CORNELL 
 
 UNIVERSITY 
 
 LIBRARY 
 
 FROM 
 
 The ^ablishers 
 
Cornell University Library 
 
 Q 127.U6C39 
 
 A Century of science in America, with spe 
 
 3 1924 010 625 816 
 
Cornell University 
 Library 
 
 The original of tiiis book is in 
 tine Cornell University Library. 
 
 There are no known copyright restrictions in 
 the United States on the use of the text. 
 
 http://www.archive.org/details/cu31 92401 062581 6 
 
YALE UNIVERSITY 
 
 MRS. HEPSA ELY SILLIMAN 
 
 MEMORIAL LECTURES 
 
 In the year 1883 a legacy of eighty thousand dollars was left to the 
 President and Fellows of Yale College in the city of New Haven, to be held 
 in trust, as a gift from her children, in memory of their beloved and 
 honored mother, Mrs. Hepsa Ely Silliman. 
 
 On this foundation Yale College was requested and directed to establish 
 an annual course of lectures designed to illustrate the presence and prov- 
 idence, the wisdom and goodness of God, as manifested in the natural and 
 moral world. These were to be designated as the Mrs. Hepsa Ely Silliman 
 Memorial Lectures. It was the belief of the testator that any orderly 
 presentation of the facts of nature or history contributed to the end of 
 this foundation more effectively than any attempt to emphasize the elements 
 of doctrine or of creed ; and he therefore provided that lectures on dogmatic 
 or polemical theology should be excluded from the scope of this foundation, 
 and that the subjects should be selected rather from the domains of natural 
 science and history, giving special prominence to astronomy, chemistry, 
 geology, and anatomy. 
 
 It was further directed that each annual course should be made the basia 
 of a volume to form part of a series constituting a memorial to Mrs. 
 Silliman. The memorial fund came into the possession of the Corporation 
 of Yale University in the year 1901 ; and the present volume constitutes 
 the fourteenth of the series of memorial lectures. 
 
SILLIMAN MEMORIAL LECTURES 
 PUBLISHED BY YALE UNIVERSITY PRESS 
 
 ELECTEICITY AND MATTER. By Joseph John Thomson, d.s c, 
 LL.D., PH.D., P.R.S., Fellow of Trinity College and Cavendish Professor of 
 Experimental Physics, Cambridge University. 
 
 {Fourth printing.) Price $1.50 net. 
 
 THE INTEGRATIVE ACTION OF THE NERVOUS SYSTEM. By 
 Charles S. Sherrington, d.sc, m.d., hon. ll.d. tor., f.r.s.. Holt Pro- 
 fessor of Physiology, Vniversity of Liverpool. 
 
 {Fifth Printing.) Price $5.00 net. 
 
 RADIOACTIVE TRANSFORMATIONS. By Ernest Rutherford, d.sc, 
 LL.D., F.R.S. , Macdonald Professor of Physics, McGill Vniversity. 
 Price $5.00 net. 
 
 EXPERIMENTAL AND THEORETICAL APPLICATIONS OP THER- 
 MODYNAMICS TO CHEMISTRY. By Dr. Walter Nernst, Professor 
 and Director of the Institute of Physical Chemistry in the Vniversity of 
 
 ■^'"■'"'- Price $1.50 net. 
 
 PROBLEMS OF GENETICS. By William Bateson, m.a., f.r.s.. Director 
 of the John Innes Horticultural Institution, Merton Park, Surrey, 
 England. {Second printing.) Pnce $5.00 net. 
 
 STELLAR MOTIONS. With Special Reference to Motions Determined 
 by Means of the Spectrograph. By William Wallace Campbell, so.d., 
 LL.D., Director of the Lick Observatory, Vniversity of California. 
 {Second printing.) Price $5.00 net. 
 
 THEORIES OF SOLUTIONS. By Svante Arrhenius, PH.D., sc.D., M.D., 
 Director of the Physico-Chemical Department of the Nobel Institute, 
 Stockholm, Sweden. 
 
 {TUrd printing.) Price $3.00 net. 
 
 IRRITABILITY. A Physiological Analysis of the General Effect of 
 Stimuli in Living Substances. By Max Verworn, m.d., ph.d.. Professor 
 at Bonn Physiological Institute. 
 
 {Second printing.) Price $5.00 net. 
 
