This was done in 1638 by Horrocks [200]. Kepler’s ellipses put an end to Greek astronomy. They destroyed the sa­ credness of circular motion and abol­ ished the celestial spheres that Eu­ doxus [27] had placed in the heavens two thousand years before, and which even Copernicus had retained. Kepler’s scheme of the solar system has been fol­ lowed by astronomers ever since, without significant modification. (Kepler’s insight was restricted to the solar system. The stars, he thought, all occupied a thin shell some two miles thick far outside the solar system. Here he was far behind Bruno [157].) With the abolition of the celestial spheres some other cause had to be found to explain the fact that the heav­ enly bodies remained in their orbits. The fact that the sun was always at one focus of the elliptical orbit, that it was always in the plane of the orbit, that planetary motion was faster the closer the planet was to the sun, made it obvious to Kepler that the sun somehow controlled the motions of the planets. He followed

KEPLER

[169]

the notions of Gilbert [155] in thinking that some magnetic force was involved, but the systems he attempted to work out on such a basis were unsatisfactory. It was left for Newton [231] to suggest a satisfactory explanation a half century later. Kepler published another book in 1619, one that was particularly full of verbose mysticism. Kepler, aware of its difficulty, despondently suspected it might have to wait a century for a reader. In it, however (rather like a pearl in a mass of seaweed), was what is now called Kepler’s third law, which stated that the square of the period of revolution of a planet is proportional to the cube of its distance from the sun. Again the sun seemed indicated as the controller of planetary motion. The book was dedicated to James I of Great Britain, a royal pedant to whom a turgid book was meat and drink and a dedication the dessert to top it with. James invited Kepler to England, but the astronomer refused to leave Germany even though that land was now plunging into the Thirty Years’ War. Kepler and Galileo [166] carried on a friendly correspondence for a time, though they never met, and Kepler com­ municated his theories to Galileo. Gali­ leo, however, in his book on the Copemican theory made no mention of Kepler’s laws. Presumably he felt they were as little to be regarded as Kepler’s fantasies about regular solids and the music of the spheres (to say nothing about his horoscopes—although Galileo, on occasion, could cast one too). As a matter of fact, the correspondence had been broken off in 1610, and this may indicate the loss of sympathy between the two. Nevertheless, when Galileo was con­ structing telescopes and sending them where he thought they would do the most good, one found its way to Kepler. Kepler used the telescope to observe Jupiter’s moons—which he had refused to accept till he saw them with his own eyes—and promptly described them as “satellites,” from a Latin term for the hangers-on of a powerful man. He began to work on the manner in which light 107

[1 6 9 ]

KEPLER

waves were refracted by lenses. He man­ aged to explain in this way how it was that telescopes (and eyes, too) per­ formed their function. He described an improved telescope in 1611, using two convex lenses in place of the one convex and one concave used by Galileo, and described, in theory, a compound microscope better than any then available. He also showed that a parabolic mirror focused parallel rays of light, a fact essential to the development of reflecting telescopes by Newton later in the century. Thus he founded the sci­ ence of modem optics. But he was not able to deduce a general mathematical relationship to express the refraction of light. That was left for his younger con­ temporary Snell [177], In 1612 Kepler’s protector, Rudolf II, died. (So did Kepler’s wife, and a sec­ ond marriage, to a younger woman, brought him happiness.) The new em­ peror, Matthias, maintained Kepler in his position as court astronomer with a salary that was usually in arrears. (Ru­ dolf n had not been a prompt payer ei­ ther. The Holy Roman emperors were usually strapped for cash.) In 1618 Kepler’s mother, who dabbled in the oc­ cult, was arrested as a witch and, al­ though not tortured, did not long survive her release, which was procured through her son’s long-sustained efforts. Kepler spent these years completing new tables of planetary motions based on Tycho’s superlative observations and his own theory of elliptical orbits. He used the newly invented logarithms of Napier [159] in his calculations, this being the first important use to which logarithms were put. Despite family troubles, financial difficulties exacerbated by the fact that Kepler fathered thirteen children, and continuing war and reli­ gious unrest, the tables, called the Rudol­ phine Tables in honor of Kepler’s old patron, were published in 1627 and dedi­ cated to the memory of Tycho. The work included tables of logarithms and Tycho’s star map as expanded by Kepler. Kepler’s final service to astronomy was his calculation of the times of passage of the inner planets Mercury and Venus across the face of the sun. Such passages 108

BAYER

[170]

had never been observed, but according to Kepler’s calculations they had to take place. In 1631 such a “transit” of Mer­ cury was observed by Gassendi [182] at the predicted time, but Kepler by then was dead of a fever, followed by enthusi­ astic medical bleeding. Kepler, by the way, wrote a story, “Somnium,” about a man who traveled to the moon in a dream. For the first time the lunar surface was described as it really was, so that “Somnium” may be considered the first piece of authentic science fiction, as opposed to fantasy. It was published after Kepler’s death. Kepler’s manuscripts were eventually bought by Catherine II of Russia over a century after his death and are preserved now at the Pulkovo Observatory in the USSR. [170] BAYER, Johann (by'er) German astronomer Born: Rain, Bavaria, 1572 Died: Augsburg, Bavaria, March 7, 1625 While Kepler [169] was putting the planetary system into its modem shape, his countryman Bayer, a lawyer by pro­ fession and adviser to the Augsburg City Council, was adding a modem touch to the stars themselves. The constellations and their names stretch back to antiquity and have al­ ways proved a useful means of dividing the starry vault. The names of the stars within the constellations were in ancient times not so well organized. The bright ones were given names of course and the present versions of those names are mostly derived from the Arabic. Betel­ geuse, Aldebaran, and Rigel bear witness to the centuries between the eighth and the eleventh when it was the Arabs who preserved Greek astronomy. Some names, such as Castor, Pollux, and Sirius, date back to classical times. How­ ever, there was no way of associating the name of a star with the constellation that contains it except brute memory. In 1603 and 1627 Bayer published edi­ tions of Uranometria, a catalogue of the heavens (the first one to show the entire

PITAGORAS

2. H ippocrates 1. P ythagoras

3. A ristotle

5. A r c h im ed e s

4. E uclid

6. P t o l e m y

7. N icolas Copernicus

9. G alen

11. G alileo G a lilei a n d th e D u k e of P adua

8. R oger Bacon

10. A ndreas Vesalius

12. J o h a n n K e p l e r

13. W illiam H arvey

15. R obert Boyle

17. I saac N e w t o n

14. R ené D escartes

16. A nton van Leeuwenhoek

18. B e n j a m in F r a n k lin

19. H enry Cavendish

2 1. A n t o in e L. L avoisier

20. Sir William H erschel

2 2. E dw ard J e n n e r

[171]

MARIUS

celestial sphere) that corrected this. He described the constellations carefully and located more stars (1,706 altogether) than Tycho Brahe [156] had done in his catalogue. In addition, and more important, Bayer listed the stars of each constel­ lation by Greek letters in order of brightness. Thus Betelgeuse, the brightest star in Orion, became Alpha Orionis, while Rigel was Beta Orionis, and Bella­ trix was Gamma Orionis. This device has been kept to the present. Indeed, some bright stars of the southern skies, which have been observed carefully only since Bayer’s day, are known only by this sys­ tem. Thus the brightest star of the south­ ern heavens and—as Henderson [505] was to show two centuries later—the star that is closest to us is in the constellation Centaurus and is known only as Alpha Centauri. (In later years, as more and fainter stars were studied, Roman letters and numbers, alone and in combination, had to be brought into use.) Bayer, who was an amateur theologian and an ardent Protestant, did not suc­ ceed in another project. Offended by the heathen names of the constellations, he tried to introduce a system whereby the northern constellations were given names from the New Testament, and southern constellations from the Old. [171] MARIUS, Simon German astronomer Born: Gunzenhausen, January 20, 1573 Died: Anspach, Bavaria, December 26, 1624 Marius’ real name was Mayer but, like many another scholar of the time, he used a Latinized version in his scholarly career. He studied astronomy under Tycho Brahe [156] and medicine in Italy and served as court astronomer for the elector of Brandenburg. His career is possibly an unsavory one. He seems to have had one of Galileo’s [166] works copied and published under another author’s name, and he claimed (apparently without justification) to have seen the four satellites of Jupiter in

OUGHTRED

[172]

1609 before Galileo had. We can well imagine that Galileo was furious at this and charged into the fight with all his strength. Yet one aspect of Marius’ work, even if false, remains. Galileo had not named Jupiter’s satellites, but Marius did. Marius made use of Greek mythology and chose the names Io, Europa, Gany­ mede, and Callisto—four individuals who were closely involved with Jupiter (Zeus) in the myths. Those names re­ main. Marius also prepared tables of their motions before Galileo did. Marius made one discovery that, ap­ parently, no one disputes as Marius’. In 1612 he was the first astronomer to men­ tion the Andromeda Nebula, the most distant object one can see without a telescope—though that fact was not to be appreciated for three more centuries. [172] OUGHTRED, William (aw'tred) English mathematician Born: Eton, Buckinghamshire, March 5, 1574 Died: Albury, Surrey, June 30, 1660 Oughtred, who obtained his master’s degree at Cambridge in 1600, was a minister and not a professional mathe­ matician, but that makes little difference since he spent almost all the time he could spare on mathematics, even when it meant sleeping but two or three hours a night. He published a textbook on mathe­ matics in 1631 in which he introduced the multiplication sign ( X ) and the ab­ breviations commonly used today for the trigonometric functions: sin, cos, and tan for sine, cosine, and tangent. His greatest innovation, however, came in 1622, and consisted of two rulers along which logarithmic scales were laid off. By manipulating the rulers and sliding one against the other, calcu­ lations could be performed mechanically by means of logarithms. We know it now as a slide rule, and, for centuries, engi­ neers carried slide rules at least as lov­ ingly as any physician ever carried his stethoscope and tongue depressor. 109

[173]

SCHEINER

He was a pronounced royalist but managed to keep his post during the time of Cromwell and the Common­ wealth. There is a story that he died of joy at hearing that Charles II had been recalled and the British monarchy was to be re-established. However, he was eighty-five at the time and undoubtedly the thread of life was sufficiently frayed to require no great drama to bring about death. [173] SCHEINER, Christoph (shigh'ner) German astronomer Born: Wald, Rhine Province, July 25, 1575 Died: Neisse, Silesia (now Nysa, Poland), June 18, 1650 Scheiner taught Hebrew and mathe­ matics, first at Freiburg and then at In­ golstadt (where he had studied). He was appointed professor of Hebrew and mathematics at Ingolstadt in 1600. He observed sunspots on a projection of the sun’s disc in March 1611. This was not really very unusual, for some spots are big enough to be seen by the unaided eye and records of their occasional observa­ tion dated back to ancient times. Scheiner claimed to have seen them be­ fore Galileo [166], however, and that ir­ ritated the contentious Italian who plunged eagerly into controversy. When Scheiner (a Jesuit since 1595) first reported his discovery to his supe­ rior, the latter warned him to be careful in his interpretations, for Aristotle [29] had said nothing about spots on the sun. Scheiner therefore judged them to be small bodies, circling the sun but not part of it. (It did not occur to him, ap­ parently, that Aristotle had said nothing about that either.) This was all Galileo needed. He at­ tacked both Scheiner and Aristotle in his best polemical style, and this helped end the brief popularity of Galileo with the church authorities and began the long road that ended in the inquisitorial chambers. Scheiner also studied the physiology of vision and showed that the curvature of 110

HARVEY

[174]

the lens changes as the eye focuses to different distances. This is called “ac­ commodation.” [174] HARVEY, William English physician Born: Folkestone, Kent, April 1, 1578 Died: London, June 3, 1657 As a young man, Harvey (the son of a well-to-do businessman and the oldest of nine children) supplemented his educa­ tion at Cambridge (from which he took his degree in 1597) by courses at the medical school in Padua, Italy, which ever since Mondino’s [110] day, three centuries before, had been the world’s greatest. There he studied under Fabricius ab Aquapendente [151] among others. Harvey was in Italy when Galileo [166] was making his mark and it was Harvey’s great feat to apply the Galilean view of science to physiology and medi­ cine. One of Galileo’s Italian colleagues, Sanctorius [165], made a start in this di­ rection, but Harvey was to outstrip him. After obtaining his medical degree in 1602 Harvey returned to England, where he married and set up a most successful practice. Francis Bacon [163] was one of his patients, and from 1618 he was court physician for James I and Charles I until the latter was beheaded in 1649. He was more interested in medical research than in routine practice. By 1616, he is supposed to have dissected eighty species of animals. In particular he studied the heart and blood vessels. Men such as Servetus [142] had groped toward the concept of the circulation of the blood. Harvey, however, was not a speculator but an experimenter. He de­ termined the heart was a muscle and that it acted by contracting, pushing blood out. Through actual dissection he noted that the valves separating the two upper chambers of the heart (auricles) from the two lower (ventricles) were one-way. Blood could go from auricle to ventricle but not vice versa. There were one-way valves in the veins too, these having been discovered by Fabricius. For

[174]

HARVEY

that reason, blood in the veins could travel only toward the heart and not away from it. In fact, it was the valves in the veins that first put Harvey on the right track, as, late in life, he explained to the young Boyle [212]. When Harvey tied off an artery it was the side toward the heart that bulged with blood. When he tied off a vein the side away from the heart bulged. Every­ thing combined to indicate that blood did not oscillate back and forth in the vessels as Galen [65] had believed but traveled in one direction only. Furthermore Harvey calculated that in one hour the heart pumped out a quan­ tity of blood that was three times the weight of a man. It seemed incon­ ceivable that blood could be formed and broken down again at such a rate. Therefore it had to be the same blood moving in circles, from the heart to the arteries, from these to the veins, from those back to the heart. The blood, in other words, moved in a closed curve. It circulated. He began lecturing on the subject in 1616, but it was not until 1628 that he published these conclusions and the evi­ dence backing them in a small book of only seventy-two pages, miserably printed in Holland on thin, cheap paper and full of typographical errors. How­ ever, the experiments it described were clear, concise, and elegant, and the con­ clusions were incontrovertible. The book became one of the great scientific clas­ sics. Its short title is Exercitatio De Motu Cordis et Sanguinis (“On the Mo­ tions of the Heart and Blood’’). Harvey was ridiculed at first, for it was no light matter to refute Galen. His practice fell off and learned doctors wrote tomes refuting him (by quoting Galen and not by repeating Harvey’s ex­ periments). Harvey was called Circula­ tor, which was a cruel pun, for it was the Latin slang for “quack,” the name given to peddlers who hawked medicines at the circus. He did not take much part in the controversy, but let the facts speak. For that matter, Harvey avoided controversy on principle and did not en­ gage in the polemics that delighted the anatomists of the day.

HARVEY

[174]

Harvey had led the team of doctors at the bedside of James I on the occasion of his last illness in 1625. James’s son, who succeeded as Charles I, had enough faith in Harvey to let him have royal deer with which to experiment, and at the king’s command, Harvey performed a postmortem on the body of Thomas Parr (“Old Parr”) who died in 1635 at a reputed, but almost certainly exagger­ ated, age of 152. Harvey was one of the first to study the development of the chick in the egg, something that had once interested Aris­ totle [29]. Although in attendance on Charles I during the English Civil War, in which Charles lost throne and head, Harvey did not fall victim to partisan passion, but returned safely to London, though revolutionaries did break into his home and destroy some notes and speci­ mens. (In particular, Harvey is supposed to have been at the battle of Edgehill in 1642 and spent his time there calmly reading a book while waiting for any royal call.) By the time of Harvey’s old age the fact of circulation was accepted by phy­ sicians generally. Even in France, where opposition was strongest, the influential Descartes [183] supported Harvey. Har­ vey was elected president of the College of Physicians in 1654. He declined the privilege, preferring to spend his last years in peace. The validity of the theory of circula­ tion depended on the blood’s passing from the arteries to the veins, but there were no visible connections between those blood vessels. Harvey, noting that both arteries and veins divided and sub­ divided into finer and finer vessels till they passed out of sight, supposed the connections were simply too fine to see. This was proved correct by Malpighi [214], who had the advantage of the use of a microscope. This final proof was not obtained until four years after Harvey’s death. Since Harvey’s small book was the end of Galen and of Greek medicine, the En­ glish physician may be considered the founder of modem physiology. His personal library, which he left to

111

[175]

HELMONT

WENDELIN

[176]

the London College of Physicians, was only water, the tree had gained 164 destroyed in the Great Fire of 1666. pounds while the soil had lost only two ounces. From this he deduced that water was converted by the tree into its own [175] HELMONT, Jan Baptista van substance. Though he was wrong, the ex­ Flemish physician and alchemist periment is of crucial importance. For Born: Brussels, January 12, 1580 one thing, he was the first to use quanti­ Died: Vilvoorde (near Brussels), tative methods in connection with a bio­ December 30, 1635, or 1644 logical problem and is sometimes called the “father of biochemistry” for that Helmont, the scion of a noble family, reason. Also he did at least prove that it obtained his medical degree in 1599 at was not from the solid soil that the chief the University of Louvain and practiced nourishment of plant life was drawn. without charge. He lived in troubled In another respect Helmont the alche­ times, for Spain was trying to suppress mist was unusually advanced. He was rebellion in the Netherlands, and was the first to recognize that there is more doing so ruthlessly. than one airlike substance; that some of Like Paracelsus [131], by whom he the vapors he obtained in his experi­ was much influenced, he was interested ments are distinct substances, as different in alchemy and given to mysticism. Hel­ in properties from ordinary air as water mont searched for the philosopher’s is. Because vapors, unlike liquids and stone and tried to fuse chemistry and solids, have no fixed volume but fill any religion into something that was not container, he considered them examples quite either. On one occasion, at least, of matter in complete chaos and, about that got him into difficulties. He main­ 1620, named them so. However, he tained that saintly relics displayed their spelled “chaos” according to its phonetic effects through magnetic influence. For sound in Flemish, which made it “gas.” ascribing earthly causes to divine phe­ This word, ignored at the time, was rein­ nomena, he got into trouble with the In­ troduced by Lavoisier [334] a century quisition in 1634. and a half later and has been used by He was very emphatic about the “phi­ chemists ever since. losopher’s stone,” which he claimed he In particular Helmont studied the gas had seen and used. He also believed in produced by burning wood. He called “spontaneous generation”; that is, the this “gas sylvestre” (“gas from wood”) development of living organisms from but we now call it carbon dioxide. Ironi­ nonliving surroundings. He declared that cally it is this gas, not water, that is mice could arise from dirty wheat, for plant life’s chief source of nourishment instance. He denied transmutation of and Helmont, in interpreting his experi­ metals, however. ment with the willow tree, had neglected In one respect he was unusually con­ to consider the air that surrounded it. He servative, for he abandoned Paracelsus had the right answer in the substance and the alchemical notions of mercury, that he himself discovered, but he did sulfur, and salt as the basis of solid sub­ not know it. stances. Instead, he moved all the way Unfortunately Helmont wrote in a back to Thales [3], Helmont, like the very obscure style, so that he was not as Greek philosopher, believed that water influential as he might have been. His was the basic element of the universe. It writings were not published till after his is symptomatic of the new era, however, death, when his son, a friend of Leibniz with new quantitative methods gaining [233], edited them. favor and the Scientific Revolution well under way, that Helmont tried to prove [176] WENDELIN, Godefroy his case by experiment. Flemish astronomer He grew a willow tree in a weighed Born: Herken, near Liège, Bel­ quantity of soil and showed that after gium, June 6, 1580 five years, during which time he added Died: Gent, 1667 112

[177]

SNELL

Wendelin was a cleric, as were so many of the astronomers of the time, and was a canon of Toumai. Despite his position in the church, he was a convinced Copemican. He re­ peated Aristarchus’ [41] attempt to de­ termine the distance of the sun by ob­ serving the geometry of the situation at the exact moment of half-moon. His ob­ servations were more accurate than Aris­ tarchus’ had been nearly two thousand years before, and his estimate of the sun’s distance was sixty million miles, which was twelve times greater than the earlier value. It was still one-third short of the ac­ tual distance, but it did give mankind a glimpse at the real size of the solar sys­ tem, a glimpse that gave way to rela­ tively clear vision with Cassini’s [209] work half a century later. [177] SNELL, Willebrord van Roijen Dutch mathematician Born: Leiden, 1580 Died: Leiden, October 30, 1626 Snell received his master’s degree in 1608 and succeeded his father as profes­ sor of mathematics at the University of Leiden in 1613. He is best known for his discovery in 1621 that when a ray of light passes obliquely from a rarer into a denser medium (as from air into water or glass) it is bent toward the vertical. The phenomenon (refraction of light) was known as long ago as the time of Ptolemy [64], but Ptolemy thought that as the angle to the vertical made by the light ray in air was changed, it main­ tained a constant relationship to the angle to the vertical made by the light ray in water or glass. Snell showed this was not so. It was the sines of the angles that bore the constant relationship. It was only because at small angles the sines are almost proportional to the angles themselves that Ptolemy was deluded. This key discovery in optics was not well publicized until 1638, when Des­ cartes [183] published it—without giving proper credit to the source. In 1617 Snell had also developed the method of

BAFFIN

[178]

determining distances by trigonometric triangulation and thus founded the mod­ em art of mapmaking. [178] BAFFIN, William English explorer Born: Probably London, about 1584 Died: off the island of Qeshm, Persian Gulf, January 23, 1622 For a thousand years after Pytheas [39] the Arctic regions slumbered un­ touched by the curiosity of men from warmer climes. From the ninth to the eleventh centuries the Vikings of Scan­ dinavia penetrated to Iceland, Green­ land, and even North America, but these were isolated ventures with no important consequences for Europe as a whole. The voyages of Columbus [121] and the subsequent realization that the land he had discovered represented new conti­ nents and not old Asia, led to attempts to reach beyond the Americas to the fabled Indies. The route of Magellan [130] south of South America was a kind of Southwest Passage, which worked but was terribly long. The search was on for a shorter Northwest Passage around northern North America. The effort to find the Northwest Pas­ sage reached an early climax with Wil­ liam Baffin. In 1612 he served as chief pilot on a ship that explored the south­ western coast of Greenland. The next year he turned his energies eastward to­ ward Spitzbergen. In 1615 he was back in Greenland waters and this time he penetrated north­ ward into the large body of water lying to the west of northern Greenland, a body now known as Baffin Bay. The large island west of the bay is Baffin Is­ land. Baffin penetrated to within eight hundred miles of the North Pole and no one else was to get closer for two and a half centuries. Baffin’s explorations caused him to doubt the existence of a Northwest Pas­ sage. He was both right and wrong, since the sea passage does exist but is so choked by ice that it is not a practical route, except perhaps for specially de­ signed icebreakers. 113

[179]

VERNIER

Baffin’s explorations were accom­ plished with scientific precision. He de­ termined latitudes and observed tides carefully. His recordings of the orienta­ tion of the compass needle led to the first magnetic chart. He was the first to try to determine longitude at sea by ob­ servations of the moon. After these Arctic explorations Baffin made a fatal switch to tropic waters, sur­ veying areas in and about the Red Sea and the Persian Gulf. He was an em­ ployee of the East India Company at this time. When the Company allied itself in 1621 with the Shah of Persia against the Portuguese, Baffin found himself in a war. During an attack on Qeshm, an is­ land at the mouth of the Persian Gulf, Baffin was killed. [179] VERNIER, Pierre (vehr-nyayO French engineer Born: Omans, August 19, 1584 Died: Omans, September 14, 1638 Vernier was the son of a lawyer and a minor government official in a part of France (Franche Comte) that was then ruled by the Hapsburg kings of Spain. Vernier was a military engineer in the employ of the Spanish king. He was interested in instruments and in particular in devices that would allow one to measure angles or small distances with great precision. Others had worked on the problem before and the idea had existed of dividing a number of intervals of progressively larger size (by small steps) into equal numbers of sub­ divisions. The measure one wanted would be bound to fall near a sub­ division on one of the scales and from that the angle or distance could be calcu­ lated quite precisely. The difficulty lay in devising these many scales with the nec­ essary precision in the first place. Clavius [152] was one of those who worked on the problem. It occurred to Vernier that only two such scales were necessary, if one was made movable. It could be adjusted against the immovable scale to just fit the angle or the linear measure and then 114

MERSENNE

[181]

the position of the moving subdivisions against the fixed ones would give the measure to an extra decimal point. Ver­ nier announced his device in 1631 and immortalized himself for the device has been known as a “vernier” ever since (pronounced “vur'nyer” in English). Since one motive force behind the ad­ vance of science has been the invention and construction of ever more precise measuring instruments, Vernier deserves mention for that feat alone. [180] CYSAT, Johann Swiss astronomer Born: Lucerne, 1586 Died: Lucerne, May 3, 1657 Cysat, a pupil of Scheiner [173], en­ tered the Jesuit order in 1604 and later became a priest. He served as professor of mathematics at the Jesuit college of Ingolstadt in Bavaria. He was one of the early users of the telescope and surveyed the sky with one as early as 1611. He studied spots on the sun and was the first to use a telescope to observe a comet. His most notable achievement was the discovery of the Orion Nebula in 1619. [181] MERSENNE, Marin (mer-senO French mathematician Born: near Oize, Sarthe, Septem­ ber 8, 1588 Died: Paris, September 1, 1648 Mersenne was a schoolfellow of Des­ cartes [183] but, unlike the latter, went on to enter the church, joining the Minim Friars, in 1611. Within the church, Mersenne did yeoman work for science, of which he was an ardent expo­ nent. He defended Descartes’s philoso­ phy against clerical critics, translated some of the works of Galileo [166], and defended him, too. Mersenne’s chief service to science was the unusual one of serving as a channel for ideas. In the seventeenth century, long before scientific journals, interna­ tional conferences, and even the estab­ lishment of scientific academies, Mer-

[182]

GASSENDI

senne was a one-man connecting link among the scientists of Europe. He wrote voluminous letters to regions as distant as Constantinople, informing one correspondent of the work of another, making suggestions arising out of his knowledge of the work of many, and constantly urging others to follow this course of copious intercommunication. He opposed mystical doctrines such as astrology, alchemy, and divination and supported experimentation. As a practi­ cal example of this belief he suggested to Huygens [215] the ingenious notion of timing bodies rolling down inclined planes by the use of a pendulum. This had not occurred to Galileo, and Huy­ gens was to take this idea to fruition in a pendulum clock. Mersenne is best known today for the “Mersenne numbers,” numbers produced by a certain formula which, Mersenne said, would yield primes. His reasons for deciding this are not known, but in any case he was wrong; some of the large numbers he maintained to be prime proved not to be. Nevertheless, the Mer­ senne primes proved to stimulate re­ search into the theory of numbers. [182] GASSENDI, Pierre (ga-sahn-deeO French philosopher Born: Champtercier, Provence, January 22, 1592 Died: Paris, October 24, 1655 Gassendi, bom of poor parents, stud­ ied and taught at the University of Aix, where he obtained his doctorate in theol­ ogy in 1616, but rebelled against its me­ dieval attitude. His philosophic views served science in two ways. In the first place, like his older contemporary Francis Bacon [163] he strongly ad­ vocated experiment in science. He came to understand the importance of experi­ mentation in his reading of Galileo [166] whom he supported even after Galileo’s condemnation by the Inquisition. Secondly he was a convinced atomist and helped bridge the gap between Epi­ curus [35] and Lucretius [53], whose nineteen-century-old views he strongly supported, and the scientific atomism

DESCARTES

[183]

that was to come two centuries after his time. More specifically, his views strongly affected those of Boyle [212]. He was interested in astronomy, too, describing the aurora borealis in 1621 and giving it its name. Another of his concrete scientific accomplishments was to observe the transit of Mercury in 1631, within five hours of the time pre­ dicted by Kepler [169]. It was the first planetary transit ever observed. He also dropped a stone from the top of the mast of a moving ship and showed that it landed at the bottom of the mast. The ship did not move from under it. This bore out one of Galileo’s “thought experiments” and disproved the Ptolemaic argument against the earth’s rotation, the one which maintained that if the earth rotated then someone jump­ ing up into the air would come back to earth far from his starting point. Gassendi vigorously opposed Des­ cartes’s [183] philosophy and Harvey’s [174] theory of blood circulation. He made up for that in his study of sound, though. He studied its velocity, which he showed to be independent of pitch, thus refuting Aristotle’s [29] contention that high notes traveled more rapidly than low notes. Gassendi published biographies of Peurbach [118], Regiomontanus [119], Copernicus [127], and Tycho Brahe [156], and it might be mentioned as a link between science and literature that among Gassendi’s pupils was the great French playwright Molière. In 1645 he became professor of math­ ematics at the Collège Royale at Paris. [183] DESCARTES, René (day-kahrt') French philosopher and mathe­ matician Born: La Haye, now called La Haye-Descartes (near Tours), March 31, 1596 Died: Stockholm, Sweden, Febru­ ary 11, 1650 As was common in his day, when Latin was the language of scholarship, Descartes used a Latinized version of his name for his writings, signing them Ren115

[183]

DESCARTES

atus Cartesius. It is because of this that Descartes’s system of philosophy is spo­ ken of as Cartesian and that the com­ mon system of plotting the curves repre­ sented by equations (a system Descartes originated) involves Cartesian coordi­ nates. Nevertheless, Descartes wrote in French rather than in Latin, another in­ dication of the continuing decline of Latin as the universal language of schol­ arship in Europe. Descartes’s mother died when he was a year old and he appears to have in­ herited her ill health. He was troubled with a chronic cough and at school was allowed to remain in bed as long as he wished. (The fact that he was a brilliant student contributed also to the fa­ voritism.) He retained the habit of doing much of his work in bed for the rest of his life and could well pamper himself in this way for he never married and thus avoided family responsibilities. From the days of his Jesuit education Descartes remained carefully devout. For instance when in 1633 he heard that Galileo [166] had been condemned for heresy, he at once abandoned a book he was writing on the universe in which he accepted the views of Copernicus [127], Instead, by 1644, he had worked out a theory according to which all space was filled with matter arranged in rotating vortices. He considered the earth at rest in the center of a vortex. It was the vor­ tex, then, that traveled about the sun. This compromise, like that of Tycho Brahe [156], was ingenious but worth­ less. Nevertheless it was accepted by many scholars until Newton [231] a gen­ eration later put all lesser theories to flight with his theory of gravitation. Des­ cartes’s vortices, however, were, in some ways, strangely like Weizsacker’s [1376] vortices three centuries later. After some years in the French army —during which time he was not exposed to actual warfare and found ample time to work out his philosophy—Descartes settled in Protestant Holland. There he remained for almost all his life until at an unlucky moment in September 1649 he succumbed most reluctantly to an in­ vitation to the Swedish court. 116

DESCARTES

[183]

The Swedish ruler at the time was Christina, who was anxious to obtain the services of a renowned philosopher in order to glorify her court. (This desire by European royalty for intellectual luster was to become particularly pronounced during the Age of Reason, as the eigh­ teenth century was to be called.) Unfortunately Christina was one of the most eccentric rulers ever to grace a throne, and her notion of utilizing Des­ cartes’s services was to have him call on her three times a week at 5 a .m . to in­ struct her in philosophy. Visiting the cas­ tle during the coldest part of a Swedish winter night three times a week was too much for Descartes’s delicate lungs and he was dead of pneumonia before the winter was over. His body, all but the head, was returned to France. In 1809 Descartes’s skull came into the posses­ sion of Berzelius [425], who turned it over to Cuvier [396], and thus Descartes came home at last. Descartes was a mechanist. Out of ex­ tension and motion, he would say, the universe could be constructed and he thought it necessary to begin with some incontrovertible fact, something that could be accepted to begin with. In his Discourse on Method, published in 1637, he began by doubting every­ thing; but this very doubt appeared to him to be the incontrovertible fact for which he searched. The existence of a doubt implied the existence of something that was doubting, hence the existence of himself. He expressed this in the Latin phrase “Cogito, ergo sum” (“I think, therefore I am”). The system he built on this was sufficiently impressive to earn the title sometimes bestowed on him: fa­ ther of modern philosophy. Descartes applied the mechanistic view even to the human body though not to the human soul, or to God. Basing his conclusions on the work of Vesalius [146] and Harvey [174] (whose work on the circulation of the blood he helped to popularize) he tried to present the purely animal workings of the body as a system of mechanical devices. The mind was outside the body and independent of it, but interacting with it through the

[183]

DESCARTES

medium of the pineal gland, a small structure attached to the brain, which Galen [65] had thought served as a channel and valve to regulate the flow of thought. Descartes may have been influenced by this, but he also chose the pineal gland because he believed it to be the one organ found only in man and not in the lower animals, which, without the pineal gland, lacked mind and soul and were merely living machines. (In this re­ spect he was shown to be wrong. A few decades later Steno [225] discovered the pineal gland in lower animals, and now we know that there is a species of very primitive reptile in which the pineal gland is far better developed than in man.) Descartes’s most important contri­ butions to science, however, were in mathematics. For one thing, he was the first to use the letters near the beginning of the alphabet for constants and those near the end for variables. This modification of Vieta’s [153] system stuck and it is to Descartes therefore that we owe the familiar x’s and y’s of algebra. He also introduced the use of exponents and the square root sign. Descartes had grown interested in mathematics while in the army, where his military inactivity gave him time to think. His great discovery came to him in bed, according to one story, while he was watching a fly hovering in the air. It occurred to him that the fly’s position could be described at every moment by locating the three mutually perpendicular planes that intersected at the position oc­ cupied by the fly. On a two-dimensional surface, such as a piece of paper, every point could be located by means of two mutually perpendicular lines intersecting at that point. In itself this was not original. All points on the earth’s surface can be (and are) located by latitude and longitude, which are analogous, on a sphere’s sur­ face, to the Cartesian coordinates on a plane surface. What was world-shaking, though, was that Descartes saw that through the use of his coordinate system every point in a

DESCARTES

[183]

plane could be represented by an or­ dered system of two numbers, such as 2, 5, or —3, —6, which can be interpreted as “two units east and five units north from the starting point” or “three units west and six units south from the start­ ing point.” For points in space an or­ dered system of three numbers is re­ quired, the third number representing the units up or down. In any algebraic equation in which one variable y is made to depend on the fluctuations of a second variable x ac­ cording to some fixed scheme, as, for in­ stance, y — 2x2 — 5, then for every value of x there is some fixed value of y. If x is set equal to 1, y becomes —3; if x is 2, y is 3; if x is 3, y is 13, and so on. If the points represented by the x, y combinations (1, —3; 2, 3; 3, 13; etc.) are converted into points on a plane ac­ cording to the Cartesian system, a smooth curve is obtained. In this case it is a parabola. Every curve represents a particular equation by this system; every equation represents a particular curve. Descartes advanced this concept in an appendix of about a hundred pages which was attached to his book (pub­ lished in 1637) on vortices and the structure of the solar system. It is not the only time in the history of science that a casual appendix proved to be ines­ timably more important than the book to which it was attached. Another exam­ ple, two centuries later, involved Bolyai [530]. The value of Descartes’s concept was that it combined algebra and geometry to the great enrichment of both. The combination of the two could be used to solve problems more easily than either could be used separately. It was this ap­ plication of algebra to geometry that was to pave the way for the development of the calculus by Newton, which is essen­ tially the application of algebra to smoothly changing phenomena (such as accelerated motion), which can be repre­ sented geometrically by curves of various sorts. Since a synonym for algebra ever since the days of Vieta is “analysis,” Des­ cartes’s system of fusing the two 117

[184]

GELLIBRAND

RICCIOLI

[185]

branches of mathematics into one has the moon. The moon revolved about the come to be called analytic geometry. earth in the Copernican system as well as in the older system of Ptolemy [64], and its investigation could raise no em­ [184] GELLIBRAND, Henry (gell'uh- barrassing problems. In connection with brand) the moon, he could produce some useful English astronomer and mathe­ results. He was the first to maintain matician there was no water on the moon. Born: London, November 17, In 1651 Riccioli published a book 1597 called New Almagest in Ptolemy’s honor Died: London, February 16, 1636 in which he accepted Tycho Brahe’s [156] system and in which he included Gellibrand was educated at Oxford, his own maps of the lunar surface, four obtaining his master’s degree in 1623. years after Hevelius’ [194] pioneer effort. He became professor of astronomy at On his maps Riccioli named the lunar Gresham College in 1627. He was a craters in honor of the astronomers of friend of Briggs [164] and finished some the past, giving due weight to his antiof the latter’s unfinished manuscripts Copemican views. Hipparchus [50], Ptol­ after Briggs’s death. His strongly Puritan emy, and Tycho Brahe received better tendencies got him into trouble with the craters than Copernicus and Aristarchus Anglican authorities in 1631, but he was [41]. These names are still used today. acquitted. Some of those honored now are AlbaGellibrand noted that the recorded di­ tegnius [83], Anaxagoras [14], Apol­ rection of the compass needle in London lonius [49], Arago [446], Archimedes changed slowly despite Gilbert’s [155] [47], Aristotle [29], Bessel [439], Biot contention, and had shifted by more [404], Bond [660], Cassini [209], Clavius than seven degrees in the previous half [152], De la Rue [589], Eudoxus [27], century. In 1635 he published his Fabricius [167], Flammarion [756], findings. This was the first indication Flamsteed [234], Gassendi [182], Gauss that the earth’s magnetic field slowly [350], Geber [76], Guericke [189], Herchanges and, indeed, not only the hori­ schel, Caroline [352], Kepler [169], zontal angle of the needle changes, but Lalande [309], Messier [305], Meton also the angle of magnetic dip. The very [23], Olbers [372], Picard [204], Picker­ strength of the field changes and, to the ing [784], Plato [24], Pliny [61], Poseidopresent day, no clear explanation for this nius [52], Rheticus [145], Roemer [232], has been given. Stevinus [158], and Riccioli himself. A mountain has been named for Huygens [215] and a mountain range for Leibniz [185] RICCIOLI, Giovanni Battista [233]. The basic system has even been (reet-chohlee) extended by astronomers to the other Italian astronomer side of the moon. Born: Ferrara, April 17, 1598 In 1650 Riccioli had used a telescope Died: Bologna, June 25, 1671 to view the star Mizar (the middle star of the handle of the Big Dipper) and Riccioli, a Jesuit from the age of six­ found it to be two stars very close to­ teen, did not accept the views of Coper­ gether. This was the first observation of nicus [127], To arguments that the Ptole­ a double star and it gave another proof maic system was impossibly complicated, that the telescope could reveal features he countered with the argument that the of the heavens not visible to the naked more complicated the system, the better eye. the evidence for the greatness of God. He also tried to measure the parallax He mentioned the ellipses of Kepler of the sun and decided it was twenty[169] but dismissed them out of hand. four million miles from the earth, a It seems natural, therefore, that he value soon to be more than tripled by should have concentrated on a study of Cassini. 118

[186]

CAVALIERI

He noticed colored bands on Jupiter parallel to its equator and, along with Grimaldi [199], improved the theory of the pendulum and made clearer the con­ ditions under which it would mark time accurately. [186] CAVALIERI, Bonaventura (kah'vah-lyeh'ree) Italian mathematician Born: Milan, 1598 Died: Bologna, November 30, 1647 Cavalieri joined the Jesuit order in 1615, where he was introduced to a thorough study of the Greek mathe­ maticians. He also met Galileo [166], corresponded with him and considered himself a disciple of that man. His vari­ ous church offices did not prevent him from working at his mathematics and from teaching. Archimedes [47] had done some of his work in measuring geometric areas by supposing such areas to be made up of very small components. Cavalieri fol­ lowed that line of reasoning to produce the notion that volumes were made up components that were not exactly lines but thin areas so small as to be no fur­ ther divisible. Making use of such “indi­ visibles” he could work out a number of theories involving areas and volumes. The importance of this is that it was a stepping-stone toward the notion of infinitesimals and the development of the calculus by Newton [231], which is the dividing line between classical and mod­ em mathematics. [187] KIRCHER, Athanasius (kirTcher) German scholar Born: Fulda, Hesse-Nassau, May 2, 1601 Died: Rome, Italy, November 28, 1680 Kircher, the youngest of six sons, re­ ceived a Jesuit education and was or­ dained a priest in 1628. Like that other cleric of two centuries before, Nicholas of Cusa [115], Kircher

FERMAT

[188]

had an uncanny knack of making intu­ itive guesses that were eventually proved correct. His early work with the micro­ scope, for instance, caused him to won­ der if disease and decay might not be brought about by the activities of tiny living creatures, a fact that Pasteur [642] would demonstrate two centuries later. He invented a magic lantern, an Aeo­ lian harp, and a speaking tube. Inter­ ested in antiquities, he was one of the very first to make an attempt to decipher the Egyptian hieroglyphics, something that was not carried much further till Young’s [402] time a century and a half later. In 1650 Kircher made use of the new methods of producing a vacuum intro­ duced by Guericke [189]. His experi­ ments demonstrated that sound would not be conducted in the absence of air. This supported one of the few theories in physics that Aristotle [29] advanced and that turned out to be correct. [188] FERMAT, Pierre de (fehr-mahO French mathematician Born: Beaumont-de-Lomagne, Languedoc, August 20, 1601 Died: Castres, near Toulouse, January 12, 1665 Fermat, the son of a leather merchant, was educated at home and then went on to study law, obtaining his degree in 1631 from the University of Orleans. He was a counselor for the Toulouse parlia­ ment and devoted his spare time to mathematics. Considering what he ac­ complished one wonders what he might have done as a full-time mathematician. Fermat had the supremely frustrating habit of not publishing but scribbling hasty notes in margins of books or writ­ ing casually about his discoveries in let­ ters to friends. The result is that he loses credit for the discovery of analytic ge­ ometry, which he made independently of Descartes [183]. In fact, where Des­ cartes’s formal analysis involves only two dimensions, Fermat takes matters to three dimensions. Fermat also loses credit for the discovery of some features of the calculus that served later to in119

[189]

GUERICKE

spire Newton [231], (However, he prob­ ably would not have cared. He engaged in mathematics for his own amusement and that he achieved.) He, together with Pascal [207], founded the theory of probability. He also worked on the properties of whole numbers, being the first to carry this study past the stage where Diophantus [66] had left it. Fermat is thus the founder of the modem “theory of num­ bers.” In that field he left his greatest mark, for in the margin of a book on Dio­ phantus he scribbled a note saying he had found that a certain equation (xn + yn = zD, where n is greater than 2) had no solution in whole numbers but that there was no room for the simple proof in the margin. For three centuries math­ ematicians, including the greatest, have been searching for the proof of what is now called “Fermat’s last theorem” (be­ cause it is the last that remains un­ proved) and searching in vain. Modem computers have shown that the equation has no solutions for all values of n up to 2,000, but this is not a general proof. In 1908 a German professor willed a prize of 100,000 marks to anyone who would find a proof, but German inflation in the early 1920s reduced the value of those marks to just about zero. In any case, no one has yet won it. Fermat did not publish his work on the theory of numbers. His son published his notes five years after Fermat’s death. [189] GUERICKE, Otto von (gay'rihkuh) German physicist Born: Magdeburg, November 20, 1602 Died: Hamburg, May 11, 1686 Guericke studied law and mathematics as a youth and attended the University of Leiden, where Snell [177] may have been one of his teachers. He then trav­ eled in France and England, and served as an engineer for the German city of Erfurt. Guericke in 1627 returned to Magdeburg and entered politics there. It 120

GUERICKE

[189]

was a bad time. The Thirty Years’ War was raging and Magdeburg, a Protestant city, was on the side that was, at the mo­ ment, losing. In 1631 it was destroyed by the imperial armies in the most savage sack of the war, and Guericke and his family barely managed to escape at the cost of all their possessions. After serv­ ing for a time in the army of Gustavus II Adolphus of Sweden (who managed to turn the tide of the war), Guericke re­ turned to a Magdeburg rising again out of mins, serving as an engineer in this rebirth effort, and in 1646 became mayor of the town, retaining that post for thirty-five years, then retiring to Hamburg in his eightieth year. In 1666, he had been ennobled, gaining the right to add “von” to his name. He grew interested in philosophic dis­ putations concerning the possibility of a vacuum. Numerous arguments denying its existence were advanced. Aristotle [29] had worked out a theory of motion in which a body impelled by a certain continuing force would move faster as the surrounding medium grew less dense. In a vacuum it would move with infinite speed. Since Aristotle did not accept the possibility of infinite speed he decided that a vacuum could not exist. This, like almost all of Aristotle’s views, was ac­ cepted uncritically by later philosophers and was expressed in the catch phrase “Nature abhors a vacuum.” Guericke decided to settle the question by experiment rather than argument and in 1650 constructed the first air pump, a device something like a water pump but with parts sufficiently well fitted to be reasonably airtight. It was run by muscle power and was slow, but it worked and Guericke was able to put it to use for pieces of showmanship of quite Madison Avenue proportions. And he spared no expense, either, for he spent $20,000 on his experiments, a tremendous sum for those days. He began with an evacuated vessel. He showed that a ringing bell within such a vessel could not be heard, thus bearing out Aristotle’s contention that sound would not travel through a vacuum, though it would travel through liquids

[189]

GUERICKE

and solids as well as through air. Guericke also showed that candles would not bum and that animals could not live in a vacuum, but the true significance of these observations had to await Lavoisier [334] a century and a quarter later. Guericke grew more dramatic. He affixed a rope to a piston and had fifty men pull on the rope while he slowly drew a vacuum on the other side of the piston within the cylinder. Air pressure inexorably pushed the piston down the cylinder despite the struggles of the fifty men to prevent it. Guericke prepared two metal hemi­ spheres that fitted together along a greased flange. (They were called the Magdeburg hemispheres, after his town.) In 1657 he used them to demonstrate the power of a vacuum to Emperor Fer­ dinand III. When the hemispheres were put together and the air within evac­ uated, air pressure held them together even though teams of horses were at­ tached to the separate hemispheres and whipped into straining to their utmost in opposite directions. When air was al­ lowed to reenter the joined hemispheres, they fell apart of themselves. It was about this time that Guericke heard of Torricelli’s [192] experiments, and he saw that the results of his more dramatic demonstrations were due to the fact that air had weight. His demon­ strations added nothing to what Tor­ ricelli had established, but they had flair and forced the world of scholarship to understand and accept the basic discov­ ery. Furthermore, he saw the application of the barometer to weather forecasting and in 1660 he was the first to attempt to use it for this purpose. Guericke also made important ad­ vances in another field. Gilbert [155] had worked with substances that could be “electrified” by rubbing and made to at­ tract light objects. Guericke mechanized the act of rubbing and devised the first frictional electric machine. This was a globe of sulfur that could be rotated on a crank-turned shaft. When stroked with the hand as it rotated, it accumulated quite a lot of static electricity. It could be discharged and recharged indefinitely.

GLAUBER

[190]

He produced sizable electric sparks from his charged globe, a fact he reported in a letter to Leibniz [233] in 1672. Guericke’s sulfur globe initiated a full century of experimentation—with other and better frictional devices—which reached its height with the work of Franklin [272]. Guericke was also interested in astron­ omy and felt that comets were normal members of the solar system and made periodic returns. This notion was to be successfully taken up by Halley [238] some twenty years after Guericke’s death. [190] GLAUBER, Johann Rudolf (glow'ber) German chemist Born: Karlstadt, Lower Fran­ conia, 1604 Died: Amsterdam, Netherlands, March 10, 1670 At an early age the self-taught Glauber, the son of a barber, lived in Vienna, then in various places in the Rhine Valley. Some time during this in­ terval, perhaps about 1625, he noted that hydrochloric acid could be formed by the action of sulfuric acid on ordinary salt (sodium chloride). This was the most convenient method yet found for the manufacture of hydrochloric acid, but what interested Glauber most was the residue (today called sodium sul­ fate). Glauber fastened on to this substance, studying it intensively and noting its ac­ tivity as a laxative. Its action is mild and gentle and throughout history there have always been those who place great value on encouraging the bowels. Glauber, en­ amored of his discovery, labeled it sal mirabile (“wonderful salt”) and adver­ tised it as a cure-all in later years. He believed its use had once cured him of typhus. (The fact that his only source of income was the sale of his chemical products forced him into a heavy sell, of course.) We don’t consider it a cure-all these days, but the common name of sodium suifate is still “Glauber’s salt.” 121

[190]

GLAUBER

Glauber made a number of discoveries that mark him as a legitimate “dawnchemist,” even if his interest in cure-alls was an alchemical hangover. He pre­ pared a variety of compounds of the metals then known. These included tar­ tar emetic, an antimony salt which has some medical use. In 1648 he moved to Amsterdam, where he took over a house that had once belonged to an alchemist. He made out of it the best chemical laboratory of the day, with special furnaces and equip­ ment that he himself had designed. One furnace had a chimney, the first ever to be so equipped. This was all symbolic of the passage from alchemy to chemistry taking place in the seventeenth century. Glauber prepared a variety of chemi­ cal compounds by secret methods and sold them for medicinal purposes. In working with vinegar, oils, coal, and other substances, he obtained organic liquids such as those we now call ace­ tone and benzene. He did well and, at one time employed five or six workmen in his laboratories. He always modeled himself on Paracelsus [131], whom he greatly admired and to whose grave he made a pilgrimage. Glauber was ahead of his time in his clear-sighted view of how a country’s natural resources could be exploited for the betterment of living conditions, and he published a book suggesting what Germany should do in this respect. He objected, for instance, to the overexport of raw materials to Austria and France. The political fragmentation of seven­ teenth-century Germany made his ideas impractical, however. Glauber’s concern with medicinal compounds carried a penalty. What is useful at one dose may be toxic at a larger one, and what is harmless in a sin­ gle administration may be dangerous in several. Glauber’s death was hastened, it is believed, by poisoning during the slow and tedious work over his compounds and he died poor and discouraged. Other chemists since Glauber’s time have been gradually killed by their work, the most notable case perhaps being that of Ma­ dame Curie [965]. 122

BORELLI

[191]

[191] BORELLI, Giovanni Alfonso (boh-reFlee) Italian mathematician and physiol­ ogist Born: Naples, January 28, 1608 Died: Rome, December 31, 1679 Borelli, the son of a Spanish soldier stationed in Naples, was a professor of mathematics at Messina in 1649 and at Pisa in 1656. He returned to Messina in 1667. His life was not entirely smooth. In 1674 he was suspected of political con­ spiracy against the occupying Spaniards and had to leave Messina again and re­ tire to Rome, where he remained under the protection of Christina, former queen of Sweden. (This was the queen whose eccentric habits had brought on the death of Descartes [183]. She ab­ dicated in 1654 and was received into the Roman Catholic Church the follow­ ing year, after which she settled in Rome.) Borelli corrected some of Galileo’s overconservatism. Galileo had neglected Kepler’s [169] elliptical orbits, but now Horrocks [200] had extended them even to the moon, and Borelli rescued the ellipses, publicizing and popularizing them. He tried to extend the vague notions of Galileo and Kepler concerning the at­ tractive forces between the sun and the planets but was not successful. He tried also to account for the motion of Ju­ piter’s satellites by postulating an attrac­ tive force for Jupiter as well as for the sun. In this he (and Horrocks also at about this time) made a tentative step in the direction of universal gravitation, but that had to wait a generation for Newton [231], Borelli suggested (under a pseud­ onym) that comets traveled in parabolic orbits, passing through the solar system once and never returning. (The parab­ ola, like the ellipse, was first studied by Apollonius [49]. A parabola is an open curve something like a hairpin.) Any body following a parabolic path would approach the sun from infinite space, round it, and recede forever. Such an

[192]

TORRICELLI

orbit would explain the erratic behavior of comets without completely disrupting the orderliness of the universe. Borelli understood the principle of the balloon, pointing out that a hollow cop­ per sphere would be buoyant when evac­ uated, if it were thin enough, but that it would then collapse under air pressure. It did not occur to him that collapse could be avoided if a lighter-than-air gas were used to fill the sphere as, in es­ sence, the Montgolfier brothers [325] were to do a century and a half later. Borelli grew interested in anatomy through his friendship with Malpighi [214]. He tried to apply the mechanistic philosophy to the working of the body after the style of Descartes and here he achieved his greatest fame. In a book en­ titled De Motu Animalium (“Concern­ ing Animal Motion”), he successfully ex­ plained muscular action on a mechanical basis, describing the actions of bones and muscles in terms of a system of levers. In it, also, he made careful studies of the mechanism of the flight of birds as Leo­ nardo da Vinci [122] had done a century and a half earlier. He attempted to carry these mechani­ cal principles to other organs such as the heart and lungs with somewhat less suc­ cess and to the stomach with (as we now understand) no success at all. He consid­ ered the stomach a grinding device and did not recognize that digestion was a chemical rather than a mechanical pro­ cess. This tendency to overmechanization of the body was in part neutralized by the labors of contemporaries such as Sylvius [196], who interpreted the body in purely chemical terms. [192] TORRICELLI, Evangelista (torrih-cheriee) Italian physicist Born: Faenza (near Ravenna), October 15, 1608 Died: Florence, October 25, 1647 Torricelli, left an orphan at an early age, received a mathematical education in Rome. He was profoundly affected

TORRICELLI

[192]

when in 1638 he first read Galileo’s [166] works. A book he himself wrote on mechanics in turn impressed Galileo, who invited him to Florence. Torricelli went gladly to meet the blind old man and served as his secretary and compan­ ion for the last three months of his life. He then succeeded him as court mathe­ matician to Grand Duke Ferdinand II of Tuscany [193] and learned how to make the best lenses for telescopes yet seen. Galileo suggested the problem through which Torricelli was to gain fame. The ability to pump water upward was attributed to the supposed fact that “Na­ ture abhors a vacuum.” When a piston was raised, a vacuum would be produced unless the water within the cylinder lifted with the piston. Since a vacuum could not occur in nature, it was thought, the water had to lift. But in that case it ought to lift upward indefinitely as long as the pump worked. Water, however, could only be raised about thirty-three feet above its natural level. Galileo, who accepted the vacuumabhorrence of nature (despite his many revolutionary deeds he was surprisingly conservative in many ways), could only suppose that this abhorrence was limited and not absolute. He suggested that Tor­ ricelli look into the matter. It occurred to Torricelli that this was no matter of vacuum-abhorrence, but a simple mechanical effect. If the air had weight (according to Aristotle [29] it didn’t but tended rather to have “levity” and to rise but Galileo had shown that a full balloon weighed more than an empty one) then this weight would push against the water outside the pump. When the piston was raised, that push would force the water up with the piston. However, suppose the total weight of the air would only balance thirty-three feet of water. In that case, further pumping would have no effect. The weight of the air would push water no higher. In 1643, to check this theory Torricelli made use of mercury, whose density is nearly thirteen and a half times that of water. He filled a four-foot length of glass tubing, closed at one end, stoppered the opening and upended it (open end 123

[192]

TORRICELLI

down) into a large dish of mercury. When the tube was unstoppered, the mercury began to empty out of the tube as one might expect, but it did not do so altogether. Thirty inches of mercury remained in the tube, supported by the weight of the air per unit area, or “pressure,” pressing down on the mer­ cury in the dish. The weight of the air could easily be used to account for the mercury column’s remaining in place in defiance of gravity. Above the mercury in the upended tube was a vacuum (except for small quantities of mercury vapor). It was the first man-made vacuum, and, thanks to the publicity given the experiment by Mersenne [181], is called a Torricellian vacuum to this day. (Seven years later Guericke [189] produced a vacuum on a far larger scale by pumping and did dra­ matic things as a result.) Torricelli noticed that the height of the mercury in the tube varied slightly from day to day and this he correctly at­ tributed to the fact that the atmosphere possessed a slightly different pressure at different times. He had invented the first barometer. (The pressure of the atmosphere is equivalent to that of a column of mer­ cury 760 millimeters high. The pressure exerted by one millimeter of mercury is sometimes defined as one torricelli, in honor of the physicist.) The fact that air had a finite weight meant it could only have a finite height, a view confirmed by Pascal [207] a few years later. This was the first definite in­ dication (aside from philosophical specu­ lation) that the atmosphere does not ex­ tend indefinitely upward and that the depths of space must be a vacuum. Thus, far from a vacuum being an im­ possibility, it is undoubtedly the natural state of most of the universe. Questions concerning the existence of a vacuum may have seemed rarefied and philosophical, but the proof of its exis­ tence led by a chain of events and rea­ soning to the development of the steam engine, the advent of the Industrial Rev­ olution, and the making of our own technological society. All resulted from the upending of a tube of mercury. 124

HEVELIUS

[194]

Torricelli died of typhoid fever only four years after his great experiment. [193] FERDINAND II OF TUSCANY, Grand Duke Italian .ruler Born: luly 14, 1610 Died: May 24, 1670 Ferdinand II was of the famous family of the Medici, who were, in his time, past their best days. Ferdinand succeeded to the ducal throne in 1621 when he was only eleven, and his reign was largely disastrous for Tuscany, which became and remained a cipher in the European arena from then on. He is remarkable, however, for the eager and liberal patronization of men of science, including Steno [225] and Gali­ leo [166] and for helping support the foundation of the Accademia del Cimento in 1657. He was a deeply religious man, and though he was a political antagonist of the pope, he could not bring himself to challenge the church on matters of her­ esy. He did not, therefore, come to Gali­ leo’s defense and for this the world of science blamed him severely. He made a personal contribution to technology. In 1654 he devised a sealed thermometer which, unlike Galileo’s open one, was not affected by changes in air pressure. This led, eventually, to the perfected instruments of Fahrenheit [254] sixty years later. [194] HEVELIUS, Johannes (heh-vay'lee-oos) German astronomer Bom: Danzig (now Gdansk, Po­ land), January 28, 1611 Died: Danzig, January 28, 1687 Hevelius was one of ten children of a prosperous brewer. As a young man, he toured Europe and, having obtained his education en route, returned to Danzig at the age of thirty. An eclipse of the sun, which he had observed in 1639, had turned his attention to astronomy, so he

[194]

HEVELIUS

established an astronomical observatory, the best in Europe at that time, atop his house. He concentrated on the moon, study­ ing its features with a succession of tele­ scopes of greater and greater power. The manufacture of these telescopes was made easier by Hevelius’ construction of a lathe to be used in the grinding of large lenses. Galileo [166], the first to study the moon by telescope, was also the first to try to draw its features. His drawings, however, were only crude sketches. He­ velius, a generation later, was the first to make drawings containing features of the lunar surface as we recognize them today. In 1647 he published a magnificent volume called Selenographia, an atlas of the moon’s surface, using hand-engraved copper plates for his illustrations. He titled the features systematically, using names taken from earth’s geography, in line with the notion that had become widespread after Galileo’s time that the moon was but a smaller earth. Thus, he named the lunar mountain chains Alps, Apennines, and so on, and these names persist. The dark, relatively flat areas of the moon, he called “seas” (maria in Latin), so that there is a Mare Serenitatis (“Pacific Ocean”) on the moon as on the earth. The maria retain their name to the present time, even though it is now known that they are but dry stretches of dust. Hevelius’ names for the individual cra­ ters, however, did not last. For this, his older contemporary Riccioli [185] can take credit. In 1644 he made out the phases of Mercury, a necessary accompaniment to Galileo’s discovery of the phases of Venus a generation before. Next to his work on the moon, He­ velius is best known for his two large volumes on comets. He listed what infor­ mation he could find on all the comets recorded in the past and discovered four more. The best he could do in connec­ tion with cometary orbits was to suggest like Borelli [191] that they might be pa­ rabolas.