 PROBLEMS OF AMERICAN GEOLOGY. By William North Rice, 
 Frank D. Adams, Arthur P. Coleman, Charles D. Walcott, Walde- 
 
 MAR LiNDGREN, FREDERICK LESLIE RaNSOME, AND WiLLIAM D. MATTHEW. 
 {Second printing.) Price $5.00 net. 
 
 THE PROBLEM OP VOLCANISM. By Joseph Paxson Iddings, ph.b., 
 {Second printing.) Price $5.00 net. 
 
 ORGANISM AND ENVIRONMENT AS ILLUSTRATED BY THE 
 PHYSIOLOGY OF BREATHING. By John Scott Haldane, m.d., 
 LL.D., F.R.S., Fellow of New College, Oxford University. 
 {Second printing.) Price $1.25 net. 
 
A CENTURY OF SCIENCE 
 IN AMERICA 
 
(y D. t7^^^(^>z--T-t--2^iJi-i^ 
 
A 
 
 CENTUEY OF SCIENCE 
 
 IN AMERICA 
 
 WITH SPECIAL KEFEREIfCE TO THE 
 
 AIVIERICAN JOURNAL OF SCIENCE 
 
 1818-1918 
 
 BY 
 
 EDWARD SALISBUEY DANA • CHARLES SCHUCHERT 
 
 HERBERT E. GREGORY ■ JOSEPH BARBELL ■ GEORGE OTIS SMITH 
 
 RICHARD SWANN LULL ■ LOUIS V. PIRSSON 
 
 WILLIAM E. FORD • R. B. SOSMAN • HORACE L. WELLS 
 
 HARRY W. EOOTE ■ LEIGH PAGE • WESLEY E. COE 
 
 AND GEORGE L. GOODALE 
 
 NEW HAVEN 
 
 YALE UNIVERSITY PEESS 
 
 LONDON • HUMPHREY MILPORD • OXFORD UNIVERSITY PRESS 
 
 MDCCCCXVIII 
 
COPYRIGHT, 1918, BY 
 YALE UNIVERSITY PRESS 
 
PREFATORY NOTE 
 
 The present book commemorates the one-hundredth anniversary 
 of the founding of the American Journal of Science by Benjamin 
 Silliman in July, 1818. The opening chapter gives a somewhat 
 detailed account of the early days of the Journal, with a sketch 
 of its subsequent history. The remaining chapters are devoted 
 to the principal branches of science which have been prominent 
 in the pages of the Journal. They have been written with a 
 view to showing in each case the position of the science in 1818 
 and the general progress made during the century ; special 
 prominence is given to American science and particularly to the 
 contributions to it to be found in the Journal's pages. Refer- 
 ences to specific papers in the Journal are in most cases included 
 in the text and give simply volume, page, and date, as (24, 105, 
 1833) ; when these and other references are in considerable 
 number they have been brought together as a Bibliography at 
 the end of the chapter. 
 
 The entire cost of the present book is defrayed from the 
 income of the Mrs. Hepsa Ely Silliman Memorial Fund, estab- 
 lished under the will of Augustus Ely Silliman, a nephew of 
 Benjamin Silliman, who died in 1884. Certain of the chapters 
 here printed have been made the basis of a series of seven Silli- 
 man Lectures in accordance with the terms of that gift. The 
 selection of these lectures has been determined by the conveni- 
 ence of the gentlemen concerned and in part also by the nature 
 of the subject. 
 
TABLE OF CONTENTS 
 
 Page 
 
 Prefatory Note vii 
 
 I. The American Journal of Science from 1818 to 1918. 
 
 Edward Salisbury Dana 13 
 
 II. A Century of Geology : The Progress of Historical 
 
 Geology in North America. Charles Schuchert 60 
 
 III. A Century of Geology : Steps of Progress in the 
 
 Interpretation of Land Forms. Herbert E. 
 Gregory 122 
 
 IV. A Century of Geology (continued) : The Growth 
 
 of Knowledge of Earth Structure. Joseph 
 Barren 153 
 
 V. A Century of Government Geological Surveys. 
 
 George Otis Smith 193 
 
 VI. On the Development of Vertebrate Paleontology. 
 
 Eichard Swann Lull 217 
 
 VII. The Else of Petrology as a Science. Louis V. 
 
 Pirsson 248 
 
 VIII. The Growth of Mineralogy from 1818 to 1918. 
 
 William E. Ford 268 
 
 IX. The Work of the Geophysical Laboratory of the 
 Carnegie Institution of Washington. E. B. 
 Sosman 284 
 
 u-X. The Progress of Chemistry during the Past One 
 Hundred Years.. Horace L. Wells and Harry 
 W. Foote : 288 
 
 XL A Century's Progress in Physics. Leigh Page. . . . 335 
 
 XII. A Century of Zoology in America. Wesley E. Coe 391 
 
 XIII. The Development of Botany since 1818. George L. 
 
 Goodale 439 
 
PORTRAITS 
 
 Benjamin Silliman .Frontispiece 
 
 From a painting tiy IT. D. Tenney, Esq., in possession of 
 Miss Henrietta W. Hnbliard 
 
 Benjamin Silliman, Jr opposite page 28 
 
 James D. Dana " " 36 
 
 Edward S. Dana " " 48 
 
 Woleott Gibbs " " 52 
 
 Benjamin Silliman " " 58 
 
 James Hall " " 84 
 
 G.K.Gilbert " " 140 
 
 Edward Hitchcock " " 156 
 
 0. C. Marsh " " 232 
 
 F. V. Hayden " " 196 
 
 J.W.Powell " ■ " 204 
 
 Clarence King " " 208 
 
 George J. Brnsh " " 276 
 
 J. Willard Gibbs " " 324 
 
 H. A. Newton " " 336 
 
 James Clerk Maxwell ,. . " " 348 
 
 Louis Agassiz " " 404 
 
 Thomas H. Huxley " " 410 
 
 A. E. Verrill " " 412 
 
 Asa Gray " " 444 
 
 Charles Darwin " " 452 
 
A CENTURY OF SCIENCE 
 IN AMERICA 
 
 I 
 
 THE AMERICAN JOURNAL OF SCIENCE 
 
 FROM 1818 TO 1918 
 
 By EDWAKD S. DANA 
 
 Introduction. 
 
 IN July, 1818, one hundred years ago, the first number 
 of the American Journal of Science and Arts was 
 given to the public. This is the only scientific 
 periodical in this country to maintain an uninterrupted 
 existence since that early date, and this honor is shared 
 with hardly more than half a dozen other independent 
 scientific periodicals in the world at large. Similar pub- 
 lications of learned societies for the same period are also 
 very few in number. 
 
 It is interesting, on the occasion of this centenary, to 
 glance back at the position of science and scientific liter- 
 ature in the world's intellectual life in the early part of 
 the nineteenth century, and to consider briefly the mar- 
 velous record of combined scientific and industrial prog- 
 ress of the hundred years following — subjects to be 
 handled in detail in the succeeding chapters. It is fitting 
 also that we should recall the man who founded the 
 Journal, the conditions under which he worked, and the 
 difficulties he encountered. Finally, we must review, but 
 more briefly, the subsequent history of what has so often 
 been called after its founder, "Silliman's Journal." 
 
 The nineteenth century, and particularly the hundred 
 years in which we are now interested, must always stand 
 out in the history of the world as the period which has 
 
14 A CENTURY OF SCIENCE 
 
 combined the greatest development in all departments oi 
 science with the most extraordinary industrial progress. 
 It was not until this century that scientific investigation 
 used to their full extent the twin methods of observation 
 and experiment. In cases too numerous to mention they 
 have given us iirst, a tentative hypothesis ; then, through 
 the testing and correcting of the hypothesis by newly 
 acquired data, an accepted theory has been arrived at; 
 finally, by the same means carried further has been 
 established one of nature's laws. 
 
 Early Science. — Looking far back into the past, it 
 seems surprising that science should have had so late a 
 growth, but the wonderful record of man's genius in the 
 monuments he erected and in architectural remains 
 shows that the working of the human mind found expres- 
 sion first in art and further man also turned to litera- 
 ture. So far as man's thought was constructive, the 
 early results were systems of philosophy, and explana- 
 tions of the order of things as seen from within, not as 
 shown by nature herself. We date the real beginning of 
 science with the Greeks, but it was the century that pre- 
 ceded Aristotle that saw the building of the Parthenon 
 and the sculptures of Phidias. Even the great Aristotle 
 himself (384-322 B. C.) though he is sometimes called the 
 "founder of natural history," was justly accused by 
 Lord Bacon many centuries later of having formed his 
 theories first and then to have forced the facts to agree 
 with them. 
 