GASCOIGNE

[195]

Although he observed the physical fea­ tures of the moon with telescopes, he re­ fused to use them for measuring the po­ sitions of the stars. He was the last im­ portant astronomer to insist on nakedeye observations, and there was reason to it, considering the imperfections of the telescopes of the day. Hevelius got into an acrimonious de­ bate on the subject with the ever quar­ relsome Hooke [223], and in 1679 he en­ tertained for two months a young Englishman named Halley [238] who had come to make peace between him and Hooke. Unfortunately Hevelius’ ob­ servatory burnt down shortly afterward. The tragedy embittered him and made him intransigent and not inclined to ac­ cept peace. Hevelius also prepared a star catalogue of 1,564 stars, which was at least as ac­ curate as that of Tycho Brahe [156]; but it was not published till 1690, after his death. [195] GASCOIGNE, William (gas'koin) English astronomer Born: Middleton, Yorkshire, about 1612 Died: Marston Moor, Yorkshire, July 2, 1644 Gascoigne did not have much of an education but picked up enough knowl­ edge of astronomy to engage in compe­ tent correspondence on the subject and to make two important advances. The telescope, first used to study the astronomical objects by Galileo [166] was scarcely suitable for determining the exact position of those bodies. It was for that reason that Hevelius [194] scorned it and depended on the eye alone. To convert the telescope to such use, Gas­ coigne devised cross hairs in the focal plane so that an object in view could be accurately centered at the intersection, and a micrometer with which to measure accurately small angular separations of one star from another. It was this that began the conversion of the telescope from a mere viewing toy to an instru­ ment of precision. 125

[196]

SYLVIUS

WALLIS

[198]

Gascoigne fought for King Charles I [197] WILKINS, John in the English Civil War and died at the English scholar Royalist defeat at Marston Moor. Born: Fawsley, Northamptonshire, 1614 Died: London, November 19, 1672 [196] SYLVIUS, Franciscus Dutch physician Wilkins, the son of a goldsmith, en­ Born: Hanau, Prussia, March 15, tered Oxford in 1627, obtaining his 1614 master’s degree in 1634, and was or­ Died: Leiden, Netherlands, dained a few years later. Eventually, he November 19, 1672 married the sister of Oliver Cromwell, Sylvius’ name is a Latinized version of who controlled England with a firm his real name, Franz de la Boe (duh-lah- hand during the 1650s. Wilkins spent most of his time on the­ boh-ay'). He was born of Dutch parents who had sought refuge in Germany from ology but he contributed to science in the Spanish armies that were trying to two ways. First, he was a powerful subjugate their homeland. Sylvius ob­ spokesman for the Copernican view, in tained his medical degree in Basle, Swit­ books written for the intelligent layman. zerland and then, after some years, re­ He laid great stress on the fact that the turned to the Netherlands, which had astronomical bodies, the moon in partic­ won a hard-earned independence. In ular, were worlds, and that therefore 1658 he became professor of medicine at they might be inhabited. In 1640 he even the University of Leiden. His contem­ speculated that methods might be discov­ porary Borelli [191] followed Descartes ered whereby the moon could be [183] in viewing the body as a mechani­ reached. In this he may have been in­ cal device, but Sylvius followed Para­ spired by the appearance in 1638 of a celsus [131] and Helmont [175] in view­ very popular work of fiction Man in the ing it as a chemical device, bringing the Moone by Francis Godwin, which dealt former’s “iatrochemistry” to a peak of with such a flight (though by the roman­ tic notion of having geese hitched to a systematization. Sylvius strongly supported Harvey’s chariot after which they fly to the [174] view of the circulation of the moon). blood and was the first to abandon the Wilkins’ book reinforced the impres­ theory that the health of the body de­ sion of the earlier one and gave rise to pended on the relative proportions of the thoughts of space flight, both in fiction four chief fluids or “humors” that it con­ and fact, that have continued to this day. Second, Wilkins was one of the mov­ tained (blood, phlegm, black bile, and yellow bile), a theory dating back to ing spirits behind the founding of the Greek medicine. Instead, he stressed the Royal Society. opposing properties of acids and bases and their ability to neutralize each other. Viewing the body as a balance of acid [198] WALLIS, John and base, though insufficient, is certainly English mathematician far nearer to what we now believe than Born: Ashford, Kent, December was the old notion of the four humors. 3, 1616 Sylvius and his followers studied diges­ Died: Oxford, November 8, 1703 tive juices (pointing out that saliva was one of them) and correctly believed di­ Wallis was the son of a rector who gestion to involve a fermenting process. died when Wallis was six. Wallis was He is credited with having developed himself ordained in 1640. By then he the alcoholic drink gin and having used had obtained both a bachelor’s and a it to treat kidney ailments. He may also master’s degree from Cambridge, having have organized the first university chem­ aimed at medicine as his profession. istry laboratory. England was in turmoil. The English 126

[198]

WALLIS

Civil War had broken out and Wallis, who had a keen sense of the prevailing wind, threw in his lot with the Parlia­ mentarians against King Charles I. Like Vieta [153] he made a name for himself by applying his mathematical training to deciphering code messages captured from Royalists. Because of this—and despite the fact that he voted against execution of the king—he received a professorial appoint­ ment at Oxford in 1649 under the Par­ liamentarian regime. The fact that he had been against execution, however, counted in his favor when in 1660 the son of Charles I came to the throne as Charles II. Wallis then became the king’s chaplain. Wallis wrote voluminously on mathe­ matics and was one of those who could serve as “calculating prodigies.” He is re­ ported to have worked out the square root of a fifty-three-digit number in his head, getting it correct to seventeen places. He was the first to extend the no­ tion of exponents to include negative numbers and fractions, so that x~ 2, for instance, was defined as \/x 2, while x1/2 was equivalent to and he was also the first (in 1656) to use » as the sym­ bol for infinity. In addition, also he was the first to interpret imaginary numbers geometrically (though he wasn’t entirely successful at this). Two centuries later Steinmetz [944] was to make this repre­ sentation fundamental to his theoretical treatment of alternating current circuits. Wallis was one of the first to write a se­ rious history of mathematics. Wallis took steps toward calculus, but it was his misfortune to be overshadowed by his younger contemporary Newton [231], soon to bring calculus into being. He was a vain and quarrelsome man, and an extremely nationalistic English­ man, eager to enter into disputes with foreigners such as Descartes [183]. He was among the first, therefore, to back Newton’s priority in calculus and to ac­ cuse Leibniz [233] of plagiarism, in what was the bitterest scientific quarrel in his­ tory. He also used his influence against the adoption of the Gregorian calendar by Great Britain on the ground that it implied subservience to Rome (and,

GRIMALDI

[199]

hence, foreigners). The inevitable adop­ tion was delayed half a century as a re­ sult. Wallis’s greatest contribution to sci­ ence, perhaps, was his role, along with his close friend Boyle [212], as one of those who, in 1663, founded the Royal Society. He accepted the challenge of the Society to investigate the behavior of colliding bodies and, in 1668, was the first to suggest the law of conservation of momentum. This was the first of the all­ important conservation laws. His findings were extended by Wren [220] and Huy­ gens [215]. [199] GRIMALDI, Francesco Maria (gree-mahl'dee) Italian physicist Born: Bologna, April 2, 1618 Died: Bologna, December 28, 1663 Grimaldi was the son of a silk mer­ chant of aristocratic lineage. He entered the Jesuit order at fifteen and became a professor at the University of Bologna after obtaining his doctoral degree there in 1647. He served as an assistant to Riccioli [185] for some time and drew the lunar map on which Riccioli placed his names. Grimaldi published his own most im­ portant discovery in a book that only ap­ peared some two years after his death. He had let a beam of light pass through two narrow apertures, one behind the other, and then fall on a blank surface. He found that the band of light on that surface was a trifle wider than it was when it entered the first aperture. There­ fore he believed that the beam had been bent slightly outward at the edges of the aperture, a phenomenon he called diffraction. This was clearly a case of light bend­ ing about an obstacle, as would be ex­ pected of waves but not of particles, and Grimaldi therefore accepted light as a wave phenomenon. More unusual still was the fact that he observed the band of light to show one to three colored streaks at its extremities. This he could not explain and it was not until the time 127

[200]

HORROCKS

BROUNCKER

[202]

of Fraunhofer [450] a century and a half [201] GRAUNT, John (grant) later that the phenomenon was taken out English statistician of cold storage and put to work. Born: London, April 24, 1620 Died: London, April 18, 1674 [200] HORROCKS, Jeremiah Graunt was the son of a draper and, English astronomer entering the family business, did well Born: Toxteth Park, near Liver­ until his business was destroyed in the pool, 1618 Great Fire of 1666. Died: Toxteth Park, January 13, More or less by accident, he found 1641 himself studying the death records in London parishes and beginning to notice Horrocks (sometimes spelled Horrox) certain regularities. As a result, in 1662 was the son of a watchmaker. He at­ he published a book on the matter; it tended Cambridge from 1632 to 1635 served to found the science of statistics but did not get a degree. He served as a and of demography, which is the branch curate at Hoole in Lancashire from 1639 of statistics that deals with human popu­ and practiced astronomy (in which he lations. This is not bad for a busi­ was self-taught) in his spare time. nessman without training in mathe­ In his short life of twenty-three years matics. he accomplished an amazing number of He noted things for the first time that things. He corrected the Rudolphine anyone might have seen if he had Tables of Kepler [169] with regard to looked, and it is to Graunt’s credit that the transit of Venus across the face of he looked. He noted that the death rate the sun and predicted an occurrence on in cities was higher than that in rural November 24, 1639. This was a Sunday areas; that while the male birth rate was and he just got away from church in distinctly higher than the female birth time to view it—the first transit of rate, a smaller percentage of boys sur­ Venus to be observed. He suggested that vived the early years, so that the propor­ observations of such a transit from tion evened out. He tried to detect the different observatories might set up a influence of occupation on the death rate parallax effect that could be used to cal­ and was perceptive enough to consider culate the distance of Venus and there­ overpopulation as itself a cause of a rise fore the scale of the solar system. This in the death rate. eventually was done. He was the first to try to establish life He was the first astronomer to accept expectancy and to publish a table in­ the elliptical orbits of Kepler whole­ dicating the percentage of people who heartedly. By observing the motions of might be expected to live to a certain the moon he was able to extend Kepler’s age, and how much longer they might, work by showing that the moon moved on the average, live, having reached a in an elliptical orbit about the earth and certain age. that the earth was at one focus of that As a result of this book, Graunt was ellipse. This completed the Keplerian elected to the Royal Society at the sug­ system by applying it to the one known gestion of Charles II himself. heavenly body that Kepler himself could not manage. [202] BROUNCKER, William, 2d Vis­ Horrocks thought that some of the ir­ count (brung'ker) regularities of the moon’s motion might English mathematician be due to the influence of the sun and Born: 1620 that Jupiter and Saturn might exert an Died: Westminster, London, influence on each other. This was a April 5, 1684 foretaste of the theory of universal gravi­ tation, which Newton [231] was to de­ Brouncker was bom into the nobility velop a generation after Horrocks’ early and inherited a viscount’s title in 1645. death. He received a doctor’s degree from Ox­ 128

[203]

MARIOTTE

ford in 1647 and cut a minor figure in the history of mathematics of the time. In particular, he popularized the use of continued fractions (first introduced in 1613 by the Italian mathematician P. A. Cataldi) when he made use of such frac­ tions to evolve an expression for pi, which enabled him to calculate its value to ten decimal places. He is best known, however, for the fact that he was the first president of the Royal Society nominated to that post by Charles II and elected without opposi­ tion. He was then reelected year after year till he resigned in 1677.

WILLIS

[205]

Picard, who eventually became a Roman Catholic priest, studied astron­ omy under Gassendi [182] and, in 1655, succeeded him as a professor of astron­ omy at the Collège de France and was one of the charter members of the French Academy of Sciences. He also helped to found the Paris Observatory and scoured Europe for men to serve in it worthily; among them, Cassini [209] from Italy and Roemer [232] from Den­ mark. Picard was the first to put the tele­ scope to use not merely for simple obser­ vations but for the accurate measure­ ment of small angles. This innovation made use of an improvement of the mi­ crometer invented by Gascoigne [195] and then reinvented by Huygens [215], He also popularized the use of Huygens’ pendulum clock to record times and time intervals in connection with astronomic observations. The feat for which Picard is most re­ nowned is the measurement of the cir­ cumference of the earth, the first mea­ surement more accurate than that of Eratosthenes [48] nineteen centuries ear­ lier. Picard made use of Eratosthenes’ principle, substituting a star for the sun. The use of a point instead of a large body made greater accuracy of measure­ ment possible. In 1671 he published the figure for the length of a degree of longitude at the equator as 69.1 miles, giving the earth a circumference of 24,876 miles and a ra­ dius of 3,950 miles (close to the values accepted today). According to one story it was the use of Picard’s values in place of somewhat smaller ones that in 1684 gave Newton [231] the correct answer to the moon’s motion, replacing the incor­ rect answer of 1666.

[203] MARIOTTE, Edmé (ma-ryut') French physicist Born: Dijon, 1620 Died: Paris, May 12, 1684 Mariotte’s life was strangely parallel to that of Boyle [212]. The two lives spanned the same decades and Mariotte was as devout as Boyle; Mariotte was, indeed, a Roman Catholic priest. As Boyle was an early member of the Royal Society in London, so Mariotte was an early member of the Academy of Sci­ ences in Paris. In 1676, fifteen years after Boyle, Mariotte discovered Boyle’s law indepen­ dently and with an important qualifica­ tion. He noticed that air expands with rising temperature and contracts with falling temperature. The inverse rela­ tionship of temperature and pressure therefore holds well only if the tempera­ ture is kept constant. This was a point Boyle had neglected to make. There is thus some justification for using the phrase Mariotte’s law. Mariotte also made important studies of rainfall and put forth modem views concerning the circulation of the earth’s water supply. He discovered the “blind spot” of the eye—the point where the [205] WILLIS, Thomas English physician optic nerve interrupts the retinal film. Born: Great Bedwyn, Wiltshire, January 27, 1621 [204] PICARD, Jean (pee-kahr/) Died: London, November 11, French astronomer 1675 Born: La Flèche, Sarthe, July 21, 1620 Willis, the son of a steward of a Died: Paris, July 12, 1682 manor, obtained his master’s degree 129

[206]

VTVIANI

from Oxford in 1642. He was a member of the losing Royalist cause during the Civil War and decided not to enter the embattled church. He turned to medicine instead, getting his license to practice in 1646. After the Restoration, of course, his activity in the Royalist cause worked in his favor and in 1666 he set up a practice in London, which was profitable indeed and he quickly became the most fashionable physician in the land. He was, however, a capable practi­ tioner. He studied epidemic disease and was the first great epidemiologist. He gave the first reliable clinical description of typhoid fever, was the first to describe myasthenia gravis, and childbed fever. It was he who named the latter “puerperal fever,” from the Latin phrase for “child­ bearing.” In 1664, he wrote a treatise on the brain and nerves that was the most complete and accurate up to that time. Most interesting of all, perhaps, was his discovery (or rediscovery in case it was known to some of the Greek physi­ cians) of the sugar content in urine among some people with diabetes. In this way he distinguished diabetes mellitus, the most serious form, from other varie­ ties. He died of pneumonia and was buried in Westminster Abbey. [206] VIVIANI, Vincenzo (vih-vee-ah'nee) Italian mathematician Bom: Florence, Tuscany, April 5, 1622 Died: Florence, September 22, 1703 Viviani was introduced to Galileo [166] by Ferdinand II of Tuscany [193]. He worked with Galileo and later with Torricelli [192]. He was a mathematician primarily and was perhaps the leading geometer of his time. He was also a practical engineer and succeeded Galileo as superintendent of the rivers of Tus­ cany. It might be argued that his most im­ portant accomplishment, however, was his founding of the Accademia del Cimento, one of the first great scientific 130

PASCAL

[207]

societies and a forerunner of the Royal Society soon to be established in En­ gland. [207] PASCAL, Blaise (pas-kalO French mathematician and physicist Born: Clermont-Ferrand, Auvergne, June 19, 1623 Died: Paris, August 19, 1662 Fortunately, in view of his short life and the fact that the last decade of it was devoted to theology and introspec­ tion, Pascal managed to accomplish a good deal. He was a sickly child whose mother died when he was three; and in infancy his life was, on one occasion, believed to have ended. Nevertheless, he was, mentally, a prodigy. His father, himself a mathematician and a govern­ ment functionary, supervised his child’s education and was determined that he study ancient languages first. He denied him, therefore, any books on mathe­ matics. When the young Pascal inquired as to the nature of geometry and was told it was the study of shapes and forms, he went on, at the age of nine, to discover for himself the first thirty-two theorems in Euclid in the correct order. (This story, told by his sister, appears too good to be true.) The awe-struck father then gave in and let the boy study mathe­ matics. When he was only sixteen Pascal pub­ lished a book on the geometry of the conic sections that for the first time carried the subject well beyond the point at which Apollonius [49] had left it nearly nineteen centuries before. Des­ cartes [183] refused to believe that a six­ teen-year-old could have written it, and Pascal, in turn, would not admit the value of Descartes’s analytic geometry. In 1642, when he was only nineteen, Pascal had invented a calculating ma­ chine that, by means of cogged wheels, could add and subtract. He patented the final version in 1649 and sent one model to that royal patron of learning. Queen Christina of Sweden. He hoped to profit from it but didn’t. It was too expensive

[207]

PASCAL

to build to be completely practical. Nev­ ertheless, it was the ancestor of the me­ chanical devices that reached their cul­ mination in the pre-electronic cash regis­ ter. Pascal corresponded with the lawyermathematician Fermat [188] and to­ gether they worked on problems sent them by a certain gentleman gambler and amateur philosopher who was puz­ zled as to why he lost money by betting on the appearance of certain combina­ tions in the fall of three dice. In the course of settling the matter, the two men founded the modem theory of prob­ ability. This had incalculable importance for the development of science because it lifted from mathematics (and the world in general) the necessity of absolute cer­ tainty. Men began to see that useful and reliable information could be obtained even out of matters that were completely uncertain. The fall of a particular coin can be either heads or tails, but which one, in any particular instance, is unpre­ dictable. However, given a vast number of falls, separately unpredictable, conclu­ sions as to the general nature of the falls (such as that the number of heads would be approximately equal to the number of tails) can be drawn with considerable confidence. Two centuries later, mathematical physicists such as Maxwell [692] were applying such considerations to the be­ havior of matter and producing great re­ sults out of the blind, random, and com­ pletely unpredictable movements of indi­ vidual atoms. Pascal also applied himself to physics. In studying fluids he pointed out that pressure exerted on a fluid in a closed vessel is transmitted undiminished throughout the fluid and that it acts at right angles to all surfaces it touches. This is called Pascal’s principle and it is the basis of the hydraulic press, which Pascal described in theory. If a small piston is pushed down into a container of liquid, a large piston can be pushed upward at another place in the container. The force pushing up the larger piston will be to the force pushing down the small one, as the cross-sec­

PASCAL

[207]

tional area of the large is to the cross­ sectional area of the small. This multi­ plication of force is made up for by the fact that the small piston must move through a correspondingly greater dis­ tance than the large. As in the case of Archimedes’ [47] lever, force times dis­ tance is equal on both sides. In fact the hydraulic press is a kind of lever. Pascal also interested himself in the new view of the atmosphere initiated by Torricelli [192], If the atmosphere had weight, then that weight should decrease with altitude, since the higher you went, the less air would remain above you. This decrease in the weight of the atmo­ sphere should be detectable on a barom­ eter. Pascal was chronically sick, suffering continuously from indigestion, headaches (a postmortem investigation showed he had a deformed skull), and insomnia, so he contemplated no mountain climbing for himself. However, on September 19, 1648, he sent his strong, young brotherin-law carrying two barometers up the sides of the Puy-de-Dôme (the mountain near which Pascal was bom). The brother-in-law climbed about a mile and found the mercury columns had dropped three inches. The brother-in-law must have enjoyed mountain climbing for he repeated the experiment five times. This established the Torricellian view quite definitely, even against the persistent doubting of Descartes. It showed, more­ over, that a vacuum existed above the at­ mosphere against Descartes’s denial of the existence of a vacuum and his con­ tention that all space is filled with mat­ ter. (Pascal also repeated Torricelli’s original experiment, using red wine in­ stead of mercury. Because red wine is even lighter than water, Pascal had to use a tube forty-six feet long to contain enough fluid to balance the weight of the atmosphere. ) In the year of the mountain climb Pascal came under the influence of Jan­ senism (a Roman Catholic sect marked by strong anti-Jesuit feeling). In 1654 he had a narrow escape from death when the horses of his carriage ran away. He interpreted this as evidence of divine dis­ pleasure and his conversion became 131

[208]

SYDENHAM

sufficiently intense to cause him to de­ vote the remainder of his short life to meditation, asceticism, religious writings (including the famous Pensées), and ill­ ness. The writings were brilliant and served to inspire Voltaire [261] but Pas­ cal worked on science and mathematics no more, except for one week in 1658 when he lived through a toothache by distracting his mind with a geometric problem, which he dispatched with great neatness. In his last years, in fact, Pascal declared reason an insufficient tool for understanding the physical universe, thus retreating beyond Thales [3], His best-known remark had nothing to do with science. It was to the effect that had Cleopatra’s nose been differently shaped, the history of the world would have been altered. [208] SYDENHAM, Thomas (sid'num) English physician Born: Wynford Eagle, Dorset, September 10, 1624 Died: London, December 29, 1689 Sydenham came of a family of the gentry that fought on the side of the Parliament in the English Civil War. Two of Thomas’s brothers died in the course of it and his oldest brother be­ came an associate of Cromwell and an important figure in the Commonwealth. Thomas himself fought, and reportedly narrowly escaped death on two occa­ sions. All the fighting interrupted his ed­ ucation, and he did not get his master’s degree till 1648. He began practicing medicine in 1656. The restoration of Charles II meant there was no chance of public life for Sydenham with his Parliamentary record so he turned entirely to medicine and made a huge success of it. Like Willis [205] he studied epidemics and the text­ book he wrote on the subject remained standard until the development of the germ theory of disease by Pasteur [642]. In the course of his practice, he insisted on detailed clinical observations and accurate records. He was the first to differentiate scarlet fever from measles, 132

CASSINI

[209]

and it was he who first called it scarlet fever. He was the first to use opium de­ rivatives (laudanum) to relieve pain and induce rest. He popularized the use of cinchona (quinine) to treat malaria. He also used iron in the treatment of ane­ mia. He produced careful descriptions of gout and of Saint Vitus’s dance (still called “Sydenham’s chorea”). Before he died, he was being called the English Hippocrates. [209] CASSINI, Giovanni Domenico (ka-see-nee': French) (ka-see'nee: Italian) Italian-French astronomer Born: Perinaldo (near Nice), June 8, 1625 Died: Paris, September 14, 1712 Cassini made his reputation in Italy, where he studied under Riccioli [185] and Grimaldi [199] and where, from 1650, he taught astronomy at the Uni­ versity of Bologna, succeeding to Cavalieri’s [186] position. The story is that he originally studied astronomy in order to gather data to disprove the follies of astrology. In 1665 and 1666 he measured the pe­ riods of rotation of Mars as twenty-four hours, forty minutes. In 1668 he issued a table of the motions of Jupiter’s moons, which was later to serve Roemer [232] in his discovery of the velocity of light. He also established Jupiter’s period of rota­ tion as nine hours, fifty-six minutes, and was the first to study the zodiacal light. (This last is a faint illumination of the night sky, stretching outward from the sun along the line of the ecliptic. We know now that it is sunlight reflected from dust particles in interplanetary space.) Picard [204] of the Paris Observatory, who was always on the lookout for for­ eign talent, persuaded Louis XIV of France to invite Cassini to Paris in 1669. The observatory was being elaborately rebuilt at the time. Cassini took one look and demanded changes in design so that the buildings would be less ornamental and more useful. King Louis pouted, but agreed, and there at the Paris Observa­

[209]

CASSINI

tory Cassini remained for the rest of his life, becoming a French citizen in 1673. He is often considered a French astrono­ mer, and his first names are often given as Jean Dominique. In Paris, Cassini continued his dis­ coveries. He located no fewer than four new satellites of Saturn using telescopes over one hundred feet long: Iapetus in 1671, Rhea in 1672, and Dione and Tethys in 1684. Then, having outdone his younger contemporary Huygens [215] in the matter of the Saturnian sat­ ellites (Huygens discovered only one), he went on to improve on Huygens’ most spectacular discovery, the rings of Saturn. In 1675 Cassini noted that the ring was actually a double one, the two rings being divided by a dark gap that is still called Cassini’s division. Cassini suspected the rings might con­ sist of myriads of small particles, but most astronomers, including Herschel [321], refused to accept that notion. They considered the rings solid, with Cassini’s division a dark marking upon it. Finally Maxwell [692] proved Cassini to have been right all along, a century and a half after the latter’s death. Outside the solar system, Cassini dis­ covered several stars to be double, in­ cluding the bright star Castor. His most valuable piece of work lay in his determination of the parallax of Mars in 1672 through his observations of the planet in Paris and Richer’s [217] simultaneous observations in French Guiana. This gave him a value for the distance of Mars. The relative distances of the sun and planets had been known quite accurately since the days of Kepler [169], so it was only necessary to deter­ mine any one of those distances accu­ rately to be able to calculate all the rest. From his value for the distance of Mars, Cassini calculated that the sun was eighty-seven million miles from the earth, a value confirmed that same year by Flamsteed [234]. This is too low a value by 7 percent, but it was the first determination ever made that was nearly right. Aristarchus [41] had placed the sun a mere five mil­ lion miles from the earth, while Poseidonius [52] had estimated forty million

BARTHOLIN

[210]

mileis and Kepler had actually cut that down to a guess (it was nothing more) of fifteen million miles. Cassini founded a dynasty of five suc­ cessive generations of astronomers that dominated French astronomy for over a century. This was not altogether fortu­ nate. Cassini himself was an opinionated, self-important person who was not nearly as good as he thought. Further­ more he was amazingly conservative for his times. He was the last of the great as­ tronomers to refuse to accept the helio­ centric views of Copernicus [127]. His descendants gradually adopted the new view of the universe but always a couple of generations too late. Thus the second of the line accepted Copernicus but rejected Kepler. The third of the line insisted that the earth was flattened at the equator when other astronomers were satisfied that it was flattened at the poles. And it was only the fourth of the line who could finally bring himself, a century after the fact, to accept Newton [231]. Eighteenth-century France suf­ fered a decline in astronomy because of the dead hand of the first Cassini, as eighteenth-century England was to suffer a decline in mathematics because of slavish adherence to Newton. [210] BARTHOLIN, Erasmus (bahrtoo'lin) Danish physician Born: Roskilde, August 13, 1625 Died: Copenhagen, November 4, 1698 Bartholin was a member of a Danish medical dynasty. His father, brother, and son were all physicians, as he was him­ self. In 1654 he obtained a medical de­ gree at the University of Padua, and was professor of medicine at the University of Copenhagen from 1656 to his death. His fame, however, did not arise from anything connected with medicine. In 1669 he received a transparent crystal from Iceland (now called Iceland spar) and he noted that objects viewed through it were seen double. He assumed that the light traveling through the crystal was refracted in two different angles, so that 133

[211]

REDI

two rays of light emerged where one had entered. This phenomenon he therefore called double refraction. Furthermore he noted that if he ro­ tated the crystal, one of the images re­ mained fixed while the other rotated about it. The ray giving rise to the fixed image he called the ordinary ray, the other the extraordinary ray. These terms are still used today. Bartholin was unable to explain these observations. Greater men than himself attempted it too, recognizing that any theory of light, if it were to be success­ ful, must explain double refraction. After all, why should some light refract through one angle, and the rest through another? Isaac Newton [231] developed a parti­ cle theory of light which did not explain double refraction, and Huygens [215] de­ veloped a wave theory that did not ex­ plain it. The whole matter of double refraction remained in a kind of cold storage where physicists refused to look at it until Young [402] finally established a new variety of wave theory a century and a half after Bartholin. Then and only then was double refraction ex­ plained and put to use in chemistry.

BOYLE

[212]

grain, or in general from corrupting mat­ ter. The living things that arose through such spontaneous generation were usu­ ally vermin such as insects, worms, frogs, and so on. One of the best attested cases was that of maggots, which ap­ peared in decaying meat, apparently out of the substance of the meat itself. In the small book on the circulation written by Harvey [174] about the time Redi was born, there was a speculation to the effect that small living things that appeared to be born spontaneously, might actually arise from seeds or eggs that were too small to be seen. Redi read this and in 1668 determined to test it. He prepared eight flasks with a variety of meats in them. Four he sealed and four he left open to the air. Flies could land only on the meat in the vessels that were open and only the meat in those vessels bred maggots. The meat in the closed vessels was just as putrid and smelly, but without maggots. To test whether it was the absence of fresh air that did it, Redi repeated the experiment without closing any flasks, but covering some with gauze instead. The air was not excluded, but flies were, and that was sufficient. There were no maggots in the gauze-covered meat. This was the first clear-cut case of the use of proper con­ trols in a biological experiment. Redi concluded that maggots were not formed by spontaneous generation but from eggs laid by flies. This finding might have been extended to all forms of life but that would have been permature. Leeuwenhoek [221] had just demon­ strated the existence of a new world of minute animals invisible to the eye. These appeared to breed in any drop of stagnant water, and the question of the spontaneous generation of these microor­ ganisms raged for two centuries.

[211] REDI, Francesco (ray'dee) Italian physician and poet Born: Arezzo, Tuscany, February 18, 1626 Died: Pisa, March 1, 1697 Redi obtained his medical degree at the University of Pisa in 1647, and was personal physician to two Medici grand dukes of Tuscany, Ferdinand II [193] and Cosimo III. As a poet, he is known chiefly for Bacco in Toscana written in 1685; but in the world of science he is known for reasons far more enduring. Or perhaps for one reason; a famous ex­ periment involving flies and their manner of breeding. [212] BOYLE, Robert It had long been held by many men, British physicist and chemist from casual observers up to careful Born: Lismore Castle, County Waterford, Ireland, January 25, thinkers such as Aristotle [29] and Hel­ mont [175], that some species of animals 1627 arose spontaneously from mud, decaying Died: London, December 31, 1691 134

[212]

BOYLE

Robert Boyle was born into the aris­ tocracy (as the fourteenth child and sev­ enth son of the earl of Cork) and was an infant prodigy. He went to Eton at eight, at which time he was already speaking Greek and Latin, traveled through Europe (with a tutor) at eleven, and at fourteen was in Italy studying the works of Galileo [166], who had just died, and finding himself also influenced by his reading of Descartes [183]. His private tutoring saved him from exposure to the didactic Aristotelianism that still vic­ timized most universities. While in Geneva he was frightened by an intense thunderstorm into a de­ voutness that persisted for the rest of his life. He never married. Back home in 1645, Boyle found his father dead and himself with an indepen­ dent income. He kept out of the English Civil War and eventually settled at Ox­ ford in 1654 and took part in the peri­ odic gatherings of scholars tackling the new experimentalism made fashionable by Francis Bacon [163] and dramatic by Galileo. It was called the Invisible Col­ lege, but in 1663 after King Charles II had been restored to the throne the asso­ ciation of scholars received official recog­ nition and a charter and became known as the Royal Society. Its motto was “Nullius in verba” (“Nothing by mere authority”). Boyle’s interest in experimentation still represented an odd innovation in science. Most scholars were still suspicious of this. The Dutch-Jewish philosopher Ben­ edict Spinoza corresponded with Boyle and tried to convince him that reason was superior to experiment. Fortunately Boyle disregarded the gentle Spinoza. In 1657 Boyle heard of the experi­ ments of Guericke [189] and set about devising an air pump of his own. This he accomplished successfully with the help of a brilliant assistant, Robert Hooke [223]. His pump was an improvement upon Guericke’s and for a while a vac­ uum produced by an air pump was called a Boylean vacuum. Boyle was one of the first to make use of an evacuated, hermetically sealed thermometer. He also made use of an

BOYLE

[212]

evacuated cylinder to show, for the first time, that Galileo was actually correct in maintaining that in a vacuum all objects fall at the same velocity. A feather and a lump of lead, in the absence of air resis­ tance, land together. Then, too, he was able to demonstrate that sound (the ticking of a clock) could not be heard in a vacuum but that elec­ trical attraction could be felt across one. All this led him to experiment with gases. He was the first chemist to collect a gas. Further, he discovered in 1662 that air was not only compressible but that this compressibility varied with pres­ sure according to a simple inverse rela­ tionship. If a quantity of gas was put under doubled pressure (by trapping it in the closed end of a seventeen-foot tube shaped like a J and adding more mercury in the long open end) its vol­ ume halved. If pressure was tripled the volume was reduced to a third. On the other hand if pressure was eased off the volume expanded. This inverse rela­ tionship is still referred to as Boyle’s law in Great Britain and America; in France it is credited to Mariotte [203]. Because the compressibility and expansibility of air in response to the force upon it was reminiscent of the coiled metal springs then being studied by Hooke, Boyle re­ ferred to it as the “spring of the air.” The most significant conclusion drawn from this experiment was that since air was compressible, it must be composed of discrete particles separated by a void. The compression consisted of squeezing the particles closer together. Hero [60] had suspected this fifteen centuries ear­ lier, but where Hero faced hordes of the­ oretical philosophers who scorned exper­ iment, Boyle was part of a growing experimentalist school. Boyle was in­ fluenced by the writings of Gassendi [182] and his experiments made him a convinced atomist. Atomism was to gain momentum steadily from that time on; after two thousand years the views of Democritus [20] prevailed. Boyle’s experiments on gases were also important because he here initiated the practice of thoroughly and carefully de­ scribing his experiments so that anyone 135

[212]

BOYLE

might repeat and confirm them—a habit which became universal in science, and without which progress would have re­ mained at a creep. Boyle had much of the alchemist about him. He believed in the transmuta­ tion of gold and, indeed, was instru­ mental in persuading the British govern­ ment in 1689 to repeal the law against the manufacture of gold, not because it was a useless law (which it was) but be­ cause he felt the government should take advantage of any gold that was formed and should encourage scientists to form it. Even so, Boyle transformed alchemy into chemistry in 1661 with the publica­ tion of The Sceptical Chemist. In it he abandoned the Greek view that made the elements mystical substances of a nature deducible from first principles. Instead he suggested that an element was a ma­ terial substance and that it could be identified only by experiment. Any sub­ stance that could not be broken down into still simpler substances was an ele­ ment. Furthermore two elements could be combined into a compound and then obtained once again out of that com­ pound. This does not mean he aban­ doned the old elements. He just wanted them established experimentally rather than intuitively. With this book, Boyle divorced chemistry from medicine and established it as a separate science. Boyle was the first to distinguish be­ tween acids, bases, and neutral sub­ stances, studying them by means of the color changes of what we would now call acid-base indicators. He showed that water expanded when it froze and, in­ deed, began to expand a little before it froze. He also came within a hair of being the first discoverer of a new element (in the modern Boylean sense). In 1680 he prepared phosphorus from urine. How­ ever, some five to ten years before that, Brand [216] had preceded Boyle in the discovery. There was fierce controversy (not including Boyle) about just who had first discovered phosphorus, largely because investigators held discoveries se­ cret. Boyle maintained strongly that all experimental work should be clearly and 136

RAY

[213]

quickly reported so that others might repeat, confirm, and profit. This has been an accepted tenet of scientific research ever since, and when industrial or mili­ tary security interferes with publication it cannot help but harm the cause of sci­ ence. In the sense that Boyle applied the philosophy of experimentalism to the study of material substances and the changes they could be made to undergo, he might be considered the father of chemistry. The reform was not thorough­ going, however, and was not to become so until the time of Lavoisier [334] a century later; and it is the latter who more properly deserves the honor of paternity. Boyle’s interest in religion grew with age. He learned Hebrew and Aramaic for his biblical studies. He wrote essays on religion and financed missionary work in the Orient. In 1680 he was elected president of the Royal Society but could not accept because he disapproved of the form of the oath. He also repeatedly re­ fused offers of a peerage. Through his will he founded the Boyle Lectures, not on science but on the defense of Chris­ tianity against unbelievers. [213] RAY, John English naturalist Born: Black Notley, Essex, No­ vember 29, 1627 Died: Black Notley, January 17, 1705 The son of a blacksmith, Ray never­ theless made his way through Cam­ bridge, obtaining his master’s degree in 1651. He stayed on as a lecturer. He had a passion for natural history and would ride for many miles through the countryside, observing and collecting plants. In 1660 he published a scientific description of plants growing near Cam­ bridge. But then Charles II was restored to the British throne, the land’s religious climate changed, and Ray had to leave the university in 1662 because of his re­ fusal to take the proper oaths. He then conceived the notion of en­ gaging in travel and preparing a descrip-

[214]

MALPIGHI

tion of all living species of both plants and animals. He was to do it in company with a younger man who was to finance the effort. The friend died soon after but left money in his will for the purpose. In 1667 Ray published a catalogue of plants in the British Isles and was elected a member of the Royal Society. He re­ fused to serve as secretary, however, as that would take time from his work. To­ ward the end of his life he had general­ ized his catalogue into a three-volume encyclopedia of plant life, published be­ tween 1686 and 1704. He described 18,600 differeht plant species and laid the groundwork for systematic classifica­ tion, which was to be brought into mod­ ern form by Linneaus [276]. Ray also tried to systematize the ani­ mal kingdom and in 1693 he published a book that contained the first logical classification of animals, based chiefly on hoofs, toes, and teeth. His descriptions finally destroyed the fanciful stories of animals inherited from Pliny [61], six­ teen centuries earlier. His views on fossils were rather enlightened for the time. In 1691 he published an account in which he de­ clared fossils were the petrified remains of extinct creatures. This was not ac­ cepted by biologists generally until a cen­ tury later. [214] MALPIGHI, Marcello (mahl-pee'gee) Italian physiologist Born: Crevalcore, near Bologna, March 10, 1628 Died: Rome, November 30, 1694 When Galileo [166] invented the tele­ scope he well realized that an arrange­ ment of lenses could also be used to magnify objects. In a sense he was inven­ tor of the microscope as well. The opti­ cal theory of the microscope was further advanced by his friend Kepler [169] and by his young assistant Torricelli [192]. In the mid-seventeenth century microscopy became all the rage and a number of first-rate investigators took it up. First by a hair and therefore entitled to be called the father of microscopy

MALPIGHI

[214]

was Malpighi. He was a physician by training, obtaining his medical degree at the University of Bologna in 1653 after an interruption caused by the death of his father. He then lectured at various Italian universities, though chiefly at Bo­ logna, and associated with Redi [211] and Borelli [191] among others. In 1691 he finally retired to Rome, rather reluc­ tantly, to become private physician to Pope Innocent XII. Malpighi began his work in micros­ copy in the 1650s by investigating the lungs of frogs. In 1660 he showed that the blood flowed through a complex net­ work of vessels over the lungs and this discovery led to important conclusions. In the first place it explained a key step in the process of respiration, for it was easy to see that air could easily diffuse from the lungs into the blood vessels and that the blood stream would then carry it to all parts of the body. Soon Swammer­ dam [224] was to detect the structures within the blood stream that were even­ tually found to carry the essential por­ tions of the air and Lower [219] was to arrive at the first suspicions of the true details of the process. Malpighi’s observations of the wing membranes of a bat showed him the finest blood vessels, which were eventu­ ally named capillaries (“hairlike”). In­ visible to the eye, these were clearly visi­ ble in the microscope. They connected the smallest visible arteries with the smallest visible veins. With this discovery Malpighi supplied the key factor lacking in the theory of blood circulation ad­ vanced a generation earlier by Harvey [174], who died a few years too soon to witness this triumph. At about this time, too, Rudbeck [218] added his final touch to the circulatory system. He disproved the impression that there were two varieties of bile, yellow and black, thus disposing of a mistaken belief that dated back to the school of Hip­ pocrates [22] two thousand years before. Malpighi went on to study other mi­ nute aspects of life—chick embryos and insects, for instance. He devoted a vol­ ume to the internal organs of the silk­ worm, the first treatise to deal with an invertebrate. Without quite realizing 137

[215]

HUYGENS

what he had discovered he found traces of gill structures in the developing chick, attesting to its descent from fishlike crea­ tures. (One of Malpighi’s contempo­ raries, Graaf [228], unwittingly went even further back than the embryo in his investigations.) Malpighi studied the respiratory ves­ sels in insects—tiny, branching tubes that filled the body and opened to the outer world through tiny apertures in the abdomen. In the stems of plant structures he found tiny tubes that pos­ sessed a spiral structure. Because of their resemblance to the tubes in insects, he wrongly believed them to be used in respiration. He described the small open­ ings (stomata) on the underside of leaves. These, whose function he could not guess, were concerned with respira­ tion. This interest in plant microscopy was shared by his younger contemporary Grew [229], Malpighi’s researches were so famous that in 1667 the Royal Society in Lon­ don suggested he send them his scientific communications. The work of Malpighi and his fellow microscopists showed that living tissue was far more complex in structure than the eye alone could tell and that the world of the very small was as grand and worthy of study as the world of astron­ omy. [215] HUYGENS, Christiaan (hoy'genz or h/genz) Dutch physicist and astronomer Born: The Hague, April 14, 1629 Died: The Hague, June 8, 1695 Huygens’ father was an important official in the Dutch government. Young Christiaan was given a good education at the University of Leiden and had the benefit of friendship with Descartes [183]. Huygens’ early training was in mathematics and he might have made a great mark in that field had he not been diverted to astronomy and physics. In 1657, for instance, he published a book on probability, the first formal book on the subject to appear, and applied the 138

HUYGENS

[215]

subject to the working out of life ex­ pectancy. In 1655, when he was helping his brother devise an improved telescope, he hit upon a new and better method for grinding lenses. (He had the help here of the Dutch-Jewish philosopher Benedict Spinoza.) At once he incorporated these improved lenses into telescopes and began to use one, twenty-three feet long, to discover new glories in the heavens, such as (in 1656) a huge cloud of gas and dust, the Orion Nebula. Another dis­ covery, that same year, was a satellite circling Saturn, one as large as any of the satellites of Jupiter that Galileo [166] had discovered nearly half a century be­ fore. Huygens named it Titan. At that moment six planets (including the earth) and six satellites (including the moon) were known and this seemed such a neat picture that Huygens declared no more of either remained to be discovered. He lived to see Cassini [209] discover four more satellites of Saturn. Huygens’ mysticism was a momentary aberration and his real achievements continued. Galileo had, in 1610, noted a peculiarity about Saturn: it seemed tri­ ple. His primitive telescope could not make out the nature of the tripleness, but Huygens’ improved instrument made it out clearly. In 1656 he was able to see that Saturn was surrounded by a thin ring which nowhere touched the planet. He announced his discovery in a cipher, protecting his priority while making cer­ tain he was correct through further ob­ servations. Cassini was to improve on Huygens, for he discovered the ring was a double one. Huygens recognized that the plane of the ring was tipped to that of earth’s orbit and that they would be seen edge-on, and therefore be briefly invisible, every fourteen years. Huygens was the first to note surface markings on Mars. In 1659 he detected the V-shaped Syrtis Major (“large bog”), whose name proved to be a mistake, for there is nothing boggy about it. He was the first to make a specific guess at the distance of the stars. By as­ suming Sirius to be as bright as the sun, he estimated its distance at 2.5 trillion miles. (This is about one-twentieth the

[215]

HUYGENS

actual distance and Huygens’ error lay in his assumption, for Sirius is actually much brighter than the sun and must be correspondingly farther to appear as dim as it does.) Huygens believed, as Nicho­ las of Cusa [115] had, that stars were uniformly distributed through infinite space, each with its complement of planets. Huygens struggled to reduce telescopic observations to a quantitative basis. This he did in two ways: in the measurement of space and the measurement of time. For the former, Huygens devised a mi­ crometer in 1658 with which he could measure angular separations of a few seconds of arc. In this form of quanti­ tative observation his work rather paral­ leled that of his contemporary Picard [204]. In the measurement of time, how­ ever, was to be found his greatest achievement. The best device the an­ cients had with which to measure time was the water clock of Ctesibius [46], but this was only accurate to rather large fractions of an hour. The late Middle Ages developed mechanical clocks in which the pointer was made to indicate the hour through the action of a slowly falling weight rather than slowly rising water. The elimination of water made the clocks more rugged, less in need of care, and therefore more suitable for in­ stallation in church towers, but they were insufficiently accurate for scien­ tific use. What was really needed was some de­ vice that kept a constant periodic motion to which a clock could be geared, but no such motion was known until Galileo discovered the isochronicity of the pen­ dulum. Galileo did not fail to recognize the possibility of hitching a pendulum to the gears of a clock and in his old age even had a design for such a clock drawn up. It was Huygens who put the possibility into practice in 1656, over a decade after Galileo’s death. He showed that a pendulum didn’t swing in exactly equal times unless it swung through an arc that wasn’t quite circular. He devised attach­ ments at the pendulum’s fulcrum that made it swing in the proper arc and then

HUYGENS

[215]

attached that to the works of a clock, using falling weights to transfer just enough energy to the pendulum to keep it from coming to a halt through friction and air resistance. It was with Huygens’ first “grandfa­ ther’s clock,” which he presented to the Dutch governing body, the estates gen­ eral, that the era of accurate timekeeping may be said to have begun. It is difficult to see how physics could have advanced much further without such an invention. Huygens extended Wallis’ [198] findings on the conservation of momen­ tum (mass times velocity, or mv). Huy­ gens showed that mv2 was also con­ served. This quantity is twice the kinetic energy of a body and this was the first step in the direction of working out the law of conservation of energy, which was to be brought to the attention of sci­ ence by Helmholtz [631] a century and a half later. Huygens’ reputation spread throughout Europe. In 1660 he visited England and in 1663 was elected a charter member of the Royal Society. Louis XIV lured him to France in 1666 in line with his policy of collecting scholars for the glory of his regime. There, Huygens helped found the French Academy of Sciences. Huygens, like Cassini might have re­ mained in Paris for the rest of his life, but he was Protestant. Louis was gradu­ ally moving in the direction of non­ toleration for the Protestants, and in 1681 Huygens returned to the Nether­ lands. As he corrected Galileo on the ques­ tion of Saturn, so he endeavored, in 1690, to correct Newton [231] on the subject of light. To Huygens it seemed quite possible that light could be inter­ preted as a longitudinal wave, a wave that undulated in the direction of its mo­ tion, as a sound wave did. The chief objection to such a wave theory was that most people, through their experience with water waves and sound waves, believed that waves would bend around obstacles. Only a stream of particles, they thought, would travel in absolutely straight lines and throw sharp shadows, as light rays did. Huygens tried to show that there were 139

[216]

BRAND

conditions under which waves would in­ deed travel a straight line and would fol­ low the laws of reflection and refraction which were observed in the case of light. In addition Grimaldi [199] showed that light had a slight tendency to bend about obstacles after all. However, Newton’s theory that light consisted of particles remained the more popular throughout the eighteenth cen­ tury, mainly because of Newton’s im­ mense prestige. The wave theory re­ mained disregarded for a full century until the time of Young [402].

RUDBECK

[218]

[217] RICHER, Jean (ree-shay') French astronomer Born: 1630 Died: Paris, 1696 Richer was elected to the French Academy of Sciences in 1666 and in 1671 led an expedition to Cayenne in French Guiana (quite near the equator). There he made careful observations of Mars while Cassini [209], his superior, did the same in Paris. Together, these measurements supplied the first adequate parallax of Mars and the first notion of the scale of the solar system. Richer also found that a pendulum beat more slowly in Cayenne than in Paris, so that a clock, correct in Paris, lost two and a half minutes a day in Cayenne. The conclusion was that the force of gravity was weaker in Cayenne because the spot was farther from the center of the earth. (The rate of beat of a pendulum varies with the size of the force of gravity acting upon it.) If Cayenne had been on a mountain­ top that would not have been surprising, but it was at sea level. Consequently Newton [231] deduced that the surface of the sea itself was farther from the center of the earth in the equatorial re­ gions than in more northerly regions. This would be true if the earth was an oblate spheroid as the theory of gravita­ tion required. (Actually it is now known that the equatorial surface is thirteen miles farther from the center of the earth than the polar surfaces.) Richer returned to Paris in 1673 to such acclaim as to rouse the jealousy of Cassini. Since Richer was a military en­ gineer as well as an astronomer, Cassini arranged to have him bundled off to the provinces to erect fortifications. The rest of his life was spent in obscurity.

[216] BRAND, Hennig German chemist Born: Hamburg, about 1630 Died: date and place unknown Brand was a military officer who called himself a physician though he had never earned a degree. He is sometimes called the last of the alchemists (which he wasn’t really), though he might better be called the first of the element discov­ erers. He was the first man known to have discovered an element that was not known in any form before his time. The date of the discovery is disputed, but it must have been somewhere between 1669 and 1675. Brand was searching for the philosopher’s stone and it occurred to him that he could find it in urine. He did not succeed, but he obtained a white, waxy substance that glowed in the dark. He therefore called it phosphorus (“light-bearer”). The glow was the result of the slow combination of the phos­ phorus with air, but that was not to be understood for another century. The glow, however, served the purpose of making the discovery mysterious and glamorous. Several men quarreled over who had first made this brilliant find, but the quarrels were less important than the [218] RUDBECK, Olof (rood'bek) fact that another step had been taken Swedish naturalist away from the mysticism of alchemy to­ Born: Westerns, December 12, ward the rationality of chemistry. 1630 What happened to Brand after his dis­ Died: Uppsala, September 17, covery is utterly unknown. 1702 140

[219]

LOWER

Rudbeck, the son of a science-minded bishop and the tenth of eleven children, was a man of encyclopedic interests. He taught at the medical school at the Uni­ versity of Uppsala, Sweden, and there took anatomy, botany, chemistry, and mathematics as his subjects. He built up a beautiful botanical garden. He was a well-read classical scholar and was made chancellor of the university at the age of thirty-one. In science his best-known discovery is the lymphatic vessels, which he demon­ strated to Queen Christina of Sweden in 1653, using a dog for the purpose. The lymphatics resemble the veins and capil­ laries but have thinner walls and carry the clear, watery fluid portion of the blood (lymph). This fluid portion is forced out of the thin-walled capillaries and into the spaces around the cells, forming the interstitial fluid. The intersti­ tial fluid is connected in the lymphatics and carried back into the blood vessels. In various regions of the body, lym­ phatic vessels gather in small knots (lymph glands or lymph nodes), which are now known to be important in de­ veloping immunity to disease. These were first noted by Malpighi [214] in 1659. Rudbeck quarreled with Bartholin [210] over priority in this discovery. Outside the world of science Rudbeck is known for a curious quirk. He thor­ oughly believed the fictional tale of Plato [24] concerning the supposedly-lost con­ tinent Atlantis and wrote a large treatise, in several volumes, attempting to prove that Atlantis was really Scandinavia and that Sweden particularly was the fount of human civilization. [219] LOWER, Richard English physician Born: near Bodmin, Cornwall, about 1631 Died: London, January 17, 1691 Lower obtained his bachelor’s degree from Oxford in 1653 and his medical de­ gree there in 1665. He was elected to the Royal Society in 1667 after being nomi­ nated by Boyle [212]. He made two dis­

WREN

[220]

coveries involving blood that had to await future centuries for proper under­ standing. He discovered that dark venous blood was converted to bright arterial blood on contact with air. Something, he believed, was absorbed from air, but what that might be had to wait a century for Lavoisier’s [334] explanation of the nature of air. In 1665 he transfused blood from one animal to another, at the suggestion of Christopher Wren [220], and demon­ strated that this technique might be use­ ful in saving lives. However, the transfu­ sion of animal blood into a man or even one man’s blood into another was too often fatal. Landsteiner [973], two and a half centuries later, demonstrated the existence of different types of human blood, and it was only in the twentieth century that transfusion became practi­ cal. Lower disproved Galen’s [65] notion that phlegm originated in the brain by showing that it was manufactured in the nasal membranes. He also showed that the heartbeat was caused by the contrac­ tion of the heart’s muscular walls. [220] WREN, Sir Christopher English architect Born: East Rnoyle, Wiltshire, October 20, 1632 Died: London, February 25, 1723 Wren was the son of a clergyman (and royal chaplain). He obtained his master’s degree at Oxford in 1654, and in 1657 became professor of astronomy at Gresham College. Although he and his family were royalists, he was left un­ disturbed by Cromwell. He is best known as an architect, hav­ ing designed the new St. Paul’s Cathe­ dral, constructed in London after the disastrous fire of 1666. He designed other churches as well and was knighted for his services in 1673. He would have deserved even more from his nation had he been allowed to carry through his orderly design for a new, rationally planned London. The interests of those who owned London land prevented it. 141

[221]

LEEUWENHOEK

The fame of his architecture has com­ pletely obscured the fact that Wren was one of the coterie of scientists who made Restoration England a brilliant spot in the history of science. He was a charter member of the Royal Society and rose to its presidency in 1681. He was a nota­ ble geometer, having studied mathemat­ ics under Oughtred [172]. He lectured in astronomy, first at Gresham College, then at Oxford, and was one of those whose speculations on the nature of gravity laid the groundwork for New­ ton’s [231] work. Wren is buried in St. Paul’s and on the commemorative tablet is one of the best-known epitaphs in history: “Si monumentum requiris, circumspice” (“If you would see his monument, look about you”). [221] LEEUWENHOEK, Anton van (lay'ven-hook) Dutch biologist and microscopist Born: Delft, October 24, 1632 Died: Delft, August 26, 1723 Of all the seventeenth-century microscopists, Leeuwenhoek was the most re­ markable. He was not the first, for Mal­ pighi [214] preceded him. Nor were his microscopes marking the way of the fu­ ture, for Hooke [223] was developing a compound microscope, one made up of more than one lens, and this was the true path of advancement. However, Hooke’s compound microscopes, with their still imperfect lenses, were quite limited in their clarity and powers of magnification. Leeuwenhoek, on the other hand, retained the simple micro­ scope based on a single lens ground with such delicacy and perfection that they could magnify up to nearly two hundred times. They were tiny and short-focus, some being no larger than the head of a pin, but through them Leeuwenhoek saw what no other man in his century could. He had had little schooling. His father, a basketmaker, died when young Leeu­ wenhoek was sixteen and the youngster became a clerk in a dry-goods store in Amsterdam, then opened a drapery shop of his own in Delft. As a sinecure he was appointed janitor at the Delft City 142

LEEUWENHOEK

[221]

Hall, a position he held for the rest of his life. His business and his appointment kept him comfortably off, and he lived only for his hobby, grinding lenses. This had begun because drapers used magnifying glasses to inspect cloth and Leeuwen­ hoek wanted to see more and better. He began feeding his mania (which is what it became) in 1674. In his lifetime he ground a total of 419 lenses, many of which were focused on some perma­ nently mounted object and through some of which no man other than himself looked. He worked alone and since he could read only Dutch, he could see the illustrations but could not read the writ­ ings of the great contemporary microscopists such as Hooke and Malpighi. Leeuwenhoek, with a passion for peering at the small, looked at every­ thing from tooth scrapings to ditch water. He noted the fine structure of muscle, skin, hair, and ivory. He also re­ ported a great deal of accurate detail on the development of tiny insects. He found tiny creatures parasitic on fleas and inspired the English author Jonathan Swift to write a famous quatrain: So naturalists observe, a flea Has smaller fleas that on him prey; And these have smaller still to bite ’em; And so proceed ad infinitum. Leeuwenhoek was the first to discover the one-celled animals now called pro­ tozoa and in 1677 opened up a whole world of living organisms as alive as the elephant and whale yet compressing all that life into a space too small to see without mechanical help. He observed human capillaries and red blood cells with more care and detail than had the original discoverers, Malpighi and Swam­ merdam [224], and was the first to de­ scribe spermatozoa. He reported this last discovery rather nervously, fearing it might be considered obscene. Beginning in 1673 he wrote volumi­ nously to the British Royal Society, in Dutch, with his letters sometimes long enough to be respectable pamphlets. The Society received the communications from this unknown Dutchman with con­ siderable reservations. However, in 1677

[222]

BECHER

BECHER

[222]

Becher was the son of a Lutheran minister who had become impoverished in the Thirty Years’ War. The necessity of helping to support his family slowed his education. Becher was a curious mixture of sense and nonsense. He was a successful physi­ cian, serving as court physician at Mainz in Germany in 1666. (Germany at the time was broken up into several hundred independent political units so that there was room for many court physicians.) He was also an economist with intelli­ gent notions concerning the regulation of trade, notions which got him into trouble with conservative merchants who con­ sidered any change subversive. As eco­ nomic adviser to Holy Roman Emperor Leopold I, he suggested a Rhine-Danube canal, cutting across from headwaters to headwaters, to facilitate trade between Austria and the Netherlands. He was also convinced that transmu­ tation was possible and tried to turn the sands of the Danube into gold. His fail­ ure, though not quite as dangerous to personal safety as Alhazen’s [85] had been, was dangerous enough. At least, he felt it wise to leave Austria, first for the Netherlands and then for England. In a book published in 1669 he tried to adapt the alchemical elements to the growing chemical knowledge of the sev­ enteenth century. To do so he divided solids into three kinds of earth. One of these he called terra pinguis (“fatty earth”), and saw this as a principle of inflammability, like the alchemical sul­ fur. His notions on the behavior of this principle were to be refined into the phlogiston theory by his follower Stahl [241] a generation later. Among his more immediately practi­ cal suggestions was one to the effect that sugar was necessary for fermentation and another that coal be distilled to ob­ tain tar. There is a statement attributed to [222] BECHER, Johann Joachim Becher that goes as follows: “The chem­ (bekh'er) ists are a strange class of mortals, im­ German chemist Born: Speyer, Palatinate, May 6, pelled by an almost insane impulse to seek their pleasure among smoke and 1635 Died: London, England, October vapor, soot and flame, poisons and pov­ erty, yet among all these evils I seem to 1682

Hooke built microscopes according to Leeuwenhoek’s specifications and con­ firmed the Dutchman’s observations. Leeuwenhoek sent twenty-six of his tiny microscopes to the Society so that members could see for themselves. In 1680 the Royal Society elected the Dutch draper to membership—and did so unanimously. In all he sent 375 communications to the Royal Society (to whose attention his work had been brought by Graaf [228]) and 27 to the French Academy of Science (to which he was elected in 1680). His discoveries were dramatic enough to make him world-famous. The Dutch East India Company sent him Asian in­ sects to put under his lenses. The queen of England paid him a visit, as did Frederick I of Prussia and Peter the Great, tsar of all the Russias, when he was visiting the Netherlands “incognito” to learn shipbuilding. It was in 1683 that Leeuwenhoek made his most remarkable discovery. He described structures that could only be bacteria. These tiny things were just at the limit of what his lenses could make out. In fact, no one else was to see bac­ teria again for over a century. Leeuwenhoek continued true to his passion and his hobby almost to the end of his long life of ninety years, cared for always by a devoted daughter, his sole surviving child. He was little interested in anything but observing and describing, but in that he was unexcelled. After his death, a number of his microscopes were sent to the Royal Society, in accordance with his last will. He competes with Malpighi for the title of father of microscopy. Even though Malpighi preceded him in time, Leeuwenhoek did more to dramatize and popularize the field.