 The bringing together of facts through observation 
 alone began, to be sure, very earlj^, for it was the motion 
 of the sun, moon, and stars and the relation of the earth 
 to them that first excited interest, and, especially in the 
 countries of the East, led to the accumulation of data as 
 to the motion of the planets, of comets and the occur- 
 rence of eclipses. But there was no coordination of 
 these facts and they were so involved in man's super- 
 stition as to be of little value. In passing, however, it is 
 worthy of mention that the Chinese astronomical data 
 accumulated more than two thousand years before the 
 Christian era have in trained hands yielded results of no 
 small significance. 
 
 Doubtless were full knowledge available as to the 
 
AMERICAN JOURNAL OF SCIENCE 15 
 
 science existing in the early civilizations, we should rate 
 it higher than we can at present, but it would probably 
 prove even then to have been developed from within, like 
 the philosophies of the Greeks, and with but minor 
 influence from nature herself. It is indeed remarkable 
 that do\\Ti to the time with which we are innnediately con- 
 cerned, it was the branches of mathematics, as arithmetic 
 and geometry and later their applications, that were first 
 and most fully developed : in other words those lines of 
 science least closely connected with nature. 
 
 Of the importance to science of the Greek school at 
 Alexandria in the second and third centuries B. C, there 
 can be no question. The geometry of Euclid (about 300 
 B. C.) was marvelous in its completeness as in clearness 
 of logical method. Hipparchus (about 160-125 B. C.) 
 gave the world the elements of trigonometry and devel- 
 oped astronomy so that Ptolemy 260 years later was able 
 to construct a system that was well-developed, though in 
 error in the fundamental idea as to the relative position 
 of the earth. It is interesting to note that the Almagest 
 of Ptolemy was thought worthy of republication by the 
 Carnegie Institution only a year or two since. This 
 great astronomical work, by the way, had no successor 
 till that of the Arab Ulugh Bey in the fifteenth century, 
 which within a few months has also been made available 
 by the same Institution. 
 
 To the Alexandrian school also belongs Archimedes 
 (287-212 B. C), who, as every school boy knows, was the 
 founder of mechanics and in fact almost a modern physi- 
 cal experimenter. He invented the water screw for rais- 
 ing water; he discovered the principle of the lever, 
 which appealed so keenly to his imagination that he 
 called for a ttov o-™, or fulcrum, on which to place it so as 
 to move the earth itself. He was still nearer to modern 
 physics in his reputed plan of burning up a hostile fleet 
 by converging the sun's rays by a system of great 
 mirrors. 
 
 To the Romans, science owes little beyond what is 
 implied in their vast architectural monuments, buildings 
 and aqueducts which were erected at home and in the 
 countries of their conquests. The elder Pliny (23-79 
 A. D.) most nearly deserved to be called a man of science, 
 
16 A CENTURY OF SCIENCE 
 
 but his work on natural history, comprised in thirty- 
 seven volumes, is hardly more than a compilation of 
 fable, fact, and fancy, and is sometimes termed a collec- 
 tion of anecdotes. He lost his life in the "grandest 
 geological event of antiquity," the eruption of Vesuvius, 
 which is vividly described by his nephew, the younger 
 Pliny, in "one of the most remarkable literary produc- 
 tions in the domain of geology" (Zittel). 
 
 With the fall of Rome and the decline of Roman civ- 
 ilization came a period of intellectual darkness, from 
 which the world did not emerge until the revival of learn- 
 ing in the fifteenth and sixteenth centuries. Then the 
 extension of geographical knowledge went hand in hand 
 with the development of art, literature, and the birth of a 
 new science'. Copernicus (1473-1543) gave the world at 
 last a sun-controlled solar system; Kepler (1571-1630) 
 formulated the laws governing the motion of the planets ; 
 Galileo (1564-1642) with his telescope opened up new 
 vistas of astronomical knowledge and laid the founda- 
 tions of mechanics; while Leonardo da Vinci (1452-1519), 
 painter, sculptor, architect, engineer, musician and true 
 scientist, studied the laws of falling bodies and solved 
 the riddle of the fossils in the rocks. Still later Newton 
 (1642-1727) established the law of gravitation, developed 
 the calculus, put mechanics upon a solid basis and also 
 worked out the properties of lenses and prisms so that 
 his Optics (1704) will always have a prominent place in 
 the history of science. 
 
 From the time of the Renaissance on science grew 
 steadily, but it was not till the latter half of the eight- 
 eenth century that the foundations in most of the lines 
 recognized to-day were fully laid. Much of what was 
 accomplished then is, at least, outlined in the chapters 
 following. 
 