143

[223]

HOOKE

live so sweetly, that may I die if I would change places with the Persian King.” Surely, with appropriate changes in phrasing, this is applicable to all those who find in the attainment of knowledge the greatest good. [223] HOOKE, Robert English physicist Born: Freshwater, Isle of Wight, July 18, 1635 Died: London, March 3, 1703 Hooke, the son of a clergyman, was a sickly youngster, scarred by smallpox, who showed himself an infant prodigy in mechanics and who managed to get into Oxford in 1653. There he supported himself by waiting on tables, and ap­ parently never got over the humiliation. At Oxford he attracted the attention of Robert Boyle [212], with whom he got his start. The association was one of mu­ tual advantage for it was Hooke’s me­ chanical skill that made a success of Boyle’s air pump. Hooke became a member of the Royal Society in 1663 and was secretary from 1677 to 1683. Moreover, from 1662 to the end of his life he held the post of “curator of experiments” to the Society. This post, the only paid one in the Soci­ ety, gave him a kind of bureaucratic power he never hesitated to use against those he conceived to be his enemies. He was on the one hand a most inge­ nious and capable experimenter in al­ most every field of science, and on the other a nasty, argumentative individual, antisocial, miserly, and quarrelsome. Since he investigated in a wide variety of fields, he frequently claimed (with some justice) that he had anticipated the more thorough and perfected ideas of others. His malignant pleasure in controversy could rarely be matched by others. He fought with Huygens [215], for instance, but his particular prey was the tran­ scendent genius (but moral coward) Isaac Newton [231], whom he more than once reduced to distraction and finally drove to nervous breakdown. In theory Hooke half accomplished much. He worked out an imperfect wave 144

HOOKE

[223]

theory of light (which contradicted Newton and anticipated Huygens); he worked out an imperfect theory of gravi­ tation (which anticipated Newton); he speculated on steam engines, toward which the work of Papin [235], Savery [236], and Newcomen [243] was point­ ing. He speculated on the atomic compo­ sition of matter, anticipating Dalton [389]. He ventured into astronomy, too, and in 1664 discovered Gamma Arietis to be a double star. Only Riccioli [185] pre­ ceded him in the discovery of such ob­ jects. Hooke suggested, too, that earth­ quakes were caused by the cooling and contracting of the earth and that Jupiter rotated on its axis. His concrete accomplishments were in two fields: physics and biology. In phys­ ics he studied the action of springs and in 1678 enunciated what is now called Hooke’s law. This states that the force tending to restore a spring (or any elas­ tic system) to its equilibrium position is proportional to the distance by which it is displaced from that equilibrium posi­ tion. Earlier he had discovered that spi­ ral springs will expand and contract about an equilibrium position in equal periods regardless of the length of the inand-out swing. It was this discovery of what we now call the hairspring that made small and accurate timepieces pos­ sible and, by eliminating the bulky pen­ dulum, led ultimately to wristwatches and ship’s chronometers. In the field of biology Hooke was one of the most eminent microscopists. In 1665 he published a book, Micrographia, written in English rather than Latin. In it are to be found some of the most beautiful drawings of microscopic obser­ vations ever made. His studies of micro­ scopic fossils led him to speculate on evolutionary development. His studies of insects are unrivaled by anyone but Swammerdam [224] and he studied feathers and fish scales with an eye to beauty as well as to accuracy. At least some of the figures were supposedly drawn by Wren [220], the famous archi­ tect. The discovery for which Hooke is best remembered, however, is that of the

[224]

SWAMMERDAM

porous structure of cork. Under the mi­ croscope, a thin sliver of cork was found to be composed of a finely serried pat­ tern of tiny rectangular holes. These Hooke called cells. The name was a good one when applied to empty struc­ tures for it is used to signify a small room. These cells turned out to be the dead remnants of structures that in life are filled with a complex fluid. Living struc­ tures retained the name of cells, how­ ever, and Hooke’s word has become as important to biology, thanks to the in­ sight of Schleiden [538] and Schwann [563] a century and a half later, as Democritus’ [20] word “atom” has be­ come to chemistry and physics. Shortly after the publication of Micro­ graphie London burned down in the Great Fire of 1666. Hooke was busily engaged in rebuilding projects and never returned to his microscopy. [224] SWAMMERDAM, Jan (svahm'er-dahm) Dutch naturalist Born: Amsterdam, February 12, 1637 Died: Amsterdam, February 17, 1680 Swammerdam was the son of a phar­ macist whose hobby was a museum of curiosities. Young Swammerdam helped his father and acquired a devouring in­ terest in natural history. He studied med­ icine at Leiden University, where Steno [225] and Graaf [228] were fellow stu­ dents. He obtained his medical degree in 1667 but never practiced, preferring in­ stead to engage in microscopy. His father, who had originally in­ tended him for the priesthood, cut off support, but that did not stop Swammer­ dam’s work, although he allowed himself to become sickly and undernourished. He spent the last half of his short life in fits of melancholia, weakened by ma­ laria, and devoted to a religious cult. In the useful portion of his life he collected some three thousand species of insects and produced excellent studies of insect microanatomy. Some of his figures are as

STENO

[225]

good as anything produced after his time, and he may be considered the founder of modern entomology. He showed that muscles changed shape but not volume, thus demonstrating that they did not contract through an influx of an­ imal spirits by way of the nerves—one of Galen’s [65] notions. He also demon­ strated the detail of the reproductive or­ gans of insects, which tended to support Redi’s [211] disproof of their sponta­ neous generation. The discovery for which Swammer­ dam is most famous is that of the red blood corpuscle, which, we now know, is the oxygen-carrying structure of the blood. He announced this discovery in 1658, when he had barely reached his majority. His work was largely neglected until it was resurrected a half century later by Boerhaave [248]. [225] STENO, Nicolaus (stay'noh) Danish anatomist and geologist Born: Copenhagen, January 11, 1638 Died: Schwerin, Germany, De­ cember 5, 1686 Steno is the Latinized form of the Danish name Stensen, and the change is but a symptom of a more general one. Steno, the son of a well-to-do goldsmith, was brought up a Lutheran and trained as a physician, obtaining his medical de­ gree from Leiden in 1664. Eventually he became court physician to the Grand Duke Ferdinand II [193] of Tuscany. The change from Lutheran Denmark to Roman Catholic Italy resulted in a per­ sonal conversion to Catholicism and in that faith Steno rose to the position of bishop in 1677, after which, like Pascal [207] and Swammerdam [224], he aban­ doned science for religion. Steno’s most important concrete dis­ coveries were in anatomy. He recognized that muscles are composed of fibrils and described the duct of the parotid gland (the salivary gland located near the angle of the jaw)—still called the duct of Steno. Also he demonstrated the exis­ tence of the pineal gland in animals other than man. In a way this was an 145

[226]

GREGORY

embarrassing discovery, since he was a follower of the philosophy of Descartes [183] and his discovery of nonhuman pineals knocked out an important por­ tion of the Cartesian system of physiol­ ogy. Steno made a promising beginning in a completely different field. Fossils (a name invented by Agricola [132] to rep­ resent anything dug out of the earth) were still a geological mystery. Many of them resembled living things in every de­ tail (and, in fact, the word “fossil” is now applied only to these objects) and an explanation was needed. The easiest explanations for the religion-centered medieval mind were that these fossils were deceiving products of the devils, or “practice-creations” of God before he buckled down to the real business of cre­ ation, or the remains of animals drowned in Noah’s Flood. Steno, however, re­ verted to the speculations of a few Greek philosophers and suggested that they were ancient animals who had lived normal lives and in death were petrified, a point in which his contemporary Hooke [223] agreed with him. No super­ natural forces were brought into the ex­ planation. Steno also described rock strata in anticipation of William Smith [395] and held that tilted strata were originally horizontal. Steno also set forth what is now called the first law of crystallography: that the crystals of a specific substance have fixed characteristic angles at which the faces, however distorted they themselves may be, always meet. [226] GREGORY, James Scottish mathematician and as­ tronomer Born: Drumoak (near Aberdeen), November 1638 Died: Edinburgh, late October 1675 Gregory, the son of a minister, gradu­ ated from Marischal College in Aber­ deen. In 1663 he published the design of a perfectly good reflecting telescope. An attempt to have it constructed ended in 146

DENIS

[227]

failure, however, largely because the art of grinding glass into accurate curves had not yet been perfected, and Newton [231] constructed his, of somewhat dif­ ferent design, first. Gregory was an ardent astronomical observer and went blind, supposedly through the eyestrain involved in peering through his telescopes. He died young but lived to see Hooke [223], Newton’s inveterate enemy, build a reflecting tele­ scope of the Gregorian variety and pre­ sent it to the Royal Society. In mathematics Gregory was the first to study systematically the convergent series. (The word “convergent” in this connection is drawn from the lenses with which Gregory was accustomed to work.) Such a series has a finite sum al­ though it is made up of an infinite num­ ber of members (which, to be sure, steadily decrease in size). This broke the back of “Achilles and the Tortoise,” the twenty-one-century-old paradox of Zeno [16]. [227] DENIS, Jean Baptiste (duh-nee') French physician Born: Paris, 1640 Died: Paris, October 3, 1704 Denis was the son of one of the engi­ neers working for Louis XTV at Ver­ sailles. He himself may have studied medicine at the University of Mont­ pellier. The establishment of the circulation of the blood by Harvey [174] had set off new interest in anything related to blood. In particular the question arose as to whether blood could be transferred from one organism to another and whether blood from a healthy organism might not be beneficial to one that was sick. Richard Lower [219], for instance, at­ tempted the transfer of blood from one dog to another. Denis, on hearing of this work, was the first to involve human beings in such transfusion. On June 15, 1667, he trans­ fused the blood of a lamb (about twelve ounces’ worth) into an ailing young man, who seemed much the better for it.

[228]

GRAAF

Another man also survived transfusion from a sheep. Two other subjects died, however, and Denis was brought into court on the charge of murder. He was acquitted of that and the court decided that Denis was engaged in a legitimate medical effort to help people. Nevertheless (and wisely) they forbade such transfusions in future, and Denis quit the practice of medicine. It was not until the time of Land­ steiner [973] over two centuries in the future that enough was learned about blood to make transfusion a safe and beneficial procedure. [228] GRAAF, Regnier de Dutch anatomist Born: Schoonhoven, July 30, 1641 Died: Delft, August 17, 1673 Graaf was a student of Sylvius [196] at the University of Leiden and obtained his medical degree from the University of Angers, France, in 1665. One of his fellow students was Swammerdam [224] with whom, in later life, he had disputes over priority. Graaf studied the pancreas and gall bladder and is notable for having col­ lected the secretions those organs dis­ charge into the intestine, work he did without a microscope. He is better known, however, for his studies of the reproductive system. In 1668 he described the fine structure of the testicles and in 1673 of the ovary (a word he was the first to use). He de­ scribed particularly certain little struc­ tures of the ovary that are still called Graafian follicles in his honor, the name having been given them by Haller [278], As he suspected, he had penetrated to the beginning of life, for within those structures the individual ova or egg cells (not actually to be discovered until the time of Baer [478] a century and a half later) are formed. It was Graaf who first appreciated Leeuwenhoek [221] and introduced his work to the Royal Society. He died, still a young man, of the plague.

MAYOW

[230]

[229] GREW, Nehemiah English botanist and physician Born: Mancetter Parish, War­ wickshire, September 1641 Died: London, March 25, 1712 Grew was the only son of a clergyman who placed himself on the side of Parlia­ ment in the English Civil War. With the return of Charles II, the father lost his income and young Nehemiah’s studies at Cambridge were interrupted. He finally obtained his medical degree at the Uni­ versity of Leiden in the Netherlands in 1671. He was one of the early members of the Royal Society, serving as secretary in 1677 along with Hooke [223]. He turned his microscope on plants, studying their sexual organs in particu­ lar, including the pistils (feminine) and stamens (masculine). He observed the individual grains of pollen produced by the latter, which were the equivalent of the sperm cells in the animal world. He wrote a book on the stomachs and intes­ tines of various creatures in 1681 and, in a lecture before the Royal Society in 1676, was the first to use the term “com­ parative anatomy.” He also isolated magnesium sulfate from springs at Epsom, Surrey, and this compound has been called “Epsom salts” ever since. [230] MAYOW, John (may'oh) English physiologist Born: Bray, Berkshire, December 1641 Died: London, September 1679 Mayow was educated at Oxford, get­ ting his bachelor’s degree in 1665 and a doctorate in civil law in 1670. He also studied medicine. He may have worked for a time with Hooke [223]. He was one of the early investigators of gases. He wondered if there might not be some substance held in common by air and by saltpeter, since both en­ couraged combustion. Mayow compared respiration to com­ bustion. He suggested that breathing was something like puffing air at a fire; that the blood carried the combustive princi147

[231]

NEWTON

pie in air from the lungs to all parts of the body (and to the fetus by way of the placenta). He held that it was this combustive principle that turned dark venous blood into bright arterial blood. He was right, completely right, but he died young and there was no one to take up his theories and carry on. Further­ more, Stahl’s [241] phlogiston theory took the stage shortly after Mayow’s death and carried all before it—in the wrong direction. It was Lavoisier [334], a century after Mayow’s death, whose work established principles like those of Mayow firmly and permanently. [231] NEWTON, Sir Isaac English scientist and mathemati­ cian Born: Woolsthorpe, Lincolnshire, December 25, 1642 Died: London, March 20, 1727 Newton was a Christmas baby by the Julian calendar, but by the Gregorian (which we now use) he was bom on January 4, 1643. Newton, adjudged by many to have been the greatest intellect who ever lived, had an ill-starred youth. He was bom posthumously and prematurely (in the year in which Galileo [166] died) and barely hung on to life. His mother, mar­ rying again three years later, left the child with his grandparents. (The stepfa­ ther died while Newton was still a schoolboy.) At school he was a strange boy, interested in constructing mechani­ cal devices of his own design such as kites, sundials, waterclocks, and so on. He was curious about the world about him, but showed no signs of unusual brightness. He seemed rather slow in his studies until well into his teens and ap­ parently began to stretch himself only to beat the class bully, who happened to be first in studies as well. In the late 1650s he was taken out of school to help on his mother’s farm, where he was clearly the world’s worst farmer. His uncle, a member of Trinity College at Cambridge, detecting the scholar in the young man, urged that he 148

NEWTON

[231]

be sent to Cambridge. In 1660 this was done and in 1665 Newton graduated without particular distinction. The plague hit London and he retired to his mother’s farm to remain out of danger. He had already worked out the binomial theorem in mathematics, a de­ vice whereby the sum of two functions raised to a power could be expanded into a series of terms according to a simple rule. He was also developing the glim­ merings of what was later to become the calculus. At his mother’s farm something greater happened. He watched an apple fall to the ground and began to wonder if the same force that pulled the apple downward also held the moon in its grip. Kepler’s [169] laws had now, after half a century, come to be accepted, and New­ ton used them in his thoughts about the apple and the moon. (The story of the apple has often been thought a myth, but according to Newton’s own words, it is true.) Now, throughout ancient and medieval times, following the philosophy of Aris­ totle [29], it had been believed that things earthly and things heavenly obeyed two different sets of natural laws, particularly where motion was con­ cerned. It was therefore a daring stroke of intuition to conceive that the same force held both moon and apple. Newton theorized that the rate of fall was proportional to the strength of the gravitational force and that this force fell off according to the square of the distance from the center of the earth. (This is the famous “inverse square” law.) In comparing the rate of fall of the apple and the moon, Newton had to dis­ cover how many times more distant the moon was from the center of the earth than the apple was; in other words, how distant the moon was in terms of the earth’s radius. Newton calculated what the moon’s rate of fall ought to be considering how much weaker earth’s gravity was at the distance of the moon than it was on the surface of the planet. He found his cal­ culated figure to be only seven eighths of what observation showed it to be in ac­ tuality, and he was dreadfully disap­

[231]

NEWTON

pointed. The discrepancy seemed clearly large enough to make nonsense of his theory. Some have explained this discrepancy by saying that he was making use of a value of the earth’s radius that was a bit too small. If this was so, then he would calculate earth’s gravity as decreasing with distance a bit too rapidly and he would naturally find that the moon was dropping toward the earth at a rate somewhat less than was actually true. (The dropping of the moon is actually the amount by which its orbit deviates from the straight line. This drop is sufficient to keep it constantly in its orbit but of course not sufficient to make it approach any closer to the earth in the long run.) Others think Newton retreated because he wasn’t sure it was right to calculate the distance from the center of the earth in determining the strength of the gravi­ tational force. Could the earth’s large globe be treated as though it attracted the moon only from its center? He was not to be reassured on that point until he had worked out the mathematical tech­ nique of the calculus. This second reason is much more probable, but whatever the reason, New­ ton put the problem of gravitation to one side for fifteen years. In this same period, 1665-66, Newton conducted startling optical experiments, inspired in that direction, perhaps, when he read a book by Boyle [212] on color. Kepler’s writings on optics had roused his interest. Newton let a ray of light enter a darkened room through a chink in a curtain and pass through a prism of glass onto a screen. The light was re­ fracted, but different parts of it were refracted to different extents, and the beam that fell on the screen was not merely a broadened spot of light, but a band of consecutive colors in the famil­ iar order of the rainbow: red, orange, yellow, green, blue, and violet. It might have been thought that these colors were created in the prism, but Newton showed they were present in the white light itself and that white light was only a combination of the colors. He did this by passing the rainbow or “spec­

NEWTON

[231]

trum” through a second prism oriented in reverse to the first, so as to recombine the colors, and, behold, a spot of white light appeared on the screen. If a second prism were placed so that only one band of color fell upon it, that band of color might be broadened or contracted, de­ pending on the orientation of the prism, but it remained a single color. (Nobody knows exactly why Newton did not report the dark lines that mark the spectrum. Some of his experiments were so conducted that a few of the lines must have been visible. However, he had an assistant run some of the experiments because his own eyes were insufficiently keen, and it may be that the assistant saw the lines but did not consider them sufficiently important to report. At any rate, the discovery, which turned out to be of first importance, had to wait a cen­ tury and a half for Wollaston [388] and Fraunhofer [450].) Newton’s prism experiments made him famous. In 1667 he returned to Cam­ bridge and remained there for thirty years. In 1669 his mathematics teacher resigned in his favor and Newton at twenty-seven found himself Lucasian professor of mathematics at Cambridge. (The chair was named after Henry Lucas, who originally provided the money to found the professorship.) A special ruling by the Crown made it un­ necessary for him to enter the church to hold his job. He only gave about eight lectures (rather poor ones) a year. The rest was research and thought. He was elected to the Royal Society in 1672 and promptly reported his experi­ ments on light and color to the Society— and as promptly fell afoul of Robert Hooke [223]. Hooke had performed some experi­ ments with light and prisms but typically had never carried them through to a de­ cent conclusion and had evolved only half-baked explanations. Nevertheless he attacked Newton at once and maintained a lifelong enmity, clearly founded on jealousy. Even if the greatest intellect that the world has produced, Newton was other­ wise a rather poor specimen of man. He never married and except for a mild 149

[231]

NEWTON

youthful romance never seemed to show any signs of knowing or caring that women exist. He was ridiculously absentminded and perpetually preoccupied with matters other than his immediate surroundings. He was also extremely sen­ sitive to criticism and childish in his re­ action to it. More than once he resolved to publish no more scientific work rather than submit to criticism. In 1673 he even tried to resign from the Royal Society in a fit of petulance and though the resigna­ tion was not accepted, relations between Newton and the Society remained cold. But Newton’s hatred of criticism did not prevent his being just as contentious as Hooke, though in a less forthright manner. He himself avoided controversy, allowing his friends to bear the brunt of the battle, secretly urging them on, mak­ ing no move either to protect them or to concede a point. Newton and Leibniz [233] developed the calculus independently and at about the same time. For years this seemed to make no difference and Newton and Leibniz were friendly, but as the fame of both men grew some people substituted “patriotism” for sense. Newton had, as usual, delayed publication, which unnec­ essarily confused matters. It began to seem a great point as to whether an Englishman or a German had made the discovery and a battle began over which of the two men had stolen the idea from the other. Neither had stolen the idea. Both were first-rate intellects capable of discovering the calculus, especially since this branch of mathematics was very much in the air and had been all but discovered a half century before by Fermat [188], But the battle continued with Newton secretly urging his followers on. The calculus is an indispensable tool in science, but English mathematicians shibbomly continued to utilize Newton’s notation even though that of Leibniz was much more convenient. Thus they cut themselves off from Continental advance in mathematics, and English mathemat­ ics remained moribund for a century. Newton’s experiments with light and color led him to theorize on the nature of light. Some scientists believed that 150

NEWTON

[231]

light, like sound, consisted of a wavelike periodic motion. The ubiquitous Hooke was one and Huygens [215] another. To Newton, however, the fact that light rays moved in straight lines and cast sharp shadows was decisive. Sound, a wave form, worked its way about obstacles so that you could hear around comers. Light does not and you cannot see around comers without a mirror. New­ ton agreed with Democritus [20], there­ fore, that light consisted of a stream of particles moving from the luminous ob­ ject to the eye. The particle theory of light was by no means cut-and-dried. Grimaldi [199] showed that light did bend around obsta­ cles to a very small extent, and that was hard to explain by particles. Then there was the double refraction of light discov­ ered by Bartholin [210] and that was even harder to explain. In attempting to handle such matters Newton developed thoughts that were quite sophisticated for the time. Actually, the modern theory of light harks back in some in­ teresting ways to Newton. Newton’s fol­ lowers, however, dropped most of the so­ phistication and revised his theory into a straightforward matter of speeding parti­ cles. This maintained its sovereignty over the competing wave theory for a cen­ tury, thanks to Newton’s prestige. (Dur­ ing the eighteenth and even into the nineteenth century Newton’s name some­ times carried the deadweight effect that Aristotle’s had in the sixteenth and sev­ enteenth.) It seemed to Newton that there was no way of preventing spectrum formation when light passed through prisms or lenses. It was for this reason that the refracting telescopes of the time were reaching their limits. It was no use mak­ ing them larger and expecting greater magnification. Light passing through the lenses cast confusing colored rims about the images of the heavenly bodies and blurred out detail—a phenomenon called “chromatic aberration.” Therefore Newton in 1668 devised a “reflecting telescope” that concentrated light by reflection from a parabolic mir­ ror, rather than by refraction through a lens. In this he was anticipated in theory

[231]

NEWTON

but not in practice by James Gregory [226], This reflecting telescope had two ad­ vantages over the refracting telescope. In Newton’s device, light did not actually pass through glass but was reflected off its surface so that there was no light ab­ sorption by the glass. Secondly, the use of the mirror eliminated chromatic aber­ ration. The reflecting telescope was a great advance. Newton’s first telescope was six inches long and one inch in diameter, a mere toy, but it magnified thirty to forty times. He built a larger one, nine inches long and two inches in diameter, in 1671 and demonstrated it to King Charles II, then presented it to the Royal Society, which chose this as the occasion for electing him to membership and which still preserves it. Hooke promptly pre­ pared one according to Gregory’s some­ what different design, but it wasn’t nearly as good as Newton’s. The largest modem telescopes are of the reflecting variety. And yet Newton was wrong just the same. It was possible to have a refracting telescope without chromatic aberration and not long after Newton’s death Dollond [273] built one. The 1680s proved the climax of New­ ton’s life. In 1684 Hooke met Wren [220] and Halley [238] and boasted in his obnoxiously positive way that he had worked out the laws governing the mo­ tions of the heavenly bodies. Wren was not impressed by Hooke’s explanation and offered a prize for anyone who could solve the problem. Halley, who was a friend of Newton, took the problem to him and asked him how the planets would move if there was a force of attraction between bodies that weakened as the square of the distance. Newton said at once, “In ellipses.” “But how do you know?” “Why, I have calculated it.” And Newton told of his theoretical specula­ tions during the plague year of 1666. Halley in a frenzy of excitement urged Newton to try again. Now things were different. Newton knew of a better figure on the radius of the earth, worked out by Picard [204], In addition he had worked out the calcu­

NEWTON

[231]

lus to the point where he could calculate that the different parts of a spherical body (with certain conditions of den­ sity) would attract in such a way that the body as a whole would behave as though all the attraction came out of the center. As he repeated his old calculations, it appeared that this time the answer would come out right. He grew so excited at the possibility (according to one story) that he was forced to stop and let a friend continue for him. Newton began to write a book em­ bodying all this, completing it in eigh­ teen months and publishing it in 1687. He called it Philosophiae Naturalis Principia Mathematica (“Mathematical Prin­ ciples of Natural Philosophy”) and it is usually known by the last two words of the title. It was written in Latin and did not appear in English until 1729, fortytwo years after its original publication and two years after Newton’s death. It is generally considered the greatest scientific work ever written. Laplace [347] considered it so, for instance, and Laplace was no more inclined to give credit to others than Newton himself was. Despite his invention of the calcu­ lus, Newton proved the propositions in this book by geometrical reasoning in the old-fashioned way. It was the last great work of science written in the Greek style. In the book Newton codified Galileo’s findings into the three laws of motion. The first enunciated the principle of iner­ tia: a body at rest remains at rest and a body in motion remains in motion at a constant velocity as long as outside forces are not involved. This first law of motion confirmed Buridan’s [108] sug­ gestion of three centuries before and made it no longer necessary to suppose that heavenly bodies moved because an­ gels or spirits constantly impelled them. They moved because nothing existed in outer space to stop them after the initial impulse. (What produced the initial im­ pulse is, however, still under discussion nearly three centuries after Newton.) The second law of motion defines a force in terms of mass and acceleration and this was the first clear distinction be­ 151

[231]

NEWTON

NEWTON

tween the mass of a body (representing its resistance to acceleration; or, in other words, the quantity of inertia it pos­ sessed) and its weight (representing the amount of gravitational force between it­ self and another body, usually the earth). Finally the famous third law of mo­ tion states that for every action there is an equal and opposite reaction. That law makes news today, since it governs the behavior of rockets. Newton considered the behavior of moving bodies both in vacuum and in media that offered resis­ tance. In connection with the latter situa­ tion, he foreshadowed modem aeronau­ tics. From the three laws Newton was able to deduce the manner in which the grav­ itational force between the earth and the moon could be calculated. He showed that it was directly proportional to the product of the masses of the two bodies and inversely proportional to the square of the distance between their centers. The proportionality could be made an equality by the introduction of a con­ stant. The equation that resulted is a fa­ mous one: Gmtm2 F —

c ? -

where mx and m2 are the masses of the earth and the moon, d the distance be­ tween their centers, G the gravitational constant, and F the force of gravitational attraction between them. It was an additional stroke of tran­ scendent intuition that Newton main­ tained that this law of attraction held be­ tween any two bodies in the universe, so that his equation became the law of uni­ versal gravitation. It remained for Cav­ endish [307] a century later to deter­ mine the value of G and, therefore, the mass of the earth, but Newton guessed that mass quite accurately and then es­ timated the mass of Jupiter and Saturn at nearly the correct value. It quickly became apparent that the law of universal gravitation was ex­ tremely powerful and could explain the motions of the heavenly bodies as they were then known. It explained all of Kepler’s laws. It accounted for the 152

[231]

precession of the equinoxes. The various irregularities in planetary motions were seen to be the result of their minor at­ tractions (perturbations) for each other superimposed on the gigantic attraction of the sun. It even accounted for the complex variations in the motion of the moon. (This motion, which Kepler had not been able to deal with, was the only problem that Newton used to admit made his head ache.) Newton even in­ cluded a drawing in his book to illustrate the manner in which gravitation would control the motion of what we today call an artificial satellite. Newton’s great book was published in an edition of only twenty-five hundred copies, but it was well accepted and its value was recognized at once by many scientists. It represented the culmination of the Scientific Revolution that had begun with Copernicus [127] a century and a half earlier. Newton made the Scientific Revolution more than a matter of mere measurement and equations that theoretical philosophers might dismiss as unworthy to be compared with the grand cosmologies of the ancients. Newton had matched the Greeks at their grandest and defeated them. The Principia Mathematica developed an overall scheme of the universe, one far more elegant and enlightening than any the ancients had devised. And the New­ tonian scheme was based on a set of as­ sumptions, so few and so simple, devel­ oped through so clear and so enticing a line of mathematics that conservatives could scarcely find the heart and courage to fight it. It excited awe and admiration among Europe’s scholars. Huygens, for example, traveled to England for the ex­ press purpose of meeting the author. Newton ushered in the Age of Reason, during which it was the expectation of scholars that all problems would be solved by the acceptance of a few axioms worked out from careful observa­ tions of phenomena, and the skillful use of mathematics. It was not to prove to be as easy as all that, but for the eigh­ teenth century at least, man gloried in a new intellectual optimism that he had never experienced before and has never experienced since.

[231]

NEWTON

Newton’s book, however, was not pub­ lished without trouble. The Royal Soci­ ety, which was to publish it, was short of funds and Hooke was at his most dispu­ tatious in claiming priority and pointing out he had written a letter to Newton on the subject six years earlier. Newton, brought to the extremes of exasperation, was finally forced (much against his rather ungenerous nature) to include a short passage referring to the fact that Hooke, Wren, and Halley had inferred certain conclusions that now Newton was to expound in greater detail. Even so the Royal Society, then under the presidency of none other than Samuel Pepys, the diarist, refused to involve it­ self in what might be a nasty controversy and backed out of its agreement to pub­ lish. Fortunately Halley, who was a man of means, undertook to pay all expenses of publication, arranged for illustrations, read galley proofs, and labored like a Trojan to keep Hooke quiet and New­ ton’s ever-sensitive nature mollified. When the book appeared, men of science rallied to the new view. David Gregory [240], the nephew of the man who had anticipated the reflecting telescope, was among the first. But continual controversy was wreak­ ing havoc with Newton, as was the terrific strain of his mental preoccu­ pations. (When asked by Halley how it was he made so many discoveries no other man did, Newton replied that he solved problems not by inspiration or by sudden insight but by continually think­ ing very hard about them until he had worked them out. This was no doubt true and if there were such a thing as mental perspiration, Newton must have been immersed in it. What’s more, he detested distractions and once scolded Halley for making a joking remark.) As though his work in mathematics and physics were not enough, Newton spent much time, particularly later in life, in a vain chase for recipes for the manufacture of gold. (He was an ardent believer in transmutation and wrote half a million worthless words on chemistry.) He also speculated endlessly on theolog­ ical matters and produced a million and

NEWTON

[231]

a half useless words on the more mysti­ cal passages of the Bible. Like Kepler, he calculated the day of creation and set it about 3500 b .c ., mak­ ing the earth five centuries younger than Kepler had done. It was not till Hutton’s [297] time, a century later, that science was freed from enslavement to biblical chronology. Apparently Newton ended with Uni­ tarian notions that he kept strictly to himself, for he could not have remained at Cambridge had he openly denied the divinity of Christ. In any case in 1692 his busy mind tot­ tered. He had a nervous breakdown and spent nearly two years in retirement. His breakdown, according to a famous tale, may have been hastened by a mishap in which Newton’s dog Diamond upset a candle and burned years of accumulated calculation. “Oh, Diamond, Diamond,” moaned poor Newton, “thou little knowest the mischief thou hast done.” (Alas, this affecting story is probably not true. It is doubtful that Newton ever even owned a dog.) Newton was never quite the same, though he was still worth ten ordinary men. In 1696, for example, a Swiss mathematician challenged Europe’s schollars to solve two problems. The day after Newton saw the problems he for­ warded the solutions anonymously. The challenger penetrated the disguise at once. “I recognized the claw of the lion,” he said. In 1716, when Newton was seventy-five, a problem was set forth by Leibniz for the precise purpose of stumping him. Newton solved it in an af­ ternoon. In 1687 Newton defended the rights of Cambridge University against the un­ popular King James II, rather quietly, to be sure, but effectively. As a result he was elected a member of Parliament in 1689 after James had been overthrown and forced into exile. He kept his seat for several years but never made a speech. On one occasion he rose and the House fell silent to hear the great man. All Newton did was to ask that a win­ dow be closed because there was a draft. Through the misguided efforts of his friends he was appointed warden of the 153

[231]

NEWTON

mint in 1696 with a promotion to master of the mint in 1699. This placed him in charge of the coinage at a generous sal­ ary, so that after his death he could leave an estate of over £.30,000. It was considered a great honor and only New­ ton’s due, but since it put an end to Newton’s scientific labors, it can only be considered a great crime. Newton re­ signed his professorship to attend to his new duties and threw himself into them with such vigor and intelligence that he revolutionized its workings for the better and became a terror to counterfeiters. He appointed his friend Halley to a posi­ tion under himself. In 1703 Newton was elected president of the Royal Society (only after Hooke’s death, be it noted) and he was reelected each year until his death. In 1704 he wrote Opticks, summarizing his work on light—having carefully waited for Hooke’s death here, too. Opticks, unlike the Principia, was written in English but it was soon translated into Latin so that Europeans outside Great Britain might read it. In 1705 he was knighted by Queen Anne. He had turned gray at thirty but his faculties remained sound into old age. At eighty he still had all his teeth, his eye­ sight and hearing were sharp, and his mind undimmed. Nevertheless, his duties at the mint neutralized this maintenance of vigor and prevented him from prepar­ ing a second edition of the Principia till 1713. Newton was respected in his lifetime as no scientist before him (with the pos­ sible exception of Archimedes [47]) or after him (with the possible exception of Einstein [1064]). When he died he was buried in Westminster Abbey along with England’s heroes. The great French liter­ ary figure Voltaire [261], who was visit­ ing England at that time, commented with admiration that England honored a mathematician as other nations honored a king. The Latin inscription on his tomb ends with the sentence “Mortals! Rejoice at so great an ornament to the human race!” Even so, national prejudices had their influence and outside Great Britain there was some reluctance to accept the 154

ROEMER

[232]

Newtonian system. It took a generation for it to win final victory. Newton had the virtue of modesty (or, if he did not, had the ability to assume it). Two famous statements of his are well known. He wrote, in a letter to Hooke in 1676, “If I have seen further than other men, it is because I stood on the shoulders of giants.” He also is sup­ posed to have said, “I do not know what I may appear to the world; but to myself I seem to have been only like a boy play­ ing on the seashore, and diverting myself in now and then finding a smoother peb­ ble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me.” However, other men of Newton’s time stood on the shoulders of the same giants and were boys playing on the same sea­ shore, but it was only Newton, not an­ other, who saw further and found the smoother pebble. It is almost imperative to close any discussion of Newton with a famous couplet by Alexander Pope: Nature and Nature’s laws lay hid in night: God said, Let Newton be! and all was light. and with a verse by William Wordsworth who, on contemplating a bust of New­ ton, found it to be The marble index of a mind forever Voyaging through strange seas of thought, alone. [232] ROEMER, Olaus (roi'mer) Danish astronomer Born: Arhus, Jutland, September 25, 1644 Died: Copenhagen, September 19, 1710 Roemer, the son of a shipowner, stud­ ied astronomy at the University of Co­ penhagen under Bartholin [210], whom he also served as secretary; but his great achievement came in Paris. It seems that in 1671 the French astronomer Picard [204] traveled to Denmark in order to

[232]

ROEMER

visit the old observatory of Tycho Brahe [156], He wished to determine its exact latitude and longitude in order to recal­ culate if necessary Tycho’s observations of a century before. While there he uti­ lized the services of young Roemer as an assistant and impressed by him brought him back to Paris. In Paris, Roemer made his mark by carefully observing the motions of Ju­ piter’s satellites. Their times of revolu­ tion were accurately known, thanks to Cassini [209], another of Picard’s im­ ports. Because of this it was theoretically possible to predict the precise moment at which they would be eclipsed by Jupiter (as viewed from the earth). To Roemer’s surprise the eclipses came progressively earlier at those times of the year when the earth was ap­ proaching Jupiter in its orbit, and pro­ gressively later when it was receding from Jupiter. He deduced that light must have a finite velocity (though Aristotle [29] and, in Roemer’s own time, Des­ cartes [183] had guessed the velocity to be infinite) and that the eclipses were delayed when the earth and Jupiter were farthest apart because it took light sev­ eral minutes to cross the earth’s orbit. All previous attempts to determine the speed of light had failed. Galileo [166] had attempted to measure it by station­ ing an assistant on a hill with a lantern and himself on another hill with a lan­ tern and flashing lights back and forth. But the time lag between the flashing of one lamp and seeing the flash of the other in response seemed entirely due to the time it took a human being to react to a stimulus. There was no change in this lag when hills separated by greater distances were used. What Roemer had were two “hills” that were separated by some half a bil­ lion miles (earth and Jupiter) and a light flash (the moment of satellite eclipse) that did not involve human reac­ tion times. He calculated the velocity of light to be (in modem units) 227,000 ki­ lometers per second. Although this value is too small (the accepted modem value is 299,792 kilometers per second) it cer­ tainly was not bad for a first attempt.

LEIBNIZ

[233]

Roemer announced the calculation at a meeting of the Academy of Sciences in Paris in 1676. Although nowadays the velocity of light is considered one of the fundamental constants of the universe, this first announcement made no great splash. Picard backed his young protégé, as did Huygens [215], but the conser­ vative Cassini was opposed. In England, Halley [238], Flamsteed [234], and New­ ton [231] favored it, but on the whole the matter faded out of astronomical consciousness until Bradley [258] a half century later proved the finite velocity of light in a new and still more dramatic fashion. However, Roemer’s work in general was highly regarded. He visited England in 1679, meeting Newton, Flamsteed, and Halley, and in 1681 he was called back to Copenhagen by King Christian V to serve as astronomer royal and as professor of astronomy at the University of Copenhagen. There he reformed the Danish system of weights and measures and introduced the Gregorian calendar. In 1705 he was mayor of Copenhagen. The record of his extensive observa­ tions from Copenhagen was lost in 1728 in a fire that swept the city. [233] LEIBNIZ, Gottfried Wilhelm (lipe'nits) German philosopher and mathe­ matician Born: Leipzig, Saxony, July 1, 1646 Died: Hannover, November 14, 1716 Leibniz, the son of a professor of phi­ losophy who died when the boy was six, was an amazing child prodigy whose uni­ versal talents persisted throughout his life. Indeed, his attempt to do everything prevented him from being truly first class at any one particular thing. He has been called the Aristotle [29] of the seventeenth century and was perhaps the last to take—with reasonable success— all knowledge for his province. He began quite young, teaching him­ self Latin at eight and Greek at fourteen. 155

[233]

LEIBNIZ

He obtained a degree in law in 1665 and, in addition, was a diplomat, philos­ opher, political writer, and an attempted reconciler of the Catholic and Protestant churches. As a diplomat he tried to dis­ tract Louis XIV from a prospective inva­ sion of Germany by suggesting a cam­ paign against Egypt instead. Louis XIV didn’t bite, but a century later Napoleon did. Leibniz also acted on occasion as adviser to Peter the Great, tsar of Rus­ sia. He was an atomist after the style of Gassendi [182] and tackled mathematics seriously after his travels brought him into contact with such men as Huygens [215] who introduced him to the mathe­ matical treatment of the pendulum. In 1671 he devised a calculating machine superior to that of Pascal [207], a ma­ chine that could multiply and divide as well as add and subtract. He was also the first to recognize the importance of the binary system of notation (making use of 1 and 0 only). (This is important in connection with modern computers.) Even earlier, in 1667, he had at­ tempted to work out a symbolism for logic. It was imperfect but it anticipated the work of Boole [595] two centuries later, in many ways. As a result, when Leibniz visited Lon­ don in 1673, where he met Boyle [212], he was elected a member of the Royal Society. In that same year he began to think of a system of the calculus, which he pub­ lished in 1684. This eventually aroused a strenuous controversy between himself and the admirers of Newton [231], with Newton himself participating secretly. In fact, Newton all but accused Leibniz of plagiarism in the second edition of the Principia. Leibniz’s activity as a diplomat had been (of necessity) shady enough to make his word suspect to the furious Newtonians, and his contact with En­ glish mathematicians in 1673 seemed all the proof of plagiarism they needed. However, there seems no doubt now that his work was independent of Newton and, in any case, his line of development of the calculus was the superior. The ter­ minology and form first advanced by 156

FLAMSTEED

[234]

Leibniz is currently preferred to New­ ton’s. Leibniz also introduced the use of determinants into algebra. In 1693 he recognized the law of con­ servation of mechanical energy (the en­ ergy of motion and of position). A cen­ tury and a half later this was to be gen­ eralized by men such as Helmholtz [631] to include all forms of energy. Leibniz was also the first to suggest an aneroid barometer that would measure air pres­ sure against a thin metal diaphragm without the inconvenience of Torricelli’s [192] column of mercury. In 1700 Leibniz induced King Fred­ erick I of Prussia to match the Royal Society in London and the Academy of Sciences in Paris by founding the Acad­ emy of Sciences in Berlin and this has been a major scientific body ever since. Leibniz served as its first president. In 1700 also, he and Newton were elected (admirable neutrality of the French!) the first foreign members of the Parisian Academy of Sciences. For forty years Leibniz served the electors of Hannover. In 1710 Leibniz published, in French, a book in which he tried to demonstrate that this was the “best of all possible worlds” to use the now popular phrase. Surely, though, Leibniz must have found that hard to believe in his last few years, and after his death this view was mer­ cilessly satirized by Voltaire [261] in his Candide. In 1714 the then elector of Hannover succeeded to the throne of Great Britain as George I, and Leibniz was eager to go with him to London. But the new king had no need of him and perhaps did not wish to offend the Newton partisans in his new kingdom. Leibniz died in Hannover, neglected and forgotten, with only his secretary at­ tending the funeral. Like his great adver­ sary, Newton, Leibniz had never married and had no family. [234] FLAMSTEED, John English astronomer Born: Denby, Derbyshire, August 19, 1646 Died: Greenwich, near London, December 31, 1719

[234]

FLAMSTEED

When only fifteen, Flamsteed, the son of a prosperous dealer in malt, was forced by bad health out of school and into the hobby of reading astronomy. He was the gainer thereby, for he grew in­ terested enough to begin to construct in­ struments and by 1670 had published some astronomical work that attracted attention. In that year he became ac­ quainted with Newton [231] and entered Cambridge. England more than any other nation was interested in improving navigational procedures, since her merchant fleet was becoming the largest in the world. Any scheme for accurate determination of longitude at sea was of interest to the government. Flamsteed was one of those called upon to pass on a method for determin­ ing longitude that had been suggested, but he shook his head. No method would work, he decided, until such time as a map of the stars more accurate than any existing was prepared. He was among those who petitioned King Charles II for the establishment of a na­ tional observatory to take care of that job. Charles II reacted favorably and had one established at Greenwich, a London suburb, putting Flamsteed in charge. Flamsteed thus became the first astrono­ mer royal, beginning work in 1675. The job was no sinecure. The king had provided the building but had supplied only a tiny salary, with no provision for assistants or instruments. Flamsteed had to build his own instruments or beg the funds with which to have them built. He had to tutor on the side to support him­ self. Fortunately he was a bear for work, making innumerable observations and then performing all the calculations nec­ essary to reduce them to useful values, work that would ordinarily be the rou­ tine functions of assistants. He used a clock systematically in his observations, the first astronomer to do so. On top of low pay (two pounds a week), no help, and poor health Flam­ steed’s perfectionism brought him into conflict with the great astronomers of the

FLAMSTEED

[234]

time. Men like Newton felt it was Flam­ steed’s function to serve as general astro­ nomical flunky, making and handing over any observations that were called for and doing it at once. Flamsteed had with justification a more exalted notion of his position and grew rebellious at Newton’s unending demands. Newton was quite incapable of seeing another man’s point of view and the two became enemies. Newton took a rather mean re­ venge by omitting certain credits to Flamsteed in the second edition of the Principia. Flamsteed was pressed to publish his work as quickly as possible, but he re­ fused to do so until he was all finished, and considering the perfectionism with which he worked, the date at which he would be all finished kept receding into the future in exasperating fashion. Fi­ nally, in 1708, Newton’s friend Halley [238] managed to get his hands on a number of Flamsteed’s observations and published them at once with the Prince Consort, George of Denmark, under­ taking the cost of printing. Flamsteed was furious. He called Halley violent names, accused him of irreligion and im­ morality—yet the two had originally been friends and Halley had helped in the design and construction of the obser­ vatory. Flamsteed burned every copy of the work he could find (at least three hundred). This incident spurred him on to com­ pletion, however, and eventually his star catalogue came out in full (though part of it appeared only after his death). It was three times as large as Tycho Brahe’s [156] and the individual stars were located (thanks to the telescope) with six times the precision. It was the first great star map of the telescopic age. When two centuries after his time the nations of the world agreed on an inter­ national system of marking off meridians of longitude (an offshoot of the problem that got Flamsteed his post in the first place), it was agreed that the meridian of the observatory at Greenwich be the starting place. It is at Longitude 0°0'0" (the Prime Meridian), and that is a kind of monument to the first astronomer royal. 157

[235]

PAPIN

[235] PAPIN, Denis (pa-pan') French physicist Born: Coudraies, near Blois, Loire-et-Cher, August 22, 1647 Died: London, England, early 1712 Papin studied medicine in his youth and obtained his medical degree in 1669 at Angers, but that is not the field in which he gained his fame. He served as assistant to Huygens [215] in 1671 and in 1674 helped introduce improvements in Boyle’s [212] air pump. Papin corre­ sponded with Leibniz [233] who intro­ duced Papin’s work to Boyle. In conse­ quence Papin went to England as Boyle’s assistant in 1675. In 1679 he developed a steam digester, in which water was boiled in a vessel with a tightly fitted lid. The accumu­ lating steam created a pressure that raised the boiling point of water and at this higher temperature, bones softened and meat cooked in quick time. A safety valve was included in case steam pres­ sure got too high. This digester was the forerunner of the modem pressure cooker, and it earned Papin membership in the Royal Society in 1680. He cooked a meal for the Royal Society in his digester and prepared a particularly im­ pressive one for King Charles II. The steam pressure within the digester must have given Papin the notion of making steam do work. He placed a lit­ tle water at the bottom of a tube and, by heating it, converted it to steam. This ex­ panded forcibly, pushing a piston ahead of it. Fifteen centuries after Hero [60], men were once again toying with steam, but this time the matter was to be fol­ lowed up and a century later reach a cli­ max with Watt [316], Papin never returned to France where, as a Protestant, he would have found the atmosphere unpleasant, thanks to the growing intolerance of Louis XIV. Papin spent some years in Italy, then in Ger­ many. where he built a steam engine in 1698. In his last years, he returned to England, where he died in obscurity and poverty. 158

HAVERS

[237]

[236] SAVERY, Thomas English engineer Born: Shilstone, Devonshire, about 1650 Died: London, May 1715 Savery, a military engineer, was a prolific inventor and he lived at a time when one particular invention was badly needed. England was deforested and what trees remained were needed for the navy and could not be used indis­ criminately for fuel. Fortunately En­ gland could use its deposits of coal. However, water seeps into coal mines and pumping this out by hand (or even by animal power) was arduous and slow. Guericke [189] had shown that air pressure could do wonders if a vacuum was produced, but producing one by an air pump worked by hand was also ardu­ ous and slow. It occurred to Savery that a vacuum could be produced by filling a vessel with steam and then condensing the steam. Burning fuel would then sup­ ply all the necessary energy and human muscle could be conserved. He con­ nected such a vessel to a tube running down into the water in the mine. The vacuum produced in the vessel would suck water some way up the tube and then steam pressure, after the principle of Papin [235], could be used to blow the water out altogether. This instrument, which Savin called the Miner’s Friend, was the first practi­ cal steam engine and about 1700 it was actually in use in a few places. Its great drawback was that it used steam under high pressure and the technology of the time was insufficient for the manufacture of vessels that could really handle it safely. [237] HAVERS, Clopton (hav'erz) English physician Born: Stambourne, Essex, about 1655 Died: Willingale, Essex, April 1702 Havers, the son of a rector, entered Cambridge in 1668 but did not graduate.

[238]

HALLEY

He did not get a full license to practice medicine until 1687, after having re­ ceived a medical education at the Uni­ versity of Utrecht in the Netherlands. The mark he made in medicine lay in the first full and complete study of bone structure. The text he published in 1691 on the subject remained standard for a century and a half. The Haversian canals in the bone are named for him. [238] HALLEY, Edmund English astronomer Born: Haggerston, near London, November 8, 1656 Died: Greenwich, January 14, 1742 Interested in astronomy from his school days, Halley, the son of a wealthy businessman, published work on Kepler’s laws when he was nineteen; and then, with Flamsteed’s [234] encouragement, set off in 1676 to record the stars of the southern hemisphere. All astronomers until his time had been based in the northern hemisphere and except for the reports of mariners and travelers the southern heavens were virgin territory. Halley established the first observatory of the southern hemisphere at the island of St. Helena in the South Atlantic (to become famous a century and a half later as the last home of Napoleon Bona­ parte). He discovered an object in Cen­ taurus that was eventually found to be a huge globular cluster of stars, Omega Centauri, closest of all such clusters to ourselves. As it turned out, though, St. Helena had a poor climate for astronomical ob­ servations and when Halley returned in 1678 he was only able to publish a cata­ logue of 341 southern stars. This was nevertheless a new and worthy addition to star lore and made his reputation. He was called the southern Tycho [156], was awarded a master’s degree from Ox­ ford despite his not having fulfilled all the requirements, and was elected to the Royal Society. In England he became a fast and en­ during friend of Newton [231] in 1684

HALLEY

[238]

and it was through Halley’s encour­ agement and financial help that the Principia was published. (Halley’s father had been found murdered in 1684 and Hal­ ley inherited a tidy sum and was well-todo thereafter.) Halley’s fame grew and he dined with Peter the Great of Russia during that monarch’s visit to England. Halley, ac­ cording to all reports, had a joyous and riotous time of it. Newton’s principle of gravitation ap­ plied easily and well to the various planets and even to the moon, but it was doubtful how well it applied to those outlaws of the skies, the comets, that seemed to come and go as they pleased. Halley (who, in 1703, was appointed professor of geometry at Oxford) addressed himself to this problem and with Newton’s help compiled records of numerous comets, working out their paths across the sky. (In 1679 Halley had visited the aged Hevelius [194], then the recognized authority on comets, and this may have inspired his interest in the problem.) One of the comets Halley dealt with was that of 1682, which he had person­ ally observed. By 1705, when he had listed the movements of two dozen comets, he was struck by the similarity of the path of the 1682 comet with those that had appeared in 1456, 1531, and 1607. These four had come at intervals of seventy-five or seventy-six years and it occurred to Halley that what he was dealing with was a single comet in a closed but very elongated orbit about the sun that was visible only when it was relatively close to the earth. Between ap­ pearances it must recede far beyond Sat­ urn, the most distant planet then known. Halley predicted, in a book written in 1705, that this same comet would return again about 1758, though he was aware that the gravitational interference of the planets might alter the orbit somewhat and change the time of appearance. (Clairaut [283] later showed this to be true.) Although Halley did not live long enough to witness the return of the comet (he would have had to live to the 159

[238]

HALLEY

age of one hundred and two to do so, in­ stead of dying at eighty-six, in the cen­ tennial year of Newton’s birth), it re­ turned as predicted, allowing for Clairaut’s changes. It has been known as Halley’s comet ever since. It has re­ turned again in 1835 and in 1910 and, it is confidently expected, will return once more in 1986. Through Halley’s work the comets were tamed once and for all and were shown to be as much subjects of the sun as the earth itself. If cometary motions seemed erratic it was only because come­ tary orbits were so elongated that some might appear only at intervals of many thousands of years and remain visible during only minute portions of their total orbit. Halley repeated the suggestion of Kepler [169] that the transit of Venus be used to determine the scale of the solar system and this suggestion bore success­ ful fruit after Halley’s death. He also traveled widely about the turn of the century measuring magnetic varia­ tions. And in a completely different field, he was the first (in 1693) to prepare de­ tailed mortality tables. This made it pos­ sible to study life and death statistically and led to modem insurance practices. In 1718 he pointed out that at least three stars, Sirius, Procyon, and Arcturus, had changed their positions mark­ edly since Greek times and had even changed position perceptibly since the time of Tycho Brahe a century and a half earlier. From this he concluded that stars had proper motions of their own which were perceptible only over ex­ tended periods of time because of their vast distances from us. The stars, after all, were not fixed. In 1720 Halley’s enemy Flamsteed was dead and the post of astronomer royal was vacant. Halley was appointed. He inherited a virtually instrumentless obser­ vatory, since the instruments that had existed had been Flamsteed’s personal property and were removed either by heirs or by creditors. Halley reequipped the observatory and devoted his twenty160

FONTENELLE

[239]

year tenure largely to careful observa­ tions of the moon. [239] FONTENELLE, Bernard le Bovier de (fohnt-nelO French science writer Born: Rouen, February 11, 1657 Died: Paris, January 9, 1757 Fontenelle, the son of a well-thoughtof but not very well-off lawyer, was educated under the Jesuits in Rouen. He originally planned to be a lawyer, but that didn’t Work out, and he turned to literature. At first he tried poetry, operas, dra­ matic stuff of all kinds, and then found himself with a book entitled Conver­ sations on the Plurality of Worlds pub­ lished in 1686. This was an introduction to the interested and intelligent layman of the new astronomy of the telescope; a careful consideration of each of the planets from Mercury to Saturn, with speculations as to the kind of life that might be found upon them. He wasn’t a scientist, and he was, in any case, a follower of Descartes [183], who never quite caught up with Newton [231], Still, his book went through nu­ merous editions and he was careful to correct the errors when he could and to bring it up to date. He was elected to the French Acad­ emy in 1691 and became perpetual sec­ retary of the French Academy of Sci­ ences in 1697. He wrote annual sum­ maries of its activities and obituaries for famous scientists as they died. He was perhaps the first person to make a repu­ tation in science on the basis of his pop­ ular science writing alone. He was that rarity; a happy man— calm, equable, doing what he most loved to do and successful at it, loving society and finding himself welcome everywhere, in constant good health and keeping all his faculties into advanced old age. In the end, he died one month before his hundredth birthday. To have lived that final month could surely have been all that remained for him to ask for.