 Our standpoint in the early years of the nineteenth 
 century, just before the American Journal had its begin- 
 ning, may be briefly summarized as follows: A desire 
 for knowledge was almost universal and, therefore, also 
 a general interest in the development of science. Mathe- 
 matics was firmly established and the mathematical side 
 of astronomy and natural philosophy — as physics w^as 
 then called— was well developed. Many of the phenom- 
 
AMERICAN JOURNAL OF SCIENCE 17 
 
 ena of heat and their applications, as in the steam engine 
 of Watt, were known and even the true nature of heat had 
 heen almost established by our countrjaiian, Count Rum- 
 ford ; but of electricity there were only a few sparks of 
 knowledge. Chemistry had had its foundation firmly 
 laid by Priestley, Lavoisier, and Dalton, while Berzelius 
 was pushing rapidly forward. Geology had also its 
 roots down, chiefly through the work of liutton and 
 William Smith, though the earth was as yet essentially 
 an unexplored field. Systematic zoology and botany had 
 been firmly grounded by Buff on, Lamarck and Cuvier, on 
 the one hand, and Linnoeus on the other ; but of all that is 
 embraced under the biology of the latter half of the 
 nineteenth century the world knew nothing. The state- 
 ments of Silliman in his Introductory Remarks in the 
 first number, quoted in part on a following page, put 
 the matter still more fully, but they are influenced by the 
 enthusiasm of the time and he could have had little com- 
 prehension of what was to be the record of the next one 
 hundred years. 
 
 Now, leaving this hasty and incomplete retrospect and 
 coming down to 1918, we find the contrast between to-day 
 and 1818 perhaps most strikingly brought out, on the 
 material side, if we consider the ability of* man, in the 
 early part of the nineteenth century, to meet the demands 
 upon him in the matter of transportation of himself and 
 his property. In 1800, he had hardly advanced beyond 
 his ancestor of the earliest ci'sdlization ; on the contrary, 
 he was still dependent for transportation on land upon 
 the muscular efforts of himself and domesticated ani- 
 mals, while at sea he had only the use of sails in addition. 
 The first application of the steam engine with commercial 
 success was made by Fulton when, in 1807, the steamboat 
 "Clermont" made its famous trip on the Hudson River. 
 Since then, step by step, transportation has been made 
 more and more rapid, economical and convenient, both on 
 land and water. This has come first through the per- 
 fection of the steam engine ; later through the agency of 
 electricity, and still further and more universally by the 
 use of gasolene motors. Finally, in these early years of 
 the twentieth centurv, what seemed once a wild dream of 
 
18 A CENTURY OF SCIENCE 
 
 the imagination lias been realized, and man has gained 
 the conquest of the air; while the perfection of the sub- 
 marine is as wonderful as its work can be deadly. 
 
 Hardly less marvelous is the practical annihilation of 
 space and time in the electric transmission of human 
 thought and speech by wire and bj' ether waves. Wliile, 
 still further, the same electrical current now gives man 
 his artificial illumination and serves him in a thousand 
 wa^^s besides. 
 
 But the limitations of space have also been conquered, 
 during the same period, by the spectroscope which brings 
 a knowledge of the material nature of the sun and the 
 fixed stars and of their motion in the line of sight ; while 
 spectrum analysis has revealed the existence of many 
 new elements and opened up vistas as to the nature of 
 matter. 
 
 The chemist and the physicist, often working together 
 in the investigation of the problems lying between their 
 two departments, have accumulated a staggering array 
 of new facts from which the principles of their sciences 
 have been deduced. Manj^ new elements have been dis- 
 covered, in fact nearly all called for hj the periodic law ; 
 the so-called fixed gases have been liquefied, and now air 
 in liquid form is almost a plaything; the absolute zero 
 has been nearly reached in the boiling point of helium; 
 physical measurements in great precision have been car- 
 ried out in both directions for temperatures far beyond 
 any scale that was early conceived possible ; the atom, 
 once supposed to be indivisible, has been shown to be made 
 up of the much smaller electrons, while its disintegration 
 in radium and its derivatives has been traced out and 
 with consequences only as yet partly understood but cer- 
 tainly having far-reaching consequences ; at one point 
 we seem to be brought near to the transmutation of the 
 elements which was so long the dream of the alchemist. 
 Still again photograplw has been discovered and per- 
 fected and with the use of X-rays it gives a picture of the 
 structure of bodies totally opaque to the eye ; the same 
 X-rays seem likely to locate and determine" the atoms in 
 the crystal. 
 