[240]

GREGORY

[240] GREGORY, David Scottish mathematician and as­ tronomer Born: Aberdeen, June 3, 1659 Died: Maidenhead, Berkshire, England, October 10, 1708 David Gregory was a nephew of James Gregory [226]. He had just be­ come professor of mathematics at the University of Edinburgh in 1683 at the recommendation of Newton [231] and Flamsteed [234], when Newton’s Principia Mathematica was published. He claimed afterward to have been the first to give public lectures on Newtonian theory. In 1702, by which time he was a professor of astronomy at Oxford and a personal friend of Newton, he published a book in defense of the theory. He did not agree with Newton on the subject of chromatic aberration, how­ ever. He noted something that had es­ caped Newton, that different kinds of glass spread out the colors of the spec­ trum to different extents. He suggested then that a proper combination of two kinds of glass might produce no spec­ trum at all. This was realized by Dollond [273] a half century later. [241] STAHL, Georg Ernst (shtahl) German chemist Born: Ansbach, Bavaria, October 21, 1660 Died: Berlin, May 14, 1734 Stahl, the son of a minister, was a physician by profession (having obtained his degree at Jena in 1684) and a suc­ cessful one. He was for a time court physician at Weimar, even before he was thirty. He also managed to marry four times, and his lectures on medicine at the University of Halle were both fa­ mous and well attended. By 1716 he be­ came physician to King Frederick Wil­ liam I of Prussia. His greatest fame, however, lies in a chemical theory he adapted from the views his teacher Becher [222] published a half century earlier. The matter of

STAHL

[241]

combustion had always interested practi­ cal chemists if for no other reason than that metals could not be formed from their ores without the action of burning wood or coal. In the seventeenth cen­ tury, scientists were beginning to play with the power of steam, and it led to the invention of the Savery [236] steam engine. This made the subject of com­ bustion (the energy of which produced the steam in the first place) even more interesting. Alchemists such as Geber [76] had tried to establish sulfur as the principle of combustion and Becher had spoken of terra pinguis. Stahl, for his part, spoke of phlogiston (from a Greek word meaning “to set on fire”). Combustible objects, Stahl held, were rich in phlogiston and the process of combustion involved a loss of phlogiston. What was left behind after combustion was without phlogiston and therefore could no longer bum. Thus wood pos­ sessed phlogiston, but ash did not. Stahl recognized that the rusting of metals was analogous to the burning of wood (a great and by no means obvious discovery) and considered that a metal possessed phlogiston but that a rust (or “calx”) did not. Air was considered only indirectly use­ ful to combustion, for it served only as a carrier, holding the phlogiston as it left the wood or metal and passing it on sometimes to something else. Thus, phlogiston could be transferred from charcoal (considered rich in it) to a metal ore, which was poor in it. In this way the charcoal burned and the ore was converted to metal. Actually this viewpoint had much to recommend it about the year 1700, which was when it was proposed. It did explain a great deal about combustion, certainly more than any previous theory had. It also helped transfer chemical in­ terest from medicine, where it had rested from the time of Paracelsus [131], to the preparation of minerals and gases— which in turn led inevitably to the devel­ opment of modern chemistry. The chief difficulty involved in the 161

[242]

POLHEM

phlogiston theory was that it did not take into account changes in weight during combustion or rusting. Thus charcoal in burning lost almost all its weight, leaving only a light ash. Metals, in rusting, actu­ ally gained weight, as Boyle [212] had shown a half century earlier. Thus the loss of phlogiston either decreased or in­ creased weight, depending on cases. Stahl apparently was not perturbed at this because he was still an adherent of the alchemical system of qualitative de­ scription only. The science of physics had been stressing the importance of quantitative measurement for over a century, since the time of Galileo [166], but that view had not penetrated the al­ lied science of chemistry. Later, when eighteenth-century chemists, under the influence of the great success of Newton [231], began to feel guilty about ignoring weight considerations they tried to intro­ duce a principle of levity, which was the reverse of gravity. Thus phlogiston, by leaving metal, reduced its levity and made it heavier. This was a foolish no­ tion, however, and did not last long. Nevertheless phlogiston, with all its contradictions, dominated chemistry for a century until the liberating influence of Lavoisier [334] was felt. Stahl’s influence on physiology was a considerable one, too. He had rational views on mental disease, but on the whole his influence was not an altogether good one from the modern point of view. He did not consider the body ei­ ther a mechanical system as did Borelli [191], or a chemical system as did Syl­ vius [196], Instead he believed it fol­ lowed laws that were different from those ruling the nonliving universe. This view is called vitalism. It remained prominent until the nineteenth century and is not really dead even yet. Stahl’s most prominent contemporary adversary was Boerhaave [248].

NEWCOMEN

[243]

Polhem, left fatherless at ten, became a clockmaker and entered the University of Uppsala in 1687. He invented a variety of machines for industrial purposes, particularly in min­ ing. He was an ardent advocate of re­ placing human muscle with water power and in 1700 built a water-powered fac­ tory for the manufacture of tools. He also recognized the value of division of labor, something in which he was two centuries ahead of his time, for it was only at the opening of the twentieth cen­ tury that Ford [929] really put the no­ tion to work. Outside his native land Polhem built a minting machine for George I of Great Britain. He would not remain in that land, however, nor would he let himself be lured to Russia by Peter I. He was knighted by Frederick I of Sweden.

[243] NEWCOMEN, Thomas English engineer Born: Dartmouth, Devonshire, February 24, 1663 Died: London, August 5, 1729 Newcomen was a blacksmith by pro­ fession but an eager and inquiring one, who was supposed to have consulted with Hooke [223] on the workings of vacuums though this may not be so. In 1698 he went into partnership with Savery [236] who had already built a steam engine and who held comprehensive pa­ tents. Newcomen devised an improved version in which high-pressure steam was never used and air pressure was made to do all the work. For the purpose he had to construct carefully polished cylinders in which pistons could be made to fit with reasonable airtightness. By 1712 such a machine was con­ structed and by 1725 it was coming into general use, where it remained for over half a century until the Watt [316] en­ [242] POLHEM, Christopher (pool'gine replaced it. Englishmen such as hem) Savery and Newcomen foreshadowed the Swedish inventor Industrial Revolution a century later, but Born: Visby, Gotland Island, De­ there were harbingers outside England, cember 18, 1661 too. Polhem [242], a Swede, is an exam­ Died: Tingstàde, August 30, 1751 ple. 162

[244]

AMONTONS

[244] AMONTONS, Guillaume (a-mohn-tohn') French physicist Born: Paris, August 31, 1663 Died: Paris, October 11, 1705 Amontons, the son of a lawyer, went deaf while still young, but he considered this a blessing because it permitted him to concentrate on his scientific work. (This view was much the same as that held two centuries later by Edison [788], who was similarly afflicted.) Amontons was interested primarily in the improvement of instruments, particu­ larly barometers and thermometers. In 1687 he invented a new hygrometer, an instrument for measuring the quantity of moisture in the atmosphere. He also de­ signed barometers that did not use mer­ cury and could therefore be used at sea, where the pitching of the waves would ordinarily cause the mercury level to os­ cillate and destroy the precision of the reading. As for thermometers, he improved on Galileo [166], who had used air trapped in a tube with a bulb at the end and leading into another tube of water. As the air expanded with a rise in tempera­ ture, the water level rose; as the air con­ tracted with a fall in temperature, the water level fell. This thermometer was not at all accurate because changes in air pressure also altered the water level, a point Galileo did not realize. Amontons used a similar air thermom­ eter, but trapped the air with mercury instead of water. Furthermore the tem­ perature was read by altering the mer­ cury height until the air was held at some fixed volume. In this way tempera­ ture was measured by changing air pres­ sure rather than changing air volume. Amontons’ thermometer was somewhat more accurate than Galileo’s, and he used it to determine that a liquid such as water always boiled at the same tempera­ ture (within the limit of precision of his instrument). However, it was still not an instrument for general scientific work; that had to wait two decades for Fahren­ heit [254], In any case, Amontons’ interest in

DE MOIVRE

[246]

thermometers led him to consider the effect of changing temperature on gas volume, which had also interested Mariotte [203]. Amontons went a step be­ yond Mariotte, however, who had merely shown that the volume of air changed with temperature. Amontons, studying different gases, showed that each gas changed in volume by the same amount for a given change in temperature. Out of this he may have gained a vision of an ultimate cold, a kind of absolute zero at which gases contracted to the point where they could contract no farther. He published his observations on gases in 1699, but they lay fallow for about a century before Charles [343] revived them. Then a half century passed before the important notion of absolute zero was firmly established by Kelvin [652], [245] HAUKSBEE, Francis English physicist Born: Colchester, about 1666 Died: London, April 1713 Hauksbee, the son of a draper, became an instrument maker, was a pupil of Boyle [212] and was elected to the Royal Society about 1705. That is virtually all that is known of his private life. He was the first to study capillary ac­ tion, effects involving the attractive forces between a liquid and a solid; that causes water, for instance, to rise within thin tubes, and spread out over a flat surface. He was also one of the earliest investi­ gators of electrical phenomena. His chief advance, made in 1706, was the con­ struction of a glass sphere, turned by a crank, which, through friction, could build up an electric charge. This was something like Guericke’s [189] sulfur ball but it was much more efficient. [246] DE MOIVRE, Abraham (duhmwah'vr) French-English mathematician Born: Vitry-le-Francois, Marne, May 26, 1667 Died: London, England, Novem­ ber 27, 1754 163

[247]

SACCHERI

De Moivre, the son of a surgeon, was a Protestant and in his youth, France was growing steadily more intolerant of its Protestant (or Huguenot) minority. In 1685, Louis XIV revoked the Edict of Nantes which had granted them tolera­ tion, and De Moivre may have been im­ prisoned for a time. He left France, when he could, and went to England where he remained for the rest of his life, one of the very many talented men whom France lost to its enemies because it could not resist the pleasure of preju­ dice. De Moivre got to know Newton [231] and Halley [238] and was elected to the Royal Society in 1697, but he never at­ tained a professorial position and had to make a poor living by tutoring. He advanced the mathematics of prob­ ability well past where it had been left by Pascal [207] and Fermat [188] and made use of factorial numbers in that connection. He was the first to advance some of the fundamental formulas of probability. He was also the founder of analytical trigonometry. Just as Descartes [183] had converted geometry to algebraic for­ mulas. so did De Moivres do the same for trigonometry. De Moivres was an early example of what we might call an “industrial mathe­ matician.” He supplemented his earnings by serving as a consultant to insurance firms, making use of his probability know-how. (He was also consulted by gamblers, naturally.) [247] SACCHERI, Girolamo (sahkkehriee) Italian mathematician Born: San Remo, September 5, 1667 Died: Milan, October 25, 1733 Saccheri was ordained a priest in 1694 and taught mathematics at the Jesuit College of Pavia from 1697 to his death. He was interested in the fifth postulate of Euclid r^O]- the one that assumes (to put it in one of several alternate forms) that through any point not on a given line, one and only one line can be drawn 164

BOERHAAVE

[248]

that is parallel to the given line. It is the only one of the statements with which Euclid starts that cannot be expressed in a few words and that is not intuitively obvious. Many mathematicians, includ­ ing Omar Khayyam [87] tried to prove the fifth postulate from the remaining axioms and failed. It is quite astonishing and a tribute to Euclid that he saw the difficulty and solved it by accepting it as an assumption and going no further with it. It occurred to Saccheri to try a novel approach. He would assume that the postulate was wrong; that through the point not on a given line, two or more parallels could be drawn to the given line. He would then follow through the consequences and find a contradiction. The existence of the contradiction would prove that more than one parallel could not be drawn and that Euclid was right. He began a systematic consideration of the consequences, went on and on, failing to find a contradiction and grow­ ing very disturbed because he felt some­ how that Euclid was a divine truth and to deny it was to deny religion. Eventu­ ally, he persuaded himself he had found a contradiction when he had, in fact, not done so and, in 1733, published the re­ sults in a book entitled Euclid Cleared of Every Flaw. It was one of the out­ standing examples of a failure of nerve in science, for Saccheri was on the point of discovering non-Euclidean geometry when he gave up. It had to wait for over a century for Lobachevski [484] and Bolyai [530], [248] BOERHAAVE, Hermann (boorhah'vuh) Dutch physician Born: Voorhout (near Leiden), December 31, 1668 Died: Leiden, September 23, 1738 Boerhaave was the son of a clergyman and it was originally intended that he study theology. For that purpose he went to the University of Leiden, where he obtained his Ph.D. in 1689. He became interested in medicine, however, ob­

[249]

HALES

tained his medical degree at Harderwyck in 1693, and returned to Leiden in 1701 as a physician and one who was to accel­ erate the process by which Leiden be­ came for a time the most famous medi­ cal center in Europe. He spent the whole of his professional life there. He taught medicine by taking his stu­ dents to the sickbed and was the founder of clinical teaching. Students came to him from all over Europe. Among them was Peter the Great, tsar of Russia, who also took the opportunity of visiting Boerhaave’s compatriot Leeuwenhoek [221 ], Boerhaave published the neglected drawings of Swammerdam [224] at his own expense. He also published a text­ book on physiology in 1708 and one on chemistry in 1724 and each was the most popular of the day and extremely influential. In the former, Boerhaave makes a thoroughgoing mechanistic in­ terpretation of the body in opposition to Stahl [241]. Though famous for his teaching and his writing, Boerhaave made few original advances of his own. He was the first to describe the sweat glands and he es­ tablished that smallpox is spread only by contact, but there is little else. Never­ theless he is possibly the most eminent European physician during the sixteen centuries between Galen [65] and Koch [767] and is sometimes known as the Dutch Hippocrates [22]. The success of his practice may be attested to by the fact that he died an extremely wealthy man. [249] HALES, Stephen English botanist and chemist Born: Bekesboume, Kent, Sep­ tember 17, 1677 Died: Teddington, Middlesex, January 4, 1761 Hales studied theology at Cambridge, obtaining his master’s degree in 1703, and was a curate at Teddington from 1708 (where the poet Alexander Pope was his neighbor and friend), dabbled in several branches of science and did well

BERING

[250]

enough to be elected a fellow of the Royal Society in 1717. He was strongly influenced by Newton’s [231] work and labored to apply the quantitative experi­ mental approach to biology. His most important experiments in­ volved plants, for he measured rates of growth, the pressure of sap, and so on. He recognized that it was a portion of the air that contributed to the nourish­ ment of plants, finally correcting Helmont’s [175] misconceptions of a century before. For this he is considered the founder of plant physiology. Hales was also the first to measure blood pressure. He advanced methods for distilling fresh water from the ocean, for protect­ ing grain from weevils by the use of sul­ fur dioxide, and fish from spoiling. He recognized the value of ventilation and he was the first to collect different gases over water. He experimented with such gases as hydrogen, carbon monoxide, carbon dioxide, methane, and sulfur dioxide, but did not clearly recognize these as distinct gases. A book on his discoveries, published in 1727, was the last to receive the official imprimatur of the aged president of the Royal Society, Isaac Newton. In 1753 he was elected one of the eight foreign members of the French Academy. [250] BERING, Vitus Jonassen (bay'ring) Danish-Russian navigator Born: Horsens, East Jutland, Summer 1681 Died: Bering Island, east of Kam­ chatka (now part of the Soviet Union), December 19, 1741 Bering, the son of an impoverished family, went to sea early. Barely twenty, he went off on a long voyage to the East Indies. When he returned, he was re­ cruited in 1703 into the Russian navy which, under the direction of the tsar, Peter I (the Great) was being rapidly modernized. Peter wanted Russia’s vast new hold­ ings in Siberia mapped, and he chose 165

[251]

MORGAONI

Bering for the job. In particular Bering was to discover whether Siberia joined North America. In 1725, he crossed Si­ beria overland and reached the great far eastern peninsula of Kamchatka, which he was the first to map. From Kamchatka, he set sail north­ ward in 1728 and reached the Arctic ice without sighting land. He had passed through what is now the Bering Strait and he correctly decided that Siberia and North America were not joined. In a second expedition from Kam­ chatka in 1741, he explored the Bering Sea (as it is now called), sighted some of the Aleutian Islands but, weakened by scurvy, died on what is now called Bering Island. He was the first to bring Siberia and its eastern shores into the sharp focus of geographic knowledge. [251] MORGAGNI, Giovanni Battista (mawr-gah'nyee) Italian anatomist Born: Forli, Papal States, Febru­ ary 25, 1682 Died: Padua, December 5, 1771 Morgagni, an only child, was brought up by his widowed mother. He was a brilliant student at the University of Bo­ logna while in his teens, graduating in 1701. In his early twenties he assisted mightily in the preparation of a book on the anatomy and diseases of the ear, which pointed his own direction, the anatomy of diseased rather than of healthy tissue. At the age of thirty he became profes­ sor of anatomy at the University of Padua and remained in that post for nearly sixty years, dying in his ninetieth year. By the time he reached Padua his book on anatomy had established his fame, but the height of his career came in his eightieth year. It was in 1761 that he published a book on the 640 post­ mortem dissections he had conducted. He tried to interpret the causes and progress of disease from the anatomical standpoint and is considered the father of pathology. 166

REAUMUR

[252]

[252] RÉAUMUR, René Antoine Fer­ chault de (ray-oh-myoori) French physicist Born: La Rochelle, Charente­ Maritime, February 28, 1683 Died: near St.-Julien-du-Terroux, October 18, 1757 Réaumur was the son of a judge who died when the boy was one year old. Réaumur went to Paris in 1703. There a relative, who was an important official, took him under his wing. He did some work in mathematics that was good enough to get him into the Academy of Sciences in 1708. In 1710 he was commissioned by Louis XIV to prepare a description of the various useful arts and manufactures of France, thus giving his active mind the opportunity of ex­ ploring many branches of science. He prepared a kind of opaque white glass still known as Réaumur porcelain, he showed that certain so-called turquoises found in southern France were really fossil teeth of extinct animals, and he did work on new methods for steel manufacturing, becoming the first to demonstrate the importance of carbon to steel. For the last, which was the first attempt to make a science out of what was almost a secret art, he earned a con­ siderable cash award, which he turned over to the Academy of Sciences. He wrote a six-volume work on insects, ap­ plying his observations on the nest­ making habits of wasps to the improve­ ment of paper manufacture, and was also the first (in 1750) to design an egg incubator. What’s more, he was the first to demonstrate that corals were animals and not plants. He interested himself in developing a thermometer, anxious to improve on that of Amontons [244], devised a generation before. He apparently did not know of the work of Fahrenheit [254] in the pre­ vious decade but went on independently. He abandoned the air thermometer used by Galileo [166] and Amontons and in 1731 measured temperature by the ex­ pansion and contraction of a liquid, using a mixture of alcohol and water for the purpose. The mixture he used ex­ panded with temperature in such a fash­

[253]

DESAGULIERS

ion that it proved convenient to divide the volume change between the freezing point and boiling point of water into eighty divisions. On the Reaumur scale, then, the freezing point of water is 0° and the boiling point is 80°. For a while the Reaumur scale held its own against the superior thermometers of Fahrenheit and of Celsius [271], but slowly it lost ground and is now virtually out of use. Reaumur’s most significant work was on the process of digestion. For a cen­ tury scholars had been divided on the question of whether digestion was a me­ chanical process, a sort of grinding as Borelli [191] had held, or a chemical process, a sort of fermentation, as Syl­ vius [196] supposed. Reaumur devised an experiment that settled the matter. In 1752 he experimented with a hawk. He placed meat in small metal cylinders open at both ends, the ends being cov­ ered by wire gauze, and persuaded the hawk to swallow them. Ordinarily a hawk swallows its food in large pieces, digests what it can, and regurgitates the remainder. Reaumur waited for the hawk to regurgitate the cylinders and found the meat partially dissolved. He concluded that the meat could not have been affected by grinding or by any mechanical action since the metal cylin­ der protected it from that. Therefore the stomach juices must have had a chemical action on the meat. He checked this by collecting a quan­ tity of the stomach juice by allowing the hawk to swallow a sponge and, after re­ gurgitation, squeezing the juice out. This fluid, he found, did indeed slowly dis­ solve meat placed in it. He experimented with dogs, too, and obtained the same results. Digestion, then, is a chemical process and no one has had occasion to doubt this in the two centuries since Reaumur’s time.

FAHRENHEIT

[254]

La Rochelle had been the center of French Protestantism in the seventeenth century. It had been taken by the French Catholic monarchy under the guidance of Richelieu in 1628, but it was not till 1685 that the repressive attitude of Louis XIV made life entirely impossible for the Protestants. In that year, Desaguliers’ family, who were Protestants, fled to England and there they remained. Desaguliers was educated at Oxford, was ordained a deacon in 1710, and even served as chaplain to Frederick, Prince of Wales. (He never reigned him­ self, but he was the father of George HI.) Desaguliers was an ardent experi­ menter in many fields and a strong expo­ nent of the Newtonian point of view. He was particularly interested in electricity and repeated and extended the experi­ ments of Stephen Gray [262] in that field. It was he who first used the word “conductor” to describe those substances that could conduct a flow of electricity. Nonconductors he called “insulators” from the Latin word for “island” since nonconductors could pen up the electric fluid as the sea penned up an island.

[254] FAHRENHEIT, Gabriel Daniel (fah'ren-hite) German-Dutch physicist Born: Danzig (now Gdansk, Po­ land), May 24, 1686 Died: The Hague, Netherlands, September 16, 1736 In 1701 Fahrenheit, the son of a wealthy merchant, emigrated to Amster­ dam after the sudden death of both par­ ents; there he became a manufacturer of meteorological instruments. Obviously one of the chief devices that can be used for studying climate is a thermometer. The thermometers of the seventeenth [253] DESAGULIERS, John Théophile century, however, such as the gas ther­ mometer of Galileo [166] or of Amon­ French-English physicist tons [244], were insufficiently exact for Born: La Rochelle, France, the purpose. March 12, 1683 Died: London, England, March Fluid thermometers had come into use, but they used either alcohol or alco10, 1744 167

[254]

FAHRENHEIT

hol-water mixtures. Alcohol alone boiled at too low a temperature to allow high temperatures to be measured, and alco­ hol-water mixtures, which did a bit bet­ ter in this respect, changed volume with changing temperature in too uneven a way. In 1714 Fahrenheit made the key ad­ vance of substituting mercury for alco­ hol. He made this practical by inventing a new method for cleaning mercury so that it wouldn’t stick to the walls of the narrow tube of the thermometer. The use of mercury meant that temperatures well above the boiling point of water as well as below its freezing point could be recorded. In addition, mercury expanded and contracted at a more constant rate than most other substances and a mer­ cury thermometer could be marked off more accurately into finer subdivisions. In 1701, for instance, Newton [231] had suggested that the temperature of freezing water and of the body be used as fixed points on the thermometer scale and that the difference in fluid level at these points be marked off into twelve equal divisions. Fahrenheit, however, added salt to water to get the lowest freezing point he could and called that zero. (He wanted to avoid negative temperatures on winter days that were well below the freezing point of pure water.) He then divided the difference in level between that point and that reached at body temperature not into twelve parts but into eight times that many (in line with the high preci­ sion of his instrument) or ninety-six “de­ grees.” He later adjusted that slightly in order to make the boiling point of water come out to 212°, exactly 180 degrees above the freezing point of pure water, set at 32°. On this Fahrenheit scale, body temperature is 98.6°. This was the first really accurate ther­ mometer, and Fahrenheit used it to ex­ pand Amontons’ finding that the boiling point of water was fixed. He checked other liquids and found that each had a fixed and characteristic boiling point under ordinary conditions. He also no­ ticed that this boiling point changed with changes in pressure. 168

DELISLE

[255]

Fahrenheit’s report on his thermom­ eter in 1724 earned him election that year to the Royal Society. The Fahren­ heit scale was adopted at once in Great Britain and the Netherlands. Most of the civilized world, and sci­ entists everywhere, however, use the scale invented by Celsius [271] a quar­ ter century after Fahrenheit’s first mer­ cury thermometer. [255] DELISLE, Joseph Nicolas (duhleel') French astronomer Born: Paris, April 4, 1688 Died: Paris, September 11, 1768 Delisle was the ninth child of a histo­ rian and geographer. He was educated at the Collège Mazarin, with no antici­ pation of a scientific career, but a solar eclipse in 1706 imbued him with a fasci­ nation for astronomy. He began studying it avidly and found work, almost any work, to do at the Paris Observatory. He showed enough talent to get a professorial appointment at the Collège Royal in 1718. Then Peter I (the Great) of Russia, who was anxious to modern­ ize Russia in his own lifetime, felt the need of a modem astronomical observa­ tory in the land and invited Delisle to do the job. In 1725 Delisle was in St. Petersburg to see what he could do in four years and, as it turned out, he stayed twenty-two years. In the process, though, he established the observatory and trained a whole generation of as­ tronomers so that while Russia remained backward in some branches of science, she developed an astronomical tradition equal to that in western Europe. He re­ turned to Paris in 1747. He was the first astronomer to take seriously the possibility of utilizing a transit of Venus as a way of determining the scale of distances in the solar system. In 1761, the year of such a transit he or­ ganized a worldwide study of the phe­ nomenon, the first such to be attempted. It was the prelude for more serious and sophisticated efforts in the next century.

[256]

GOLDBACH

[256] GOLDBACH, Christian (gold+ahkh) German-Russian mathematician Born: Königsberg, Prussia (now Kaliningrad, Soviet Union), March 18, 1690 Died: Moscow, Russia, Novem­ ber 20, 1764 Goldbach, the son of a minister, stud­ ied medicine and mathematics at the University of Königsberg. In 1710, he made a grand tour of Europe (a com­ mon way of attaining an education for those who could manage it). In 1725, he settled down in Russia, becoming profes­ sor of mathematics at the Imperial Acad­ emy of St. Petersburg; in 1728 he served as tutor to the short-lived Peter II (grandson of Peter the Great). Goldbach is most famous in mathe­ matics for “Goldbach’s conjecture,” something Goldbach mentioned in 1742 in a letter to Euler [275]. (Goldbach was a voluminous correspondent with the mathematicians of the time.) The conjecture is this: “Every even number greater than 2 can be expressed as the sum of two prime numbers.” Thus 4 = 2 + 2; 6 = 3 + 3; 8 = 3 + 5; 10 = 3 + 7; 12 = 5 + 7; and so on. Mathematicians have found it to be true by actual testing for all even numbers up to 10,000 and for some beyond; and no one really expects to find any exceptions. The catch is, though, that in over two centuries, no mathematician has man­ aged to prove his conjecture. How can something so simple and so apparently true avoid proof? It is one of the frustra­ tions of mathematics. [257] MUSSCHENBROEK, Pieter van (mois'en-brook) Dutch physicist Born: Leiden, March 14, 1692 Died: Leiden, September 19, 1761 Musschenbroek was born into a family of instrument makers who by the time of his birth had turned to the manufacture of scientific instruments such as tele­

BRADLEY

[258]

scopes, microscopes, and air pumps. Pieter studied at the University of Lei­ den and received his medical degree in 1715, and a Ph.D. in 1719. From 1721, he held professorial positions first at Duisberg, then at Utrecht, and finally at Leiden. Musschenbroek is most famous for his invention of the first truly efficient device for storing static energy. Until then, there were such things as the sulfur ball of Guericke [189] which could be charged with enough electricity to pro­ duce interesting phenomena, but not with enough to be truly startling. Musschenbroek, however, placed water in a metal container suspended by in­ sulating silk cords and led a brass wire through a cork into the water. He built up a charge in the water but had not the slightest idea of how great a charge until an assistant happened to pick up the container and then touch the brass wire outside the cork. The container promptly discharged through the assistant’s body and gave him a fearful shock; the first good-sized artificial electric shock any­ one had ever received. (The lightning stroke is a natural one, of course.) This happened at the University of Leiden, also spelled Leyden, in January 1746. The news spread rapidly and soon “Leyden jars” were being prepared and improved everywhere. For the first time, physicists had a way of preparing an in­ tense electric charge and studying its properties. Within six years, Franklin [272] was to make astonishing use of it. [258] BRADLEY, James English astronomer Born: Sherborne, Gloucestershire, March 1693 Died: Chalford, Gloucestershire, July 13, 1762 Bradley was educated at Oxford and received his master’s degree in 1717. He was introduced to astronomy through the interest taken in him by his uncle, the Reverend James Pound, himself an as­ tronomer. The young man’s aptitude in mathematics gained him the friendship 169

[258]

BRADLEY

of Newton [231] and Halley [238] and he was elected to the Royal Society in 1718. Not really expecting to make a liv­ ing as an astronomer, he became a vicar in the Church of England in 1719 but resigned in 1721 in order to teach at Ox­ ford. As it happened, astronomy sup­ ported him the rest of his life, though he labored hard in return. His major astronomical concern was to measure the parallax of the stars. When Copernicus [127] first suggested that the earth moved about the sun, it seemed inevitable that because of this motion the nearer stars would be dis­ placed—compared with the more distant ones—because they would be viewed at varying angles as the earth moved. No such parallax was, in fact, observed. Co­ pernicus declared this was because the stars were so distant that the parallax was too small to measure. His opponents said that the parallax was not observed because the earth was not moving. Al­ though by Bradley’s time the Copemican position was accepted by all astrono­ mers, it would still have been satisfying to measure the parallax and obtain some idea of the distance of the stars that was more exact than the phrase “very dis­ tant.” Bradley’s close observations, with a telescope 212 feet long, did, indeed, indi­ cate to him that the stars showed a tiny displacement through the year, moving in a small ellipse. However, the motion did not jibe with the earth’s motion in exactly the way expected of a parallactic displacement. It was not until 1728 that the true explanation occurred to him, during a boat ride on the Thames River when he noticed the wind vane on the mast shift direction whenever the boat put about. The usual explanation advanced to ac­ count for Bradley’s effect, however, in­ volves the rain. If rain falls vertically, a man holds an umbrella directly over his head. If he walks he must angle the um­ brella in the direction in which he walks. The faster he walks the more he must angle the umbrella. In the same way, to observe light from a moving earth the telescope must be angled very slightly. The angling of the telescope makes the 170

BRADLEY

[258]

star appear in a slightly different position as the year moves on. From the amount of angling, the amount of the “aberration of light,” it was possible for Bradley to tell the ratio between the velocity of the earth about the sun and the velocity of light. In this way he was able to produce a second method of estimating the velocity of light, which had first been reported by Roemer [232] a half century before. He succeeded in confirming Roemer’s re­ sults and rescuing them from oblivion, although Bradley’s figure was the more accurate and very much like the cur­ rently accepted value for the velocity of light. To be sure, Bradley did not detect the parallax of the stars and could not tell how distant they were. That had to wait for Bessel [439] a century afterward. However, his main purpose was solved. Light would not undergo aberration if the earth were not moving, and his dis­ covery was the first direct evidence that the earth was not at rest and that Coper­ nicus’ view was more than merely a mat­ ter of simplifying the basis of calcula­ tions. The phenomenon of aberration also tended to support the Newtonian theory of light as a shower of particles (like rain). In his careful positioning of stars Brad­ ley also discovered that the earth’s axis underwent small periodic shifts, which he called “nutation.” This was due to changes in the direction of the gravita­ tional attraction of the moon as our sat­ ellite moved on its rather complicatedly irregular orbit. To detect nutation Brad­ ley had to determine differences of two seconds of arc. Since he could not detect stellar parallax, that must involve posi­ tion shifts that were smaller still. Hence, stars had to be very far off. He didn’t publish his discovery till 1748, testing it first by a careful nineteen-year study of stellar positions. In 1733 he measured the diameter of Jupiter and, for the first time, astrono­ mers began to realize just how much larger some of the planets were than our own earth—for so long regarded as the massive center of the universe. In 1742, upon the death of Halley,

[259]

HARRISON

Bradley was appointed the third astrono­ mer royal and in 1748 he was awarded the Copley medal. He finally managed to get a decent appropriation out of the government and with it bought instru­ ments. He is supposed to have turned down a salary increase, however, observ­ ing that if the position of astronomer royal were made too lucrative, astrono­ mers would not be appointed to it. He devoted himself to preparing a star map that was even more extensive and accurate than that of Flamsteed [234]. He had the same industry and applica­ tion as Flamsteed, and also the advan­ tage of being able to correct for the tiny errors introduced by aberrations and nu­ tation, of which Flamsteed, of course, had been unaware. He strongly supported the adoption of the Gregorian calendar by Great Britain in 1752, a view that brought upon him the displeasure of much of the unthink­ ingly conservative public. [259] HARRISON, John English instrument maker Born: Foulby, Yorkshire, March 24, 1693 Died: London, March 24, 1776 The eighteenth century saw the British government still deeply concerned with the problem of determining longitude at sea, the problem that on the advice of Flamsteed [234] had inspired the found­ ing of the Greenwich Observatory. One way was for the navigator to know the Greenwich time accurately wherever he might be on the face of the earth. From the difference between Greenwich time and the local time, as established astronomically, the longitude could be calculated. For this, though, an accurate timepiece was needed, and one that could be used on board ship. An or­ dinary pendulum clock could not, be­ cause the swaying upset the periodic mo­ tion of the pendulum. In 1707 a British fleet miscalculating its position came to grief on rocks off Cornwall. In 1713, therefore, the British government offered a series of prizes of up to £20,000 for an accurate ship’s

HARRISON

[259]

chronometer. A century earlier, in 1598, Philip III of Spain had offered a prize, never claimed, for the same thing. Now, however, the problem was tackled by John Harrison, a Yorkshire mechanic and the son of a carpenter, self-trained and equipped with nothing but an almost supernatural mechanical sense. Beginning in 1728 he built a series of five clocks, each better than the one be­ fore. Each clock was so mounted that it could take the sway of a ship without being adversely affected. He designed a pendulum of different metals so that temperature changes expanded both metals in such a way as to leave the overall length the same, and the period of beat, in consequence, unaltered. He also inserted a mechanism that allowed the clock to continue to keep time undis­ turbed while it was being wound. Any one of Harrison’s clocks met the demands of the prize conditions. In fact they were more accurate at sea than any other clock of the time was on land. One of them was off by less than a minute after five months at sea. To be sure, the first four clocks were heavy (one weighed sixty-six pounds) and complicated and expensive, but the conditions of the prize said nothing about size or complexity or expense. The fifth clock, moreover, was no bigger than a large watch and it was even better than the others. However, the British Parliament put on an extraordinary display of meanness in this connection. It wore Harrison out with its continual delays in paying him the money he had earned. It repeatedly demanded ever greater perfection, and although Harrison always met those de­ mands it would pay him only niggardly sums. Possibly this was because Harrison was a provincial mechanic and not a gentleman of the Royal Society. Finally the young King George III took a personal interest and announced that he himself would serve as Harrison’s counselor—one of the shining acts of that well-intentioned but stubbornly wrongheaded monarch. Harrison finally received his money in 1765. Harrison’s chronometer introduced the modern era of ship navigation and was 171

[260]

BRANDT

not really displaced until a century and a half later when radio communications made the whole world one, and a single clock could be made to do for everybody everywhere. [260] BRANDT, Georg Swedish chemist Born: Riddarhyttan, Vastmanland, July 21, 1694 Died: Stockholm, April 29, 1768 Brandt was the son of an apothecary who had gone into metallurgy. From the time of Agricola [132], minerals and medicines were grouped and the difference between the apothecary and the chemist was to remain nearly invisi­ ble well into the nineteenth century, reaching its climax with Scheele [329]. Brandt helped his father both in chem­ ical and metallurgical work and then went on to study medicine and chemistry under Boerhaave [248]. He obtained a medical degree in 1726 but did not prac­ tice. However, by 1751 his fame had grown so that he was one of the doctors called in to attend the dying Swedish king, Frederick I. Brandt’s metallurgical experience was useful to him, for in 1727 he was placed in charge of the Bureau of Mines at Stockholm, and three years later was made assay master of the Mint. He did considerable work on arsenic, but the deed for which he is best known was in connection with a particular min­ eral that had been used for a couple of centuries to make a deep blue pigment. The mineral resembled a copper ore in some of its properties but it yielded no copper, so German miners of the day had named it kobold after an earth spirit which, they believed, had bewitched the copper ore. About 1730 Brandt was able to treat the dark blue pigment in such a manner as to obtain out of it a new metal. It wasn’t copper, and it much resembled iron. Brandt gave it the name of the earth spirit, spelling it “cobalt,” and that is still the name of the metal. Brandt was the first man to discover a new element since Brand’s [216] discovery of phos­ 172

VOLTAIRE

[261]

phorus three quarters of a century ear­ lier, but from his time on the pace of discovery of new elements never lagged. He was the first man to discover a metal entirely unknown to the ancients. Brandt differed from his predecessors such as Brand, Becher [222], and Stahl [241] and even from such great dabblers in chemistry as Boyle [212] and Newton [231] in that he was the first to be com­ pletely free of any alchemical taint. In his later years, in fact, Brandt made almost a hobby out of combating al­ chemy, much as men today might make one of exposing fortune-telling frauds. He showed that gold could be dissolved in hot nitric acid and made to precipitate out when the acid was cooled and shaken. Gold would then seem to appear out of nowhere, and this explained one of the ways knaves imposed on fools. When Brandt died, chemistry was about to reach full maturity under La­ voisier [334]. The end of alchemy for all but the most eccentric faddists, he did not live to see. [261] VOLTAIRE (François Marie Arouet) French author Born: Paris, November 21, 1694 Died: Paris, May 30, 1778 Voltaire was the son of a minor gov­ ernment functionary and his real name was François Marie Arouet. Voltaire was blessed, and cursed, with one of the sharpest wits of modem times. It was a blessing in that he could win any argu­ ment, for there is no one on record who ever involved himself in a controversy with Voltaire without coming out shred­ ded and a laughingstock. It was a curse in that he could not resist lampooning and satirizing the most respected beliefs of the nation and the most highly placed individuals. This led to his being imprisoned in the Bastille now and then, and on at least one occa­ sion of being beaten up by thugs hired by a gentleman who, smarting under rid­ icule, thought that sticks were more striking arguments than words. In 1726 Voltaire was sent off to En-

[262]

GRAY

gland for his own protection, where he remained three years. While there he made friends in the highest literary cir­ cles. He also studied the Newtonian theory and was present at the funeral of Newton [231], After returning to France (where he was to experience a continual series of ups and downs at the court of Louis XV, according to the manner in which he ex­ ercised his sharp tongue) he had one of his mistresses, the marquise de Châtelet [274], translate Principia Mathematica into French and he himself in 1737 wrote a commentary on the book. New­ ton was fortunate in his interpreter, for to find anyone who could write more charmingly than Voltaire was a task for a long summer’s day indeed. It was Voltaire, more than anyone, who made Newton fashionable among nonscientists. This was particularly im­ portant in France where the pre-New­ tonian views of Descartes [183] still dominated. Voltaire, in fact, was the liv­ ing embodiment of the Age of Reason, the most shining light of the last period in history in which it was chic for a man of humanistic culture to understand and admire science and for a scientist to love the humanities. Voltaire died on the eve of the French Revolution, which his writings had done much to bring about. The quiet twilight of the feudal aristocracy of Europe, with its condescending patronage of things scientific, was broken in that holocaust. Science itself, after 1800, expanded in so many directions that it became no longer possible to study it as a mere minor ad­ junct to a humanistic education. It re­ quired a specialist to learn as much of science as was necessary to advance re­ search. The Age of Reason died with Voltaire. The Age of Specialized Science took its place and is still with us, now more than ever. [262] GRAY, Stephen English electrical experimenter Born: about 1696 Died: February 25, 1736

MACLAURTN

[263]

Gray, the son of a dyer, may have re­ ceived instruction from Flamsteed [234], He grew avidly interested in the infant study of electricity and made his key dis­ covery in 1729. He found that when a long glass tube was electrified by fric­ tion, the corks at the end (which were not touched) were also electrified. The electric fluid, whatever it was, had trav­ eled from the glass to the corks and he thus discovered electrical conduction. He experimented further, conducting electricity through long stretches of twine and, eventually, found that not ev­ erything would suffice for the purpose. Some substances would not conduct elec­ tricity. Desaguliers [253] soon catego­ rized the situation by speaking of “con­ ductors” and “insulators.” [263] MACLAURIN, Colin (mak-law'rin) Scottish mathematician Born: Kilmodan, February 1698 Died: Edinburgh, January 14, 1746 Maclaurin, the son of a minister, lost his father six weeks after his birth and his mother when he was nine years old. He was brought up by an uncle, also a minister. In 1709, at age eleven, Mac­ laurin entered the University of Glasgow intending to study for the ministry but grew interested in mathematics instead, and obtained his master’s in that disci­ pline in 1715. In 1717, when he was still not yet twenty, he was appointed profes­ sor of mathematics at Marischal College, Aberdeen, and two years later was elected to the Royal Academy. He met Newton [231] in London, and in 1724, moved on to a professorial chair with Newton’s strong recom­ mendation. Maclaurin was probably the greatest mathematician in the British Isles in the generation following Newton and did much to tighten and extend the calculus. In particular, in 1742 he wrote in defense of Newton against the criti­ cisms (well-based) of the foundations of calculus by the philosopher George Berkeley. In so doing, he did much to improve matters so as to make the criti­ 173

[264]

BOUGUER

cisms less trenchant. In a way this con­ tributed to the British idolatry of New­ tonian mathematics, so that after Maclaurin mathematics vegetated in Great Britain and made no further progress, Babbage [481] and his friends stirred things up again. In 1745 a Highland army, supporting Charles Stuart (“Bonnie Prince Charlie,” the Stuart Pretender) marched on Edin­ burgh. Maclaurin supervised the defense with remarkable energy for a mathe­ matician but was forced to flee when the Highlander Jacobites took the city. The Jacobite ascendancy was short-lived and Maclaurin soon returned to Edinburgh, but his health had been undermined and he died soon after. [264] BOUGUER, Pierre (boo-gairi) French mathematician Born: Le Croisic, Loire-Inférieur, February 16, 1698 Died: Paris, August 15, 1758 Bouguer’s father was a hydrographer (that is, a geographer of the waters of the earth, both fresh and salt) and math­ ematician who brought his son up in the same profession. By 1730 Bouguer was a professor of hydrography at Le Havre, succeeding his father, and he was one of the foremost on the La Condamine [270] expedition. He wrote a useful book about the expedition. He also invented a heliometer, to mea­ sure the light of the sun and other lumi­ nous bodies. With it he was the first to attempt a quantitative measurement of the comparative luminosities of the sun and moon and is considered a founder of photometry, the measurement of light in­ tensities.

DU FAY

[266]

the opportunity to read books, including some on microscopy. He later stayed with a relative whose daughter had been born deaf. Baker undertook to teach her to speak and to read, and was successful —so successful that he made a profes­ sion out of teaching those with a variety of speech defects and made a good living out of it. He kept his methods secret for the natural reason that only so could he continue to command high fees. Through work of this sort he attracted the interest of the novelist Daniel Defoe (the author of Robinson Crusoe), and in 1729 Baker married the youngest of De­ foe’s daughters. Baker was also a science writer, and in particular he wrote on the microscope and introduced it to the general lay pub­ lic, describing its construction and its uses. Like Leeuwenhoek [221], he used the microscope to observe everything he could and reported on all of it. Of par­ ticular importance was his observation of the shapes of various kinds of crystals.

[266] DU FAY, Charles François de Cistemay French physicist Born: Paris, September 14, 1698 Died: Paris, July 16, 1739 Du Fay served in the army from the age of fourteen, but after his retirement became the superintendent of gardens for King Louis XV in 1732, a post that gave him security plus time for experi­ mentation. He repeated the experiments of Gray [262] on electrical conduction, and noted that damp twine was a con­ ductor while dry twine was an insulator. In 1733 Du Fay experimented with suspended bits of cork, which he elec­ trified by touching them with an already electrified glass rod. He found the pieces [265] BAKER, Henry of cork repelled each other. This effect English naturalist of repulsion had been noted by Guericke Born: London, May 8, 1698 [189] but Du Fay now studied it in de­ Died: London, November 25, tail. 1774 He found that two electrified objects sometimes attracted and sometimes re­ Baker, the son of a law clerk, was ap­ pelled each other. A cork ball electrified prenticed to a bookseller where (like by means of a glass rod attracted an­ Faraday [474] a century later) he took other which had been electrified by 174

[267]

MAUPERTUIS

means of a resinous rod. If both were electrified in the same way, either both by glass or both by resin, they repelled each other. Du Fay postulated the existence of two different electrical fluids: “vitreous electricity” and “resinous electricity.” Each repelled itself but attracted the other. It remained for Franklin [272] to introduce the modem convention of call­ ing them “positive” and “negative.” Du Fay, who never married, died of smallpox at forty. [267] MAUPERTUIS, Pierre Louis Moreau de (moh-pehr-tyoo-ee') French mathematician Born: St. Malo, Ille-et-Vilaine, September 28, 1698 Died: Basel, Switzerland, July 27, 1759 Maupertuis, the spoiled child of wellto-do parents, spent part of his youth as a musketeer in the army, joining in 1715 but leaving in 1723 to become an in­ structor in mathematics at the French Academy of Sciences. In 1728 he visited England, was elected to the Royal Soci­ ety, and became an extravagant admirer of Newton [231], who had just died. He leaped at the chance in 1736 to head an expedition to Lapland, in conjunction with the expedition of La Condamine [270] to the equator, to measure the cur­ vature of the earth. After all, a success­ ful result would help establish Newton’s theory. Maupertuis’ group completed its task far more quickly than La Condamine’s, but not nearly so precisely. In 1743 Maupertuis was elected to the French Academy and in 1744 yielded to the blandishments of Frederick II of Prussia. He went to Berlin and was ap­ pointed head of the Academy of Sci­ ences there in 1746. He was, however, a quarrelsome and unlikable man and con­ ducted a loud argument with Voltaire [261] (who had befriended him, but whose witty comments Maupertuis found insupportable) over the principle of least action. This principle, first advanced by Maupertuis in 1744 (and sharpened a century later by Hamilton [545]),

BERNOULLI

[268]

seemed to show that nature chose the most economical path for moving bodies, rays of light, and so on. Maupertuis worked out theological implications from this and, though Euler [275] supported him, Voltaire scoffed. Maupertuis lost the argument of course, since one could not bandy words with Voltaire and come out the winner. Voltaire’s ridicule drove Maupertuis to Basel, where he took the side of Newton against Leibniz [233] in the argument over which man had priority in the cal­ culus. On the continent he was in the minority. This argument is supposed to have hastened his death. [268] BERNOULLI, Daniel (ber-nool'ee) Swiss mathematician Born: Groningen, Netherlands, February 8, 1700 Died: Basel, March 17, 1782 Daniel Bernoulli came of an amazing line of Swiss mathematicians and phys­ icists descended from a Flemish fam­ ily, driven out of the Netherlands in the late sixteenth century because of their Protestant beliefs. His uncle Jacob (or Jacques), a contemporary of Newton [231] and Leibniz [233], was a mathe­ matician nearly in their class. His father, Johann (or Jean), was almost as capa­ ble and was a professor at Groningen when Daniel was bom, though the family returned to Switzerland in 1705. Both uncle and father extended the cal­ culus to new applications. Two brothers, a cousin, and a couple of nephews (not to mention other relations) were also mathematicians or scientists. As for Daniel, he began as a mathe­ matician, despite his father’s desire that the young man follow a business career. Daniel’s older brother taught him geome­ try, and though he studied medicine and obtained a medical degree in 1721, it was as a professor of mathematics that he began teaching in St. Petersburg, Rus­ sia, in 1725. He returned to Switzerland in 1733 and grew interested in science. In doing so, he became the first non­ English scientist to accept without reser175

[269]

KLEIST

vation the Newtonian view of the uni­ verse. His book on the flow of fluids (hydro­ dynamics) in 1738 showed that, as the velocity of fluid flow increases, its pres­ sure decreases. This is still called Ber­ noulli’s principle and is used in produc­ ing vacuums in chemical laboratories by connecting a vessel to a tube through which water is running rapidly. Bernoulli was the first to attempt an explanation of the behavior of gases with changing pressure and temperature. The changes had been observed by men such as Boyle [212], Mariotte [203], and Amontons [244], but none of them had attempted an explanation. Bernoulli began by assuming that gases were made up of a vast number of tiny particles, a suggestion that was at least as old as Hero [60]. Bernoulli pro­ ceeded to treat the situation mathe­ matically, using the probability tech­ niques of Pascal [207] and Fermat [188]. He obtained fair results although his methods were not rigorous. The mere fact that he could do so would have given a powerful boost to the concept of atomism if his work had been paid more attention. A century later Joule [613] im­ proved the treatment and still later Max­ well [692] and Boltzmann [769] were to complete it, but by then atomism was well established. [269] KLEIST, Ewald Georg von (kliste) German physicist Born: Pomerania, about 1700 Died: Köslin, Pomerania (now Koszalin, Poland), December 11, 1748 Kleist was the son of a district magis­ trate. He was educated at the University of Leiden where he picked up an interest in science then returned home to become dean of the cathedral of Kamin in Pomerania. Kleist’s contribution to science con­ sisted of his attempt to store an elec­ tric charge and the accidental invention of an efficient means of doing so. He had, in fact, invented Musschenbroek’s 176

LA CONDAMINE

[270]

[257] Leyden jar, independently of Musschenbroek and at just about the same time. He had discovered what he had done in the same way, too, by giving himself an accidental shock that all but jarred his teeth loose. [270] LA CONDAMINE, Charles Marie de (la-kohn-duh-meen') French geographer Born: Paris, January 27, 1701 Died: Paris, February 4, 1774 La Condamine, bom into the wealthy nobility, joined the army at the age of seventeen but left it to engage in a scientific career. In La Condamine’s time most of the world, except for the polar regions and some of the empty stretches of the Pacific, had been opened up, but much was left to do. Areas had been crossed without having been carefully studied by a scientific eye. La Condamine en­ deavored to correct that with trips along the coasts of Africa and Asia and in 1730 had, as a result, been elected to the Academy of Sciences. His great adventure, however, lay in an expedition to South America. It had, as its purpose, nothing less than the de­ termination of the shape of the earth. The earth was, roughly speaking, a sphere, of course, but Newton [231] had pointed out that the speed of rotation of the earth’s surface increased steadily from zero at the poles to a bit over a thousand miles an hour at the equator. Centrifugal force increased corre­ spondingly and, in theory, the earth should then be an oblate spheroid, bulg­ ing at the equator and flattened at the poles. The pendulum data reported by Richer [217] seemed to back Newton’s views. However, Cassini [209] and his son, with their usual wrongheadedness, insisted on the basis of inadequate sur­ veys in France that the earth’s surface curved more and more as one traveled north. Therefore the earth was flattened at the equators and bulged at the poles and was a prolate spheroid. If the Cas­

[270]

LA CONDAMINE

sinis were right, then the theory of uni­ versal gravitation was wrong. It became more and more important to check the matter. It was decided to survey regions of the earth accurately to determine differences in surface curvature. To get the greatest differences in curvature, one expedition under La Condamine was sent in 1735 to Peru, almost on the equator. Another expedition, under Maupertuis [267], was sent to Lapland in the far north of Sweden. These expeditions were gather­ ings of giants, for included were Bouguer [264], Clairaut [283], and others of like caliber. The results were quite conclusive. The earth’s curvature was distinctly higher at the equator than at the poles. The earth was therefore an oblate spheroid, bulging at the equator and flattened at the poles. Newton, as was to be expected, was right, while the Cassinis, as was even more to be expected, were wrong. La Condamine used his stay in South America to go off on an exploratory jaunt. He was the first European to ex­ plore the Amazon territory with any thoroughness, and he sent home quanti­ ties of a peculiar tree sap called caou­ tchouc, thus introducing what we now call rubber to Europe. He also discov­ ered and brought back curare, the origi­ nal of the mysterious South American poisons so beloved by mystery writers, which, however, is also used clinically as a muscle relaxant. The expeditions to Peru and Lapland had made it quite plain that the delicate measurements being undertaken in the eighteenth century were being hampered by the lack of internationally accepted standard units of measure. La Conda­ mine was in the forefront of the fight to establish such a system of measure but did not live long enough to see it ac­ complished in the 1790s, with the intro­ duction of the metric system. He was also one of those who speculated on the feasibility of inoculation against small­ pox but died twenty-two years before Jenner [348] introduced such inoculation successfully.

FRANKLIN

[272]

[271] CELSIUS, Anders (sel'see-us) Swedish astronomer Born: Uppsala, November 27, 1701 Died: Uppsala, April 25, 1744 Celsius was of a famous scientific fam­ ily. His father and grandfather were mathematicians, his uncle a botanist. He studied the aurora borealis and, in his re­ port in 1733, was the first to associate it with changes in the earth’s magnetic field. He also took part in the expedition to Lapland under Maupertuis [267]. In 1730 he became professor of as­ tronomy at Uppsala and in 1740 was placed in charge of a large new observa­ tory there, which, however, he was not to enjoy for long, for he died at an early age. He was the first to try to determine the magnitude of stars by measuring the intensity of their light by a device other than the human eye. His greatest accomplishment, as it happened, had nothing to do with as­ tronomy. It concerned the temperature scale he devised, which divided the tem­ perature difference between the boiling point and freezing point of water into an even hundred degrees. He first described this in 1742 when he placed the boiling point at 0° and the freezing point at 100°, but the next year this was re­ versed. This is the centigrade scale (“hundred steps”) and is used by scien­ tists everywhere. In 1948 it was decided by general agreement to begin to refer to it as the Celsius scale. [272] FRANKLIN, Benjamin American statesman and scientist Born: Boston, Massachusetts, January 17, 1706 Died: Philadelphia, Pennsylvania, April 17, 1790 Benjamin Franklin was the fifteenth child of seventeen, born to a poor candlemaker. He was printer, writer, politi­ cian, diplomat, and scientist, quite a phe­ nomenon in the New World in the eigh­ teenth century, yet he only had two years of formal schooling. He was the only 177

[272]

FRANKLIN

American of colonial days to achieve a European reputation. He is best known to Americans, of course, as one of the founding fathers of the nation, but his fame in his own time, at least in Europe, was that of a natural philosopher. He founded America’s first scientific society, the American Philosophic Society, in 1743. His ingenuity showed itself in nu­ merous inventions, notably the Franklin stove and bifocal glasses. However, it was in the field of electricity that he achieved his greatest results. Static electricity had become a fas­ cinating toy in the century since Guericke [189] had produced the first electric machine and Musschenbroek [257] his Leyden jar in 1745. The latter was actually a “condenser,” a name coined by Volta [337] a half century later. It could store large quantities of static electric charge poured into it from a machine in which the charge was pro­ duced through friction. The Leyden jar could then be discharged when a hand was brought near the center rod, and if enough electricity had been stored in the first place, the owner of the hand would be given a shock he was not likely to forget. If the jar was brought near metal, a tiny jagged spark would leap across the air gap and this would be accompanied by a sharp crackle. Many scientists were experimenting with Leyden jars, and Franklin was one of them. He noted the spark of light and the crackle and wondered whether these might not be a very miniature lightning and thunder. Or perhaps, looking at it from another standpoint, might not the majestic thunder and lightning of the heavens be but the interplay of elec­ tricity, with earth and sky making up the halves of a gigantic planetary Leyden jar? Benjamin Franklin decided to attempt an experiment—one for which he lives dramatically in the minds of posterity. He flew a kite in a thunderstorm in 1752. The kite carried a pointed wire to which Franklin had attached a silk thread that could be charged by the elec­ tricity overhead; that is, if there was electricity overhead. 178

FRANKLIN

[272]

As the storm clouds gathered and lightning flickered, Franklin put his hand near a metal key tied to the silk thread and the key sparked just as a Leyden jar would have. Moreover, Franklin charged a Leyden jar from the key just as easily as he would have from a man-made elec­ trical machine. Franklin’s kite electrified the scientific world, and he was made a member of the Royal Society. Franklin’s luck was extreme, for the experiment is a killer. The next two men who tried to duplicate his feat were both killed. (At about the same time, how­ ever, Canton [290], in observations that involved no danger, pointed up another and more subtle connection between electricity and the sky.) Franklin was able to put his experi­ ment to practical use at once. His experi­ mentation with the Leyden jar had shown him as long before as 1747 that it discharged more readily and over greater gaps of air if it came near a pointed sur­ face. It was as if the pointed surface at­ tracted the electricity. Franklin therefore suggested that pointed metal rods be placed above the roofs of buildings, with wires leading to the ground. Such light­ ning rods would discharge the clouds safely and protect the buildings them­ selves. They did indeed prove efficacious and by 1782 there were four hundred lightning rods in use in Philadelphia alone. Franklin had averted the artillery of Zeus. When a quarter century later the aged Franklin represented the infant United States during the Revolutionary War at the court of France, he proved the ideal man for the job. Not only did his care­ fully affected Republican simplicity per­ versely appeal to the aristocrats at Ver­ sailles, but it was the Age of Reason, and educated Frenchmen fell all over the man who had tamed the lightning of the sky and brought it to earth. How much of America’s successful birth can be traced back to a kite flying in a thunder­ storm? Franklin also performed an inesti­ mable theoretical service to the science of electricity, with one accidental flaw. It was known that there were two kinds of electric charge. Two amber rods repelled

[272]

FRANKLIN

each other if both were rubbed and elec­ trified. Similarly two electrified glass rods repelled each other. An electrified amber rod, however, attracted an electrified glass rod. It seemed a case of “opposites attract and likes repel,” as in magnetism, where the north pole of a magnet at­ tracts the south pole of another, while two north poles repel each other and two south poles repel each other. Franklin reasoned that this could be explained by supposing electricity to con­ sist of a subtle fluid that could be present either in excess or in deficiency. Two substances containing an excess of the fluid repelled each other, as did two sub­ stances containing a deficiency. An ob­ ject with an excess, however, would at­ tract one with a deficiency; the excess would flow into the deficiency (over an air gap and accompanied by thunder and lightning sometimes) and the two elec­ trifications would be neutralized. Franklin suggested that an excess of the fluid be called positive electricity and a deficiency be called negative electricity. A century and a half after Franklin’s day, electricity came to be associated with subatomic particles, particularly with the electron, discovered by J. J. Thomson [869], However, if static elec­ tricity is considered an accumulation of electrons or a deficiency of them, the situation as we understand it today is ex­ actly what Franklin proposed. Unfortunately the objects Franklin guessed contained the excess of elec­ tricity actually contain a deficiency of electrons. (He took an even-money stab in the dark and missed.) The electrician in setting up his circuits even today as­ sumes that the electric current flows from the positive terminal to the nega­ tive, but the physicist knows that elec­ trons flow from the negative terminal to the positive. It doesn’t matter, however, which convention is followed as long as whoever is working with the circuit sticks to the same convention through­ out. Franklin’s busy mind concerned itself with other matters as well. While in France he watched with extreme interest the early attempts at ballooning and in­ volved himself in the medical theories of

DOLLOND

[273]

Mesmer [314], coming to some remark­ ably sound conclusions as to psycho­ neuroses as a result. He worked out (as well as he could) the course of storms over the North American continent and was the first to study the circulating belt of warm water in the North Atlantic that we now call the Gulf Stream. In 1900 Franklin was selected as one of the charter members of the Hall of Fame for Great Americans. [273] DOLLOND, John English optician Born: London, June 10, 1706 Died: London, November 30, 1761 Dollond was the son of a Huguenot refugee from France. (Louis XIV, be­ cause of his measures against the French Protestants in the 1680s, lost thousands of useful subjects to surrounding nations. Adolf Hitler was to make a similar mis­ take two and a half centuries later.) Dollond began work in his father’s trade of silk weaving but educated him­ self in his spare time, teaching himself Latin, Greek, mathematics, and science. In middle life he joined his own son in manufacturing optical instruments. Their work was unsurpassed until the time of Fraunhofer [450] over half a century later. He followed the suggestions of David Gregory [240] and others and tried to develop lenses that in spite of Newton’s [231] theories would not show chromatic aberration. Actually this feat had been accomplished in 1733, it is now known, but the results had not been published. Even so, Dollond had to fight the matter through the courts before he was awarded a patent. In any case Dollond succeeded in 1758 and announced his results to the Royal Society, which awarded him the Copley medal and three years later elected him a member. In 1761 (the year of his death) he was even appointed optician to King George III. Dollond solved the problem by using two different kinds of glass, which re179

[274]

CHÂTELET

fracted the various colors of light in different ways and combined them in such a fashion that the action of one glass just counterbalanced the action of the other. The invention of such an achromatic telescope kept the refracting instruments in the race with reflectors, though by the twentieth century the reflecting telescope was definitely the winner, thanks to the energy and enterprise of Hale [974]. Doflond’s work also led to the invention of achromatic microscopes, a more im­ portant consequence, for in microscopy there was no easy substitute for refrac­ tion. Furthermore Dollond showed that Newton was definitely wrong in his con­ tention that chromatic aberration could not be avoided, and it was a healthy thing for science to be shown that even Newton could be wrong. [274] CHÂTELET, Gabrielle Emilie le Tonnelier de Breteuil, marquise du (shah-tlayO French science writer Born: Paris, December 17, 1706 Died: Luneville, Meurthe-etMoselle, September 10, 1749 Of noble birth, Gabrielle Emilie mar­ ried the marquis de Châtelet in 1725. She bore him three children, after which he grew quite serious about his military career and saw her but infrequently. She didn’t seem to take that much to heart but pursued her own life with the greatest of satisfaction. She had been well educated in all the subjects deemed necessary to a cultured existence, including science, and from 1733 on she established a liaison with the leading intellectual figure of the age, Voltaire [261]. She was also a close friend of Maupertuis [267] who taught her mathematics and who encouraged her to continue with her science educa­ tion and, later on, with Clairaut [283]. Because Voltaire was a great admirer of Newton [231], he urged the brilliant marquise to undertake the task of trans­ lating the Principia Mathematica from Latin into French. She began the task in 1745 and continued it till her death (in 180

EULER

[275]

childbirth) and did a masterly job of it. Voltaire wrote a preface and it appeared, complete, in 1759. Since most of Europe’s intellectuals in those days could manage to make themselves understood in French and could read the language, her translation (still the only one in French) opened the meaning of the Newtonian universe to those continentals who were not at home in either Latin or English. [275] EULER, Leonhard (oiler) Swiss mathematician Born: Basel, April 15, 1707 Died: St. Petersburg, Russia, Sep­ tember 18, 1783 Euler, the son of a Calvinist minister who dabbled in mathematics, studied under the Bemoullis and was a friend of Daniel Bernoulli [268]. Euler received his master’s degree at sixteen from the University of Basel. When the Bernoullis went to St. Petersburg, Russia, they persuaded Euler (in 1727) to follow, for there the Em­ press Catherine I (widow of Peter the Great) had recently founded the Peters­ burg Academy and there he succeeded Bernoulli as professor of mathematics in 1733. In St. Petersburg in 1735 Euler lost the sight of his right eye through tooardent observations of the sun in an at­ tempt to work out a system of time de­ termination. In 1741, at a time when the young Ivan VI succeeded to the throne and times in Russia grew troubled, Euler went to Berlin. There he was to head and revivify the decaying Academy of Sciences, founded by Leibniz [233] at the invitation of the new king, Frederick II. He didn’t get along with Frederick, a king who demanded approval of his wretched poetry and who had no appre­ ciation for pure mathematics. Euler was remembered in Russia, however, and in 1760, during the Seven Years’ War, when Russian troops occupied Berlin, Euler’s house was given special protec­ tion. In 1766, at the invitation of the new

[275]

EULER

empress, Catherine II (the Great), he re­ turned to St. Petersburg and remained there for the rest of his life. During his second stay in Russia he challenged the visiting Diderot [286] to a debate on atheism. Euler, a religious man who in his youth had contemplated entering the ministry like his father, advanced his own argument in favor of God in the form of a simple and completely irrele­ vant algebraic equation. Poor Diderot, who knew no mathematics whatever, was speechless. Feeling a fool, he left Russia. Euler was the most prolific mathe­ matician of all time, writing on every branch of the subject and being always careful to describe his reasoning and to list the false paths he had followed. He lost the sight of his remaining eye in 1766 but that scarcely seemed to stop him or even slow him down, for he had a phenomenal memory and could keep in mind that which would fill several blackboards. He published eight hundred papers, some of them quite long, and at the time of his death, left enough papers behind to keep the printing presses busy for thirty-five years. He applied his mathematics to astron­ omy, working out the nature of some perturbations, being in this respect the precursor of Lagrange [317] and Laplace [347]. He began to replace the geometric methods of proof used by Galileo [166] and Newton [231] with the algebraic, a tendency carried to its conclusion by Lagrange. In particular he worked on lunar theory, that is, on the analysis of the exact motion of the moon, the com­ plications of which have been the despair of astronomers and mathematicians since the time of Kepler [169]. Although his results were far from perfect, they repre­ sented an improvement on what had gone before. He also held that light was a wave form and that color depended on wave­ length. A generation later, Young [402] demonstrated this conclusively. Euler published a tremendously suc­ cessful popularization of science in 1768, one that remained in print for ninety years. He died shortly after working out certain mathematical problems in con­

LINNAEUS

[276]

nection with ballooning, inspired by the successful flight of the Montgolfier brothers [325]. He introduced the sym­ bol “e” for the base of natural log­ arithms, “i” for the square root of minus one, and “f () ” for functions. [276] LINNAEUS, Carolus (lih-nee'us) Swedish botanist Born: Sôdra, Råshult, Småland, May 23, 1707 Died: Uppsala, January 10, 1778 Linnaeus’ name is the Latinized form of Carl von Linné. As a child he seemed rather dull, but his father, a pastor, sent him to medical school, first at Lund, then at Uppsala, a bit against his will. Fortunately, put to the test, young Lin­ naeus made out well scholastically. Fi­ nancially, though, he came close to di­ saster at this time. Luckily for him, Cel­ sius [271], then teaching at Uppsala, took the young man into his home. Linnaeus had always been interested in plants and even as an eight-year-old he had gained the affectionate nickname of “the little botanist.” This interest contin­ ued at college and he studied, in particu­ lar, the stamens and pistils. Linnaeus wrote a paper on the subject and this led him to feel that he could in­ troduce a new and better classification of plants based on their sexual organs. In 1732 the University of Uppsala (where he was already lecturing on botany as Rudbeck [218] had done before him) asked him to visit Lapland to examine its flora. This he did, traveling forty-six hundred miles throughout northern Scandinavia, discovering a hundred new species of plants and carefully observing the animal life as well. His interest in sex led to an interesting by-product: he was the first to use the symbols $ and $ for “male” and “female.” He followed this up by traveling through England and west Europe. In 1735 Systerna Naturae was published. In this famous book Linnaeus established the classification of living things in a particularly methodical way, completely overshadowing the prior work of Ray 181

[276]

LINNAEUS

[213] and emerging as the founder of modern taxonomy. In the first place he developed a clear and concise style of describing species that pointed out exactly how each differed from other species. In the sec­ ond place he popularized binomial no­ menclature, in which each type of living thing is given first a generic name (for the group to which it belongs) and then a specific name for itself. Linnaeus’ book, published originally in seven large pages, had expanded to twenty-five hun­ dred pages by the tenth edition. Linnaeus’ passion for classification amounted almost to a disease. He was not content merely to list the species and collect them into related groups, or gen­ era. He grouped related genera into classes, and related classes into orders. (Later Cuvier [396] was to extend this notion by grouping related orders into phyla.) Linnaeus, despite his conser­ vative piety, dared even to include man in his classification, giving the human species the name of Homo sapiens (“Man, wise”) though he confined this classification to man’s body alone. He considered his soul to be outside the ani­ mal kingdom. He included the orangutan in the same genus with man as Homo troglodytes (“Man, cave-dwelling”), but this did not endure. He also classified whales and re­ lated species as mammals, thus finally es­ tablishing a point of view first advanced by Aristotle [29] two thousand years earlier. While classification is perhaps not the highest function of science, it can be in­ dispensable in a diverse and amorphous field of study. It was only after Linnaeus had imposed order (somewhat arti­ ficially, to be sure) upon life, that bi­ ologists could search confidently for great generalizations. The manner in which the classification began with large groups, divided into smaller groups, then still smaller groups, ending finally with individual species, gave the system of liv­ ing organisms the appearance of a tree. The very existence of such a tree of life helped activate and sharpen the hazy no­ tions of an evolution of living things from simple beginnings to modern com­ 182

LINNAEUS

[276]

plexity. Such thoughts can be traced back to the ancient Greeks, but after Linnaeus the search for some way to sys­ tematize those thoughts began in earnest. Linnaeus himself fought the whole idea of evolution stubbornly, insisting that all species were created separately in the beginning, that no new species had ever been formed since Creation and that none had ever become extinct. He may have begun to waver toward the end of his life, but in any case his opposition could not stem the tide. His own view had affected his philosophy of classification, for he was not concerned in ordering the world of living things to show family relationships that he did not believe existed. He wanted only to differentiate the various species in the clearest way he could, so his classifica­ tion was an artificial one based on the external characteristics most obvious to the eye. Men who followed him, like Cuvier, Jussieu [345], and Candolle [418], kept the principles of Linnaean classification but changed the details to make it a natu­ ral one showing relationships. Once that was done, more followed inevitably. Linnaeus had begun a train of thinking that led inexorably to Darwin [554], and the rigidly orthodox Swedish botanist could have done nothing to stay that. When Linnaeus finally returned to Sweden he entered medical practice and in 1741 was appointed to the chair of medicine at Uppsala. One year later he exchanged it for the chair of botany. He spent the remainder of his life in teach­ ing. He was an excellent teacher, inspir­ ing his students with the same ardor that had moved him, for he sent them out (and they went gladly) through the world in search of new forms of life. It is estimated that one out of three died in the search. In 1761—by an act antedated to 1757—he was ennobled and given the right to call himself Carl von Linné and was appointed a member of the Swedish House of Nobles. He died in Uppsala Cathedral, where he is interred. After his death, his books and collec­ tions were bought by the rich English naturalist Sir J. E. Smith, who took them

[277]

BUFFON

to England. There they served as the basis of the famous English biological as­ sociation called the Linnaean Society, which was founded in 1788, ten years after Linnaeus’ death. There is a famous story (dramatic, but untrue) that the Swedish navy sent a warship to try to capture the ship that was carrying these Swedish treasures to England. In 1866, changes were reported in the lunar crater named for him; these changes have not yet been satisfactorily explained. [277] BUFFON, Georges Louis Leclerc, comte de (byoo-fohn7) French naturalist Born: Montbard, Burgundy, Sep­ tember 7, 1707 Died: Paris, April 16, 1788 Buffon came of a well-to-do family. He traveled extensively and was able to indulge his taste for learning. He studied both law at Dijon and medicine at An­ gers, obtaining a degree in the former in 1726. A duel he fought in Angers made it seem wise to him to get out of town. He fell in with a young Englishman at Nantes and they traveled together, in­ cluding a trip to England. Buffon was strongly impressed by En­ gland’s upsurge of science and translated Newton’s [231] work on the calculus in order to practice his English. He was in­ terested in the work of Stephen Hales [249] on plants and this too he trans­ lated. He also conducted experiments to see if Archimedes [47] could really have burned Roman ships with lenses focusing the sun’s rays; he decided it was possible. He was elected to the Royal Society in 1730, while he was in England, to the Academy of Sciences in 1733, and in 1739 became keeper of the Jardin du Roi, the French botanical gardens, and was thus led into a permanent interest in natural history. Beginning in 1752 and continuing for fifty years, volume after volume of his Natural History appeared. There were forty-four volumes alto­ gether, written with various collabo­ rators, the last eight volumes being pub­ lished after his death.

BUFFON

[277]

The treatise was written clearly and at­ tractively for the general public and was the first modem work to attempt to treat the whole of nature. It was deservedly popular but was nevertheless better as popular writing than as science, for Buffon wanted to see grand designs in nature even when it meant doing vio­ lence to details. As a result he had a ten­ dency to superficiality and too-easy gen­ eralization. In short, there was rather a touch of the Pliny [61] in him. Buffon was groping toward a concept of evolution in his work. He was temper­ amentally unsuited to the painstaking work of a Linnaeus [276], which made it all the easier for him to see life as a grand movement. He noted that some creatures had parts that were useless to them (such as the lateral toes of the pig) and from this deduced that parts might degenerate and whole animals do the same. An ape might be considered, then, an imperfect or corrupted man, a don­ key an imperfect horse, and so on. These ideas were carried further by Erasmus Darwin [308]. Buffon also advanced generalized no­ tions, more rhetoric than reasoned sci­ ence perhaps, concerning the slow devel­ opment of the earth. He suggested, in 1745, that the earth might have been created by the catastrophic collision of a massive body (he called it a comet) with the sun. The view was outdistanced by the nebular hypothesis of Kant [293] and Laplace [347], but a form of it was to make a strong showing in the first half of the twentieth century. Buffon also felt the earth might have been in existence for as much as seventy-five thousand years, with life itself having come into existence perhaps forty thousand years ago. This was the first attempt in Chris­ tian Europe to probe back beyond the six-thousand-year limit apparently set by the Book of Genesis, something soon to reach a climax with Hutton [297]. Buffon also felt that the earth might last ninety thousand years before cooling completely. These evolutionary views concerning earth and man, although cautiously phrased, were daring in an epoch when the view was that earth and man were 183

[278]

HALLER

created whole and at once some six thousand years before. Nevertheless Bufion was a diplomatic person who knew when to recant any views that aroused too much opposition. He had only minor difficulties with authority and was eventually made a count by Louis XV. His son was less fortunate and was guillotined during the French Revolu­ tion. [278] HALLER, Albrecht von (hahl'er) Swiss physiologist Born: Berne, October 16, 1708 Died: Berne, December 17, 1777 Haller, the son of a lawyer, was forced into quiet amusements as a child, be­ cause of ill health, and quickly showed himself to be a prodigy. He began writ­ ing on scholarly subjects at the age of eight, prepared a Greek dictionary at ten, and kept right on going. He studied under Boerhaave [248], whose favorite student he was, and eventually became a physician with wide-ranging tastes, be­ ginning his practice in 1729 when he was only twenty-one. He was interested in botany, among other things, and collected plants, even­ tually writing a large book on the flora of Switzerland. For seventeen years, from 1736 to 1753, he taught at the University of Gottingen as professor of medicine, anatomy, surgery, and botany. Then he retired to his hometown to write an encyclopedic summary of medicine, and various romances in addition, to say nothing of didactic poetry (rather better than that of Erasmus Darwin [308]) and works on politics. His most important contribution to science was his research on muscles and nerves, published in 1766. Until his time it was believed that nerves were hollow and carried a mysterious spirit or fluid, which was never demonstrated. Even Boerhaave, a great rationalist otherwise, made this concession to mysticism. Haller, however, believing in no spirit that could not be seen or worked with, stuck to the experimental observations. He recognized that muscles were irrita­ 184

MARGGRAF

[279]

ble, that is, that a slight stimulus to the muscle would produce a sharp contrac­ tion. He also showed that a stimulus to a nerve would produce a sharp contraction in the muscle to which it was attached. The nerve was the more irritable and required the smaller stimulus. Haller judged that it was nervous stimulation rather than direct muscular stimulation that controlled muscular movement. He also showed that tissues themselves do not experience a sensation but that the nerves channel and carry the impulses that produce the sensation. Furthermore Haller showed that nerves all led to the brain or the spinal cord, which were thus clearly indicated as the centers of sense perception and responsive action. He experimented by stimulating or damaging various parts of the animal brain and then noting the type of action or paralysis that resulted. Haller may therefore be considered the founder of modem neurology. In later life, Haller seems to have be­ come an opium addict, as a result of using opium to counteract insomnia. [279] MARGGRAF, Andreas Sigjsmund (mahrk'grahf) German chemist Born: Berlin, March 3, 1709 Died: Berlin, August 7, 1782 Marggraf was the son of the apothe­ cary to the Prussian court, and he him­ self had a kind of itinerant education studying under apothecaries, chemists, and metallurgists in various parts of Ger­ many. Eventually he returned to Prussia, was elected to the Royal Academy of Sci­ ences there, and made the director of its chemical laboratory by Frederick II. Among Marggrafs achievements in chemistry was the fact that in 1754 he distinguished alumina from lime. That discovery was a harbinger of the time when each would be found to contain a different chemical element: alumina is aluminum oxide and lime is calcium oxide. He also studied the oxidation of phos­ phorus in 1740 (which of course he

[280]

GMELIN

didn’t understand as an oxidation, since oxygen and its significance had to await Lavoisier [334]). He recorded the fact that phosphorus gained weight when it was oxidized, which did not fit in with Stahl’s [241] phlogiston theory, which Marggraf wholeheartedly accepted. (He was the last important German chemist to do so.) The gain in weight, which Marggraf reported but did not attempt to explain, was important to Lavoisier later on. Marggraf s greatest achievement, how­ ever, was the extraction of a crystalline substance from various common plants, including beets, which, on investigation, turned out to be identical to cane sugar. This finding, made in 1747, laid the foundation of Europe’s important sugarbeet industry. [280] GMELIN, Johann Georg (guhmayfiin) German explorer Born: Tübingen, Württemberg, August 10, 1709 Died: Tübingen, May 20, 1755 Gmelin, the son of an apothecary, ob­ tained his medical degree in 1727. He followed a couple of his teachers to St. Petersburg, and by 1731 held a profes­ sorial appointment in chemistry there. In 1733, he joined one of the expedi­ tions that Russia was sending out to study and explore the Siberian wilderness in the wake of Bering’s [250] important explorations. Among the interesting observations Gmelin made in the course of his explo­ rations were the barometric pressure readings he took in Astrakhan, at the mouth of the Volga River where it flows into the Caspian. He was thus able to show for the first time that the shores of the Caspian lie below sea level. In 1735, at the Siberian town of Yeniseysk, he recorded the lowest tempera­ ture recorded up to that time. It was the first indication that the earth could, in spots, be far colder than home-bound Europeans realized. In eastern Siberia, he was the first to note that though the frost in the upper­

WRIGHT

[281]

most layer of soU melted under the sum­ mer sun, the ground a little way beneath remained solidly frozen all summer long. He thus discovered the existence of per­ mafrost, a very important feature of the polar regions. At home in Tübingen, where he be­ came professor of medicine, botany, and chemistry in 1749, he reported on the appearance of five or six new plant forms in his St. Petersburg garden. He couldn’t explain this in terms of the fixity of species which Linnaeus [276] believed in and which the Biblical ac­ count of creation made orthodox. The explanation awaited De Vries [792] a century and a half later. [281] WRIGHT, Thomas English astronomer Bom: Byers Green, near Dur­ ham, September 22, 1711 Died: Byers Green, February 25, 1786 Wright did not exactly have an easy youth. He was the son of a carpenter, and he had little schooling because a speech impediment made life difficult for him. When he grew interested in astron­ omy and began to study it feverishly, his unsympathetic father burned his books, holding them to be frivolous and timewasting. Wright was apprenticed to a clockmaker but at eighteen some sort of scandal impelled him to flee home. He continued to study and, away from his father’s influence, he suffered no fur­ ther book binning. In the course of a continued unsetded life he studied navi­ gation and astronomy; and, speech impediment notwithstanding or sur­ mounted, he began to teach these sub­ jects. By 1742, he was even offered a formal teaching position in St. Peters­ burg, but that fell through. Wright was a religious man who tried to build a model of the universe, with God and heaven at the center and a re­ gion of darkness and doom at the rim, and with the stars (including the solar system) circling the center inside the outer region of doom. This notion, first advanced in 1750, was the first indica­ 185

[282]

LOMONOSOV

tion that the sun was no more the center of the universe than the earth was, but that all the stars including the sun moved in orbit. Furthermore, he reasoned from the ex­ istence of the Milky Way that the system of stars was not symmetrical in all direc­ tions but was flattened. The Milky Way was the appearance of the stars viewed through the long axis of the flattened system. Stripped of its mysticism, Wright was the first to see the stars as existing in a flattened, rotating galaxy. [282] LOMONOSOV, Mikhail Vasilievich (luh-muh-noh'suf) Russian chemist and writer Born: Denisovka (near Archan­ gel), November 19, 1711 Died: St. Petersburg (modem Leningrad), April 15, 1765 Lomonosov was the bookish son of a well-to-do shipowner. He made his way to Moscow when he was seventeen (partly to escape a stepmother) and managed to secure admission to school by pretending to be the son of a noble­ man. His excellent progress resulted in his being sent first to St. Petersburg and then to the University of Marburg in Germany (advanced education in chem­ istry was not to be had in Russia in those days). He returned to St. Peters­ burg and was appointed a professor of chemistry at the university in 1745. In the course of his work he published antiphlogistic views during the 1740s and 1750s and suggested the law of con­ servation of mass. In important ways he anticipated Lavoisier [334]. He also held atomist views, which he thought were too revolutionary to publish. He es­ poused the theory of heat as a form of motion as Rumford [360] was to do and the wave theory of light as Young [402] was to do. In all these cases, he was ahead of his time. He was the first to record the freezing of mercury. (This took place during a very cold Russian winter, for mercury freezes at forty degrees below zero.) He and a friend tried to repeat the kite ex­ 186

CLAIRAUT

[283]

periment of Franklin [272]. The friend was killed and Lomonosov barely es­ caped. In astronomy he was the first to ob­ serve the atmosphere of Venus, during its transit across the sun in 1761, though the fact of his discovery remained un­ known outside Russia for a century and a half. Lomonosov was the founder of Russian science, and he would be univer­ sally recognized as a great pioneer of sci­ ence had he only been born a West Eu­ ropean. He was famous also for his liter­ ary works, including poems and dramas. In 1755 he wrote a Russian grammar that reformed the language and in the same year he, along with Euler [275], helped found the University of Moscow. In 1760 he published the first history of Russia; he was also the first to prepare an accurate map of that country. And yet Russian scientists were looked down upon, even inside Russia, by the men of German extraction who monopolized Russian science through the nineteenth century. Lomonosov quarreled with his German colleague, grew embittered, and in his last years took to drink. Virtually unknown to the Western na­ tions, he is amply honored by the Soviet Union now. His birthplace of Denisovka had its name changed to Lomonosov in 1948. In 1960, when a Soviet satellite circled the moon and photographed part of its hidden side, one of the craters revealed was named for him. [283] CLAIRAUT, Alexis Claude (klay-roh') French mathematician Born: Paris, May 7, 1713 Died: Paris, May 17, 1765 Clairaut, who was tutored by his mathematician father, was a prodigy, studying the calculus at ten, writing mathematical papers at thirteen, publish­ ing a book of mathematics at eighteen. The last earned him a membership in the French Academy of Sciences in 1731 even though he was below the legal age. (He had a brother who wrote on mathe­ matics at the age of nine, but that brother died at sixteen.) Clairaut accompanied Maupertuis

[284]

LACAILLE

[267] to Lapland, where he helped deter­ mine the length of the meridian. This led in 1743 to his writing a book on the shape of a rotating body like the earth, acting under the influence of gravity and centrifugal force. He went far beyond Newton [231] in his analysis and pro­ duced what is virtually the last word on the subject. He also showed how the shape of the earth could be calculated experimentally by measuring the force of gravity at different points through the timing of pendulum swings. Clairaut was one of those who did much work on the motions of the moon (lunar theory), a popular pastime among eighteenth-century astronomers. He calculated the effects of the gravita­ tional pull of Venus on earth as com­ pared with the pull of the moon. Com­ bining this with some of the observations of Lacaille [284], he obtained in 1757 the first reasonable figure for the mass of Venus (% that of the earth) and a new figure for the mass of the moon (%7 that of the earth). The former estimate is now known to be somewhat too small, the latter too high, but both were the best obtained up to that time. For a while, his studies on celestial mechanics created a particular stir for they seemed to disprove Newton’s theories. On the advice of Buffon [277], he extended his observations and found Newton to be right after all. As the year approached during which —as Halley [238] had predicted a half century before—Halley’s comet would return, Clairaut with the assistance of Lalande [309] worked out the effect of the gravity of Jupiter and Saturn upon the comet. He found that the two giant planets would slow it to the point where it would not reach the point closest the sun in its orbit (perihelion) until April 13, 1759. It was spotted on Christmas Day 1758 and reached perihelion within a month of the predicted time. [284] LACAILLE, Nicolas Louis de (la-kah'yuh) French astronomer Born: Rumigny, Marne, May 15, 1713 Died: Paris, March 21, 1762

NEEDHAM

[285]

Lacaille, the son of a gendarme, in­ tended to enter the Roman Catholic priesthood, but, with the help of Cassini [209], his interests drifted toward astron­ omy and mathematics and the church lost out. He was commonly referred to by the title “abbé,” however. He attained professorial rank at Ma­ zarin College in 1739. The most important event of Lacaille’s life was directing an expedition to the Cape of Good Hope from 1750 to 1754. His purpose was to obtain an accurate figure for the moon’s parallax in combi­ nation with observations by Lalande [309] in Berlin. From his observations in South Africa he prepared a catalogue of nearly two thousand southern stars plus a star map which was much more extensive and ac­ curate than Halley’s [238]. He discov­ ered Alpha Centauri, our nearest stellar neighbor, to be a double star and he filled the southern heavens with constel­ lations named for astronomical instru­ ments. In 1757 he prepared 120 copies of a small but very accurate catalogue of 400 of the brightest stars, more accurate, in fact, than any work except that of Brad­ ley [258], which was then being issued. Despite his poverty Lacaille gave away copies of his chart to any who asked. In 1761 he made a new and more accurate estimate of the distance of the moon, using calculations that for the first time took into account the fact that the earth was not a perfect sphere. His unremitting labor at his star charts, singlehanded, is supposed to have shortened his life. [285] NEEDHAM, John Turberville English naturalist Born: London, September 10, 1713 Died: Brussels, Belgium, Decem­ ber 30, 1781 Needham was ordained a Roman Catholic priest in 1738, and to get an ed­ ucation for that purpose in those days, he had to leave England. He finally set­ tled in Brussels in 1768. 187

[286]

DIDEROT

His most notable contribution to sci­ ence was his experimentation in 1748, in collaboration with Buffon [277], on spontaneous generation. He boiled mut­ ton broth and sealed it in glass con­ tainers. When the containers were opened a few days later, there were numerous microorganisms present. These, he concluded, had arisen from nonliving matter. It was twenty years later that Spallanzani [302] showed that Needham simply hadn’t boiled his broth long enough and that some spores had survived the short boiling period. In 1768, he was elected to the Royal Society, the first Roman Catholic to ac­ quire the distinction. When he died, he was the director of the Academy of Sci­ ences at Brussels. [286] DIDEROT, Denis (dee-drohO French encyclopedist Born: Langres, Haute-Mame, Oc­ tober 5, 1713 Died: Paris, July 31, 1784 As a youngster Diderot, the son of a master cutler, was educated at a Jesuit school, but the education did not take in certain ways, although he received a master’s degree from the University of Paris in 1732. He might have been a doctor or a lawyer, but he preferred to make a precarious living by small writ­ ings of all sorts, fiction, essays, transla­ tions, anything and to teach himself sci­ ence, as well. He produced some valu­ able material, too. He wrote a pamphlet, for instance, that represented the first se­ rious study of deaf-mutes. He developed notions on religion, despite his training, that seemed heretical, even atheistic, and spent three months in jail in 1749 possi­ bly because in one of his essays he spec­ ulated on the possibility that evolution might take place through a form of natu­ ral selection. In this there was an in­ teresting anticipation of Charles Darwin [554] and the theory he was to propound a century later. Life really began for Diderot when he emerged from prison. A bookseller suggested to him that he translate an En­ 188

DIDEROT

[286]

glish encyclopedia into French. Diderot agreed and quickly decided to make it a different and better project, to commis­ sion the best scholars in France to write articles on every facet of the new learn­ ing of Newton [231] and his followers. The mathematician D’Alembert [289] became his colleague and the first vol­ ume was published in 1751. For twenty years thereafter, additional volumes, first of text, then of plates, were produced, the Encyclopedia being completed in 1772 in twenty-eight volumes. It was a superhuman labor, for the au­ thorities from the beginning frowned on a work that, while not openly subversive, was riddled with views that ran counter to the accepted theories of monarchic absolutism and religious orthodoxy. It was legally suppressed in 1759, when it was half done. Diderot continued working on it clan­ destinely. Many of his collaborators and commissioned writers, including D’Alem­ bert, quit, not wishing to risk imprison­ ment. Diderot continued virtually alone, performing prodigies of self-education and composition, ending by writing many major articles himself. In the end the bookseller who was publishing the volumes turned prudent and eliminated many passages he believed too risky to include. The work, when done, accomplished a great deal. It was the first of the great encyclopedias, and it brought all the scientific views of the Age of Reason into one place where the general public might reach them. The Encyclopedia may have made Di­ derot famous, but it did not make him rich. Over a period of twenty years it had earned him perhaps twelve dollars a week. Once it was completed he decided to sell his library, out of financial neces­ sity, in order to supply a dowry for his daughter. The empress of Russia, Cath­ erine II (the Great) intervened. She bought it for five thousand dollars, then asked him to keep it for her and serve as her librarian at an annual salary. He was even invited to St. Petersburg in 1773 for some months of philosophizing with the empress. (She was even more op­ pressive in her country than Louis XV

[287]

GUETTARD

was in France, but she fancied herself a liberal, as long as that liberality was confined to high philosophy and never had to be put into practice.) Diderot died just five years too soon to see the beginning of the French Revolu­ tion. The Encyclopedia had done much to rouse the emotions that were to ex­ plode in violence in 1789 and thereafter, so perhaps the old French government had been right to fear the industrious scribbler. [287] GUETTARD, Jean Étienne (gehtahrd') French geologist Born: Étampes, Seine-et-Oise, September 22, 1715 Died: Paris, January 6, 1786 Guettard studied medicine at the Uni­ versity of Paris and like other physicians of the day was keenly interested in natu­ ral history, botany in particular. He kept the natural history collections of the duke of Orléans. Guettard observed the rocks of central France and, although he had never seen a volcano, he had read enough descrip­ tions of eruptions and their results to de­ cide that the rocks he saw had been formed at high temperatures. He was not quite ready to suppose the existence of a volcanic past, but others, notably Desmarest [296], took this logical final step. [288] LIND, James Scottish physician Born: Edinburgh, October 4, 1716 Died: Gosport, Hampshire, En­ gland, July 13, 1794 Lind, the son of a merchant, began his medical career as surgeon’s mate in the British navy and was promoted to sur­ geon in 1747. He left the navy in 1748 and obtained a medical degree at the University of Edinburgh in that year. It was natural for him to become in­ terested in scurvy, a disease that at­ tacked men on long sea voyages. Great

LIND

[288]

Britain, as a maritime nation and depen­ dent for its national security on the efficiency of its fleet, was most threat­ ened by this disease, which killed far more sailors than enemy action did. (Its most eminent victim, perhaps, was Be­ ring [250].) Lind believed scurvy to be caused— and curable—by diet, after reading of the disease in besieged towns and explor­ ing expeditions, wherever the diet was limited and monotonous, without fresh fruits and vegetables. In 1747, he treated scurvy-ridden sail­ ors with various foods and found that citrus fruits worked amazingly well in effecting relief. When he was placed in charge of the naval hospital at Haslar in 1758 he began attempts to get the navy to adopt citrus fruit as a dietary staple. Unfortunately, brass hats are notoriously conservative and progress was slow. Cap­ tain Cook [300] kept off scurvy by this means in his great expedition in the 1770s, losing only one man in three years, and still the navy hesitated. Lind became physician to King George III in 1783 and still could not carry his point. In 1795, British sailors mutinied against vile treatment of all sorts. The British suppressed the mutiny brutally, but they were engaged in a desperate war with the French revolutionaries and they could not afford to keep the sailors sullen and disaffected. They therefore in­ stituted reforms. One of the sailors’ de­ mands had been to make use of Lind’s findings, so the navy adopted the prac­ tice of feeding lime juice to the sailors. Scurvy was wiped out, and British sailors have been called “limeys” ever since. It was to be a century before the work of Eijkman [888] and others showed that Lind unknowingly was treating a vi­ tamin-deficiency disease by supplying vi­ tamins in the diet. Lind also strove for the establishment of hospital ships in tropic waters, for cleanliness and good ventilation in sick bays, and is generally considered the fa­ ther of naval hygiene. He also suggested that sea water be made a source of ship­ board fresh water, through distillation, a matter now of world importance. 189

[289]

D’ALEMBERT

[289] D’ALEMBERT, Jean le Rond (dah-Iahn-bearO French mathematician Born: Paris, November 16, 1717 Died: Paris, October 29, 1783 D’Alembert was brought up by a gla­ zier and his wife, after having been found abandoned at the church of St. Jean-le-Rond, from which he derived his name. He was the illegitimate son of an aristocrat who did, however, contribute to his support. In later years, when his talents were clearly evident, his mother tried to claim him, but D’Alembert proudly refused her. “The glazier’s wife is my mother,” he said. He never mar­ ried and lived with his foster parents till he was forty-seven. He graduated from Mazarin College in 1735 and was admitted to the Academy of Sciences in 1741, becoming its perpet­ ual secretary in 1772. He worked on gravitational theory, particularly on the precession of the equinoxes, and spon­ sored both Lagrange [317] and Laplace [347], who completed the job. For a time, he aided in the preparation of the great Encyclopedia of Diderot [286], writing the introduction to it, yet despite the “anti-establishment” character of this work, he received a pension from Louis XV. As was tme of many of the great minds of the time D’Alembert was in­ vited to Berlin by Frederick II and to St. Petersburg by Catherine II, but he re­ fused both invitations. Rather out of character for D’Alembert is the fact that he bitterly disputed with Clairaut [283], apparently driven by jealousy of the lat­ ter’s work on Halley’s comet. [290] CANTON, John English physicist Born: Stroud. Gloucestershire, July 31, 1718 Died: London, March 22, 1772 Canton, the son of a weaver, had little formal schooling, since his father took him out of school to work at the family business. Canton persisted in studying at 190

BONNET

[291]

night and a minister in the neigh­ borhood, recognizing the young man’s talent, offered to take charge of him. With this help, Canton eventually learned enough to become a school­ master. He made a number of minor dis­ coveries in physics and chemistry. He prepared artificial magnets in 1749 and was elected to the Royal Society as a re­ sult. In 1762 he demonstrated the fact that water was slightly compressible. He invented a number of devices in connec­ tion with electricity. His most interesting observations were made between 1756 and 1759, when he noted that on certain days the compass needle was more irregular than usual and that on those same days the aurora borealis was sometimes very conspic­ uous. This was the first observation of what are now called magnetic storms and led to the discovery of electric charges in the sky far higher than the clouds, by such men as Appleton [1158], a century and a half later. [291] BONNET, Charles (boh-nayO Swiss naturalist Born: Geneva, March 13, 1720 Died: Genthod, near Geneva, May 20, 1793 Bonnet, born of a wealthy French family, was not a good student in his youth. It didn’t help him that he was afflicted with increasing deafness. A pri­ vate tutor was engaged and eventually he studied law and obtained his degree in 1743. His hobby was natural history, how­ ever, and in the pursuit of that hobby he spent his quiet life, during the course of which he never left Switzerland. His most interesting discovery was that the tiny insects called aphids could re­ produce parthenogenetically—the female eggs could develop without the fertilizing action of the sperm. He also studied the respiration of insects and found in 1742 they breathed through pores which he named “stigmata.” He noted the capacity of a very simple animal, the freshwater hydra, to regenerate lost parts. The re­

[292]

CRONSTEDT

suit was that at the age of twenty-three, when he received his law degree, he was also elected to the Royal Society. In the 1750s his eyes began failing him, and to concentrate on tiny lifeforms came to be beyond his powers. He turned to speculation. The fact that aphids produced parthenogenetically made him feel that every creature al­ ready existed, preformed, in the egg, and somewhere within that creature was a smaller egg with another creature, pre­ formed, within it, and so on without end. Generation nested within generation. This made it seem that species were fixed and could not change and this, in turn, made it necessary to explain those fossils that resembled no living creatures. This explanation Bonnet found by pos­ tulating periodic catastrophes involving all the earth. The fossils were remnants of creatures that dwelt before a catas­ trophe. Bonnet believed that after each catastrophe all forms of life stepped a notch upward, and he predicted a future catastrophe after which apes would be men and men would be angels. The principle of catastrophism domi­ nated geological thinking for a genera­ tion after Bonnet’s death, thanks to its adoption by Cuvier [396]. It was Bonnet who first made use of the term “evolu­ tion." [292] CRONSTEDT, Axel Fredrik (kroon'stet) Swedish mineralogist Born: Stroepsta, Sodermanland, December 23, 1722 Died: Stockholm, August 19, 1765 Cronstedt was the son of a high army officer and received a good education. As a youngster he grew interested in mining and mineralogy and studied under Brandt [260]. His career was interrupted by army service between 1741 and 1743 when Sweden was at war with Russia. Cronstedt’s researches paralleled those of his teacher. Brandt had discovered cobalt in an ore that resembled copper ore but was not copper ore. Well, there

CRONSTEDT

[292]

was a second type of ore that resembled copper ore without being copper ore, and this, too, received a name that testified to the belief of the miners that the false ore was bewitched. It was called Kupfemickel (“Old Nick’s cop­ per,” in reference to the devil). On the other hand, this false copper ore was not a cobalt ore either and did not impart a blue color to glass as cobalt ore did. In 1751 Cronstedt tackled this ore and obtained green crystals that, when heated with charcoal, yielded a white metal that certainly was not copper. It resembled iron and cobalt, though it was different from both. Cronstedt discovered that, like iron but much less strongly, the new metal was attracted by a magnet—the first time anything but iron had been found subject to magnetic attraction since the days of Thales [3] twenty-three centuries before. In 1754 Cronstedt gave the new metal a shortened form of the old miners’ name and called it nickel. There fol­ lowed twenty years of controversy as to whether nickel was really a new metal or just a complex mixture of old ones, but Cronstedt’s view won out, though he did not live to see it. Cronstedt was one of those who re­ formed mineralogy and initiated a classification of minerals not only ac­ cording to their appearance, but also ac­ cording to their chemical structure. A book detailing this new form of classification was published in 1758. Cronstedt introduced the blowpipe into the study of minerals. By directing a thin jet of air into a flame, it increased the heat of the flame. When this hot flame impinged on minerals, much infor­ mation could be learned from the color of the flame, the vapors formed, the color and nature of the oxides or metal­ lic substances formed out of the mineral, and so o a He thus systematized and sharpened the technique of observing color changes as a means of chemical analysis—a technique which had been foreshadowed a century earlier by Glauber [190], For a century the blowpipe remained the most useful instrument in the armory of the chemical analyst, but its use called 191

[293]

KANT

LE GENTIL

[295]

for a great skill that not all chemists pos­ [294] MICHELL, John (mich'el) sessed. It was rendered obsolete by the English geologist invention of the system of spectral analy­ Born: Nottinghamshire, 1724 sis by Kirchhoff [648]. Died: Thornhill, Yorkshire, April 21, 1793 Michell obtained a master’s degree at [293] KANT, Immanuel Cambridge in 1752. He was appointed German philosopher rector of St. Michael’s Church in Leeds Born: Königsberg, East Prussia and held the post till his death. (now Kaliningrad, Soviet Union), He presented solid reasons for think­ April 22, 1724 ing the stars were light-years distant in Died: Königsberg, February 12, 1784, half a century before Bessel [439] 1804 and others demonstrated the fact. He also preceded Herschel [321] in suspect­ Kant, the son of a saddlemaker of ing the existence of binary stars. Scottish descent, spent all his life in his He invented a torsion balance similar obscure home town, never traveling to that which Coulomb [318] later in­ more than sixty miles from it in his vented. With it he was going to measure eighty years of life, following a regime the strength of the gravitational constant, so time-bound that his neighbors could but he died before he had the chance almost set their clocks by him. and it was Cavendish [307] who carried He is best known as a profound phi­ it through. losopher and as the author of Critique of Michell is remembered for another ac­ Pure Reason, published in 1781, a com­ complishment. In 1760, five years after prehensive scheme of philosophy of most an earthquake at Lisbon that was so sud­ Teutonic thoroughness. In his youth, den and destructive that Europe was however, he had studied mathematics nearly panicked, Michell suggested that and physics at the University of Königs­ set up wave motions in the berg and in 1755, the year he obtained earthquakes earth. He noted the frequency of earth­ his doctor’s degree, he had published his quakes in the vicinity of volcanoes and physical view of the universe in General suggested that the quakes started as the History of Nature and Theory of the result of gas pressure produced by water Heavens. through volcanic heat. He felt This book contained three important boiling might start under the anticipations. First, he described the neb­ that earthquakes floor and argued that the Lisbon ular hypothesis, anticipating Laplace ocean was an example of that. He [347], Second, he suggested the Milky earthquake pointed out that by noting the Way was a lens-shaped collection of further stars and that other such “island uni­ time at which the motions were felt, one verses” existed, an anticipation of Her- could calculate the center of the earth­ schel [321] and of twentieth-century as­ quake. A century and a quarter later, tronomy. Finally he suggested that tidal this was brought to pass by Milne [814], friction slowed the rotation of the earth, Michell is rightly considered the father a suggestion that was correct but could of seismology. not be demonstrated for another century. In 1770 he became professor of math­ ematics at the University of Königsberg, but in 1797 he shifted his attention to [295] LE GENTIL, Guillaume Joseph Hyacinthe Jean Baptiste (luhmetaphysics and to logic. His daring zhahn-teel') speculations were made possible by the fact that he was patronized and pro­ French astronomer tected by the freethinking Frederick II Born: Coutances, Manche, Sep­ of Prussia. After Frederick’s death, Kant tember 12, 1725 had to be more cautious. Died: Paris, October 22, 1792 192

[296]

DESMAREST

Le Gentil, the son of a good-familycome-down-in-the-world, studied theol­ ogy at the University of Paris and grew interested in astronomy there. Soon, he involved himself in work at the Paris Observatory, and the stage was set for an almost unbelievable set of astro­ nomical misfortunes. He was commissioned to go to India in order to observe the transit of Venus in 1761. He was to view it from Pon­ dicherry on India’s southeastern coast. The Seven Years’ War was raging and Great Britain was fighting France in India. Just as Le Gentil reached India he found the British had taken Pondicherry and he was forced to remain on board ship during the transit. No decent obser­ vations were possible. However, another transit was due in 1769. There were no airplanes then and Le Gentil did not wish to go back to France and then back to India in long, long voyages on the miserable ships of the day. He decided to remain in India for eight years. There were no electric communications in those days and no easy way to inform the people back home of this decision. In 1769, he had to choose between Manila and Pondicherry for the observa­ tion. He decided on Manila but Pon­ dicherry was again a French possession land political decisions on the spot forced him to remain there. Came the crucial day: In Manila, the sun shone out of a cloudless sky. In Pondicherry, where Le Gentil was observing, clouds obscured the sun just during the time of transit. He returned to France to find himself considered dead and his heirs in posses­ sion of his property. —Oh, well, he straightened things out as best he could, married, had a daughter, and wrote a monumental and highly regarded twovolume book on India, so all was not lost.

HUTTON

[297]

Just before the French Revolution, Desmarest, the son of a schoolteacher, was appointed inspector general and di­ rector of manufactures of France. As a royal appointee, he could not help but be under suspicion, and at the worst of the eventual Terror he was imprisoned. He survived, however, to be recalled to gov­ ernment service. A contemporary of Hutton [297], Des­ marest dealt with changes on the earth’s surface in similar fashion. Desmarest was the first to maintain that valleys had been formed by the streams that ran through them. He also carried forward Guettard’s [287] ideas, maintaining that basalt was volcanic in origin and that large sections of France’s rocks, for in­ stance, consisted of ancient lava flows. Unfortunately, A. G. Werner’s [355] er­ roneous theories that almost all rocks were formed by sedimentation from water held sway for a while, though the volcanic theories of Guettard and Des­ marest eventually won out.

[297] HUTTON, James Scottish geologist Born: Edinburgh, June 3, 1726 Died: Edinburgh, March 26, 1797 Hutton, the son of a merchant, was left fatherless at three. He became a law­ yer’s apprentice, but grew interested in chemistry and returned to school to study medicine. He obtained his medical degree at Leiden in 1749, but he never practiced. Instead, he worked on various agricultural projects and set up a factory to manufacture ammonium chloride. From chemistry he went on to miner­ alogy and geology, interest in which was stimulated by his journeys on foot to different parts of England. Hutton’s in­ terest in this direction, which was heart­ ily encouraged by his good friend Black [296] DESMAREST, Nicolas (day-muh- [298] , absorbed him more and more and in 1768 he retired on the proceeds of his restO factory and devoted himself to geology. French geologist By that time he had already founded Bom: Soulaines, Aube, Septem­ the science, for until then geology did ber 16, 1725 Died: Paris, September 28, 1815 not really exist as an organized field of 193

[297]

HUTTON

study. Isolated scholars such as Steno [225] and Buffon [277] had speculated on the past history of the earth and com­ mented on rock strata, but there were no overall generalizations in the subject. A strong inhibiting factor was the conven­ tional belief in an earth created six thou­ sand years before according to the de­ scription in the Book of Genesis. Any countering argument seemed irreligious and offended the more conservative. Hutton’s careful studies of the earth’s terrain convinced him—as it had con­ vinced others before him—that there was a slow evolution of the surface structure. Some rocks, it seemed clear to him, were laid down as sediment and compressed; other rocks were molten in the earth’s interior and were then brought to the surface by volcanic ac­ tion; exposed rocks were worn down by wind and water. His great intuitive addition to all this was the suggestion that the forces now slowly operating to change the earth’s surface had been operating in the same way and at the same rate through all earth’s past. This is the “uniformitarian principle” and it was countered by those like Bonnet [291] who maintained that the history of the earth was one of sharp, catastrophic changes (“catastrophism”). He also felt that the chief agent at work here was the internal heat of the earth. The planet, in short, was a gigan­ tic “heat-engine,” a not-unnatural con­ clusion, perhaps, for one who was a friend of Watt [316] as well as of Black. To Hutton it seemed as though the earth’s history must be indefinitely long, since, although the actions involved were creepingly slow, vast changes had never­ theless had time to take place. There seemed no sign of a beginning, he wrote, and no prospect of an end. Hutton summarized his views in a book called Theory of the Earth, pub­ lished in 1785. Since it first advanced the general principles upon which geology is now based, he is often called the “father of geology.” In the book Hutton also dealt with rainfall and reached essen­ tially modern conclusions, to wit: the amount of moisture that the air could 194

BLACK

[298]

hold rose with temperature. Conse­ quently when a warm air mass met a cold one so that the temperature of the former dropped, some of the moisture could no longer be held in vapor form and precipitated as rain. Hutton’s geological views met with strong resistance and objection from those who held to the biblical account of creation. It was the time of the French Revolution and England was going through a strong conservative reaction. Anything smacking ever so faintly of going against establishment views was suspect. It was not until the popularizing work of Lyell [502] a half century later and well after Hutton’s death that the view of the Theory of the Earth came into its own. At the time of his death, Hutton was working on a book in which he ex­ pressed a belief in evolution by natural selection, a view to be made famous by Charles Darwin [554] six decades later. However, Hutton’s manuscript was not examined till 1947, so that his antici­ pation of Darwin remained unsuspected for a century and a half. [298] BLACK, Joseph Scottish chemist Born: Bordeaux, France, April 16, 1728 Died: Edinburgh, December 6, 1799 Black’s father, a Scots-Irish wine mer­ chant living in France, sent young Jo­ seph (one of thirteen children) back to the British Isles in 1740 for his educa­ tion. Black studied medicine at Glasgow, then, after 1750, at Edinburgh and even­ tually held professorial positions at each of these institutions and proved an excel­ lent and popular lecturer. While still a medical student he grew interested in kidney stones and from these moved on to minerals that were similar. His thesis for his medical degree— obtained in 1754—proved to be a classic in chemis­ try. The work was published in 1756 (the year in which he became professor of chemistry at Glasgow) and in it Black reported that the compound we now call

[298]

BLACK

calcium carbonate was converted to cal­ cium oxide upon strong heating, giving off a gas that could recombine with the calcium oxide to form calcium carbonate again. Black called the gas “fixed air” because it could be fixed into solid form again. We call it carbon dioxide. Carbon dioxide was studied by Hel­ mont [175] a century and a quarter be­ fore, but Black was the first who showed that it could be formed by the decom­ position of a mineral as well as by com­ bustion and fermentation. Furthermore, by involving a gas in a chemical reaction he divested it of its mystery and made it not so very different, from the stand­ point of chemistry, from liquids and solids. And since calcium oxide could be converted to calcium carbonate simply by exposure to the air, it followed that carbon dioxide was a normal component of the atmosphere. He also recognized the existence of carbon dioxide in ex­ pired breath. In studying the properties of carbon dioxide, Black found that a candle would not bum in it. A candle burning in ordi­ nary air in a closed vessel would go out eventually and the air that was left would no longer support a flame. This might seem reasonable since the burning candle formed carbon dioxide. However, when the carbon dioxide was absorbed by chemicals, the air that was left and was not carbon dioxide would still not support a flame. Black turned this prob­ lem over to Daniel Rutherford [351], his young student, and within a decade chemistry was in part revolutionized by just such experiments. In studying the effect of heat on cal­ cium carbonate, Black measured the loss of weight involved. He also measured the quantity of calcium carbonate that would neutralize a given quantity of acid. This technique of quantitative measurement, as applied to chemical re­ actions, was to come into its own a few decades later with Lavoisier [334]. Black’s work in physics was equally important. In 1764 he grew interested in the phenomenon of heat and was the first to recognize that the quantity of heat was not the same thing as its inten­ sity. It was the latter only that was mea­

BLACK

[298]

sured as temperature. Thus, he found that when ice was heated, it slowly melted but did not change in tempera­ ture. Ice absorbed a quantity of “latent heat” in melting, increasing the amount of heat it contained but not the intensity. An even larger quantity of latent heat was involved in the conversion of water to vapor by boiling. Furthermore, when water vapor con­ densed to water, or when water froze to ice, an amount of heat was given off equal to that taken up by the reverse change. Yet the act of condensation or freezing involved no temperature change either. The fact that the heat taken up in one change was given off in the reverse change was a step in the direction of un­ derstanding the great generalization called “conservation of energy,” which was to be clearly established some three quarters of a century later with the work of such men as Mayer [587], Joule [613], and Helmholtz [631]. The heat taken up by water in boiling was a clue to the far greater energy con­ tent of steam at the boiling point temper­ ature as compared with an equal weight of liquid water at the same temperature. This fine theoretical point was known to James Watt [316], who was aware of Black’s work, and Watt used it in de­ veloping his steam engine. (It is never sufficiently realized, particularly in the United States, how much the “down-toearth” inventor is indebted to the “ivory tower” theoretician.) Black also showed that when equal weights of two different substances at different temperatures are brought to­ gether and allowed to come to tempera­ ture equilibrium, the final temperature is not necessarily at the midway point. One substance might lose 30°, for instance, while the second was gaining only 20°. The same quantity of heat, in other words, might effect a temperature change 50 percent greater in one sub­ stance than in another. This charac­ teristic temperature change resulting from the input of a particular amount of heat is now called the specific heat. Black had trouble accounting for all this. He, in common with other chemists of his time, believed heat to be an im­ 195

[299]

LAMBERT

COOK

[300]

ponderable fluid, like light, electricity, or firmed by the careful work of Herschel the phlogiston postulated by Stahl [241]. [321] a generation later. In terms of an imponderable fluid pour­ ing from one substance to another, the concept of specific heat and latent heat [300] COOK, James could be explained only by troublesome English navigator and implausible arguments. When the ki­ Bom: Marion village, Cleveland, netic theory of heat was finally devel­ Yorkshire, October 27, 1728 oped by men such as Maxwell [692], Died: Kealakekua Bay, Hawaii, Black’s experiments fell neatly into February 14, 1779 place. Cook’s reputation as a seaman is proved by the fact that he is hardly known by any name other than Captain [299] LAMBERT, Johann Heinrich Cook. His first name is all but forgot­ (lahm'behrt) ten. German mathematician He was the son of a farmhand and his Born: Mulhouse, Alsace, August first job was in a haberdasher’s shop. 26, 1728 While still young he was apprenticed to Died: Berlin, September 25, 1777 a firm of shipowners and worked his way up to mate. In 1755 he joined the Royal Lambert was the son of a poor tailor. Navy and by 1759 had qualified as a He had to quit school at twelve to help master and took part in Wolfe’s expedi­ his father and was forced thereafter to tion against Quebec in the French and scrimp what education he could out of Indian War. life. Fortunately, men of great talent can The expeditions in which he engaged make do even under difficulties. He were intended for sounding and survey­ began to earn his living as a tutor until ing, for gaining knowledge of the ocean he attracted the attention of Frederick II and of the geographical nature of the of Prussia who saw to it, in 1764, that earth. Thus he spent several years in the the final decade of his life was passed in sixties surveying the coasts of Labrador reasonable comfort. In mathematics and Newfoundland. He observed a solar Lambert, in 1768, proved pi to be an ir­ eclipse on August 5, 1766, near Cape rational quantity (though a century later Ray, Newfoundland. He was the first of Lindemann [826] was to give it an even the really scientific navigators. more subtle distinction) and introduced In 1768 he made the first of three voy­ hyperbolic functions into trigonometry. ages into the Pacific that were to make In 1760 he published his investigations him the most famous navigator since of light reflection. His book was in Latin Magellan [130], two and a half centuries and his word for the fraction of light earlier. Under the auspices of the Royal reflected diffusely by a body was albedo Society (through the Admiralty) he was (“whiteness”). The term is still com­ sent to the South Pacific to observe the monly used in astronomy to represent transit of Venus from the newly discov­ the reflectivity of planetary bodies. He ered island of Tahiti. In the course of was the first to devise methods for mea­ that expedition he discovered the Ad­ suring light intensities accurately, and miralty Islands and the Society Islands, the unit of brightness is the lambert, in named for his sponsors. He also circum­ his honor. In 1761 he speculated that the navigated New Zealand, explored its stars in the neighborhood of the sun shores, and landed in Australia, being made up a connected system and that the first to gain a notion of the size and groups of such systems made up the position of this last of the inhabited con­ Milky Way. He suspected that there tinents to be opened to the Europeans. might be other conglomerations like the Accompanying him as ship’s botanist Milky Way in the far reaches of space. was Banks [331]. The accuracy of his guesses was con­ In a second expedition, from 1772 to 196

[301]

TITIUS

1775, perhaps the greatest single sea voyage ever made, Cook took his ship throughout southern waters down to the Antarctic circle and proved the nonexis­ tence of any vast southern continent other than Australia, or rather proved that any that did exist had to be confined to the Antarctic regions. This expedition outlined the southern hemisphere, except for Antarctica itself, in approximately the form in which it is now known to exist. Except for the polar regions the oceans of the earth had been entirely opened. It was on this voyage, too, that Cook tested the dietary theories of Lind [288] and found them to be sound. He re­ ceived a medal from the Royal Society for this. In his third and last voyage, from 1776 to 1779, he was commissioned to explore the far northern Pacific. He sailed the full north-south length of the ocean, discovering the Hawaiian Islands on the way. After following the Alaskan and Siberian coasts as far as the ice would permit, he returned to Hawaii. There, after one of the ship’s boats was stolen by the natives, a scuffle took place in which he was killed, and at the spot today an obelisk stands in his memory. Since the natives practiced cannibalism he was presumably eaten. For his last voyage, which took place during the American Revolutionary War, Benjamin Franklin [272], who fully appreciated the scientific importance of Cook’s work, arranged that he should not be molested by American privateers. [301] TITIUS, Johann Daniel (tish'us) German astronomer Born: Konitz, Prussia (now Chojnice, Poland), January 2, 1729 Died: Wittenberg, Saxony, Decem­ ber 16, 1796 Titius, the son of a draper who was also a city councillor, was brought up by his uncle after his father’s death. His uncle, a naturalist, encouraged the youngster’s interest in science. He ob­ tained his master’s degree from the Uni­ versity of Leipzig in 1752. In 1756, he

SPALLANZANI

[302]

was appointed to a professorial position at the University of Wittenberg, where he remained for the rest of his life. The one thing for which he is remem­ bered in the history of science is his sug­ gestion in 1766 that the mean distances of the planets from the sun very nearly fit a simple relationship of A = 4 + (2n X 3), where the value of n is, suc­ cessively, —oo, 0, 1, 2, 3 and so on. This works out to the series: 4, 7, 10, 16, 28, 52, 100, . . . which fits the rela­ tive distance of Mercury, Venus, earth, Mars, --------- , Jupiter and Saturn. The dash between Mars and Jupiter was not filled by any planet. The relationship was not noted when first advanced and only came to the at­ tention of astronomers generally when Bode [344] publicized it in 1772. And then it was called Bode’s law, with poor Titius ignored. It turned out, how­ ever, that once Neptune was discovered seven decades later the “law” was only a coincidence with no actual scientific significance. Nevertheless, it did encour­ age Olbers [372] and others to search for the planetary objects in the empty spot and to discover the asteroids. [302] SPALLANZANI, Lazzaro (spahllahn-tsah'nee) Italian biologist Born: Scandiano, Modena, Janu­ ary 12, 1729 Died: Pavia, Lombardy, February 11, 1799 Spallanzani, the son of a successful lawyer, attended the University of Bo­ logna, where his cousin, Laura Bassi, was a singular anomaly for that time—a woman professor of physics who man­ aged to have twelve children in her spare time. It is thought she influenced him in the choice of a scientific career. He obtained his Ph.D. in 1754 and then became a priest in order to help support himself. He taught at several Italian universities, visited Naples in 1788 while Vesuvius was in eruption, and, unlike Pliny [61], survived. He had made trips along the shores of the Medi­ terranean and even into Turkey in 1785 197

[302]

SPALLANZANI

to collect natural history specimens for the museum at Pavia, where Maria Theresa of Austria had placed him in charge. His most dramatic work is in connec­ tion with the question of spontaneous generation. By the eighteenth century the matter of the spontaneous generation of animals visible to the naked eye was a closed one. Thanks mainly to the experi­ ments of Redi [211] a century before, even insects were known to arise only from eggs. But regarding the microor­ ganisms discovered by Leeuwenhoek [221] at about the time of Redi’s experi­ ments, the question remained open. Needham [285] had conducted experi­ ments that seemed to show microor­ ganisms did appear through spontaneous generation. Spallanzani tackled the prob­ lem in 1768, determined to be thorough. He not only boiled solutions that would ordinarily breed microorganisms, he boiled them for between one half and three quarters of an hour. Then he sealed the flasks. No microorganisms ap­ peared in the solutions however long they stood. His conclusion was that mi­ croorganisms appeared in such solutions only because they already existed in it in spore form, or were on the inner walls of the flask or in the air within the flask. Some of these organisms were resistant to brief boiling, but all succumbed to prolonged boiling. Spallanzani believed his own procedure killed all the microor­ ganisms in the solution, in the air above it or on the inner walls about it. Sealing the flask prevented new spores from en­ tering. The fact that no microorganisms appeared in such flasks meant that there was no spontaneous generation. This made possible Appert’s [359] advance in food preservations. But the battle was not over. Those who favored spontaneous generation maintained that by long boiling, Spallan­ zani had destroyed some “vital principle” in the air and that without this principle microorganisms could not breed. It was another century before that objection was finally taken care of by Pasteur [642]. At the request of his friend Bonnet [291], Spallanzani studied the mechanics 198

BOUGAINVILLE

[303]

of the development of eggs. He showed in 1779 that sperm cells had to make ac­ tual contact with egg cells if fertilization was to take place. He also carried through artificial insemination on a dog in 1785. In the last decade of his life Spallan­ zani grew interested in the problem of how nocturnal animals found their way. Bats flew easily in the most complete darkness. He blinded some bats and found them still capable of flying with perfect ease. Some days later he caught several and dissected them. Their stom­ achs were crammed with insect remains. Not only could they fly while blinded, but also they could catch insects. In his usual thorough manner he tackled the other senses (for he could not believe that the ability was what we would today call “extrasensory”). He found that when he plugged the bats’ ears, they were helpless. He had no explanation for this and the experiment seemed so bizarre—could an animal see with its ears?—that it was forgotten. It was only with developing knowledge of ultrasonic sound vibrations a century and more later that an answer to the problem became possible. [303] BOUGAINVILLE, Louis Antoine de (boo-gan-veelO French navigator Born: Paris, November 11, 1729 Died: Paris, August 31, 1811 Bougainville was the son of a notary and, to avoid becoming a notary himself, he enlisted in the French army. He fought in North America as an aide-de­ camp to General Louis Joseph de Mont­ calm in the battles that lost French Can­ ada to the British. After the war was over in 1763, Bougainville joined the navy and led an expedition to the Falk­ land Islands off the shore of southern Argentina, but failed to establish a col­ ony in that rather forbidding territory. He was commissioned by the French government to set sail on a voyage of ex­ ploration and with this end in mind, he sailed in December 1766. The voyage took him around the world, and he led

[304]

MÜLLER

the first French ships to accomplish the feat. He lost only seven men to scurvy, even though he did not have Cook’s [300] preventive of lime juice. He almost reached Australia but turned north too soon to sight its shores. He did sail along the Solomon Islands, the largest of which is Bougainville Is­ land, named in his honor since, in 1768, he was the first European to sight it. He confirmed the existence of marsupials in the eastern islands of Indonesia, some­ thing Buffon [277] had refused to be­ lieve. His voyage and those of Captain Cook finally completed the geography of the Pacific Ocean. After the voyage he became secretary to Louis XV, and then fought against the British in the course of the American Revolutionary War. Despite his royalist connections, he managed to avoid the guillotine in the French Revolution, and lived to be honored as a senator and count by Napoleon Bonaparte. [304] MÜLLER, Otto Friedrich Danish biologist Born: Copenhagen, March 2, 1730 Died: Copenhagen, December 26, 1784 Müller, the son of a court trumpeter, studied theology and law at the Univer­ sity of Copenhagen, then served an aris­ tocratic family for twenty years as tutor. In 1773 he married a wealthy widow, re­ tired, and devoted his remaining years to science. Müller was one of the early microscopists and concentrated on the tiny bacteria first dimly seen by Leeuwenhoek [221 ], These were at just about the limits of resolution of the primitive microscopes that antedated the modern achromatic varieties introduced by J. J. Lister [445], and Müller was the first who saw them well enough to divide them into catego­ ries. He introduced the terms “bacillum” and “spirillum” to describe two of the categories. He was also the first to classify mi­ croorganisms, generally, into genera and

MESSIER

[305]

species after the fashion of Linnaeus [276]. [305] MESSIER, Charles (meh-syayO French astronomer Born: Badonviller, Meurthe-etMoselle, Vosges, June 26, 1730 Died: Paris, April 11, 1817 Messier, the tenth of twelve children, was left fatherless when he was eleven. He went to work as an assistant to Delisle [255] in 1755 and became an ac­ complished astronomical observer. Messier was the first in France to spy Halley’s comet on the famous 1758 re­ turn that Halley [238] had predicted. This inspired him to become a comet hunter and his greatest pleasure was to track down those fuzzy creatures at their first appearance. Louis XV referred to him, with patronizing affection, as “my little comet ferret.” In his systematic searchings, however, he was constantly being fooled by fuzzy nebulosities that occurred here and there as permanent heavenly objects. In 1781 he made a compilation of a little over a hundred such objects in order that neither he nor any other comet hunter would be fooled by them. If a suspected comet were to be spotted, its position would first be checked against Messier’s list before being announced as a discovery. The objects in Messier’s list are still frequently known as Messier 1, Messier 2, or just M l, M2, and so on. They cover a wide variety of objects. Some are indeed nebulosities. Others are collec­ tions of stars that, to Messier’s weak telescope, showed up simply as blurs. Thus Messier 13, first noted by Halley in 1714, is a huge cluster of stars, perhaps a million of them, all told, that is now known as the Great Hercules Cluster be­ cause it occurs in the constellation Her­ cules. About a hundred such clusters exist in our galaxy and all were noted down by Messier. Herschel [321] re­ solved them into stars. It was these clus­ ters that were used by Shapley [1102] a century and a quarter after Messier’s time to demonstrate the true size of the Milky Way. 199

[306]

INGENHOUSZ

In addition, some of Messier’s listed objects are systems of stars as large as or larger than the entire Milky Way. Thus, Messier 31 is the great Andromeda gal­ axy, which, a century and a half later, Hubble [1136] was to resolve, at least partly, into stars. As a comet hunter Messier was as good as could be expected, discovering twenty-one, but none of the comets he discovered are of any particular interest. The miscellany of objects he recorded in order to clear the way for his comets, however, have immortalized his name. He could not have predicted this, for in his time the true grandeur of the uni­ verse was unknown, though some, like Lambert [299] and Kant [293], were be­ ginning to suspect a bit of the truth. [306] INGENHOUSZ, Jan (ing'enhows) Dutch physician and plant physiologist Born: Breda, December 8, 1730 Died: Bowood Park, Wiltshire, England, September 7, 1799 Ingenhousz, the son of a leather mer­ chant, got his medical training at the universities of Louvain and Leiden, re­ ceiving his medical degree in 1752. He traveled to England in 1764, where he eventually grew expert in the technique of smallpox inoculation. He went on to Vienna to inoculate the royal house and to become personal physician to Empress Maria Theresa in 1772. In 1779 he re­ turned to England and became a member of the Royal Society. In that year he published experiments clarifying the previous work of Hales [249] and Priestley [312]. He showed that green plants take up carbon dioxide and give off oxygen, but only in the light (hence “photosynthesis”—formation in light—is the name we now give the pro­ cess). In the dark, they, like animals, give off carbon dioxide and absorb oxy­ gen. This was the first indication of the role of sunlight in the life activities of green plants. Ingenhousz had thus dem­ onstrated the broad scheme of balance in nature. Plants, in the presence of light, 200

CAVENDISH

[307]

consume the carbon dioxide produced by animals, and give off the oxygen that is in turn consumed by animals. The activ­ ity of both plants and animals brought about a balance in which oxygen and carbon dioxide were, in the long run, neither used up nor overproduced. It remained to fill in the details of these processes, of course, and those de­ tails after over a century and a half are only now falling into place. [307] CAVENDISH, Henry English chemist and physicist Born: Nice, France, October 10, 1731 Died: London, February 24, 1810 Cavendish, of an aristocratic English family, was bom in Nice because his mother was there on a trip to improve her health in the salubrious climate of the Riviera. In this she did not succeed, and died when her son was two. Cavendish was educated in England and eventually spent four years at Cam­ bridge, but he never took his degree, partly because he would not participate in the obligatory religious exercises. He also seems to have thought he could not face the professors during the necessary examinations. In all his life, he had difficulty facing people. Mad scientists are many in fiction, few in real life. Yet certainly Cavendish comes as near to qualifying as any one of the truly first-class scientists of his­ tory. He was excessively shy and absentminded. He almost never spoke and when he did it was with a sort of stam­ mer. He might, in an emergency, ex­ change a few words with one man, but never with more than one man, and never with a woman. He feared women to the point where he could not bear to look at one. He communicated with his female servants by notes (to order din­ ner, for instance) and any of these fe­ male servants who accidentally crossed his path in his house was fired on the spot. He built a separate entrance to his house so he could come and leave alone, and his library in London was four miles

[307]

CAVENDISH

from his house, so that people who had to use it would not trouble him. In the end he even literally insisted on dying alone. This eccentric had one and only one love, and that was scientific research. He spent almost sixty years in exclusive preoccupation with it. It was a pure love, too, for he did not care whether his findings were published, whether he got credit, or anything beyond the fact that he was sating his own curiosity. He wrote no books and published only twenty articles altogether. As a result, much of what he did remained unknown until years after his death. His experiments on electricity in the early 1770s anticipated most of what was to be discovered in the next half century, but he published virtually none of it. It was only a century afterward that Maxwell [692] went through Cav­ endish’s notes and published his work. There is no way of estimating what that unnecessary secrecy cost the human race in scientific progress. His electrical ex­ periments also proved his superhuman devotion to science. He had no talent for inventing instruments and he measured the strength of a current in a very direct way, shocking himself with the current or the charge and estimating the pain. Nevertheless he managed to live to be nearly eighty. Fortunately he suffered few economic pressures. He came of a noble family that included the dukes of Devonshire and he had a comfortable allowance. At the age of forty he inherited a fortune of over a million pounds but paid no partic­ ular attention to it; he continued living as before. On his death, the fortune, vir­ tually untouched, went to relatives, and his unpublished notes remained a rich mine for later scientists. In 1766 he communicated some early researches to the Royal Society, describ­ ing his work with an inflammable gas produced by the action of acids on metals. This gas had been worked with before—for instance, by Boyle [212], who had collected some, and by Hales [249]—but Cavendish was the first to in­ vestigate its properties systematically and he is usually given the credit for its dis­

CAVENDISH

[307]

covery. Twenty years later the gas was named hydrogen by Lavoisier [334]. Cavendish was the first to measure the weight of particular volumes of different gases to determine the density. He found hydrogen unusually light, with only onefourteenth the density of air. The lightness of the gas and its easy inflam­ mability led him to believe he had actu­ ally isolated the phlogiston postulated by Stahl [241], a view quickly adopted by another well-known phlogistonist, Scheele [329]. On January 15, 1784, he was able to demonstrate that hydrogen, on burning, produced water. In this way water was shown to be a combination of two gases and if the Greek notion of the elements still required a deathblow, this was it. As was fashionable at the time, Cav­ endish experimented with air. In 1785 he passed electric sparks through air, forcing the nitrogen to combine with the oxygen (to use modem terminology) and dissolving the resulting oxide in water. (In doing so, he worked out the composition of nitric acid.) He added more oxygen, expecting to use up all the nitrogen in time. However, a small bub­ ble of gas, amounting to less than 1 per­ cent of the whole, remained uncombined no matter what he did. He speculated that air contained a small quantity of a gas, then, that was very inert and resis­ tant to reaction. As a matter of fact, he had discovered the gas we now call argon. This experiment was ignored for a century, however, until Ramsay [832] repeated it and followed it up. Cavendish’s most spectacular experi­ ment involved the vast globe of the earth itself. The law of gravitation as worked out by Newton [231] placed the mass of the earth in the equation representing the attraction between the earth and any other body (say, a falling object). How­ ever, the mass of the earth could not be calculated from the mass of the falling object, its rate of fall, and its distance from the earth’s center because the equation also contained G, the gravita­ tional constant, of which the value was not known. If the value of the gravitational con­ stant were known, then all the quantities 201

[307]

CAVENDISH

in the equation but the earth’s mass would be known and the earth’s mass could be calculated. It was assumed that the gravitational constant was the same for all bodies and that it could, in theory, be determined if only the gravitational attraction between two objects, each of known mass, could be measured. The trick was to measure this attraction, for gravitational force is very weak and it takes a very large body, far too large to work with in a labora­ tory, to pile up enough of it to measure easily. Cavendish tackled the problem in 1798. Using a method suggested by Michell [294], he performed what is now commonly referred to as the Cavendish experiment. Cavendish suspended a light rod by a wire attached to its center. At each end of the rod was a light lead ball. The rod could twist freely about the wire and a light force applied to the balls would produce such a twist. Cavendish mea­ sured how large a twist was produced by various small forces. He brought two large balls near the two light balls, one on either side. The force of gravity between the large balls and light ones twisted the wire. From the extent of twist, Cavendish calculated the gravitational force between the two pairs of balls. He knew the distance between them, center to center, and the mass of each. This meant he had all the figures required for Newton’s equadon, except for the gravitational constant, and he could now solve for that. Once the constant was determined, it could be put into the equation represent­ ing the attraction between the earth and some object of known mass upon its sur­ face. Again all quantities were known with one exception—the mass of the earth, and now that could be calculated for. The earth turned out to have a mass of 6,600,000,000,000,000,000,000 tons and to have a density of about five and a half times that of water. (Newton with his clear intuition had guessed it might come to that a century before.) The Cavendish Physical Laboratory at Cambridge—which a century after Cav­ endish’s time was to produce work of 20?

DARWIN

[308]

unparalleled excellence in nuclear phys­ ics—is named in his honor. [308] DARWIN, Erasmus English physician Born: Elton, Nottinghamshire, December 12, 1731 Died: Breadsall Priory, near Derby, April 18, 1802 Darwin, the son of a prosperous law­ yer, studied at Cambridge and obtained his medical degree at the University of Edinburgh in 1754. He was one of the foremost physicians of his day so that George III asked him to become his per­ sonal physician in London. Darwin, however, refused. He was a man of decided opinions, radical, freethinking, and a prohibi­ tionist. He was a member of the Lunar Society, as were Watt [316] and Priestley [312], He had the deplorable habit of writing long, didactic poems that had some in­ terest as far as scientific content was concerned but no discernible poetic value. His early poems dealt largely with botany and in them he backed the classification system introduced by Lin­ naeus [276]. His second most famous accom­ plishment is his last book, Zoonomia, written 1794-1796, in which he elabo­ rated on Buffon’s feelings about evolu­ tion and anticipated some of the sugges­ tions of Lamarck [336] on the subject. Darwin argued that evolutionary changes were brought about by the direct influence of the environment on the or­ ganism. The accomplishment for which he is most famous, however, is his being the grandfather (by his first wife) of Charles Darwin [554], who a little over half a century later was to advance the theory of evolution, which, with necessary modifications, is now believed to be the correct one. In addition Erasmus Darwin became the grandfather (by his second wife) of Francis Galton [636]. Erasmus Darwin’s reputation has suffered partly by his being overshad­ owed by his more famous grandson and

[309]

LALANDE

ARKWRIGHT

[311]

partly by a campaign of ridicule set in [310] MASKELYNE, Nevil (masTaihline) motion by the conservative British gov­ English astronomer ernment during the French revolutionary Born: London, October 6, 1732 era against Darwin and others who sym­ Died: Greenwich, London, Feb­ pathized with the French revolutionaries. ruary 9, 1811 Maskelyne, bom into an upper-class [309] LALANDE, Joseph Jérôme Le family, graduated from Cambridge Uni­ versity in 1754 and was ordained as a Français de (la-lahndO clergyman in 1755. However, he had French astronomer Born: Bourg-en-Bresse, Ain, July done well in mathematics and in science, and an eclipse he had viewed in 1748 11, 1732 had interested him permanently in as­ Died: Paris, April 4, 1807 tronomy. Someone was needed to head an expe­ Lalande, the son of a post office official, had studied law as a young man, dition to St. Helena to view the transit of but he happened to lodge near an astro­ Venus in 1761 and Bradley [258] recom­ nomical observatory, and this caught his mended Maskelyne. The transit observa­ fancy. He completed his legal education, tion as a method of determining the dis­ but did not practice. Instead, in 1751 he tance of Venus and, therefore, of other went to Berlin to take observations on bodies of the solar system, was a failure the parallax of the moon, as Lacaille because of clouds and other problems. [284] was sent to southern Africa for the On the way there, however, Maskelyne worked on methods of determining lon­ purpose. He became professor of astronomy at gitude by lunar observations, and this the Collège de France in 1762 and in method competed with that of the use of 1795 became director of the Paris Obser­ the chronometer devised by Harrison vatory. In the hectic decade of the [259], Harrison won out for the prize that 1790s, he was openly anti-Jacobin and did what he could to save some who had been offered, but Maskelyne went were threatened by the Reign of Terror. on to produce lunar tables and the Nau­ Later, he did not hesitate to indicate his tical Almanac, which remained a useful opposition to the war policies of Napo­ navigational aid for well over a century. He was appointed fifth astonomer royal, leon Bonaparte. He devoted much of his time to pre­ succeeding Nathaniel Bliss, in 1765. paring a catalogue of forty-seven thou­ He was the first man to make time sand stars which he published in 1801. measurements that were accurate to a One of the stars, listed Lalande 21185, tenth of a second. turned out eventually to be the third nearest to the sun and to be one of those which in the mid-twentieth century was [311] ARKWRIGHT, Sir Richard English inventor discovered by Van de Kamp’s [1247] ob­ Born: Preston, Lancashire, De­ servatory to possess a planet. He was cember 23, 1732 also one of those who observed Neptune Died: Cromford, Derbyshire, Au­ and recorded its position (but without gust 3, 1792 realizing it was a planet and not a star) a full half century before its discovery Arkwright, the youngest of thirteen by Leverrier [564], He was a great popularizer of astron­ children, was a barber and wigmaker in omy and wrote all the astronomical arti­ his youth. A secret process for dyeing cles in Diderot’s [286] Encyclopedia. In hair was the foundation of his fortune. 1798 he made a balloon ascension and He had little formal education, but in later suggested improvements in the mechanical invention this is not neces­ sarily a handicap. By 1769, with help parachute. 203

[312]

PRIESTLEY

from others and with guidance from the work of previous inventors, he patented a device that would spin thread by me­ chanically reproducing the motions or­ dinarily made by the human hand. At first, this was powered by animals, then by falling water, and finally, in 1790, by steam. Arkwright invented (or pro­ moted) machinery that would replace handwork in other steps of textile manu­ facture and became the first “capitalist” of the newborn industrial age. The ma­ chines not only replaced handwork; they produced so rapidly and efficiently that handworkers were permanently out of business. Popular rage against his ma­ chines put his mills and himself in dan­ ger more than once, but the progress of mechanization was too obviously profitable for society in general and for a small group of hard-driving men in par­ ticular. In 1782, Arkwright was employing five thousand men. He was appointed high sheriff of Derbyshire in 1783 and was knighted in 1786. At his death his fortune amounted to two and a half mil­ lion dollars, an enormous sum for those days. [312] PRIESTLEY, Joseph English chemist Born: Birstal Fieldhead, Yorkshire, March 13, 1733 Died: Northumberland, Pennsyl­ vania, February 6, 1804 Priestley’s mother died when he was six and he was brought up by a pious aunt. The boy was slight, rather sickly, and suffered from an impediment in his speech. In his youth he studied lan­ guages, logic, and philosophy and showed himself a prodigiously good stu­ dent in all these, learning a variety of languages, including Hebrew and Arabic, rather like Hamilton [545] seventy years later. He never studied science formally, yet it was in science that he made his name. He was the son of a Nonconformist preacher and was himself even more rad­ ical in religion, despite his aunt’s up­ bringing, for he eventually became a 204

PRIESTLEY

[312]

Unitarian minister. He was radical in politics as well, openly supporting the American colonists when they were re­ volting against George III. He was also against the slave trade and against reli­ gious bigotry of all sorts. One of his books seemed radical enough to be officially burned in 1785. It was his sym­ pathy for the French Revolution that eventually got him into the most serious trouble. In 1766, on one of his periodic visits to London, Priestley met Benjamin Frank­ lin [272], who was then in England in a vain attempt to adjust the dispute with the American colonies over taxation. That apparently was what influenced him to take up a scientific career. Shortly after, he took over a pastorate in Leeds; there was a brewery next door, and this was another piece of scientific good fortune. Under Franklin’s in­ fluence, Priestley did some research on electricity, becoming the first to discover that carbon was an electrical conductor. He then wrote an important history of electrical research in 1769, and later one on the history of optics. He was the first to suggest that electricity would prove of importance to chemistry, and eventually he turned to chemistry itself. Fermenting grain produces a gas, the properties of which Priestley took to studying with interest and curiosity. He noted that it put out flames, was heavier than air, and dissolved to a certain ex­ tent in water. It was, in fact, carbon dioxide, the “fixed air” of Black [298]. When Priestley dissolved carbon diox­ ide in water he tasted the solution and found that he had created a pleasantly tart and refreshing drink, the one we call seltzer or soda water today. The Royal Society awarded him the Copley medal for this. Since it required only flavoring and sugar to produce soda pop, Priestley may be viewed as the father of the mod­ em soft-drink industry. Priestley’s interest in gases grew. Only three gases were known at the time he began work—air, carbon dioxide, and hydrogen, the last having just been dis­ covered by Cavendish [307], Priestley changed that drastically for he went on to isolate and study a number of

[312]

PRIESTLEY

them, such as nitrous oxide, in 1772. He collected gases over mercury and thus was able to isolate ones that cannot be collected over water—such as ammonia, sulfur dioxide, and hydrogen chloride, which are water soluble. His experiments earned him membership in the French Academy of Sciences in 1772 and a lu­ crative post as librarian and companion to Lord Shelburne, who had lost a gov­ ernment post because of his own liberal tendencies. (He, too, sympathized with the rebellious American colonies.) During his eight years with Lord Shel­ burne, Priestley did his most interesting work. In 1774, for instance, the mercury he used in his work with gases was the occasion of his most important discov­ ery. Mercury, when heated in air, will form a brick-red “calx,” which we now call mercuric oxide. Priestley heated some of this calx in a test tube with a lens that he had just obtained and was yearning to use. This concentrated sun­ light upon the calx. It broke down to mercury again, this appearing as shining globules in the upper portion of the test tube. In addition, a gas was given off that possessed most unusual properties. Com­ bustibles burned more brilliantly and rapidly in it than in air. Priestley, who accepted the phlogiston theory of Stahl [241], reasoned that the new gas must be particularly poor in phlogiston and there­ fore accepted the phlogiston of wood so eagerly that the combustion that accom­ panied phlogiston loss was hastened. Priestley called the new gas “dephlogisticated air,” since a couple of years ear­ lier D. Rutherford [351] had named a gas of opposite properties “phlogisticated air.” A few years later, Lavoisier [334] killed the phlogiston theory and named the gas oxygen, which is the name it is still known by. Priestley, however, as conservative in chemistry as he was lib­ eral in politics and religion, remained a convinced phlogistonist to the end of his life. (Actually Scheele [329] had isolated oxygen a couple of years earlier than Priestley had. Through no fault of Scheele, news of the discovery was not

PRIESTLEY

[312]

published until after Priestley had re­ ported on his own experiments. For that reason Priestley is usually given the credit for the discovery.) Priestley experimented enthusiastically with his “dephlogisticated air.” He found that mice were particularly frisky in it and he himself felt “light and easy” when he breathed it. He imagined that breathing “dephlogisticated air” might some day become a fashionable minor vice among the rich. He also recognized the fact that plants restored used-up air to its original freshness by dephlogisticating it. (We say the plants release oxygen into the air.) This observation was sharpened by Priestley’s contemporary, Ingenhousz [306], It is almost anticlimactic to add that Priestley also gave the modern name “rubber” to the product of the South American tree sap which La Condamine [270] had introduced to Europe. He used that name simply because the substance could be used to rub out pencil marks. Priestley’s scientific achievements were not sufficient to make him popular with his neighbors. A Unitarian is not popular among people of more orthodox religion, since Unitarianism denies the divinity of Jesus. Add to that Priestley’s sympa­ thetic views toward the French revolu­ tionaries, whose activities were shocking British conservative opinion, and it is not surprising that the populace of Bir­ mingham (where he had settled in 1780 after retiring on a small pension) viewed him with suspicion. In Birmingham he joined the Lunar Society, which included Watt [316] and Erasmus Darwin [308], who had been its founder. The name of the society was derived from the fact that the meetings were held near the night of the full moon so that members would have something to light their way home. On July 14, 1791, some Birmingham pro-French Jacobins held a celebration in honor of the second anniversary of the fall of the Bastille. An angry mob retal­ iated against the best-known Jacobin in the city and burned down Priestley’s house. The next Sunday, Priestley took as the text for his sermon, “Father, for­ give them for they know not what they 205

[3 1 3 ]

WOLFF

do.” He managed, eventually, to escape with his family to London. He wasn’t much better off there, for people avoided him as a dangerous radical, particularly after France became a republic, cut off the head of its ex-king, Louis XVI, and went to war with Great Britain. Nor did it help him that the French Republican government made Priestley a French cit­ izen. (Of course, attitudes toward Priest­ ley changed after he was safely dead. In 1875, at the centenary of the discovery of oxygen, Birmingham raised a statue to Priestley.) In 1794 Priestley gathered some money and left Great Britain forever just one week before his French colleague Lavoisier was executed by the intolerants of France. Priestley crossed the sea to the land of his old friend Benjamin Franklin, the now independent nation of the United States, where the populace was at that time anti-British and pro­ French, and where he was welcomed gladly and where he gained the friend­ ship of Thomas Jefferson [333], The last ten years of his life were spent in peace, and he did much to further the cause of Unitarianism in the new nation. He turned down offers of a Unitarian minis­ try in New York and of a professorship of chemistry at the University of Penn­ sylvania. He wanted only a chance to write quietly. [313] WOLFF, Kaspar Friedrich German physiologist Bom: Berlin, January 18, 1734 Died: St. Petersburg (now Lenin­ grad), Russia, February 22, 1794 In 1759, when Wolff, the son of a tai­ lor, had just obtained his medical degree from the University of Halle and was serving as army surgeon during the Seven Years’ War, he published a book­ let on the development of living things that was revolutionary in its implica­ tions. Until his time many biologists, for example. Bonnet [291], were of the opin­ ion that a living creature existed pre­ formed and perfect in every miniature detail in the egg or sperm. Textbooks even had diagrams showing these tiny 206

MESMER

[3 1 4 ]

"homunculi” within sperm cells, these having been seen, described, and drawn by microscopists with enthusiasm and imagination. Wolff, however, reported that special­ ized organs arose out of unspecialized tissue. Thus, the tip of a growing plant shoot consists of undifferentiated and generalized cells. As these divide and subdivide, however, specialization de­ velops and some bits of tissue develop into flowers, while other bits, originally indistinguishable, develop into leaves. Even more important (from our hu­ man-centered view) was the fact that he could show that this same principle held for a developing animal, such as a chick, within the egg. Undifferentiated tissue gave rise to the different abdominal or­ gans, he showed, through gradual special­ ization. Wolff may thus be considered the founder of modern embryology, al­ though unfortunately his work was largely neglected for over half a century. Nevertheless, it made enough of an im­ pression on the new Empress Catherine II of Russia (that collector of scholars and lovers) to cause her to invite him to St. Petersburg in 1764, when the Seven Years’ War had ended. He became professor of anatomy and remained there until his death. His name is preserved in several anatomic terms, notably in the Wolffian body, an early form of kidney in embryonic animals preceding the true kidney. [314] MESMER, Franz Anton German physician Bom: Iznang am Bodensee, Ba­ den, Germany, May 23, 1734 Died: Meersburg, Germany, March 5, 1815 Mesmer, the son of a forester, entered the University of Vienna in 1759. He began by studying law but shifted to medicine and obtained his medical de­ gree in 1766. He was a mystic, very much interested in astrology. He was a follower of Para­ celsus [131] and believed in the existence of cosmic forces permeating the earth

[314]

MESMER

and affecting the lives of human beings. In any age he would have been inter­ ested in whatever ill-understood phenom­ enon was claiming the attention of scholars. In the late eighteenth century this meant electricity and magnetism, and as a physician he naturally at­ tempted to turn these forces to the cur­ ing of disease. He began by passing magnets over the bodies of his patients and managed to effect cures in some cases. Later he dis­ covered that magnets were unnecessary and that the same happy results could be achieved by the simple passing of hands. He decided that in the latter case he was making use of “animal magnetism.” His practice in Vienna was not with­ out troubles. His undoubted cures (well advertised by doctor and patient alike) were mixed with failures. The patients who suffered these failures naturally felt aggrieved, and charges of malpractice multiplied. The unsympathetic police or­ dered Mesmer to move on. He went to Paris in 1778 and there became the rage. The volatile French so­ ciety of the day, in the twilight of the Age of Reason, was ready for any nov­ elty expressed in scientific-sounding words. Orthodox Parisian doctors were naturally enraged, and eventually a com­ mission of experts investigated Mesmer’s methods. Among the experts was Ben­ jamin Franklin [272], who was then in Paris representing the brand-new United States, Lavoisier [334], and Joseph Guillotin, the inventor of the guillotine. The experts reported unfavorably and in 1785 Mesmer was forced to leave Paris. He retired to Versailles, then to Swit­ zerland, then to his native region, and obscurity. (Franklin, by the way, al­ though denying the validity of Mesmer’s work, made it clear he felt that cures could be effected by suggestion and went on to discuss psychosomatic ailments in almost modern terms.) Although Mesmer was 90 percent gobbledygook, he was in earnest and there is no reason to doubt that his cures were genuine. His followers raised the gobbledygook percentage to 100, but it remains clear, in retrospect, that Mesmer was curing psychosomatic ailments by

BERGMAN

[315]

suggestion. His methods, refined and freed of some of their mumbo-jumbo, became respectable once more a half century later when Braid [494] rein­ troduced what he called hypnotism. An accepted synonym for hypnotism is, even today, mesmerism, in honor of the Aus­ trian doctor. [315] BERGMAN, Torbem Olof Swedish mineralogist Born: Katrineberg, Vastmanland, March 9, 1735 Died: Medevi, July 8, 1784 Bergman, the son of a tax collector, obtained his doctor’s degree at the Uni­ versity of Uppsala in 1758. Though a physicist and mathematician as well as a chemist, he was chiefly interested in min­ eral classification, which is not surpris­ ing, considering that he had studied under that great classifier Linnaeus [276]. Bergman based his classification on chemical characteristics rather than on appearance alone, as his older contem­ porary Cronstedt [292] was also doing. Bergman evolved a theory to explain why one substance reacted with a second but not, perhaps, with a third, by sup­ posing the existence of “affinities” (that is, attractions) between substances in varying degrees. He prepared elaborate tables listing affinities, and they were very influential during his lifetime and for a few decades after. He also attempted to produce exact determinations of mineral composition (“quantitative analysis”) by producing precipitates and weighing them accu­ rately (“gravimetric determinations”). Yet neither these things nor such specific discoveries as the fact that car­ bon dioxide possessed acidic properties in solution is what he is best remem­ bered for. His greatest discovery was a human being, Scheele [329], the apothe­ cary of genius whom Bergman helped and encouraged. Bergman was forced into retirement in 1780 because of bad health, and died of tuberculosis before he was fifty. 207

[316] WATT [316] WATT, James Scottish engineer Born: Greenock, Renfrew, Janu­ ary 19, 1736 Died: Heathfield, near Birming­ ham, England, August 19, 1819 Watt was a rather sickly child who could not go to school and was taught to read and write by his mother. He suffered from chronic migraine head­ aches and was suspected of being men­ tally retarded. His mother died while he was in his teens and his father, originally a prosperous merchant, experienced hard times that grew progressively worse. Watt traveled to England, reaching Lon­ don eventually, and there went through a hard year of apprenticeship, during which he learned the use of tools and the craft of instrument maker. In 1756 he returned to Scotland and tried to establish himself as an instru­ ment maker in Glasgow. However, he did not meet the municipal require­ ments, for he lacked a sufficient period of apprenticeship, so he obtained a posi­ tion at the University of Glasgow, which was outside municipal jurisdiction. There he met Joseph Black [298] and learned of the matter of latent heat. Un­ doubtedly this set him to thinking how steam engines might be improved. Savery [236] and Newcomen [243] had devised engines that were in use as power sources for water pumping. How­ ever, such machines were terribly inefficient. This had been brought forci­ bly to Watt’s attention when in 1764 the university gave him a model of a New­ comen steam engine to repair after a London instrument maker had failed. Watt could repair it without trouble, but that was not enough for him. He wanted to improve it. During the course of a thoughtful Sun­ day walk, it seemed to him that he per­ ceived the chief source of inefficiency. In the Newcomen engine, the steam cham­ ber was cooled to condense the steam and produce the vacuum. It then had to be filled with steam again, but, since it had been cooled, a great deal of steam was first necessary just to heat up the chamber. All that steam was wasted. At 208

[316] every cycle, immense quantities of fuel were required to undo the work of the cold water. Watt introduced a second chamber (a “condenser”) into which the steam could be led. The condenser could be kept cold constantly while the first chamber (the “cylinder”) was kept hot constantly. In this way the two processes of heating and cooling were not forced to cancel each other. By 1769 Watt had a steam engine working with greater efficiency than the Newcomen variety. Further­ more, since there was no long pause at each cycle to heat up the chamber, Watt’s engine did its work much more quickly. So impressed was Black with this development that he lent him a large sum of money to keep the project in op­ eration. Watt introduced other ingenious im­ provements, such as allowing steam to enter alternately on either side of a pis­ ton. Previously air pressure had driven the piston rapidly in only one direction as a vacuum was produced when steam was condensed. It was only mounting steam pressure, then, that slowly moved it back in the other direction. With steam entering and condensing on both sides, air pressure drove the piston rap­ idly in both directions alternately. In 1774 Watt went into partnership with a businessman and began to manufacture steam engines for sale. (In 1784 he used steam pipes to heat his office, so he also invented “steam heat.”) By 1790 the Watt engine had com­ pletely replaced the older Newcomen va­ riety and by 1800 some five hundred Watt engines were working in England. In fact so superior was the Watt engine that the very existence of the Newcomen engine was all but forgotten and Watt began to be looked upon as the inventor of the steam engine. In a sense, however, this was justified, for Watt not merely improved the New­ comen engine, he was the first to make such an engine more than a pump. In 1781 he devised mechanical attachments that ingeniously converted the back and forth movement of a piston into the ro­ tary movement of a wheel, and by one type of movement or the other, the WATT

[316] WATT

steam engine could then be made to power a variety of activities. Soon iron manufacturers were using it to power bellows to keep the air blast going in their furnaces and to power hammers to crush the ore. The now-versatile steam engine had thus become the first of the modem “prime movers,” the first modem device, that is, to take energy as it occurred in nature (in fuel) and apply it to the driv­ ing of machinery. It was just at this time, too, that the textile industry, En­ gland’s most important, was being mech­ anized by men such as Arkwright [311]. The steam engine proved to be the right invention at the right time. The consequences were incalculable. Steam engines, powered by burning coal, could deliver large quantities of energy constantly, at any needed spot. Manufac­ turing locations were not confined to rapid streams where water power might be used. Large and massive machinery, powered by steam, could be constructed and housed in factories. Large-scale pro­ duction in such factories made handwork at home uneconomical. The artisan was replaced by the factory worker. Cities mushroomed; slums boomed; farming withered. All the benefits and evils of the factory system blossomed. In short, the Industrial Revolution began. Watt started another revolution, which, however, was not to bloom for a century and a half. He invented a “cen­ trifugal governor” that automatically controlled the engine’s output of steam. The steam output whirled the governor about a vertical rod. The faster it whirled, the farther outward were thrown two metal spheres (through the action of centrifugal force). The farther outward the balls were thrown, the more they choked off the steam outlet. The steam output thus decreased, the gover­ nor whirled more slowly, the spheres dropped and the outlet was widened. In this way the steam output hovered be­ tween two limits and was never allowed to grow too large or too small. In this is the germ of automation, since the centrifugal governor was a de­ vice that controlled a process by means of the variations in the process itself.

LAGRANGE

[317]

Automation has not come into its own until recent decades, but it began with James Watt, and the word governor, via the Greek, has given us the modem term “cybernetics.” Watt enjoys one honor that arose out of his efforts to measure the power (that is, the rate of doing work) of his steam engine. In 1783 he tested a strong horse and decided it could raise a 150-pound weight nearly four feet in a second. He therefore defined a “horsepower” as 550 foot-pounds per second. This unit of power is still used. However, the unit of power in the metric system is called the watt, in honor of the Scottish engineer. One horsepower equals 746 watts. In 1800, prosperous, successful, and respected, Watt retired. He received an honorary doctorate from Glasgow Uni­ versity and was elected to the Royal So­ ciety. He refused the offer of a baron­ etcy and lived to be the last survivor among the founders of the famous Lunar Society of Birmingham, to which Priestley [312] and Erasmus Darwin [308] had belonged. [317] LAGRANGE, Joseph Louis, comte de (la-grahnzh') Italian-French astronomer and mathematician Bom: Turin, Piedmont, January 25, 1736 Died: Paris, France, April 10, 1813 Lagrange was of French ancestry, though born and raised in the Italian kingdom of Piedmont. His parents were wealthy but his father had speculated his fortune into oblivion. He was the youngest of eleven children and the only one to survive to adulthood. His father intended him for the law, but at school he came across an essay by Halley [238] on the calculus and was at once con­ verted to mathematics. By the age of eighteen he was teaching geometry at the Royal Artillery School in Turin. There he organized a discussion group that be­ came the Turin Academy of Sciences in 1758. Lagrange’s mathematical ability was 209

[317]

LAGRANGE

recognized by Euler [275], who at that time headed the Berlin Academy of Sci­ ences under Frederick II (a monarch who rifled all Europe for scientific talent). In 1755 Lagrange had sent Euler a memorandum on the “calculus of vari­ ations” on which Euler himself had been working. So impressed was Euler that he deliberately held back his own work to allow Lagrange to publish first. (How­ ever, Euler and Lagrange never met.) In 1766 Euler moved to St. Peters­ burg, Russia (where Catherine II was also bidding for scientific talent—it was the royal fashion to do so during the Age of Reason). At the recommendation of Euler and D’Alembert [289], the young Lagrange, aged forty, was ap­ pointed head of the Berlin Academy. As Frederick II put it, rather vaingloriously, the “greatest king in Europe” ought to have the “greatest mathematician in Europe” at his court. Lagrange applied his mathematical ability to a systematization of mechanics, which had begun with Galileo [166]. His interest in the subject was aroused when he read Wallis’s [198] treatise on the subject. Using the calculus of variations, he worked out very general equations from which all problems in mechanics could be solved. He summarized his methods in his book Analytical Me­ chanics, published in Paris in 1788 by a most reluctant publisher. The book was purely algebraic or, to use the term of Vieta [153], analytic, as the title pro­ claimed. There was not one geometric diagram in it. In astronomy Lagrange addressed him­ self to a general problem left open by Newton [231]. (Lagrange once said that Newton was the luckiest man in the his­ tory of the world, for the system of the universe could only be worked out once and Newton had done it; however, in this he was too pessimistic, for there was to be room for Einstein [1064] a century and a half later, and Lagrange himself proceeded to make significant additions to the knowledge of the universe.) Newton’s law of universal gravitation could deal with two bodies if they were alone in the universe, but the solar sys­ tem consists of many bodies. To be sure, 210

LAGRANGE

[317]

the sun’s influence is supreme, but the minor bodies affect each other in minor ways called “perturbations” and these could not be ignored. Lagrange worked out mathematical treatments of the motions of systems containing more than two bodies, such as the earth-moon-sun system and the sys­ tem of Jupiter and its four moons. He included a study of situations in which three bodies might form a stable configuration as at the apices of an equi­ lateral triangle (provided one body was very small). Such a system (now called a “Trojan system”), including the sun, Jupiter, and certain asteroids, was actu­ ally discovered a century and a half later. Lagrange thought there might be two kinds of perturbations, periodic and sec­ ular. The periodic type causes a planet’s orbit to vary first in one direction, then in the opposing direction, leading to no permanent change in the long run. The secular type caused an accumulating variation in one direction only so that the orbit is completely disrupted eventu­ ally. Lagrange tackled the problem of determining whether any of the observed perturbations in the solar system were indeed secular. In this he was joined by his younger contemporary Laplace [347], and together they answered, “No!” After Frederick the Great’s death, La­ grange moved to Paris in 1787 at the in­ vitation of Louis XVI and was there lionized by Marie Antoinette, though he had then entered a period of deep depression that made the final decades of his life largely unproductive. With the coming of the French Revolution it might have been better for Lagrange to depart, in view of his friendship with the royal family. He remained, however, and lived through the Terror, partly because of the general respect for his accom­ plishments and partly because of his for­ eign birth. The revolution gave him the opportu­ nity for one last service to science. He was appointed in 1793 to head a com­ mission to draw up a new system of weights and measures. Laplace and La­ voisier [334] were among the other members. Out of the deliberations of

[318]

COULOMB

that commission came, in 1795, the met­ ric system, the most logical system of measurement ever devised. It is now the universal language of scientists, although (to our shame, be it said) the United States, almost alone, clings to the illogi­ cal English system of measurement in daily life. Napoleon delighted to honor Lagrange in the evening of his life and eventually made him a senator and a count. [318] COULOMB, Charles Augustin (koo-lome') French physicist Born: Angouleme, Charente, June 14, 1736 Died: Paris, August 23, 1806 Coulomb was a military engineer in his younger days, serving in the West Indies for nine years beginning in 1764. There, he supervised the building of fortifications in Martinique. He returned to Paris in 1776, with his health im­ paired, and his search for a quieter life drew him toward scientific experi­ mentation. When the disturbances of the French Revolution began he combined discretion with inclination and retired to the provincial town of Blois to work in peace. He rode out the Terror handily and was eventually restored to those posts he had lost, by an appreciative Na­ poleon. By then he had made his name. In 1777 he invented a torsion balance that measured the quantity of a force by the amount of twist it produced in a thin, stiff fiber. Weight is a measure of the force of gravity upon an object, so a tor­ sion balance can be used to measure weight. A similar instrument had been invented earlier by Michell [294], but Coulomb’s discovery was independent and in 1781 he was elected to the French Academy. Coulomb put the delicacy of his in­ strument at the service of electrical ex­ periments. In a course of experi­ mentation that began out of a desire to improve the mariner’s compass, he placed a small electrically charged sphere at different distances from another small

GUYTON DE MORVEAU

[319]

electrically charged sphere and measured the force of attraction or repulsion (de­ pending on whether the charges were op­ posite or similar) by the amount of twist produced on his torsion balance. In this way he was able to show in 1785 that the force of electrical attraction or repul­ sion is proportional to the product of the charges on each sphere and inversely proportional to the square of the distance between the spheres, center to center. (Priestley [312] had come to this conclu­ sion a few years earlier on the basis of indirect evidence.) This meant that elec­ trical forces obeyed a rule similar to that of gravitational forces as worked out by Newton [231]. This is still called Cou­ lomb’s law. In his honor, an accepted unit for quantity of electric charge is the coulomb. Cavendish [307] had actually discov­ ered Coulomb’s law before Coulomb, but Cavendish never published his results, and they were not discovered until half a century after his death. [319] GUYTON DE MORVEAU, Baron Louis Bernard (gee-ton' duh mawr-voh') French chemist Born: Dijon, Côte d’Or, January 4, 1737 Died: Paris, January 2, 1816 Guyton de Morveau, the son of a law­ yer, was himself a lawyer by profession and served in the Dijon parliament be­ fore the French Revolution. Science was his hobby and, in 1782, when he retired from his legal position, he turned to chemistry. Already, in 1772, he had as an ama­ teur demonstrated by careful weighing that rusted metals were indeed heavier than the metals themselves as earlier chemists had maintained on the basis of cruder observations all the way back to Boyle [212]. This fit Lavoisier’s [334] new chemistry when that was developed. His problems with chemical nomencla­ ture led to a fruitful collaboration with Lavoisier. With the revolution in full swing, he turned to politics again, on the side of the revolutionists, and lived 211

[320]

GALVANI

through the period—which is more than Lavoisier did. Sadly enough, Guyton de Morveau was another of Lavoisier’s as­ sociates who, like Fourcroy [366], made no move to save the great man. Guyton de Morveau suggested to the French revolutionaries that balloons be used for military reconnaissance and so he may be considered the great-grand­ father of aerial warfare. He served as master of the mint under Napoleon, and in 1811 he was made a baron. [320] GALVANI, Luigi (gahl-vah'nee) Italian anatomist Born: Bologna, September 9, 1737 Died: Bologna, December 4, 1798 Galvani studied theology in early life but turned to medicine and received his medical degree in 1759 from the Univer­ sity of Bologna. In 1762, he began lec­ turing on medicine there and in 1775 he became professor of anatomy. It was his good fortune that electrical machines, such as Leyden jars, were the scientific rage of the time. They could be found in most laboratories, including the one in which Galvani carried on his anatomical and physiological researches. Galvani noticed, in 1771, that the muscles of dissected frog legs (some say they were in the laboratory because they were about to be used in the preparation of soup) twitched wildly when a spark from an electric machine struck them, or when a metal scalpel touched them while such a machine was in operation, even though the spark made no direct contact. This was, in itself, not too surprising. Electric shocks made living muscles twitch, why not dead ones too? Since Franklin [272] had shown light­ ning to be electrical in nature a genera­ tion before, the frog muscles might be expected to twitch during a thunder­ storm. This would be independent confirmation of the electrical nature of lightning. Galvani therefore laid frog muscles out on brass hooks outside the window so that they rested against an iron latticework. The muscles did indeed twitch during the thunderstorm, but they also twitched 212

HERSCHEL

[321]

in the absence of it. In fact, they twitched whenever they made contact with two different metals. Apparently electricity was involved, but where did it come from—the metals or the muscle? Being an anatomist he had a natural predilection toward living tissue, and he decided on the muscle. He declared there was such a thing as ani­ mal electricity and clung to that view fiercely. He was proved wrong some years later by Volta [337] and ended his life in disappointment. Even his univer­ sity appointment was lost, for in 1797 he refused to swear allegiance to a new gov­ ernment set up in northern Italy by the young French general, Napoleon Bona­ parte—so that he died in poverty, too. In the last decade of his life, however, Galvani had succeeded in making his name a household word. The steady electricity set up by two metals in con­ tact was called galvanic electricity, as op­ posed to the static electricity set up by rubbing amber or glass. A person stung into sudden action by an electric current (or by any attack of strong emotion) is galvanized. Iron on which crystals of zinc are layered by means of an electric current (or even, eventually, by means other than an electric current) is said to be galvanized iron. Finally an instrument designed to detect electric current was invented in 1820 and, at the suggestion of Ampère [407], was named a gal­ vanometer. [321] HERSCHEL, Sir William German-English astronomer Born: Hannover, Germany, No­ vember 15, 1738 Died: Slough, Buckinghamshire, England, August 25, 1822 At the time of Herschel’s birth, Han­ nover was a possession of King George II of England (though it was not actu­ ally part of the British realm). Herschel’s father was a musician in the Han­ noverian army and Herschel himself was headed toward the same profession. The coming of the Seven Years’ War, how­ ever, and the occupation of Hannover by the French made army life somewhat

[321]

HERSCHEL

unattractive, and Herschel’s parents managed in 1757 to spirit him out of the service and smuggle him into England. Herschel stayed in England for the rest of his life and adapted himself thor­ oughly to his new home, changing his German name of Friedrich Wilhelm to the English “William.” His musical tal­ ents brought him success in England. He arrived in Leeds in 1757 and by 1766 he was a well-known organist and music teacher at the resort city of Bath, tutoring up to thirty-five pupils a week. Economic security gave him a chance to gratify his fervent desire for learning. He taught himself Latin and Italian. The theory of musical sounds led him to mathematics and that to optics. Optics led him to a book about Newton’s work and suddenly he was filled with a desire to see the heavens for himself. Since he could not afford to buy good telescopes, he decided to grind lenses and make his own instruments for viewing the heavens. He tried two hundred times be­ fore he made one that satisfied him. In 1772 he returned to Hannover long enough to collect his sister Caroline [352] and take her to England. This proved an exceedingly fortunate move, for Caroline proved as fanatic a lens grinder and amateur astronomer as Herschel himself, and it is not likely that Herschel could have accomplished as much without the heroically single­ minded help of his sister. (She became the first important woman astronomer.) Together the Herschels ground excel­ lent lenses. Caroline read aloud to Wil­ liam and fed him meals a bit at a time, while he ground for hours. They ended with the best telescopes then in exis­ tence. Herschel made up his mind to look in systematic fashion at everything in the sky. By 1774 he had not only made him­ self the best reflector in the world but the first that was actually more efficient than any refractor then existing, so he certainly had the tool for the job. He began to bombard the scientific world with papers describing his observations of the mountains of the moon, on vari­ able stars, on the possibility that changes

HERSCHEL

[321]

in sunspot activity might affect agricul­ ture on earth, and so on. In 1781, while systematically moving from star to star with his excellent tele­ scope, Herschel came across an object that appeared as a disc instead of a mere point of light. He made the natural as­ sumption that he had discovered a new comet and reported it as such. However, additional observations showed that the disc had a sharp edge like a planet and not fuzzy boundaries like a comet. Fur­ thermore, when enough observations had been made to calculate an orbit, he and others, notably Laplace [347], found that orbit to be nearly circular, like a planet’s, rather than elongated, as a com­ et’s would be. And to top it off, the orbit of the object lay far outside that of Saturn. The conclusion Herschel came to, with great wonder and delight, was that he had discovered a new planet and had doubled the extent of the known solar system. It was the first new planet to be discovered in historic times. Actually the planet is just barely visi­ ble to the naked eye and it had been ob­ served a number of times earlier. It was even included in the star map prepared by Flamsteed [234], who noted it a cen­ tury earlier in the constellation Taurus and recorded it as 34 Tauri. In 1764 it had been spotted near Venus and it was reported as a satellite of that planet. However, it was Herschel’s telescope that showed the disc and Herschel that finally recognized the object as a planet. Herschel tried to name the planet Georgium Sidus (“George’s Star”) after George III, then king of England. Some astronomers, at the suggestion of Lalande [309], named it Herschel in his honor. In the end, it was decided to stick to mythological names for planets. Bode [344] had suggested the new planet be named Uranus after the father of Saturn (in Greek “Cronos”) and by the mid­ nineteenth century this was universally accepted. The news of the discovery of Uranus made a tremendous sensation. Astrono­ mers had thought that Newton [231] left them nothing to discover, and Frederick II of Prussia (no scientist, to be sure, 213

[321]

HERSCHEL

though a patron of scientists) believed all scientific findings had already been made. Herschel’s announcement was like a breath of fresh air, indicating that there yet remained portions of the un­ known. (The same false complacency and sharp awakening was to take place a century later in Michelson’s [835] time.) Herschel was elected to membership in the Royal Society in 1781 and awarded the Copley prize. George III, who was of Hannoverian extraction and who was pleased with the achievement of a fellow countryman, pardoned Herschel’s youth­ ful desertion from the Hannoverian army and appointed him his private as­ tronomer at a salary of three hundred guineas a year. Herschel started astronomical observa­ tions in earnest. For a while he had to continue to manufacture and sell tele­ scopes (the king’s subsidy was not much), but in 1788 he married a wealthy widow and became a full-time observer. (Caroline remained unmarried and continued to devote herself to her now-famous brother and to astronomy.) Herschel became the most important and successful astronomer of his time. No one else could have been mentioned in the same breath. Like Bradley [258], Herschel tried to observe the parallax of stars and failed. However, he used a method first suggested by Galileo [166], which was to concentrate on pairs of stars in close proximity (such pairs hav­ ing first been discovered by Riccioli [185] nearly a century and a half be­ fore). At the time it was thought that these stars were close together only through the accident of happening to lie in nearly the same line of sight, and that one might, in actuality, be very many times farther away than the other. If that were so, the nearer star ought to show a parallactic shift in position in compari­ son with the farther one. This is undoubtedly the situation on occasion, but in a number of cases that Herschel tried, he found that neither showed a parallactic shift in position. They moved, but from the manner in which they were moving he could only conclude that they were close to each other not only in appearance, but also in 214

HERSCHEL

[321]

actuality. By 1793 he was convinced that they were circling each other. In the course of his career he discovered some eight hundred such double stars or “bi­ nary stars,” as he called them. This was the first indication that dou­ ble stars might really be just that. Fur­ thermore, by studying them it was possi­ ble to show that their motions were in accord with Newton’s law of gravity. Until then the validity of the law could only be tested within the solar system. Now, a century after the establishment of the law, it was traced out in the mo­ tions of incredibly distant stars and the theory first truly earned its title of Uni­ versal. Herschel was as thorough in ob­ serving stars whose luminosity varied and was the first systematic reporter on variable stars. In 1801, during a short lull in the Napoleonic Wars, Herschel visited Paris and met Laplace and Napoleon himself. Herschel was unimpressed with Napo­ leon, detecting the latter’s way of affect­ ing to know more than he really did know. Herschel’s voluminous observations of the stars gave him an overall view of the starry universe that no predecessor had had. In fact, Herschel was the first to present an astronomical picture in which the solar system was reduced to what, in point of fact, it really was, a tiny and in­ considerable speck in the vast universe of the stars. For instance, in analyzing the proper motions of a large number of stars, he believed, by 1805, that he could explain the regularities he observed by assuming that the sun itself was moving toward a point in the constellation Her­ cules, a matter studied more thoroughly by Argelander [508]. Just as Copernicus [127] had dethroned the earth as the mo­ tionless center of the universe, so Her­ schel dethroned the sun. By studying the Milky Way and count­ ing stars in various directions, Herschel prepared a picture of the starry system as a whole. He viewed the visible uni­ verse as representing a gigantic collection of stars arranged roughly in the shape of a grindstone. Our own sun, he believed, was located somewhere near the center of the system and when we looked out in

[321]

HERSCHEL

the directions of the long axis of the grindstone, we saw a vast multiplicity of stars that faded (through distance) into the general faint glimmer of the Milky Way. (The sun’s apparent position in the center of this system was to be shown an illusion a century later by Shapley [1102].) Herschel also viewed various cloudy objects in the skies, cataloguing some twenty-five hundred of them. His own better telescopes resolved into stars some of the objects viewed and recorded by Messier [305], so that he discovered the large “galactic cluster,” like the one in Hercules. Other objects remained unre­ solved, and Herschel speculated that they might be other huge star collections (or “galaxies”) like our own. He also observed dark areas in the Milky Way which we now know to be clouds of dust. Herschel believed they were empty gaps and said, “Surely this is a hole in the heavens.” Nor did he entirely neglect the solar system after his discovery of Uranus. He returned to Uranus with improved tele­ scopes and in 1787 discovered two of its satellites, Titania and Oberon. (He had become more English than the English and abandoned classic mythology for Shakespeare.) He reported four other satellites, but those proved to be mis­ takes. He built a brand-new telescope, forty feet long with a 48-inch reflector. George III contributed £4,000 toward its construction and took proprietary delight in showing the instrument to visi­ tors. On the first night of observation Hershel turned the telescope on Saturn and discovered two new satellites, Enceladus and Mimas, which, added to the one discovered by Huygens [215] and the four by Cassini [209], made a total of seven for the ringed planet. Herschel also timed the period of rotation of Sat­ urn and showed that its rings rotated as well. He was not without an occasional pe­ culiar idea, however. He thought the moon and the planets were inhabited. He also suggested that the luminosity of the sun might be confined to its atmosphere and that under its belt of fire was a cold,

SAUSSURE

[322]

solid body that might even be inhabited. The sunspots, he speculated, were holes in the atmosphere through which the cold surface could be seen. No one took this notion seriously except cranks and faddists, who were pleased to use the great name of Herschel to cover their own follies. Herschel also extended man’s view in a direction that had nothing directly to do with astronomy. In 1800 he tested various portions of the sun’s spectrum by thermometer to see if he could find in­ teresting differences in the amount of heat the different colors delivered. He did, but in a rather unexpected way, for he found that the temperature rise was highest in no color at all, at a spot be­ yond the red end of the spectrum. He concluded that sunlight contained invisi­ ble light beyond the red. This is now called infrared radiation. The following year Ritter [413] was to extend the visi­ ble spectrum in the other direction. Herschel was knighted in 1816 and died in the fullness of years and fame, working almost to the end and making his last observations in 1819 when he was in his eighty-first year. He lived eighty-four years, which is Uranus’ pe­ riod of revolution about the sun. Her­ schel left a son, John Herschel [479], who was likewise a renowned astronomer. [322] SAUSSURE, Horace Benedict de (soh-syoori) Swiss physicist Born: Geneva, February 17, 1740 Died: Geneva, January 22, 1799 Saussure was the son of a noted agri­ cultural scientist. He earned his Ph.D. at the University of Geneva in 1759 and in 1762 he obtained a professorial position there, on the recommendation of Haller [278]. He was an enthusiastic mountaineer and was among those who helped create the mountain-climbing craze that has continued ever since. Certainly, he was the first to climb mountains with the no­ tion of making scientific observations in the process. For the purpose, he devised an electrometer, the first device used to 215

[323]

MÜLLER

measure electric potential. He also con­ structed a hygrometer for measuring hu­ midity, the first to use a human hair for the purpose. His investigations produced useful data in both meteorology and ge­ ology. (In fact, Saussure was the first to use the word “geology,” in 1779.) In 1787 Saussure climbed Mont Blanc, the highest peak of the Alps, and led the second expedition to do so successfully. His own thoughts of the development of the earth were in line with those that Hutton [297] was just publishing, and, in fact, some of the data Saussure gathered was used by Hutton in his book.

MONTGOLFIER

[325]

practicing lawyer and was a Member of Parliament in 1799. He was elected a member of the Royal Society in 1771. This was for his anti­ quarian interests. In 1790 he discovered shaped flints which, he suggested, were tools formed by people who did not have the use of metal, and which, he thought, were very old. What’s more, the site seemed to be the source of a great many such tools. He reported this in 1797, but the mat­ ter roused no interest since the ortho­ doxy of the time insisted that humanity (and, indeed, the whole universe) was less than six thousand years old. The clear indication of human tools many [323] MÜLLER, Franz Joseph (myoo'- times older than this was therefore sim­ ler) ply ignored. It was not until similar finds Austrian mineralogist were made by Boucher [458] a half cen­ Born: Nagyszeben, Transylvania, tury later, that the matter could no (now Sibiu, Romania), July 1, longer be set aside. 1740 Died: Vienna, October 12, 1825 [325] MONTGOLFIER, Joseph Michel Müller, the son of a treasury official, (mohn-gohl-fyay') studied law and philosophy in Vienna, French inventor but he attended a school of mines, too, Born: Vidalon-les-Annonay, Au­ and became most interested in mineral­ gust 26, 1740 ogy. Emperor Joseph II appointed him Died: Balaruc-les-Bains, June 26, chief inspector of mines in Transylvania 1810 and, on his retirement in 1818, Emperor MONTGOLFIER, Jacques Etienne Francis I raised him to the nobüity as French inventor Baron von Reichenstein. Born: Vidalon-les-Annonay, Jan­ In 1782, while working with a gold uary 6, 1745 ore, he obtained a substance that he de­ Died: Serrieres, August 1, 1799 cided was a new element. He sent a specimen to Bergman [315], who died These brothers were two of the sixteen before he could complete his investi­ children of a well-to-do paper manufac­ gation. Müller then sent a sample to turer, a family trade of romantic ante­ Klaproth [335], who confirmed the cedents. An ancestor at the time of the finding, gave due credit to Müller, and Crusades was supposed to have discov­ named the element “tellurium.” ered the process while a prisoner in Damascus and to have brought Tsai Lun’s [63] invention to France. [324] FRERE, John (freer) The Montgolfiers were first inspired to English archaeologist aeronautics by observing the manner in Born: Westhorpe, Suffolk, August which the smoke of fire caught up light 10, 1740 objects and sent them flying into the air. Died: East Dereham, Norfolk, (A less romantic story has it that Jo­ July 12, 1807 seph, the elder brother, had his mind turned toward ballooning by reading Frere, the son of a landowner, entered Priestley’s [312] account of his experi­ Cambridge in 1758 and attained his mas­ ments with various gases.) ter’s degree there in 1766. He was a Hot air seemed clearly lighter than 216

[326]

LEXELL

cold air, and floated on cold air as wood floated on water. It seemed natural to suppose that if a light bag were held, opening downward, over a fire, it would fill with hot air and be carried upward. This proved to be the case. On June 5, 1783, in the market place of their home town, the brothers filled a large linen bag, thirty-five feet in diame­ ter, with hot air. It lifted fifteen hundred feet upward, and floated a distance of a mile and a half in ten minutes. By No­ vember they went to Paris, where they managed a flight of six miles before a crowd of three hundred thousand that included Benjamin Franklin [272], Hot air, however, has very little buoy­ ancy and as soon as it cools down it has none. With Charles’s [343] suggestion that hydrogen be used, balloons that could lift men came into fashion. Man­ kind had always filled its myths and leg­ ends with flying men, flying horses, flying carpets, and so on. Leonardo da Vinci [122] had even tried to design flying machines two centuries before the Montgolfier brothers. However, 1783 was the first year in which men were ac­ tually lifted off the ground for prolonged periods. The scientific exploration of the upper atmosphere became a possibility.

LEBLANC

[328]

by Herschel [321] who himself thought the object must be a comet. It was Lexell’s observations that proved the orbit of the object to lie everywhere outside the orbit of Saturn and therefore to be a new planet—eventually called Uranus. What is more, Lexell eventually pointed out that the difficulties of establishing an accurate orbit might be the result of the gravitational interference of a hitherto unknown planet beyond Uranus—a sug­ gestion that was borne out a half century later with the work of Adams [615] and Leverrier [564] and the discovery of Neptune. [327] WITHERING, William English physician Born: Wellington, Shropshire, March 1741 Died: Birmingham, October 6, 1799 Withering, the son of a surgeon, ob­ tained his medical degree from the Uni­ versity of Edinburgh in 1766. In 1775, he moved his practice to Birmingham where he prospered and where he joined the Lunar Society, whose members in­ cluded Priestley [312] and Watt [316]. He had an interest in botany, which caused him to listen with more patience than might otherwise have been possible to “old wives’ tales” concerning the folk remedies used by herb-gatherers. He picked up the use of foxglove, learned of its efficacy in the case of certain cases of edema (caused by heart failure) and of the doses safe to use. In 1785 he pub­ lished a careful report of his findings that added the very useful drug digitalis to the pharmaceutical armory of physi­ cians.

[326] LEXELL, Anders Johan Swedish astronomer Born: Abo, Sweden (now Turku, Finland) December 24, 1740 Died: St. Petersburg (now Lenin­ grad), Russia, December 11, 1784 The son of a city councillor, Lexell graduated from the University of Abo in 1760 and gained a professorial position at Uppsala in 1763. Invited to St. Peters­ burg by the Academy of Sciences, he ac­ cepted a post there in 1769 and re­ mained there for the rest of his life. In [328] LEBLANC, Nicolas (luh-blankO French chemist St. Petersburg, he was a close associate Born: Ivoy-le-Pre, Indre, Decem­ of Euler [275], ber 6, 1742 In 1770 Lexell worked out the orbit of Died: St.-Denis (near Paris), Jan­ a comet observed in that year and deter­ uary 16, 1806 mined its period of revolution to be five and a half years. It was the first short­ Leblanc, who was orphaned at an term comet to have its orbit calculated. In 1781 he studied the object discovered early age, was apprenticed to an apothe217

[329]

SCHEELE

cary by his guardian, a physician. He studied surgery and in 1780 became phy­ sician to the future duke of Orleans, who during the early days of the French Rev­ olution gained a dubious fame as Phi­ lippe Égalité, an aristocrat who voted for the death of the king but who was him­ self guillotined in 1793. In 1775 the French Academy of Sci­ ences had offered a prize for a practical method of manufacturing sodium hy­ droxide and sodium carbonate out of salt (sodium chloride). Leblanc developed what is now called the Leblanc process which, together with the work of Chevreul [448], made soap manufacture on a large scale possible for the first time with important effects on personal hy­ giene. In 1783 he was awarded the prize, which, however, was not paid. It was the first chemical discovery that had an im­ mediate commercial use. During the revolution the government (which definitely did need scientists re­ gardless of the comment to Lavoisier [334]) needed soda badly for a variety of industrial chemical industries and forced Leblanc to make his process pub­ lic without remuneration after the execu­ tion of his patron, Philippe Égalité. Le­ blanc was reduced to poverty in this fash­ ion. He received his factory back in 1802 but lacked the capital to start things rolling. In 1806 he killed himself. On the whole the revolution had been kinder to Lavoisier. In 1855, Napoleon III made restitution to Leblanc’s heirs. The Leblanc process was ultimately re­ placed by that of Solvay [735]. [329] SCHEELE, Karl Wilhelm (shay'luh) Swedish chemist Born: Stralsund, Pomerania, De­ cember 9, 1742 Died: Koping, Vastmanland, May 21, 1786 Pomerania has been part of Germany through most of its history (it is now part of East Germany). At the time of Scheele’s birth it belonged to Sweden, because of that country’s participation in 218

SCHEELE

[329]

the Thirty Years’ War a century earlier. Scheele can therefore be considered Ger­ man by ancestry; he usually wrote in German. But he did all his adult work in Sweden and is generally considered a Swedish chemist. He was the seventh child of eleven, and with children the only form of wealth in that family young Karl Wil­ helm could not be supported in idleness. At fourteen he was apprenticed to an apothecary. In those days this, for a boy with an active mind, was as good as a university education in chemistry, for apothecaries were profoundly interested in minerals and usually prepared their own drugs. Scheele taught himself chemistry and became an apothecary extraordinary, passing periodically to more and more famous establishments, till finally he was working at Stockholm and at Uppsala. (Later in life, he had ample opportunity to obtain a university position and all its prestige, but he preferred to remain an apothecary and concentrate on research. As a professor, he would have been one of many. As an apothecary, he was the greatest the world has seen. He also re­ fused to serve Frederick II of Prussia as court chemist and turned down the offer of a similar position in England.) In 1770 he met the Swedish miner­ alogist Bergman [315], who sponsored and encouraged him. This meeting was arranged through another chemist, Gahn [339], who was a friend, as was another excellent chemist, Hjelm [342]. (Sweden, in proportion to its population, has prob­ ably produced more first-rate chemists in the last two centuries than any other na­ tion in the world.) In the course of his research career Scheele probably discovered or helped discover more new substances in greater variety than any other chemist in a like period of time. He discovered a number of acids, in­ cluding tartaric acid, citric acid, benzoic acid, malic acid, oxalic acid, and gallic acid in the plant kingdom; lactic acid and uric acid in the animal; and molybdic acid and arsenious acid in the min­ eral. He prepared and investigated three

[329]

SCHEELE

highly poisonous gases, hydrogen flu­ oride, hydrogen sulfide, and hydrogen cyanide and managed to avoid killing himself. (He even recorded the taste of hydrogen cyanide—a report one would swear could only be made posthu­ mously. ) He was involved in the discovery of the elements chlorine, manganese, bar­ ium, molybdenum, tungsten, nitrogen, and oxygen, and yet he is undoubtedly the unluckiest chemist in history, for de­ spite his phenomenal labors in uncover­ ing new elements, he does not receive undisputed credit for having discovered a single one. In some cases chemists in­ dependently made the same discovery a little sooner. In others Scheele did not quite carry matters far enough and chemists such as Hjelm, Gahn, and d’Elhuyar [367] took the last step and got the credit. In the case of chlorine, Scheele prepared it in the 1770s but did not recognize it as an element. He thought it an oxygen-containing com­ pound. It was Davy [421], over thirty years later, who recognized the elemen­ tary nature of chlorine and he is the one usually given credit for its discovery. The most tragic case of all was that of oxygen, which, from the standpoint of chemical history, was the most sig­ nificant of all his discoveries. He pre­ pared it in 1771 and 1772 by heating a number of substances that held it loosely, including the mercuric oxide used by Priestley [312] a couple of years later. This was a clear “first” for Scheele, who described his experiments carefully in a book, which, however, through the negli­ gence of his publisher, did not appear in print until 1777. By that time Priestley had reported his own experiments, and it is Priestley who gets the credit for oxy­ gen. (Scheele called oxygen “fire air.” Like Priestley, Scheele was a confirmed phlogistonist and did not interpret the role of oxygen in combustion correctly. That was left for Lavoisier [334].) However, copper arsenite, which Scheele studied, is still called Scheele’s green, while a calcium tungstate mineral is called scheelite. He also discovered the

FITCH

[330]

effect of light on silver compounds, which, half a century later, Daguerre [467] and others were to use in the de­ velopment of photography. Scheele’s private life had its share of misfortune. He suffered poor health and agonizing pain from rheumatism, which was aggravated by his long hours of work. He eschewed virtually all social life in favor of science, his only passion, and when he decided to marry he found he had time for it only on his deathbed. When he died he was only forty-three, and his death may have been hastened by his habitual tasting of the new com­ pounds he prepared. His final symptoms resembled those of mercury poisoning. [330] FITCH, John American inventor Born: Windsor, Connecticut, Jan­ uary 21, 1743 Died: Bardstown, Kentucky, July 2, 1798 It is hard to find a man so beset by misfortune as John Fitch. He had little schooling, a harsh father, and a nagging wife, whom he deserted. He made some money during the Revolutionary War when he was in charge of a gun factory, but the colonial currency became worth­ less. He passed the last part of the war as a British prisoner. In Pennsylvania in 1785 Fitch thought of building a steamship. With superhu­ man effort he obtained the capital and the necessary grants of monopoly from five states. In 1790 his fourth and best steamship traveled from Philadelphia to Trenton and back on a regular schedule. However, there were few passengers, the ship operated at a loss, his backers quit, and finally the ship was destroyed in a storm in 1792. He tried to begin again in France in 1793 but could obtain no funds. He re­ turned to America in deep depression and died (perhaps a suicide) nine years before Fulton [385] repeated his work and received credit for the invention of the steamship. 219

[331]

BANKS

[331] BANKS, Sir Joseph English botanist Born: London, February 13, 1743 Died: Isleworth, near London, June 19, 1820 Banks was that convenient but rare phenomenon, a scientist of great inde­ pendent wealth (which he inherited from his father in 1761) who spends that wealth liberally in the support of science. His interest in botany arose at the age of fifteen, when he became entranced with the flowery beauty of a country lane. While still a student at Oxford he financed a lectureship in botany, which is how the subject came to be taught there for the first time. In 1766 he made his first trip abroad, accompanying an expedition to New­ foundland, where he gathered new varie­ ties of plants and insects and earned a membership in the Royal Society. It became fashionable at about that time for sea expeditions intent on scientific exploration to carry naturalists who could make appropriate studies of the flora and fauna encountered. (This was to reach its peak some three quar­ ters of a century later, when Charles Darwin [554] made his first reputation on such a voyage.) Banks had his chance in 1768 on Cook’s [300] first expedition to the Pacific. He not only accompanied the ex­ pedition around the world but paid for all the necessary equipment. He hired a pupil of Linnaeus [276] as assistant and four artists as well. (Those were the days before photography.) The whole thing is supposed to have cost him £10,000 but at least he had an unparalleled chance to explore, for Cook landed on Australia. There Banks could browse through an isolated continent with life forms unlike those of any other. In fact the first point of landing, in 1770, near what is now Sydney, was named Botany Bay because of the delight of Banks in the prospect of ex­ ploration. (A quarter century later, Bot­ any Bay became a penal establishment.) A peninsula just south of the present city of Christchurch in New Zealand was 220

BANKS

[331]

named Banks Peninsula by Cook in honor of his botanist. Banks was the first to show that al­ most all the Australian mammals were marsupials and were more primitive than the placental mammals inhabiting the other continents. A century later Wallace [643] was to draw far-reaching conclu­ sions from this. After Banks returned from the South Pacific, he had a personal audience with George III, who wanted to know about his discoveries. He then accompanied an expedition to the North Atlantic, in 1772. In Iceland he discovered great geysers. In 1778 he was elected president of the Royal Society, thanks to the influence of George III. He kept that post until his death, forty-one years later. This long tenure was not entirely good. Banks grew lax with age and while the membership of the Society grew, the standards declined and it became nearly moribund. In 1781 Banks was made a baronet. He remained a philanthropist to the end, supporting young men of talent, notably Robert Brown [403] and making his home a gathering place for men of sci­ ence. Banks was interested in helping found colonies in the far regions of the world, and it was largely through his efforts that the first colonies were established in Aus­ tralia. He is sometimes called the father of Australia. He also labored to trans­ plant plants from their native regions to other lands where they might be useful. It was through his efforts that the bread­ fruit plant was brought from Tahiti to the West Indies. One ship transporting these bread­ fruits, in 1788, was the Bounty under William Bligh, who had been a ship’s master under Cook on the latter’s final voyage to the Pacific. The crew of the Bounty mutinied against harsh treatment by the captain and against having to leave Tahiti (and thus supplied Charles B. Nordhoff and James N. Hall with a good theme). Banks was impressed with Franklin’s [2721 action in persuading the American rebels to leave Cook unmolested.

[332]

HAÜY

Through the Napoleonic Wars he la- ' bored to follow this precedent and keep scientists above national angers and prej­ udices. It was an enterprise doomed to failure in later wars as nationalism grew more heated and as science began to play a greater and greater role in war­ making technology. [332] HAÜY, René Just (a-yoo-eeO French mineralogist Born: St.-Just-en-Choisée, Oise, February 28, 1743 Died: Paris, June 1, 1822 Haiiy, the son of a poor weaver, trained for the church and became a priest in 1770. He grew interested in natural history and mineralogy only after he was thirty, through the circumstance of making friends with an old priest whose hobby was botany. In 1781 Haiiy had a fortunate acci­ dent. He dropped a piece of calcite and it broke into small fragments. It had been part of the collection of a friend and Haiiy was mortified. His embar­ rassment was assuaged somewhat when he noticed that the fragments clove along straight planes that met at constant angles, something Steno [225] had casu­ ally noted a century before but had not followed up. Haiiy broke more pieces of calcite and found that no matter what the original shape, the broken fragments were rhombohedral (that is, slanted “cubes”). He hypothesized that each crystal was built up of successive additions of what we now call a “unit cell” to form—in the absence of external interference—a sim­ ple geometric shape with constant angles and with sides that could be related by simple integral ratios. He maintained that an identity or difference in crys­ talline form implied an identity or dif­ ference in chemical composition. This was the beginning of the science of crystallography, which was to attain maturity over a century later with the development of X-ray techniques by Laue [1068] and Bragg [922], Haiiy was involved in the labors that went into the establishment of the metric

JEFFERSON

[333]

system. With Lavoisier [334] he deter­ mined the density of water in order to set up a standard of mass. During the French Revolution, how­ ever, Haiiy, as a priest, was in consid­ erable danger. Scientific friends, who were in better standing with the govern­ ment, kept him alive, though he was im­ prisoned for a time. Despite his own in­ security, Haiiy tried, unsuccessfully, to intercede for Lavoisier, which was more than a few other friends of Lavoisier, more favorably situated, dared do. Haiiy survived to become a professor of mineralogy at the Museum of Natural History under Napoleon and wrote the first important texts on crystallography at Napoleon’s specific request. After Na­ poleon fell, however, Haiiy was deprived of his post, and spent his few remaining years in retirement. [333] JEFFERSON, Thomas American statesman and scholar Born: Shadwell, Virginia, April 13, 1743 Died: Monticello, Virginia, July 4, 1826 The chief events of the life of Jeffer­ son are known to every well-read Ameri­ can. He was educated at William and Mary College and was admitted to the bar in 1767. He served in the Virginia legislature, took an active part in the American revolution and wrote the Dec­ laration of Independence. During the War of Independence he was governor of Virginia and after its end he succeeded Franklin [272] as min­ ister to France. He was secretary of state under Washington, the first President; and Vice-President under John Adams, the second. In 1800 he was elected third President and served two terms. After retiring in 1809 he remained a revered elder statesman until his death on the fiftieth anniversary of the adoption of the Declaration he wrote. What is not so well known is that Jefferson was an accomplished scholar and gentleman-scientist of the last dec­ ades of the Age of Reason. He knew many languages, interested himself 221

[334]

LAVOISIER

deeply in scientific research (was inti­ mately acquainted with Priestley [312] for instance), studied agriculture and ex­ perimented with new varieties of grain. He also studied and classified fossils un­ earthed in New York state at a time when the investigation of these objects was in its infancy. He was also an archi­ tect of considerable excellence. He was the closest approach to scientist-in-office among all the Presi­ dents of the United States. [334] LAVOISIER, Antoine Laurent (la-vwah-zyayO French chemist Born: Paris, August 26, 1743 Died: Paris, May 8, 1794 Lavoisier was born of a well-to-do family, was loved and pampered to an extreme, first by his mother and then, after her early death in 1748, by an adoring aunt, and was given an excellent education. This good fortune was not wasted, for the young man, suffering from chronic dyspepsia, devoted himself to his studies by both inclination and ne­ cessity, and proved a brilliant student. His father, a lawyer, hoped his son would follow in that profession, but young Lavoisier, who obtained his li­ cense in law in 1764, attended lectures on astronomy by Lacaille [284] and grew interested in science. After dabbling in geology, and doing creditable work in that field, he veered toward chemistry, and that became his life work. From the very beginning of his chemi­ cal researches he recognized the impor­ tance of accurate measurement. Thus his first important work, in 1764, lay in an investigation of the composition of the mineral gypsum. This he heated to drive off the water content, and he measured accurately the water given off. There were chemists before Lavoisier, notably Black [298] and Cavendish [307], who devoted themselves to measurement, but it was Lavoisier who pounded away at it until, by his very successes, he sold the notion to chemists generally. He did for chemistry what Galileo [166] had done for physics two centuries earlier and the 222

LAVOISIER

[334]

effect on chemistry was just as fruitful. It is partly for this that Lavoisier is often called the father of modem chemistry and sometimes the Newton [231] of chemistry. Lavoisier was a most public-spirited citizen, joining numbers of boards and commissions designed to improve the lot of the people. In the 1760s he worked on improved methods of lighting towns (making a splash as a twenty-year-old with an essay on the subject), while in the 1770s he designed new methods for preparing saltpeter, a substance needed in the manufacture of gunpowder. These new methods made it unnecessary for government officials to ransack cellars and bams for crystals of the stuff, an in­ vasion of privacy that was sometimes brutally carried out and was strongly resented by the populace. In the 1780s he worked on the modernization of agri­ culture, and his researches involved a model farm he had established in 1778. All this public spirit was not to help him in the end, because of two mistakes. In the first place, he invested half a mil­ lion francs in the Ferme Générale in 1768 in order to earn money for his researches. The Ferme Générale was a private firm engaged by the French gov­ ernment, at a fixed fee, to collect taxes. Anything they collected over and above the fee they could keep. Naturally the “tax-farmers” gouged every last sou, and no group was more hated in eighteenthcentury France than those same taxfarmers. Lavoisier himself was not en­ gaged in active tax-collecting, of course, but he worked busily in an adminis­ trative capacity. Nor did he use the money earned for selfish purposes but plowed it back into chemical research, setting up a magnificent private labora­ tory in which the scientific leaders of France regularly gathered. The envoys from the new republic across the sea, Thomas Jefferson [333] and Benjamin Franklin [272], were particularly wel­ come there. Nevertheless, Lavoisier was a taxfarmer and earned one hundred thou­ sand francs a year out of it. What’s more, in 1771 he married Marie-Anne, the daughter of an important executive

[334]

LAVOISIER

of the Ferme Générale. She was young (only fourteen at the time), beautiful, and intelligent, and she threw herself wholeheartedly into his work, taking his notes, translating from English, illus­ trating his books, and so on. In general it was a splendid love-match, but she was the daughter of an executive taxfarmer. Lavoisier’s second mistake involved the French Academy of Sciences, to which honored association he was elected in 1768, when only twenty-three. In 1780 a certain Jean-Paul Marat, a journalist who fancied himself a scientist, applied for membership and Lavoisier was active in blackballing him, for the very good reason that the papers he offered the academy (containing some foolish home-grown notions on the nature of fire) were worthless. Marat, however, was not the man to forget, and the time came when he was to take a fearful re­ venge. Lavoisier in the early, happy days was busily engaged in breaking down, one by one, the antique chemical notions that still cobwebbed the thinking of eigh­ teenth-century chemists. There were still some who maintained the old Greek notion of the elements and said that transmutation was possible be­ cause water could be turned to earth on long heating. This seemed so, for water heated for many days developed a solid sediment. Lavoisier decided, in 1768, to test the matter and boiled water for one hundred and one days in a device, called a “peli­ can,” that condensed the water vapor and returned it to the flask so that no water was lost in the process. And, of course, he employed his method of care­ ful measurement. He weighed both water and vessel before and after. Sediment appeared, but the water did not change its weight during the boiling. Therefore, the sediment could not have been formed out of the water. However, the flask itself had lost weight, a loss just equal to the weight of the sediment. In other words, the sediment was not water turning to earth, it was material from the glass, slowly etched away by the hot water and precipitating in solid frag­

LAVOISIER

[334]

ments. Here was a clear-cut example of the manner in which observation without measurement could be useless and mis­ leading. Lavoisier’s interest in street lighting introduced him to the whole problem of combustion. The phlogiston theory of Stahl [241] had been in existence for a century now, and there were many things it could not explain. The resulting confusion among chemists was clarified by Lavoisier’s work and only after that clarification could chemistry move for­ ward (a second reason he is called the father of modem chemistry). Lavoisier began heating things in air in 1772. For instance, he and some other chemists bought a diamond and placed it in a closed vessel under the focused sun­ light of a magnifying glass. The diamond disappeared. Carbon dioxide gas ap­ peared within the vessel, proving the dia­ mond to be carbon or, at least, to con­ tain carbon. Lavoisier also took particu­ lar note of the fact that the diamond would not burn in the absence of air. Burning diamonds may seem pretty steep, just to prove a scientific point, but a prominent Parisian jeweler had made the claim that diamonds would not bum without air, and so confident was he of this and so anxious to prove himself right that he supplied the diamonds for the experiment and was willing to have one burned in the presence of air. Lavoisier went on to bum phosphorus and sulfur and to prove that the prod­ ucts weighed more than the original, so that he suspected some material had been gained from the air. (He didn’t be­ lieve phlogiston could have negative weight.) In 1774, to test this point, he heated tin and lead in closed containers, with a limited supply of air. Both metals formed a layer of calx on the surface. The calx was known to be heavier than the metal it replaced, but Lavoisier found that the entire vessel (metal, calx, air, and all) was no heavier after the heating than before. This meant that if the calx represented a gain in weight, there must be a loss in weight elsewhere, possibly in the air. If that was so, then a partial vacuum must exist in the vessel. 223

[334]

LAVOISIER

Sure enough, when Lavoisier opened the vessel, air rushed in and then the vessel and its contents gained in weight. Lavoisier was thus able to show that the calx consisted of a combination of the metal with air, and that rusting (and combustion) did not involve a loss of phlogiston but a gain of at least a por­ tion of the air. When this notion finally made its way through the ranks of the chemists, it killed the phlogiston theory and es­ tablished chemistry on its modern basis. Furthermore, Lavoisier’s demonstration that mass was never altogether gained or lost but was merely shifted from one point to another in the course of chemi­ cal changes, is the law of conservation of mass, a bulwark of chemistry throughout the nineteenth century (and a third rea­ son why he is proclaimed father of mod­ ern chemistry). Einstein [1064] extended and refined the concept. In October 1774 Priestley [312] went to Paris. He visited Lavoisier and dis­ cussed his experiments with “dephlogisticated air.” Lavoisier repeated the ex­ periments and realized at once that the dephlogisticated-air notion was nonsense. Here instead was the portion of the air that combined with metals to form calxes. The very reason that objects burned so readily in the new gas was that it was undiluted by that portion of the air in which objects did not bum. By 1778 Lavoisier’s ideas were clear. He was the first to announce what other great chemists of the time, particularly Scheele [329], had only dimly sus­ pected: that air consisted of two gases, one of which supported combustion and one of which did not. In 1779 he called the former “oxygen” (from Greek words meaning “to give rise to acids,” because he believed that all acids contained this element, in which belief he was, for once, wrong). The latter he called azote (from Greek words meaning “no life”), but in 1790 it was named nitrogen by Chaptal [368] and that is the name it now bears. In one respect Lavoisier displayed a deplorable infirmity of character, for he avoided mentioning the help he had re­ ceived from Priestley and, without actu­ 224

LAVOISIER

[334]

ally saying so, did his best to give the impression that he, himself, had discov­ ered oxygen. To be sure, Priestley’s help was not great and Lavoisier looked down upon Priestley as a mere tinkerer. Lavoi­ sier saw the true significance of Priest­ ley’s work which Priestley himself did not, so that Lavoisier deserves full marks for everything but the actual discovery of oxygen. However, it was the last bit of credit that he most coveted; he wanted to discover an element. He would do more for chemistry than any man before or since, but he would never discover an element. Lavoisier also studied the behavior of animals in air, in oxygen, and in nitro­ gen. He measured the amount of heat they produced and was able to show that life was very like combustion in that re­ spect. In 1783 Cavendish had shown that water could be formed by burning his inflammable gas in air. Cavendish, a con­ vinced phlogistonist, insisted on in­ terpreting this in terms of phlogiston. Lavoisier promptly repeated the experi­ ment in an improved manner and named the inflammable gas hydrogen (from Greek words meaning “to give rise to water”). This fitted in well with his new view of chemistry. He could see that when animals broke down foodstuffs (composed very largely of carbon and hydrogen), they did it by adding the ox­ ygen they breathed and forming carbon dioxide and water, both of which ap­ peared in the expired breath. Here, too, Lavoisier implied that the experiment of burning hydrogen was original with him. In fact, Lavoisier has such a dubious reputation as a credit snatcher that when it was discovered that a Russian chemist, Lomonosov [282], had published views like those of Lavoi­ sier a quarter century before the French­ man, some people began to wonder if Lavoisier had read Lomonosov’s works and didn’t bother to mention the matter. However, this is doubtful. The new chemistry began to catch on at once. In England, Hutton [297], Cav­ endish, and Priestley refused to aban­ don phlogiston, but Black [298] became a follower of Lavoisier. In Sweden, Berg­

[334]

LAVOISIER

man [315] went along with the new view, and in Germany, Klaproth [335]. At about this time, Guyton de Morveau [319] was trying to write an article on chemistry for an encyclopedia. He was having a miserable time trying to sum­ marize the knowledge of centuries and turned to Lavoisier for help. Lavoisier gave the problem some thought and de­ cided that the difficulty was a matter of language. (Guyton de Morveau had not accepted the new views of Lavoisier but, after collaborating with him for a while, he became another convert.) Having put chemistry on a new foun­ dation, Lavoisier went to work to give it a sensible language. The alchemists and early chemists had no fixed standard for naming the various chemical substances, and the alchemists, indeed, went out of their way to use obscure and fanciful names. The result was that no chemist could be sure exactly what another chemist was talking about. In collaboration with other chemists, including Berthollet [346] and Fourcroy [366], Lavoisier published a book, Methods of Chemical Nomenclature, in 1787. In this book were established the principles whereby every substance was assigned a definite name based on the el­ ements of which it was composed. The idea was that the name should indicate the composition. The system was so clear and logical that it was adopted by chem­ ists everywhere after some short-lived opposition on the part of a few phlogistonists. It still forms the basis of chemi­ cal nomenclature (a fourth reason why Lavoisier can be considered the father of modern chemistry). In 1789 Lavoisier went on to publish a textbook, Elementary Treatise on Chem­ istry, which served to present a unified picture of his new theories and in which he clearly stated the law of conservation of mass. It was the first modern chemical textbook (a fifth reason for his paternity of modem chemistry) and, among other things, it revived Boyle’s [212] notion of an element, and contained a list of all the elements then known; that is, all the substances that had not yet been broken down into still simpler substances. For the most part the list was quite

LAVOISIER

[334]

accurate, and no material substance was listed that is not recognized today as ei­ ther an element or the oxide of an ele­ ment. However, Lavoisier listed light and heat as elements, though we now recog­ nize them to be nonmaterial. Lavoisier believed heat consisted of an “impon­ derable fluid” called “caloric.” He had eradicated one imponderable fluid, phlogiston, but it was partly through his influence that caloric, just as false, re­ mained in existence in the minds of chemists for a half century. Lavoisier extended his interest in com­ bustion into biology. From 1782 to 1784, with the assistance of the young Laplace [347], he tried to measure heats of combustion and work out some of the details of what went on in living tissue. In connection with these experiments, he made the first crude attempts at the anal­ ysis of compounds characteristic of liv­ ing tissue, something that was to be de­ veloped successfully by Liebig [532] a half century later. But in the same year that his textbook appeared the French Revolution broke out. By 1792 the radical antimonarchists were in control, France was declared a republic, and the tax-farmers began to be hunted down. Lavoisier was first barred from his laboratory and then arrested. When he objected that he was a scientist and not a tax-farmer (not quite true), the arresting officer is supposed to have responded with the famous remark, “The republic has no need of scientists.” (The republic quickly found out how wrong it was, as in the case of Chaptal and Le­ blanc [328].) The trial was a farce, with Marat— now a powerful revolutionary leader and eager for revenge—accusing Lavoisier of all sorts of ridiculous plots, such as that of “adding water to the peoples’ to­ bacco,” and wildly demanding his death. Marat was assassinated in July 1793, but the damage had already been done. Lavoisier (along with his father-in-law and other tax-farmers) was guillotined on May 8, 1794, and buried in an un­ marked grave. Two months later the rad­ icals were overthrown. His was the most deplorable single casualty of the revolu­ tion. 225

[335]

KLAPROTH

Lagrange [317] mourned: “A moment was all that was necessary to strike off his head, and probably a hundred years will not be sufficient to produce another like it.” Within two years of Lavoisier’s death, the regretful French were unveil­ ing busts of him.

LAMARCK

[336]

later, uranium, in the hands of Fermi [1243] and Hahn [1063], was to achieve an unexpected and grisly fame.) In that same year Klaproth also ob­ tained a new oxide from the semipre­ cious jewel the zircon, and named the new metal contained in the oxide “zir­ conium.” In 1795 he isolated the oxide of a new metal he named titanium (after the Titans of Greek mythology). Klap­ roth, unlike Lavoisier, was not covetous of honor and gave full credit to Gregor [377] for the initial discovery of this metal. On January 25, 1798, he was one of those instrumental in recognizing tel­ lurium to be a new element, but again he pointed out he was not the first to do so and in reporting on it he was careful to give credit to the original discoverer, F. J. Muller [323], Klaproth was hard on the heels of Berzelius [425] and Hisinger [390] in the discovery of cerium in 1803 and he was one of those who early showed the unex­ pected complexity of the rare earth min­ erals discovered by Gadolin [373]. This portion of his work was to be carried further by Mosander [501], Klaproth was one of the outstanding analytical chemists of his age and is sometimes referred to as the father of analytic chemistry. He was meticulous in his analytical work, publishing all his figures and making no attempt to adjust them in order to have them come out neatly, as even Lavoisier did on occa­ sion. Klaproth was a pioneer in analytic chemistry and in the application of chemistry to archaeological objects, studying coins, glass, and ancient metal objects. When the University of Berlin was founded in 1810, Klaproth, although sixty-seven years old, was named its first professor of chemistry and served in that post until his death seven years later.

[335] KLAPROTH, Martin Heinrich (klap'rote) German chemist Born: Wernigerode, Prussian Sax­ ony, December 1, 1743 Died: Berlin, January 1, 1817 When Klaproth, the son of a tailor, was eight his family was impoverished as a result of a fire. At the age of sixteen he was apprenticed to an apothecary, which was, as Scheele [329] showed, an excel­ lent route to chemistry. Like Scheele, Klaproth rose from shop to shop and reached eminence, entering chemical re­ search on his own in 1780. (It didn’t hurt that in that year he gained eco­ nomic security by marrying the well-todo niece of Marggraf [279]. He was one of the early converts to the new theories of Lavoisier [334] and this was important. Stahl [241], whose phlogiston theory Lavoisier had over­ thrown, had been a German and there was a nationalistic resistance to the new “French chemistry.” Klaproth helped break that down with conclusive experi­ ments in 1792. He made his own mark, however, mainly in the discovery of new elements. His first adventure in this direction proved to be the most meaningful. In 1789 he investigated a heavy black ore called pitchblende. He obtained a yellow compound from it that he was quite cer­ tain contained a hitherto unknown ele­ ment. He obtained the oxide of the metal—thinking it was the metal itself— and named it uranium after the fashion of the old alchemists who named metals [336] LAMARCK, Jean Baptiste Pierre after planets. The planet Uranus had Antoine de Monet, chevalier de been discovered eight years before by French naturalist Herschel [321] and it seemed to Klap­ Born: Bazentin-le-Petit, Somme, roth fitting to have a new metal named August 1, 1744 for a new planet. (A century and a half Died: Paris, December 28, 1829 226

[336]

LAMARCK

Lamarck took a long time finding him­ self. He was the eleventh child of a fam­ ily of impoverished aristocrats who rec­ ognized no honorable profession (assum­ ing that money had to be made some­ how) but the army and the church. Young Lamarck was marked for the church very much against his will. His father died in 1760, however, and that event left him free to turn soldier. He did well enough, fighting with some distinction in the Seven Years’ War, where he received an officer’s com­ mission for bravery. By 1766 illness, resulting from overrough horseplay, had forced his resignation and he resumed ci­ vilian life. He tried his hand at several occupations and finally went into medi­ cine, writing a couple of overambitious books. An interest in plant life had been stirred when he was stationed in the army on the Mediterranean coast. Even­ tually this interest led to a book on French flora in 1778, and, with help from Buffon [277], he found himself on the road of natural history. In 1781 he was appointed botanist to the king, which meant a salary and the chance of traveling; then, in 1793, he became pro­ fessor of invertebrate zoology at the Mu­ seum of Natural History in Paris. Here, at last, at the age of nearly fifty, he came into his own. Linnaeus [276] had left the inverte­ brates rather in a mess from the stand­ point of classification. It was as though, having expended unbelievable energy and pains on the vertebrates, he had grown tired and thrown a bunch of the most diverse creatures into a single pi­ geonhole and called them “worms.” Lamarck tackled the miscellany and began to make order out of them. He differentiated the eight-legged arachnids (spiders, ticks, mites, and scorpions) from the six-legged insects. He es­ tablished a reasonable category for the crustaceans (crabs, lobsters, and so on) and for the echinoderms (starfish, sea urchins, and so on). He summarized his findings in publications that appeared be­ tween 1801 and 1809 and finally pro­ duced a gigantic seven-volume work be­ tween 1815 and 1822 entitled Natural

LAMARCK

[336]

History of Invertebrates which founded modem invertebrate zoology. (It was Lamarck who first used the terms “ver­ tebrate” and “invertebrate.” He also pop­ ularized the word “biology.” More important in the memory of pos­ terity than the very real and fruitful la­ bors summarized in these volumes is a theory of evolution advanced in his book Zoological Philosophy, published in 1809. It is very difficult to classify living species without thinking in terms of evo­ lution. Linnaeus had refused to face the possibility, and Cuvier [396] avoided it by adopting Bonnet’s [291] catastrophism. Erasmus Darwin [308] was an evolutionist a half century before La­ marck, but he was a minor figure and rather a dilettante. Lamarck was the first biologist of top rank to devise, boldly and straight­ forwardly, a scheme rationalizing the evolutionary development of life, and maintaining that the species were not fixed but that they changed and devel­ oped. Unfortunately the scheme was wrong. Organisms, Lamarck suggested, made much use of certain portions of thenbody in the course of their life and un­ derused others. Those portions that were used, such as the webbed toes of water birds, developed accordingly, while the others, such as the eyes of moles, with­ ered. This development and withering were passed on to descendants. Lamarck used the recently discovered giraffe for his most often quoted exam­ ple of this. A primitive antelope, he said, fond of browsing on the leaves of trees would stretch its neck upward with all its might to get all the leaves it could. It would stretch out its tongue and legs as well. In the process, neck, tongue, and legs would become slightly longer than they would have been otherwise. These longer body parts would be passed on to the young and when these had grown to adulthood, they would have a longer neck, tongue, and legs to begin with, would stretch them more, pass on still longer ones to their young and so on. Little by little the antelope would turn into a giraffe. This is an example of the “inheritance of acquired characteristics.” 227

[337]

VOLTA

The theory foundered on the rock of fact, however. In the first place, La­ marck visualized evolution as the prod­ uct of attempts by the animal to change. This might be imagined in the case of long necks since necks can be stretched voluntarily. But how would it work in the development of protective color­ ation? Surely a creature couldn’t try to become striped or splotched. Secondly there was no reason to think that ac­ quired characteristics could be inherited. In fact all available experimental evi­ dence pointed in the opposite direction, that acquired characteristics could not be inherited. Mistaken or not, Lamarck moved evo­ lutionary theory into the forefront of bi­ ological thinking and for this deserves full credit. However, in his lifetime (during which he married three times and had eight children) he was overshad­ owed by the greater renown of the nonevolutionist Cuvier and died blind, penniless, and largely unappreciated. Cu­ vier had taken a strong dislike to La­ marck, as a matter of fact, owing to Lamarck’s sarcastic references to Cu­ vier’s theories of catastrophism. Cuvier was powerful at the time and those he opposed simply did not do well. Lamarck’s reputation was not helped by the fact that he was a vociferous op­ ponent of Lavoisier’s [334] new chemis­ try. Then, thirty years after his death, when evolutionary views finally won out, it was Charles Darwin [554] with his su­ perior mechanism of evolution by natu­ ral selection who gained the fame. Every once in a while Lamarckism (that is, the inheritance of acquired characteristics) comes to the fore in one form or another. The most recent exam­ ple is that of Lysenko [1214] in the So­ viet Union.

VOLTA

[337]

Volta was born into a noble family that had come down in the world. Most of his brothers and sisters (he was one of nine children) entered the church. Not so, young Alessandro. He was not an infant prodigy by any means. He did not talk until he was four and his family was convinced he was re­ tarded. By seven, however, when his fa­ ther died, he had caught up with other children and then began to forge ahead. When he was fourteen, he decided he wanted to be a physicist. Volta was interested in the phenome­ non of the age, electricity, that interest having been aroused by Priestley’s [312] history of the subject. He even wrote a long Latin poem (considered rather good) on the subject. In 1774 he was ap­ pointed professor of physics in the Como high school and the next year he in­ vented the electrophorus, describing it first in a letter to Priestley. This was a device consisting of one metal plate cov­ ered with ebonite and a second metal plate with an insulated handle. The ebonite-covered plate is rubbed and given a negative electric charge. If the plate with a handle is placed over it, a positive electric charge is attracted to the lower surface, a negative charge re­ pelled to the upper. The upper negative charge can be drawn off by grounding and the process repeated until a strong charge is built up in the plate with the handle. This sort of charge-accumulating machine replaced the Leyden jar and is the basis of the electrical condensers still used today. Volta’s fame spread as a result. In 1779 he received a professorial appoint­ ment at the University of Pavia, where he continued his work with electricity. He invented other gadgets involving static electricity and received the Copley medal of the Royal Society in 1791. He was elected to membership in the Soci­ ety. [337] VOLTA, Alessandro Giuseppe The major feat of his life involved not Antonio Anastasio, Count (vole'- static electricity, but dynamic electricity tah) —the electric current. He had followed Italian physicist the experiments of Galvani [320], who Born: Como, Lombardy, Febru­ was a friend of his and who sent Volta ary 18, 1745 copies of his papers on the subject. Volta Died: Como, March 5, 1827 took up the question of whether the

228

[337]

VOLTA

electric current resulting when muscle was in contact with two different metals arose from the tissue or from the metals. To check this he decided in 1794 to make use of the metals alone, without the tissue. He found at once that an elec­ tric current resulted and maintained that it therefore had nothing to do with life or tissue. This sparked a controversy be­ tween the two Italians with the German Humboldt [397], the chief of Galvani’s supporters, and the Frenchman Coulomb [318], the chief of Volta’s. The weight of evidence leaned more and more heavily toward Volta, and Galvani died embit­ tered. In 1800 Volta virtually clinched the victory by constructing devices that would produce a large flow of electricity. He used bowls of salt solution that were connected by means of arcs of metal dipping from one bowl into the next, one end of the arc being copper and the other tin or zinc. This produced a steady flow of electrical current. Since any group of similar objects working as a unit may be called a battery, Volta’s de­ vice was an “electric battery”—the first in history. Volta made matters more compact and less watery by using small round plates of copper and zinc, plus discs of card­ board moistened in salt solution. Starting with copper at the bottom, the discs, reading upward, were copper, zinc, card­ board, copper, zinc, cardboard, and so on. If a wire was attached to the top and bottom of this “Voltaic pile” an electric current would pass through it if the cir­ cuit was closed. Within a short time the voltaic cell was put to practical use by William Nicholson [361] and this led directly to the astonishing work of Davy [421], The invention of the battery lifted Volta’s fame to the peak. He was called to France by Napoleon in 1801 for a kind of “command performance” of his experiments. He received a stream of medals and decorations, including the Legion of Honor, and was even made a count and, in 1810, a senator of the kingdom of Lombardy. Throughout his life, though, Volta, like Laplace [347], had the ability to

PINEL

[338]

shift with the changing politics of the time and to remain in good odor with whatever governments were in power. After Napoleon fell and Austria became dominant in Italy once more, Volta con­ tinued to do well and to receive posts of honor. Volta received his greatest honor, however, at the hands of no potentate, but of his fellow scientists. The unit of electromotive force—the driving force that moves the electric current—is now called the “volt.” The energy of moving charged parti­ cles produced by modern atom-smashing machines is measured in electron-volts. A billion electron-volts is abbreviated “bev,” and when we speak of the partic­ ular atom-smasher called the bevatron, the “v” in the name stands for Volta. Volta was also the first, in 1778, to isolate the compound methane, a major constituent of natural gas. [338] PINEL, Philippe (pee-nelO French physician Born: Saint-André, Tarn, April 20, 1745 Died: Paris, October 26, 1826 Pinel took his doctor’s degree at the University of Toulouse in 1773, and went to Paris in 1778. He supported himself first by teaching mathematics and translating scientific books. Under the influence of Linnaeus [276] he classified diseases into species, genera, orders, and so on. The labor was useless, but he became interested in the problem of mental disease after a friend of his had gone violently mad. Until his time the insane in most cul­ tures were believed to be possessed of demons and were often treated with a certain reverence. While this may seem fine for the insane, it was not treatment. If they grew violent, the only remedy was to put them in chains. Hospitals for the insane were dreadful nightmares of howling, demented people, imprisoned and often subjected to the most brutal treatment. It was even a form of amusement for presumably sane 229

[339]

GÄHN

people to visit the hospitals for a look at the antics of the unfortunates. In 1791 Pinel published his views on “mental alienation,” referring to a mind alienated from its proper function (and even today, especially in connection with courtroom evidence, a psychiatrist is sometimes called an alienist). Pinel ad­ vocated considering them as people, sick in mind, to be treated with the same consideration as the sick in body; and he advocated talking to patients, rather than manhandling them. The French Revolution was in full swing then and it was the time for upset­ ting encrusted tradition. In 1793 Pinel was placed in charge of an insane asy­ lum and there he struck off the chains from the insane and began to adopt sys­ tematic studies. He was the first, for in­ stance, to keep well-documented case histories of mental ailments. His methods were slow to be accepted, but within half a century they were dom­ inant in medicine, reaching a climax with the work of Freud [865]. [339] GAHN, Johann Gottlieb Swedish mineralogist Born: Voxna, South Halsingland, August 19, 1745 Died: Falun, Kopparburg, December 8, 1818 Gahn was born in an iron-mining town and began life as a miner (a practi­ cal, if not very easy, introduction to mineralogy). He worked himself upward not only in science but in business as well, for he ended life owning and man­ aging mines. He also took part in Swedish politics, serving in the legisla­ ture for a time. He studied under Bergman [315] and became especially proficient in the use of the blowpipe, the convenient analytical tool that had been introduced by Cronstedt [292]. It was Gahn who trained Berzelius [425] in this technique. Gahn’s proficiency in mineralogy is marked by the fact that a zinc aluminate mineral is still called gahnite, but his best-known achievement is the isolation of metallic manganese in 1774. He gets the credit as 230

MONGE

[340]

discoverer of the metal although his friend Scheele [329] had done much of the preliminary spadework. In collabo­ ration with Scheele, Gahn discovered about 1770 that phosphorus was an es­ sential component of bone. Gahn had a connection with American history: during the Revolutionary War, copper was needed by the young nation for sheathing ships, and it was one of his companies that filled the rush order. [340] MONGE, Gaspard (mohnzh) French mathematician Born: Beaune, Cote d’Or, May 9, 1746 Died: Paris, July 28, 1818 Monge, the son of a merchant, showed remarkable mathematical ability in his early years. At sixteen he made a largescale plan of Beaune, using original methods that impressed a military officer, who hired him as a draftsman. Monge’s methods of using geometry to work out quickly constructional details that ordinarily required complicated and tedious arithmetical procedures was the foundation of what is called “descriptive geometry.” It was so important in con­ nection with fortress construction that for a couple of decades it was guarded as a military secret. With the French Revolution, Monge became increasingly involved in public affairs. He was on the committee that worked out the metric system. He founded the ficole Polytechnique and was its first director. He worked out fur­ ther details of descriptive geometry which showed how to describe a struc­ ture fully by plane projections from each of three directions and finally received permission to publish and teach his methods in 1795. He was a close friend of Napoleon Bonaparte and accompanied him on his campaign in Egypt in 1798, returning in 1801. Having supported both the revolu­ tion and Napoleon, he was appropriately rewarded. He was made president of the senate in 1806 and comte de Peluze in 1808. After the fall of Napoleon, he was deprived of all his honors by the new

[341]

PIAZZI

government of Louis XVIII and harassed in many ways. He did not long survive. In chemistry, Monge was the first to liquefy a substance that ordinarily oc­ curs as a gas. In 1784 he liquefied sulfur dioxide, the normal boiling point of which is —72.7°C. [341] PIAZZI, Giuseppe (pyah'tsee) Italian astronomer Bom: Ponte de Valtellina (now located in Switzerland), July 16, 1746 Died: Naples, July 22, 1826 Piazzi was a Theatine monk and priest, having entered the order in 1764. He received his early training in philoso­ phy but later in life took up mathematics and astronomy. The government of Naples (then an independent kingdom), having decided to establish observatories in its two largest cities, Naples and Palermo, put Piazzi in charge in 1780. He traveled to the observatories in France and England as preparation and in England visited Herschel [321]. There he had the doubtful privilege of falling off the ladder at the side of Herschel’s great reflector and breaking his arm. Piazzi established his observatory at Palermo and by 1814 had mapped the position of 7,646 stars. He showed that the proper motions first detected by Hal­ ley [238] were the rule among stars and not the exception. He also discovered a dim star called 61 Cygni with an unusu­ ally rapid proper motion, a star that was to play an important role a genera­ tion later when Bessel [439] came to ob­ serve it. Piazzi’s chief accomplishment did not, however, involve the stars at all. After Herschel’s discovery of Uranus, the as­ tronomical world was abuzz with plans for the discovery of additional planets. Uranus was in the position predicted for it by a mathematical rule popularized by Bode [344] and therefore called Bode’s law. Following this same rule, astrono­ mers suspected a planet to be lying be­ tween the orbits of Mars and Jupiter. (Even Kepler [169] had commented on the unusual size of the gap between the

PIAZZI

[341]

orbits of those two planets.) A group of German astronomers, of whom the most distinguished was Olbers [372], made preparations for a thorough survey of the heavens to locate this planet, if it existed. While preparations were under way, Piazzi, on January 1, 1801, in the course of his systematic observation of the stars, came across one in the constellation Taurus that changed its position over a period of several days between observa­ tions. He began to follow its course. It appeared to be a planet lying between Mars and Jupiter, since it moved more slowly than Mars and more quickly than Jupiter. He wrote about this to Bode, but before its orbit could be determined, Piazzi fell sick and when he returned to the telescope the object was too near the sun to be observed. At this point Gauss [415] worked out a new method for calculating an orbit from only three reasonably spaced obser­ vations. Piazzi’s observations were sufficient, the orbit was calculated, the planet relocated, and it proved indeed to lie between the orbits of Mars and Ju­ piter. The new heavenly object was named Ceres after the Roman goddess most closely associated with Sicily. How­ ever, the planet was so dim, considering its distance, that it had to be very tiny. Herschel estimated a diameter of two hundred miles, and the modem figure is 485 miles. In any case it scarcely seemed a respectable planet. The search for additional bodies took place therefore (since the German as­ tronomers were all prepared for it) and in the next few years three more planets were discovered, each even smaller than Ceres. They were named the asteroids (“starlike”), a name suggested by Her­ schel because they were too small to show as discs in the telescope but ap­ peared as starlike points of light. (Some have suspected that Herschel wanted to reserve planetary discoveries for himself and therefore moved to refuse the tiny new worlds the name of planet.) “As­ teroids” is, however, a poor name, for the bodies are not really starlike and the alternate names “planetoids” or “minor planets” are usually considered prefera­ 231

[342]

HJELM

ble, though “asteroids” may always re­ main more popular. Over sixteen hundred planetoids are now known, so that Piazzi’s discovery was not that of a planet merely, but of a whole zone of planets. At the time of Piazzi’s death, however, the number of known planetoids was still only four. When the thousandth planetoid was dis­ covered in 1923, it was named Piazzia in his honor. [342] HJELM, Peter Jacob (yelm) Swedish mineralogist Born: Sunnerbo Harad, October 2, 1746 Died: Stockholm, October 7, 1813 Hjelm was a friend of Scheele’s [329] who gets credit for discovering a metal on which Scheele worked. In 1781 at the suggestion of Scheele, Hjelm used methods similar to Gahn’s [339] in iso­ lating manganese. The result was the iso­ lation of still another metal, and new ele­ ment, molybdenum. [343] CHARLES, Jacques Alexandre César (shahrl) French physicist Born: Beaugency, Loiret, Novem­ ber 12, 1746 Died: Paris, April 7, 1823 Teaching at the Sorbonne, Charles, who held a minor government post and was granted a small pension by Louis XVI, popularized Franklin’s [272] onefluid theory of electricity. He proved a skillful and popular lecturer on science for the layman. Upon hearing of the experiments of the Montgolfier brothers [325] on bal­ loons, he realized at once that hydrogen, the lightness of which had been discov­ ered fifteen years earlier by Cavendish [259], would be a far more efficient buoyant force (though much more ex­ pensive) than hot air. On August 27, 1783, he constructed the first hydrogen balloon, inventing, in the process, all the 232

BODE

[344]

devices used to handle and manipulate balloons. He himself went up several times, reaching a height of over a mile, and helped establish an aeronautic craze, ex­ emplified by such men as Blanchard [362], Louis XVI, who was fascinated by balloons, continued to patronize Charles, which made him unpopular to the revo­ lutionaries. During the French Revolu­ tion he might have been killed by a mob, had he not won them over by reciting his ballooning achievements. His most important discovery was re­ ally a rediscovery. He repeated the work of Amontons [244] about 1787 and showed that different gases all expanded by the same amount with a given rise in temperature. Charles’s advance lay in his being the first to make an accurate esti­ mate of the degree of expansion. For each degree (Centigrade) rise in temper­ ature, he found, the volume of a gas ex­ panded by % 7 3 of its volume at 0°. For each degree of fall, the volume con­ tracted by % 7 3 of that volume. This meant that a temperature of —273°C the volume of a gas would reach zero (if the law held good) and that there could be no lower tempera­ ture. It was two generations later that Kelvin [652] was to crystallize this no­ tion of an absolute zero. Charles did not publish his experi­ ments, and about 1802 Gay-Lussac [420], also a balloon-ascensionist, pub­ lished his own observations in this mat­ ter, duplicating those of Charles. The rule that the volume of a given quantity of gas is proportional to the absolute temperature where pressure is held con­ stant is sometimes called Gay-Lussac’s law and sometimes Charles’s law. [344] BODE, Johann Elert (boh'duh) German astronomer Born: Hamburg, January 19, 1747 Died: Berlin, November 23, 1826 Bode, the son of a teacher, was self­ educated in astronomy and was writing astronomy texts in 1766, while he was still a teenager. In 1777 he took a posi­

[345]

JUSSIEU

tion as assistant to Lambert [299] and advanced rapidly. He became director of the Berlin Observatory in 1786, and was the author of a vast catalogue of star po­ sitions, issued in 1801. Nevertheless he is best known for pop­ ularizing a relationship that he did not originate. It had been pointed out in 1772 by Titius [301] that one might start with the series 0, 3, 6, 12, 24, 48, 96, 192, . . . each number (after the first two) double the one before. If one added 4 to each, then the series became 4, 7, 10, 16, 28, 52, 100, 196. . . . If one sets the earth’s distance from the sun at 10, then Mercury is, in proportion, at dis­ tance 4 and Venus at distance 7 (at least roughly). Similarly Mars is at 16, Jupiter at 52, and Saturn at 100 (roughly). This relationship is still known as Bode’s law, though lately quite often as the Bode-Ti­ tian law. At the time it was popularized, no planet was known for position 28, though even Kepler [169], nearly two centuries before, had felt the gap be­ tween Mars and Jupiter to be too large, and had suggested that a small planet might exist there. When Uranus was discovered and found to be at position 196 (roughly), astronomers could no longer resist. The search began for the planet at position 28, which Ceres filled nicely. However, when Leverrier [564] discovered Nep­ tune, it was found in a position quite far from that predicted by Bode’s law, al­ though Leverrier had made use of it in his calculations, and the law’s impor­ tance vanished. [345] JUSSIEU, Antoine Laurent de (zhyoo-syuh') French botanist Born: Lyon, April 12, 1748 Died: Paris, September 17, 1836 Jussieu was a member of a distin­ guished family of botanists. An uncle, Bernard, had first identified sea anem­ ones and related creatures as animals rather than as plants, which they resem­ ble. Another uncle, Joseph, had been a

BERTHOLLET

[346]

member of the Peruvian expedition of La Condamine [270]. Antoine Laurent himself began his work in 1765 under his uncle Bernard and obtained his doctorate in 1780. He popularized a system of natural classification of plants in 1789 that was the base upon which Cuvier [396] and Candolle [418] built, a generation later. Jussieu was placed in charge of the hospital of Paris during the French Rev­ olution and in 1793 was appointed pro­ fessor of botany at the Jardin des Plantes, a post he held till his retirement in 1826. [346] BERTHOLLET, Claude Louis, Comte (ber-toh-lay') French chemist Born: Talloires, Haute Savoie, December 9, 1748 Died: Arcueil, near Paris, No­ vember 6, 1822 Berthollet was bom of poor French parents in what was then part of Italy. He obtained his medical degree at the University of Turin in 1768 and moved to Paris in 1772. He was one of the first to accept Lavoisier’s [334] new theories, and he joined with him in devising the new chemical nomenclature. On his own, Berthollet continued Scheele’s [329] research on chlorine, showing in 1785 how it could be used for bleaching, but like Scheele he was convinced that it was a compound and contained oxygen. He continued Priest­ ley’s [312] investigation of ammonia and was the first to show its composition (of nitrogen and hydrogen) with reason­ able precision. He discovered potassium chlorate and Lavoisier thought its explo­ sive qualities might make it a substitute for gunpowder. However, it was too ex­ plosive. Two men died in a potassium chlorate explosion and Lavoisier aban­ doned the project. In 1781 he was elected to the Acad­ emy of Sciences against the opposition, for some reason, of Fourcroy [366], and in 1794 was appointed professor at the ficole Normale. Unlike Lavoisier, he got along well with the revolutionaries. In 233

[347]

LAPLACE

1798, while in Egypt on a business trip, he met Napoleon and attached himself to the rising star, teaching him chemis­ try. Napoleon eventually made him a senator and a count. Later, Berthollet voted for the deposition of Napoleon and the returning Bourbons made him a peer. His great service to chemistry was his realization in 1803 that the manner and rate of chemical reactions depended on more than just the attraction of one sub­ stance for another. The “affinities” of Bergman [315] were not enough. Sub­ stance A would react with Substance B and not with Substance C, though its affinity for Substance C was greater, if Substance B was present in sufficiently greater quantity. This was a foreshadow­ ing of the extremely important law of mass action. Here, however, Berthollet’s views were ignored and they did not enter the mainstream of chemistry until the rise of the physical chemists, three quarters of a century later. Berthollet also maintained that the composition of the products of a reac­ tion varied with the relative masses of the substances taking part in the reac­ tion, but in this respect he was proved wrong by Proust [364]. This, unfortu­ nately, helped discredit his sound views on mass action. He was wrong, also, in his views on the nature of heat, which he considered a fluid, in opposition to the more accurate view of men such as Rumford [360]. [347] LAPLACE, Pierre Simon, mar­ quis de (la-plahs') French astronomer and mathe­ matician Born: Beaumont-en-Auge, Calvados, March 28, 1749 Died: Paris, March 5, 1827 Not much is known of Laplace’s early life, because he was one scientist who was a snob and, ashamed of his origins, spoke little of them. It is usually stated that he came of a poor family and that well-to-do neighbors helped the obvi­ ously bright boy get an education. Re­ cent researchers, however, indicate he 234

LAPLACE

[347]

may have been of comfortable middleclass birth. At eighteen he was sent to Paris with a letter of introduction to D’Alembert [289], who refused to see him. Laplace sent him a paper on mechanics so excel­ lent that D’Alembert was suddenly over­ joyed to act as his sponsor. He obtained for the young man a professorship in mathematics. Early in his career Laplace worked with Lavoisier [334], determining specific heats of numerous substances. In 1780 the two men demonstrated that the quantity of heat required to decompose a compound into its elements is equal to the heat evolved when that compound is formed from its elements. This can be considered the beginning of ther­ mochemistry and as another pointer— following the work of Black [298] on la­ tent heat—toward the doctrine of con­ servation of energy, which was to come to maturity six decades later. However, Laplace turned his chief powers to a study of the perturbations of the members of the solar system and to the question of the general stability of that system, the problem that was al­ ready exercising Lagrange [317]. In 1787 Laplace was able to show the moon was accelerating slightly more than could earlier be explained. This he attributed to the fact that the eccen­ tricity of the earth’s orbit was very slowly decreasing as a result of the gravi­ tational influence of other planets. This meant a slightly changing gravitational influence of the earth upon the moon, which was not earlier allowed for and which could account for the moon’s trifling quantity of extra acceleration. He also studied certain anomalies in the mo­ tions of Jupiter and Saturn and, by building on some of Lagrange’s work, showed that they could be accounted for by the gravitational attraction of each planet upon the other. Laplace and Lagrange, working sepa­ rately but cooperatively, managed to generalize matters and show, for in­ stance, that the total eccentricity of the planetary orbits of the solar system had to stay constant, provided all planets revolve about the sun in the same direc­

[347]

LAPLACE

tion (which they do). If the orbit of one planet increases its eccentricity, that of others must decrease in eccentricity sufficiently to strike a balance. The same sort of constancy holds for the inclina­ tion of a planet’s orbit to the plane of the ecliptic. The total stock of either ec­ centricity or inclination in the entire solar system is so small that no one planet could change its orbital charac­ teristics very much even if it drew upon the entire supply. This showed that as long as the solar system remained effectively isolated, and as long as the sun did not change its na­ ture drastically, the solar system would remain much as it is now for an indef­ inite period in the future. In this way Laplace rounded off the work of Newton [231], at least as far as planetary astronomy is concerned, and he is sometimes called the French New­ ton in consequence. Further refinements had to wait for men such as Leverrier [564] fifty years later and Poincare [847] fifty years later still. Laplace summed up gravitational theory in a monumental five-volume work called Celestial Mechanics, which appeared over the time interval from 1799 to 1825. His work was not inter­ rupted significantly by the political changes that swept France in that pe­ riod, including the rise and fall of Napo­ leon, even though he dabbled in politics. His prestige protected him and so did his ability to apply his mathematics to prob­ lems involving artillery fire. He also dis­ played a not-altogether-admirable ability to change his political attitude to suit changing circumstance. Another unattractive facet of La­ place’s personality was that he (like La­ voisier) was reluctant to give credit to others. He did less than justice to La­ grange’s contributions to their joint work on celestial mechanics, something the gentle Lagrange didn’t seem to mind. Napoleon made Laplace minister of interior, and when the astronomer proved incompetent in that post, he was promoted to the purely decorative posi­ tion of senator. Yet when Louis XVIII came to the throne after Napoleon’s fall, Laplace was not penalized for attaining

LAPLACE

[347]

office under Napoleon, as Haiiy [332] and Chaptal [368] were, but was made a marquis. Other honors were his. He had been elected to the Academy of Sciences in 1785, but that was rather to be ex­ pected. In 1816 he was elected to the far more exalted and exclusive literary soci­ ety, the French Academy, and in 1817 became president of that body. Celestial Mechanics, by the way, is no­ torious for its habit of stating that from Equation A “it is obvious” that Equa­ tion B follows—except that students must often spend hours and days deter­ mining just why it is so obvious. Napo­ leon is supposed to have remarked, on leafing through this book, that he saw no mention of God. “I had no need of that hypothesis,” said Laplace. When La­ grange heard this, he said, “Ah, but it is a beautiful hypothesis just the same. It explains so many things.” In pure mathematics Laplace wrote a treatise on the theory of probability be­ tween 1812 and 1820 that gave this por­ tion of mathematics its modem form. Oddly enough Laplace is best known for a speculation he published as a note at the end of later editions of a non­ mathematical book on astronomy meant for the general public, a speculation that he did not himself take any too seriously. Since all the planets revolve about the sun in the same direction and in just about the same plane, Laplace suggested that the sun originated as a giant nebula or cloud of gas that was in rotation. As the gas contracted, the rota­ tion would have to accelerate and an outer rim of gas would be left behind (by centrifugal force). The rim of gas would then condense into a planet. With continued contraction, this would hap­ pen over and over until all the planets were formed, still moving in the direc­ tion of the original nebular rotation. The core of the nebula finally would con­ dense into the present-day sun. This nebular hypothesis caught the fancy of astronomers and remained pop­ ular throughout the nineteenth century as the favored explanation of the origin of the solar system. After a period of eclipse in the first few decades of the twentieth, it returned about mid-century 235

[3481

JENNER

in Weizsacker’s [1376] modified form to greater popularity than ever. Possibly unknown to Laplace, a simi­ lar suggestion, not quite as thoroughly worked out, had been advanced forty years earlier by Kant [293]. [348] JENNER, Edward English physician Born: Berkeley, Gloucestershire, May 17, 1749 Died: Berkeley, January 26, 1823 Jenner was the son of a clergyman and lost his father and mother when he was only five. Under the guardianship of an elder brother, he had some schooling and was then apprenticed to a surgeon in 1762. He eventually obtained his medi­ cal degree from St. Andrew’s in 1792. His interests ranged far beyond medi­ cine, however, into music, poetry, and natural history. He was sufficiently com­ petent in the last to be given the job of preparing and arranging zoological speci­ mens collected by Captain Cook [300] after his first voyage to the Pacific. He was even offered a post as naturalist on the second voyage, but he refused, pre­ ferring to remain in practice at home. In medicine Jenner’s chief interest was smallpox, one of the most dreaded dis­ eases of its time. Almost everyone got it, in varying degrees of virulence, and in bad epidemics as many as one out of three died. The survivors were usually pockmarked, their skin pitted and scarred. The disfiguration at its worst al­ most robbed a face of any appearance of humanity. Many feared such disfigura­ tion worse than death. A very mild case of smallpox was far better than none at all, for once the pa­ tient recovered he became immune to all future attacks. In Turkey and China there were attempts to catch the disease from those with mild cases. There was even deliberate inoculation with matter from the blisters of such cases. Unfortu­ nately one could not always guarantee that the disease would be mild in the new host, so that this sort of inoculation was a rather grisly form of Russian 236

JENNER

[348]

roulette. Nevertheless, the notion was making an impression on western Europe. Diderot [286], for instance, sup­ ported it ardently. In the early eighteenth century that Turkish habit of inoculation had been in­ troduced into England. It did not catch on, but inoculation was much in the air and as early as 1775 it set Jenner think­ ing. There was an old wives’ tale current in Gloucestershire that anyone who caught cowpox (a mild disease of cattle resembling smallpox) was immune not only to cowpox but also to smallpox. Jenner wondered if it might not be true. He observed a disease of horses called the grease, in which there was a swelling and blistering in part of the leg. People working in stables and barnyards might get some blisters of their own this way, and they too seemed rarely to get small­ pox. It was something that had to be tested and the test was a fearsome one. On May 14, 1796, Jenner found a milkmaid, Sarah Nelmes, who had cowpox. He took the fluid from a blister on her hand and injected it into a boy, named James Phipps, who of course got cowpox. Two months later he inoculated the boy again, this time with smallpox. Had the boy died or even been badly sick, Jenner would clearly have been a criminal. The boy did not die; the smallpox did not touch him; and Jenner was a hero. Jenner wanted to try it again to make sure, but it took him two years to find someone else with active cowpox. In 1798 he was able to repeat his experi­ ment with equally happy results and finally he published his findings. The Latin word for cow is vacca and for cowpox, vaccinia. Jenner coined the word vaccination to describe his use of cowpox inoculation to create immunity to smallpox. He had, in this way, founded the science of immunology. So widespread was the dread of small­ pox that the practice of vaccination was accepted quickly and spread to all parts of Europe. The British royal family was vaccinated, and the British Parliament, never noted for wild generosity, voted Jenner £10,000 in 1802 (and another

[348]

JENNER

£20,000 in 1806). A Royal Jennerian Society, headed by Jenner, was founded in 1803 to encourage vaccination. In eighteen months, twelve thousand people were vaccinated in England and the number of deaths from smallpox was re­ duced by two thirds. A hundred thou­ sand were vaccinated the world over by 1800. In parts of Germany, Jenner’s birthday was celebrated as a holiday and in 1807 Bavaria led the way in making vaccina­ tion compulsory. Even backward Russia adopted the practice. The first child to be vaccinated there was named Vaccinov and was educated at the expense of the nation. Jenner’s name even transcended war­ time passions. After the short Peace of Amiens ended and Great Britain re­ sumed its war with Napoleonic France, some British civilians were held pris­ oners. They were released because Jenner’s name was included on the peti­ tion addressed to Napoleon on their be­ half and Napoleon, alive to the advan­ tages of the gesture, freed them for the physician’s sake. He even had a medal struck in Jenner’s honor and made vacci­ nation compulsory in the French army. English medicine, however, did not hasten to honor Jenner. In 1813 he was proposed for election to the College of Physicians in London. The college wanted to test him in the classics, that is, in the theories of Hippocrates [22] and Galen [65], Jenner refused, being of the opinion that his victory over smallpox was qualification enough. The gentlemen of the college did not agree and Jenner was not elected. It was a small loss to Jenner, who died knowing that for the first time a major disease had been completely conquered. And it is true that smallpox has never been a problem for the medically ad­ vanced portions of the earth since Jenner’s time and has, in the 1970s, been declared by the World Health Organi­ zation to have been eradicated. Jenner’s discovery was a purely prag­ matic one, of course. Neither he nor anyone else knew why vaccination worked. The fact that it did was cer­

GOETHE

[349]

tainly satisfying enough, but more knowledge was required for further progress. Smallpox remained the only disease to be conquered for another half a century until the causes of disease came to be known as a result of the work of Pasteur [642]. [349] GOETHE, Johann Wolfgang von (gerituh) German poet Born: Frankfurt-am-Main, Hesse­ Nassau, August 28, 1749 Died: Weimar, Thuringia, March 22, 1832 Goethe, the son of a lawyer, took a degree in law himself in 1771 at the University of Strasbourg, but he never practiced. The fact that Goethe was one of the super-figures in literature, and perhaps the only German man of letters who can be mentioned in the same breath with Shakespeare, tends to obscure the fact that he had wide-ranging intellectual in­ terests and wrote ably (if usually wrongly) on scientific matters. He wrote a large volume on the nature of light, in which he opposed Newton’s [231] views on the formation of colors out of white light. His own view that white light was not a mixture of colors was based on intuition alone and the whole book is worthless. He was also a convinced neptunist in geology after the fashion of A. G. Werner [355]. Then, too, he concerned himself with biology in the years between 1790 and 1810 and held, for instance, that all plant structures were modified leaves, that plants and animals originated as separate archetypes which were differen­ tiated and specialized through the ages to their present forms (a clear expression of the evolutionary view). He studied bone structure in competent fashion, ex­ cept that, following his own theory of archetypes, he involved himself in the fallacious theory of the vertebral struc­ ture of the skull, which Oken [423] was later to popularize. It was Goethe who coined the word 237

[350]

DELAMB RE

HERSCHEL

[352]

“morphology” to represent the system­ [351] RUTHERFORD, Daniel atic study of the structure of living Scottish chemist things. Born: Edinburgh, November 3, 1749 Died: Edinburgh, November 15, [350] DELAMBRE, Jean Baptiste 1819 Joseph (duh-lahm'br) French astronomer Rutherford, the son of a professor of Born: Amiens, Somme, Septem­ medicine, was a step-uncle of Walter ber 19, 1749 Scott, the writer. He studied medicine at Died: Paris, August 19, 1822 the University of Edinburgh, where Black [298] was one of his teachers. Delambre was bom into poverty and Black set him the problem of working gained an education under great difficul­ with the portion of the air that would ties. For a time he lived, literally, on not support combustion, and Rutherford bread and water. He attracted the atten­ reported on it in his doctor’s thesis in tion of Lalande [309] in 1780 and it was 1772. (He received his medical degree in then only that he began seriously to in­ 1777.) terest himself in astronomy. He was He let a mouse live in a confined skilled at computation and, in 1786, pro­ quantity of air till it died, then burned a duced new tables of the planetary mo­ candle and then some phosphorus in that tions of Jupiter, its satellites, Saturn, and same air as long as they would bum. He the newly discovered planet Uranus. presumed the air contained carbon diox­ Just before the French Revolution, the ide as a result and removed it by passing Academy of Sciences decided to work on the air through strong alkali. What was a new system of measures based on some left contained no carbon dioxide and yet natural phenomena. The revolutionaries was still “mephitic” and “noxious.” A pushed for this enthusiastically as an­ candle would not bum in it and a mouse other break with the past. It was decided would not live. to make the fundamental measure of Rutherford, following the phlogiston length the “meter” (from a Greek word theory of Stahl [241], believed that the for “measure”), which was to be one air had accepted all the phlogiston it ten-millionth of the distance from the could carry and that such “phlogisticated North Pole to the equator. For this air,” being unable to accept more, could reason it was decided to make an accu­ no longer support respiration and com­ rate measure of at least a portion of the bustion, two processes that depended on meridian, a large enough portion to give the giving off of phlogiston. Rutherford’s the meter an accurate length. phlogisticated air is now called nitrogen The task fell to Delambre and Pierre and he is usually given the credit for its F. A. Mechain, who measured the dis­ discovery, although it remained for La­ tance from Dunkerque to Barcelona, voisier [334] a few years later to describe across the full north-south distance of its real nature. France. Under the conditions of revolu­ Rutherford was appointed professor of tion and war, the task was an enormous botany at the University of Edinburgh in one that took six years. It was only when 1786 and in 1794 he designed the first the final figure was attained and brought maximum-minimum thermometer. to the French government that the met­ ric system was formally adopted, in June 1799. In 1807, Delambre became professor [352] HERSCHEL, Caroline Lucretia of astronomy at the Collège de France, German-English astronomer succeeding his old patron, Lalande. He Born: Hannover, Germany, spent the last decade of his life writing a March 16, 1750 monumental history of astronomy. Died: Hannover, January 9, 1848 238

[353]

DOLOMIEU

Caroline Herschel joined her brother, William Herschel [321], in England in 1772. He was an organist and she was training to be a concert singer. Both were successful and both gave up their musical careers for the sake of their all­ consuming interest in astronomy. Caro­ line never married and submerged her­ self almost completely in her brother’s career. In what spare time she could find she observed the heavens on her own with a small telescope her brother made for her. She did good work and became the first woman astronomer of note. She searched for comets particularly and discovered eight of them. After her brother’s death she returned to Hannover, enjoyed the astronomical success of her nephew (William’s son), John Herschel [479], and died at nearly ninety-eight. [353] DOLOMIEU, Dieudonné de Gratet de (doh-loh-myoo') French geologist Bom: Dolomieu, Dauphiné, June 23, 1750 Died: Châteauneuf, Saône-etLoire, November 28, 1801 Dolomieu, the son of an aristocrat, was enrolled in the Order of the Knights of Malta when only two years old and rose to the rank of commander in 1780, although he seemed to be in perpetual trouble with his superiors. He was interested in science as a hobby, and particularly in geology. His military travels enabled him to study minerals in various places and to make an excellent mineralogical collection. De­ spite his aristocratic heritage, Dolomieu was strongly in favor of the French Rev­ olution when it broke out and only turned against it at the time of the Ter­ ror. He accompanied Napoleon Bonaparte to Egypt in 1798, but on his return was forced into Taranto by a storm and there underwent imprisonment and solitary confinement for nearly two years through the machinations of enemies in

SPRENGEL

[354]

the Knights of Malta. He died not long after his release. Dolomieu was particularly interested in volcanoes and studied them more thoroughly than anyone before him. He could not bring himself to go against Werner’s [355] neptunism, however, and tried to work out the activity of vol­ canoes without making volcanic action responsible for the power that lay behind the geologic changes of the earth. The common mineral dolomite, a calcium magnesium carbonate, is named in his honor. He is supposed to have begun his trea­ tise on mineralogy, published in 1801, while he was in prison, using a pen he had made out of wood, soot from his lamp, and the margins of his Bible as writing paper. [354] SPRENGEL, Christian Konrad (shpreng'el) German botanist Born: Brandenburg, Prussia, Sep­ tember 22, 1750 Died: Berlin, April 7, 1816 Sprengel was the fifteenth and last child of an archdeacon and was himself educated for the clergy. He graduated from Halle University in 1774 and in 1780 was appointed rector of a school where he taught languages and science. Botany was his hobby. His theological training led him to think that every part of the flower was created for a reason and this included the fact that some flowers had markings that seemed to point the way to the nectar. This he felt had to be for the purpose of attracting and guiding insects. He began, in 1787, to study the phe­ nomena of plant fertilization in detail, and he published his findings in a book in 1793. He clearly described the role of insects in plant fertilization and pointed out that in other cases, plants were ferti­ lized by the wind. He also noted that in some plants, stamens and pistils devel­ oped at different times so that self­ pollination was made impossible. His absorption in his work caused him 239

[355]

WERNER

to neglect his school and he was pen­ sioned off in 1794 and spent his last years in Berlin as a private tutor. His book attracted no attention at first and was brought before the eyes of scientists only through the enthusiastic praise of Darwin [554] a half century after its publication. [355] WERNER, Abraham Gottlob (vehriner) German geologist Born: Wehrau, Silesia (modem Osiecznica, Poland), September 25, 1750 Died: Dresden, Saxony, June 30, 1817 Werner’s life was impregnated with minerals, so to speak, from the start. His father was an inspector at an ironworks and he himself entered mining school at Freiburg, a Saxon mining center. By 1775 he was a teacher at the mining school and stayed there the rest of his professional life. He devoted himself to establishing a language for mineralogy, classifying minerals as Linnaeus [276] had classified life forms a half century earlier. Like Hutton [297] he recognized the fact that strata occurred in a definite succession and were evolved rather than created, with the deepest stratum the oldest. Unlike Hutton, who believed in the overriding importance of heat and volcanic action in geologic history (and was therefore a vulcanist), Werner believed that virtually all strata had been laid down as sediment through the action of water (and was therefore a nep­ tunist). Werner believed that volcanic action was very much the exception. Whereas Hutton accepted processes that were visibly taking place in the pres­ ent and asked nothing more of the past, Werner found it necessary to suppose that there had been a primeval ocean covering all the earth, although there was no evidence of this. After the conti­ nents had been laid down through sedi­ mentation, most of this primeval ocean had to disappear in some fashion, which Werner left unexplained. As for vol­ 240

PRÉVOST

[356]

canoes, they were merely the manifes­ tation of burning coal seams near the surface—and of no geologic importance. At least so Werner maintained. Werner was almost a caricature of the stage Teuton, self-satisfied and self-as­ sured. He did not travel at all and knew only the rocks of Saxony, but he calmly assumed that what was true for Saxony was true for the whole world. He reso­ lutely refused to accept any evidence or even to listen to any that went counter to his theories. He paid no attention to the experimental work of James Hall [374] and blissfully ignored the clearest obser­ vations that large tracts of Europe gave every sign of having once consisted of lava flows. He considered volcanoes re­ cent phenomena. Nevertheless he was an electrifying teacher, who attracted students from all over Europe and who left behind him a whole generation of evolutionary geolo­ gists, some of whom eventually broke away from neptunism. During his life­ time and for some years after his death his views completely overshadowed those of Hutton, partly perhaps because nep­ tunism was at least reminiscent of the biblical story of the Flood and therefore seemed more reconcilable with Genesis. The coming of Lyell [502] was to be the defeat of Werner and neptunism. [356] PRÉVOST, Pierre (pray-voh') Swiss physicist Born: Geneva, March 3, 1751 Died: Geneva, April 8, 1839 Prévost, the son of a minister, studied first theology and then law, receiving his doctor’s degree in 1773. He went to Berlin for a while at the invitation of Frederick H, returned to Geneva on his father’s death in 1784, and in 1793 was appointed professor of philosophy and of physics at the University of Geneva. There he clearly established the fact that cold was not a second “impon­ derable fluid” opposed to caloric, the ex­ istence of which Lavoisier [334] had postulated to explain heat, but showed that all the observed facts concerning heat could be interpreted by means of a

[357]

BLUMENBACH

single fluid, much as Franklin [272] had interpreted electrical observations by means of a single fluid. In 1791 Prévost pointed out that cold did not flow from snow to a hand, but that heat flowed from the hand to the snow. It was the loss of heat, not the gain of cold that gave rise to the sensa­ tion of cold. In fact, he held that all bod­ ies of all temperatures radiated heat. The hotter the body, the more heat was ra­ diated so that heat always flowed from the hot body to the cold. A body that was not changing temperature was still radiating heat. It was, however, receiving heat from its surroundings at a rate that just matched its heat loss. In all this, he was perfectly right. Nev­ ertheless, although it all fitted in with the caloric theory and was held to confirm that theory, it also proved to fit in with the heat-as-motion of “kinetic” theory, as Maxwell [692] was to make perfectly plain, seven decades later. Prévost lived through the perilous rev­ olutionary and Napoleonic period, dur­ ing which Geneva was annexed to France, with only a brief arrest in 1794. After Geneva regained its freedom in 1814, he served on its legislature. [357] BLUMENBACH, Johann Fried­ rich (bloo'men-bahkh) German anthropologist Born: Gotha, Saxony, May 11, 1752 Died: Gottingen, Saxony, January 22, 1840 Blumenbach was the son of a well-todo headmaster. He studied at the univer­ sities of Jena and of Gottingen and re­ ceived his medical degree from the latter institution in 1775. His doctoral thesis dealt with his thoughts on the origin of the different human races and is consid­ ered one of the basic works on anthro­ pology. In fact, he is the founder of scientific anthropology and was the first to view the human being as an object of study in the same fashion that other animals were. Blumenbach used comparative anat­ omy as a guide to early human history,

LEGENDRE

[358]

trying to show by cranial measurements how groups of men migrated from one place to another. He was the first to at­ tempt a rational division of human beings into divisions. He coined the term “Caucasian” for what we ordinarily refer to as the “white race” because he thought that the cranial measurements of some of the Caucasian tribes were per­ fect examples of that division. Similarly, he coined “Mongolian” and “Ethiopian” for the “yellow race” and the “black race,” as well as “American” and “Ma­ layan” for the “red race” and “brown race.” The division was far too simple and gave a false impression to the general public of airtight divisions, making it a little more possible to speak racist non­ sense in what sounded like scientific terms. This was certainly not in Blumenbach’s mind; for one thing, he spoke out strongly against beliefs that blacks were somehow less human than whites. [358] LEGENDRE, Adrien Marie (luhzhahn'dr) French mathematician Born: Paris, September 18, 1752 Died: Paris, January 9, 1833 Legendre was bom into a well-to-do family and had enough money to allow him to dedicate himself to mathematics. He made important contributions to the theory of numbers and to a branch of calculus that dealt with what are called elliptical integrals, though in the latter case he was quickly surpassed by the work of Abel [527] and Jacobi [541]. Legendre rejoiced in these new dis­ coveries regardless of the fact that they overshadowed his own years of labor. Legendre recast the textbook of Euclid [40] into a simpler and better-ordered form so that from his day students study “Legendre” rather than “Euclid.” He showed that not only pi but the square of pi was irrational and conjectured that pi was transcendental, something that Lindemann [826] was to show was so a century later. In number theory, he was the first to work out the method of least squares as 241

[359]

APPERT

a way of calculating orbits, something that Gauss [415] was soon to perfect. The upheaval of the French Revolu­ tion cost him his financial independence, but by that time he was sufficiently well known to be able to support himself by teaching and by accepting government positions. He never did as well as he deserved, apparently because of the en­ mity of Laplace [347], a small-minded man. [359] APPERT, Nicolas (François) (a-pairi) French inventor Born: Châlons-sur-Marne, Octo­ ber 23, 1752 Died: Massy, near Paris, June 3, 1841 Appert, the son of an innkeeper, was a cook and confectioner, working in his fa­ ther’s establishment at first and then for several noblemen in the days before the French Revolution. Self-educated, he was interested in de­ vices for preserving food, for profes­ sional purposes. So was Napoleon, for economic and military purposes. Napo­ leon offered a prize in 1795 for practical preservation methods, and Appert spent fourteen years working out a system in which by first heating the food and then sealing it from air, putrefaction was pre­ vented. He opened a factory to produce such sealed products in 1804. (This was an application, whether Appert knew it or not, of Spallanzani’s [302] experiment and depended for its efficacy on the fact that spontaneous generation of microor­ ganisms did not take place. It foreshad­ owed pasteurization a half century later, as Pasteur [642] himself freely ad­ mitted.) Napoleon gave him 12,000 francs in 1809 and Appert then published his dis­ covery—which served as the foundation of the vast canning industry of today and, with Borden’s [524] work a half century later, altered the food habits of man. Appert, who also developed the bouil­ lon cube, did well for a while but was financially ruined after Napoleon’s fall 242

RUMFORD

[360]

and died poor. The commercial cannery he founded—the first in the world— remained in business, however, and did not close its doors till 1933. [360] RUMFORD, Benjamin Thompson, Count American-British physicist Bom: Woburn, Massachusetts, March 26, 1753 Died: Auteuil (near Paris), France, August 21, 1814 Benjamin Thompson (better known as Count Rumford) was born the son of a farmer, only two miles from the birth­ place, a half century before, of that other Benjamin, Benjamin Franklin [272], He began life quietly as an apprentice to a storekeeper in Salem, but in 1766 he was nearly killed in the explosion of some fireworks he was making to help celebrate the repeal of the Stamp Act. After recovery, he returned to Boston to become an assistant in another store. At nineteen he married a rich widow con­ siderably older than himself and lived with her in Rumford (now Concord), New Hampshire. All would have gone well were it not that the Revolutionary War broke out and young Thompson’s sympathies were with the king. Indeed, he served the British troops by spying on his countrymen. When the British troops left Boston, Thompson went with them (leaving wife and child behind) and spent the war in minor government offices in England, ending with a short stay in the still em­ battled colonies as a lieutenant colonel in the king’s forces. When the Revolu­ tionary War was over and the colonials had won their independence, Thompson knew himself to be in permanent exile. Thompson’s character did not improve in England. He took bribes and was sus­ pected of selling war secrets to the French. In 1783, with the permission of George III, he found it safer to go to the Continent in search of adventure. There he fell in with Elector Karl Theodor of Bavaria, for whom he worked as an intelligent and capable ad­ ministrator. He established workhouses

[360]

RUMFORD

for Munich beggars, for instance, and had them turn out army uniforms with an efficiency that helped both the beg­ gars and the army. He also introduced Watt’s [316] steam engine and the potato to the Continent. The elector expressed his gratitude in 1790 by making Thompson a count, and Thompson chose Rumford as his name, for that was the town in which his wife was bom and near which he had had an estate. In the Bavarian service he grew interested in the problem of heat and that was the occasion for his most im­ portant contribution to science. In the eighteenth century, heat was looked upon as an imponderable fluid, like phlogiston. Lavoisier [334], who demolished phlogiston, continued to think of heat as a fluid that could be poured from one substance to another and called it caloric. Rumford, however, while boring can­ non in Munich in 1798 noticed that the blocks of metal grew hot as blazes as the boring tool gouged them out, so that they had to be cooled constantly with water. The orthodox explanation was that caloric was being loosened from the metal as the metal was broken down into shavings by the boring. Rumford noticed that the heating continued as long as the boring did, with no letup, and that enough caloric was removed from the brass to have melted the metal if it were poured back in. In other words, more caloric was being removed from the brass than could have been contained in it. In fact, if the boring instruments were dull so that no metal was ground to shavings, the caloric did not stop pouring out of the metal. On the contrary, the metal heated up more than ever. Rumford’s conclusion was that the me­ chanical motion of the borer was being converted to heat and that heat was therefore a form of motion, a view that had been groped toward for a century and more by such men as Francis Bacon [163], Boyle [212], and Hooke [223], And in this, they and Rumford are now considered to have been right. Rumford even tried to calculate how much heat was produced by a given quantity of mechanical energy. He was

RUMFORD

[360]

thus the first to set a figure for what we now call the mechanical equivalent of heat. His figure was far too high, how­ ever, and a half century passed before Joule [613] reported the correct value. Rumford, through his arrogance and the general unpleasantness of his charac­ ter, finally outwore his welcome in Ba­ varia too, particularly after the death of the elector. That, and the pressure of Napoleon’s victories, made it advisable for Rumford to return to England in 1799, and there his achievements were recognized and he was admitted into the Royal Society. In that year he weighed a quantity of water both as water and as ice and could detect no change in weight with the most delicate balance. Since water lost heat when it froze and gained it when it melted, as had been demon­ strated by Black [298], it followed that caloric, if it existed, must be weightless. The fate of phlogiston made weightless fluids suspect and this experiment weak­ ened the caloric theory, too. Rumford, with the encouragement of that scientific Maecenas, Sir Joseph Banks [331], founded the Royal Institu­ tion in 1799 and obtained young men such as Young [402] and Davy [421] as lecturers. Rumford was a little dubious about the latter until he heard him give a lecture. That resolved all doubts, and in­ deed Davy was to grow famous through his lectures. In addition, Davy had just conducted some experiments that led him to the same conclusions as Rum­ ford. Davy had arranged for ice to be rubbed mechanically, the entire system being kept one degree below the freezing point. There was insufficient caloric in the whole system, according to the or­ thodox view, to melt the ice, and yet it melted. Davy decided that the mechani­ cal motion was converted to heat. Cer­ tainly this experiment didn’t hurt Davy in Rumford’s regard. (Historians of sci­ ence doubt that the experiment could have worked as described by Davy, but Davy believed it worked and described the results in his first publication.) In any case, neither Rumford’s nor Davy’s experiment was convincing to physicists. The caloric theory, which seemed to be substantiated by the work 243

[361]

NICHOLSON

of Prévost [356], and was strongly backed by such men as Berthollet [346], lived on for another half century until Maxwell [692] killed it once and for all. In 1804 Rumford went to Paris, though Great Britain and France were at war and France was threatening an inva­ sion. (Political passions were milder then, it would seem.) While he was in Paris, his path crossed that of the dead Lavoisier a second time. Having pro­ duced evidence against Lavoisier’s theory of heat, he (having outlived his first wife) proceeded to marry Lavoisier’s widow (who was rich and who kept the famous name of her martyred first hus­ band). It was a late marriage—he being slightly over fifty, she slightly under— and an unhappy one, their first quarrel coming the day after their marriage. After four years they separated and Rumford was so ungallant as to hint that she was so hard to get along with that Lavoisier was lucky to have been guillo­ tined. However, it is quite obvious that Rumford was no daisy himself. In 1811 his American daughter by his first wife joined him and cared for him in his last years. Incidentally, despite all the unpleasant messes of Rumford’s character, there was a strong streak of idealism in him. He believed it better to make people happy first as a way of making them vir­ tuous later (rather than the reverse, which has been the seemingly hopeless tactic of religions for so long). Then, too, like Franklin he refused to patent his inventions, which included a double boiler, a drip coffeepot, and a kitchen range. He even attempted a recon­ ciliation with the United States in the end, and though he died, as he had lived, in exile, he left most of his estate to the United States and endowed a profes­ sorship in applied science at Harvard.

BLANCHARD

[362]

man in the service of the East India Company. He made two or three voy­ ages to the East Indies while so em­ ployed. Then he worked in a lawyer’s office and finally as a waterworks engi­ neer. He never married. He became a science writer, turning out a successful Introduction to Natural Philosophy in 1781. Oddly enough, though, it was in connection with water (a natural subject of interest for an ex­ midshipman) that he had his opportunity of doing as well as writing. In 1790 he invented a hydrometer for measuring the density of water, but his most significant work was in 1800. On March 20 of that year Volta [337] wrote to Banks [331], president of the Royal Society, informing him of his con­ struction of an electric battery. Nichol­ son heard of this and with the aid of a friend built his own Voltaic pile by May 2, making no attempt, apparently, to point out that Volta had priority. It was the first in England. Nicholson’s great contribution was to place wires attached to the two ends of the pile in water. He found that with the current flowing, bub­ bles of gas (hydrogen and oxygen) were given off. He had “electrolyzed” water, breaking up the molecules into the indi­ vidual elements. He thus reversed the demonstration of Cavendish [307], that hydrogen and oxygen could unite to form water. This was the first demon­ stration that an electric current could bring about a chemical reaction—the re­ verse of Volta’s demonstration that a chemical reaction could bring about an electric current. Nicholson edited a chemical journal, which he founded in 1797 and in which he reported his own work with the Vol­ taic pile even before Volta himself got a chance to publish. It was the first inde­ pendent scientific journal. In 1808 he compiled a Dictionary of Practical and Theoretical Chemistry. [361] NICHOLSON, William English chemist [362] BLANCHARD, Jean Pierre Fran­ Born: London, 1753 çois (blan-shahri) Died: London, May 21, 1815 French aeronaut Born: Les Andelys, Eure, July 4, Nicholson, the son of an attorney, left 1753 school at sixteen and became a midship­ Died: Paris, March 7, 1809 244

[363]

MURDOCK

PROUST

[364]

was politically liberal and was brought to an end in the disorders in 1791 that burned down Priestley’s house. Murdock invented various devices in connection with the steam engine, but his great feat was in another direction. He was the first to see in coal something more than a simple solid fuel. In 1792 he began to heat coal (also peat and wood) in the absence of air, and to store the gases that were driven off. These gases were, like the materials from which they came, inflammable, but being gases they possessed certain conveniences. They could be piped from place to place and required no strenuous transport. They could easily be set alight and the flame could easily be controlled by adjusting the rate of gas flow. Although the idea was ridiculed by many (includ­ ing the poet and novelist Walter Scott), Murdock persisted. By 1800 Murdock had set up an ex­ perimental gas light, using coal gas. In 1802 he celebrated the temporary Peace of Amiens with Napoleon by setting up a spectacular display of gas lights, and by 1803 he was routinely lighting his main factory with them. In 1807 some Lon­ don streets began to use gas lighting. It was the first new form of lighting of the industrial age, and gas lighting was to expand in importance for nearly a cen­ tury, until superseded by Edison’s [788] electric light. Gas flames are of course still used in heating and cooking. As in the case of Whitney’s [386] cot­ [363] MURDOCK, William ton gin, gas lighting proved too simple Scottish inventor Born: Auchinleck, Ayrshire, Au­ an invention for the inventor’s peace of mind. Others exploited it and Murdock gust 21, 1754 Died: Birmingham, Warwickshire, had to expend considerable effort to maintain his own claims for priority. England, November 15, 1839 Murdock, largely uneducated, cut his eyeteeth in 1777 in James Watt’s [316] [364] PROUST, Joseph Louis (proost) French chemist firm near Birmingham when Watt was Born: Angers, Maine-et-Loire, beginning to sell his steam engines. Mur­ September 26, 1754 dock went down to Cornwall to super­ Died: Angers, July 5, 1826 vise the installation of engines in the mines there and by 1800 had risen to be The son of an apothecary, Proust had a partner in the concern. He joined the Lunar Society, a group the opportunity of passing his youth in of Birmingham scientists that included an atmosphere saturated with chemistry. Watt, Priestley [312], and Erasmus Dar­ He went to Paris while still a young man win [308], among others. This society and established himself there as an

Blanchard, born of poor parents, had a natural mechanical ability. When he was sixteen, he constructed a kind of bi­ cycle. Then, in the 1770s, he tried to construct a flying machine, but once he heard of the Montgolfier [325] balloons, equipped with hydrogen, that was enough for him. He began to make daring flights in both England and France in 1784 and on March 2, 1784, he and an American physician, John Jeffries, were the first to float across the English Channel, carry­ ing the first airmail in history. They landed near Calais. He went to the United States in 1793 and made balloon ascensions there, with President George Washington among the spectators on one occasion. He suffered a heart attack in the course of his sixtieth balloon ascension (this one in the Neth­ erlands), fell from it, was badly hurt, and died not long after. His great contribution was the inven­ tion of the parachute. In 1785 in Lon­ don he became the first man in history to make use of a parachute, dropping a dog (or cat) in a basket attached to one. But despite all the feats of daring of men such as Blanchard the balloon remained a dead end for aeronautics, even after it was powered by Zeppelin [737] a cen­ tury later. The true road was to be found by the Wright brothers [961, 995].

245

[364]

PROUST

apothecary-chemist. He was one of the first to take part in the balloon rage of the 1780s, making an ascension in 1784. He avoided the upheaval of the French Revolution since he traveled to Spain shortly before it began. There he spent two decades in fruitful labor in Madrid under the patronage of the Spanish king, Charles IV, who supplied him lavishly, for instance, with platinum vessels. In 1808 Charles IV was ousted from his throne by Napoleon, and Proust, his laboratory looted by the French soldiers, lost his position. He re­ turned to France and lived out his life in retirement. Napoleon offered him a grant to enable him to continue his research, but he was in poor health and turned it down. After Napoleon’s fall, Proust was made a member of the French Academy and was given a pension by Louis XVIII. Proust investigated different sugars and distinguished between different varieties. He was the first to study the sugar in grapes, which we now call glu­ cose. However, the great event of his life was an eight-year running controversy of epic proportions with his contemporary Berthollet [346], (This did not prevent Berthollet from greeting Proust cordially on the latter’s return to France.) Berthollet believed that the course of reactions depended on the mass of the reacting materials present and that this dictated both the rate of action and the nature of the composition of the final products. He was right in the first con­ clusion but, as Proust showed, wrong in his second. Using painstakingly careful analysis Proust showed in 1799 that copper car­ bonate contained definite proportions by weight of copper, carbon, and oxygen no matter how it was prepared in the lab­ oratory or how it was isolated from na­ ture. The preparation was always 5 of copper to 4 of oxygen to 1 of carbon. He went on to show a similar situation for a number of other compounds and formulated the generalization that all compounds contained elements in cer­ tain definite proportions and no others, regardless of conditions of production. 246

FOURCROY

[366]

This is called the law of definite propor­ tions, and sometimes Proust’s law. Proust also showed that Berthollet, in presenting evidence that certain com­ pounds varied in composition according to the method of preparation, was misled through inaccurate analyses and through the use of products he had insufficiently purified. Proust’s victory in this battle was quite clear and was to be made con­ clusive a generation later by Berzelius [425], Proust’s law went a long way toward persuading Dalton [389] that elements must occur in the form of atoms and thus paved the way for the final and long-delayed victory of atomism. [365] PARKINSON, James English physician Born: Hoxton Square, London, April 11, 1755 Died: London, December 21, 1824 Parkinson, the son of a surgeon, was a practicing surgeon himself by 1784. He was a political and social liberal who wrote pamphlets in favor of parlia­ mentary reform and for better treatment of mental patients. He was the first to write a medical re­ port on a perforated appendix (in 1812) and to recognize it as a cause of death. In 1817 he wrote a medical description of a condition he called “the shaking palsy,” but which others have called Par­ kinson’s disease ever since. Geology and the study of fossils was an avocation of his. He was correct in thinking that coal was of plant origin, but he favored Werner [355] over Hut­ ton [297] and accepted Cuvier’s [396] catastrophism. [366] FOURCROY, Antoine François, comte de (foor-krwah') French chemist Born: Paris, June 15, 1755 Died: Paris, December 16, 1809 Fourcroy, the son of an apothecary, worked as a clerk early in his life. He

[367]

d ’elh u y a r

was fortunate enough to interest an anat­ omist in his obvious intellect, and that man arranged to have him receive a medical education. Fourcroy obtained his degree in 1780, but found his interest in chemistry. He became a professor of chemistry at the Jardin du Roi in 1784. An excellent and successful teacher, he obtained his chief fame in connection with others. He was one of the first converts to the theories of Lavoisier [334], with whom he collab­ orated in establishing the new chemical nomenclature. During the French Revolution he was a violent partisan of the radicals, suc­ ceeding to the seat that had been held by the assassinated demagogue Marat. He helped engineer the temporary suppres­ sion of the Academy of Sciences, which was suspected of being an aristocratic or­ ganization. Nor did he use his influence to save Lavoisier. Indeed, his testimony was damaging to his old associate— perhaps deliberately so. Later, however, he used his influence to save other scien­ tists. Under Napoleon he served as Minister of Public Instruction and in later lif£ he was the patron of Vauquelin [379], He died on the day Napoleon made him a count. [367] D’ELHUYAR, Don Fausto (deloo'yahr) Spanish mineralogist Born: Logrono, northern Spain, October 11, 1755 Died: Madrid, January 6, 1833 D’Elhuyar and his older brother, Juan José, studied mineralogy in Germany and became disciples of the theories of Werner [355]. They visited Sweden in 1782, studied with Bergman [315], and visited Scheele [329]. They analyzed a mineral called wolframite, which had been obtained from a tin mine, and in 1783 obtained a new metal from it, called wolfram. The same metal is also called tungsten from the Swedish words meaning “heavy stone.” Scheele had in­ vestigated tungsten-containing minerals but had missed spotting the new metal.

CHAPTAL

[368]

The D’Elhuyar brothers were eventu­ ally sent to Latin America (then under Spanish domination) to supervise mining there. Fausto’s older brother died in what is now Colombia, but Fausto, hav­ ing served in Mexico with distinction, lived to return to Spain after Mexico gained its independence. [368] CHAPTAL, Jean Antoine Claude, comte de Chanteloup (shap-tal') French chemist Born: Nogaret, Lozère, June 4, 1756 Died: Paris, July 30, 1832 Chaptal, the son of a small landowner, had a rich physician as an uncle, which was helpful. The young man studied medicine, receiving his medical degree at Montpellier in 1777. Against his uncle’s will, he grew interested in chemistry, though, and obtained a professorship at the University in 1781. He was one of the first to adopt Lavoisier’s [334] new view of chemistry. He was particularly interested in the application of chemistry to industry and, having inherited a large sum from his uncle and having married a wife with a large dowry besides, he had the where­ withal to establish a plant at Montpellier in 1781 for the first commercial produc­ tion of sulfuric acid in France. His use­ fulness was such that both Spain and the infant United States bid for his services (both without success). After the French Revolution broke out he was arrested, in 1793, but he was soon liberated and put in charge of a plant manufacturing gunpowder. The re­ public did have need of scientists, after all (though they had thought otherwise in the case of Lavoisier), for without the development of new chemical methods France (which was at war with all the surrounding nations) could not have produced the gunpowder she needed and the republic would have been crushed. Under Napoleon, Chaptal was placed in charge of education and was a strong advocate of the writing of science for the layman. He supervised the introduction of the metric system and was eventually 247

[369]

MCADAM

made a count. When Napoleon fell, and the old monarchy returned with Louis XVIII, Chaptal was relieved of his title but was done no other harm. He lost much of his wealth, however, paying the debts his son ran up when he conducted the family firm in a slipshod manner. It was Chaptal, by the way, who, in 1790, suggested the name “nitrogen” for the element Lavoisier had called “azote.” His most important book was Chemis­ try Applied to the Arts, published in 1807. This was the first book to be devoted specifically to industrial chemis­ try. [369] McADAM, John Loudon Scottish engineer Born: Ayr, Ayrshire, September 21, 1756 Died: Moffat, Dumfriesshire, No­ vember 26, 1836 In 1770, after his father died, McAdam traveled to New York to work for his uncle, who during the war was a well-to-do Tory. McAdam, naturally, was a Tory too and made a comfortable living as agent for the sale of war prizes. Once the peace treaty was signed and the colonies established as an indepen­ dent power, he returned to Scotland, in 1783. His true fame began in 1806, when he became paving commissioner in Bristol. He began to push energetically for new and rational principles of paving: mak­ ing roads out of crushed rock, with proper allowance for drainage, instead of the alternating ruts and mud (depending on whether the weather was dry or wet). There was strong economic motivation for this since the first third of the nine­ teenth century was the golden age of stagecoaches. After McAdam’s death, Stephenson’s [431] locomotive—traveling on iron rails rather than on paving—killed the coaches. Nevertheless the time was to come when paved roads would carry au­ tomobiles on rubber tires and that in turn was to send the railroad into de­ cline. To macadamize is still sometimes used to mean the paving of a road, in honor of McAdam. 248

CHLADNI

[370]

[370] CHLADNI, Ernst Florens Fried­ rich (klahd'nee) German physicist Born: Wittenberg, Saxony, No­ vember 30, 1756 Died: Breslau, Silesia (modern Wroclaw, Poland), April 3, 1827 Chladni, the son of a lawyer, found his own education directed to the law, much against his will. He received his degree from the University of Leipzig in 1782, but when his father died Chladni was able to consult his own interests more freely, and these lay in the direc­ tion of science. Since he was interested in music and was himself an amateur musician, he began to investigate sound waves mathe­ matically in 1786. He was the first to work out the quantitative relationships governing the transmission of sound and is therefore called the father of acous­ tics. Chladni set thin plates, covered with a layer of sand, to vibrating. The plate vi­ brated in a complex pattern, with some portions (nodal lines) remaining motion­ less. The nodal lines retained sand shaken onto them by the neighboring areas that were vibrating. In this way the plates came to be covered with charac­ teristic sand patterns from which much could be deduced concerning vibrations. The patterns (which are still called Chladni figures) fascinated the audience when they were exhibited before a gath­ ering of scientists at Paris in 1809. Na­ poleon had the demonstration repeated for himself. The velocity of sound had already been measured in air by Gassendi [182] and others two centuries earlier, but Chladni went a step further. He filled organ pipes with different gases and from the pitch of the note sounded on those pipes was able to calculate the ve­ locity of sound in each of those cases. The free vibration of a column of gas determines its pitch, and that vibration depends on the natural mobility of the molecules making it up. The velocity of sound through the gas also depends on the natural mobility of those molecules, so that the velocity of sound in a partic­

[371]

GALL

ular gas can be calculated from the pitch sounded by an organ pipe filled with gas. Chladni invented a musical instrument called the euphonium, made of glass rods and steel bars that were sounded by being rubbed with the moistened finger, and traveled about Europe performing on this instrument and giving scientific lectures. He also had a