 Here and at many other points w^e are reaching out to 
 a knowledge of the ultimate nature of matter. 
 
AMERICAN JOURNAL OF SCIENCE 19 
 
 In geology, vast progress lias been made in the 
 knowledge of the earth, not only as to its features now 
 exhibited at or near the surface, but also as to its history 
 in past ages, of the development of its structure, the 
 minute history of its life, the phenomena of its earth- 
 quakes, volcanoes, etc. Geological surveys in all civilized 
 countries have been carried to a high degree of per- 
 fection. 
 
 In biology, itself a word which though used by 
 Lamarck did not come into use till taken up by Huxley, 
 and then by Herbert Spencer in the middle of the cen- 
 tury, the progress is no less remarkable as is well devel- 
 oped in a later chapter of this volume. 
 
 Although not falling within our sphere, it would be 
 wrong, too, not to recognize also the growth of medicine, 
 especially through the knowledge of bacteria and their 
 functions, and of disease germs and the methods of com- 
 bating them. The world can never forget the debt it 
 owes to Pasteur and Lister and many later investigators 
 in this field. 
 
 To follow out this subject further would be to encroach 
 upon the field of the chapters following, but, more 
 important and fundamental still than all the facts dis- 
 covered and the phenomena investigated has been the 
 establishment of certain broad scientific principles which 
 have revolutionized modern thought and shown the rela- 
 tion between sciences seemingly independent. The law 
 of conservation of energy in the physical world and the 
 principle of material and organic evolution may well be 
 said to be the greatest generalizations of the human 
 mind. Although suggestions in regard to them, particu- 
 larly the latter, are to be found in the writings of early 
 authors, the establishment and general acceptance of 
 these principles belong properly to the middle of the 
 nineteenth century. They stand as the crowning achieve- 
 ment of the scientific thought of the period in which we 
 are interested. 
 
 Any mere enumeration of the vast fund of knowledge 
 accumulated by the efforts of man through observation 
 and experiment in the period in which we are interested 
 would be a dry summary, and yet would give some meas- 
 ure of what this marvelous period has accomplished. As 
 
20 A CENTURY OF SCIENCE 
 
 in geography, man's energy has in recent years removed 
 the reproach of a "Dark Continent," of "unexplprecr^ 
 central Asia and the once "inaccessible polar regions," 
 so in the different departments of science, he has opened 
 np many unknown fields and accumulated vast stores of 
 knowledge. It might even seem as if the limit of the 
 unknovm were being approached. There remains, how- 
 ever, this difference in the analogy, that in science the 
 fundamental relations — as, for example, the nature of 
 gravitation, of matter, of energy, of electricity; the 
 actual nature and source of life — the solution of these 
 and other similar problems still lies in the future. What 
 the result of continued research may be no one can pre- 
 dict, but even with these possibilities before us, it is 
 hardly rash to say that so great a combined progress of 
 pure "and applied science as that of the past hundred 
 years is not likely to be again realized. 
 
 Scientific Periodical Literature in 1818. 
 
 The contrast in scientific activity between 1818 and 
 1918 is nowhere more strikingly shown than in the 
 amount of scientific periodical literature of the two 
 periods. Of the thousands of scientific journals and reg- 
 ular publications by scientific societies and academies 
 to-day, but a very small number have carried on a con- 
 tinuous and practically unbroken existence since 1818. 
 This small amount of periodical scientific literature in 
 the early part of the last century is significant as giving 
 a fair indication of the very limited extent to which 
 scientific investigation appealed to the intellectual life of 
 the time. Some definite facts in regard to the scientific 
 publications of those early days seem to be called for. 
 
 Learned societies and academies, devoted to literature 
 and science, were formed very early but at first for occa- 
 sional meetings only and regular publications were in 
 most cases not begun till a very much later date. Some 
 of the earliest — not to go back of the Renaissance — are 
 the following: 
 
 1560. Naples, Academia Secrelorum Naturs. 
 
 1603. Rome, Accademia del Lincei. 
 
 1651. Leipzig, Academia Naturae Curiosum. 
 
AMERICAN JOURNAL OF SCIENCE 21 
 
 1657. Florence, Aeeademia del Cimento. 
 1662. London, Royal Society. 
 1666. Paris, Academie des Sciences. 
 1690. Bologna, Aeeademia delle Scienze. 
 1700. Berlin, Societas Regia Seientiarum. This was the 
 forerunner of the K. preuss. Akad. d. Wissenschaften. 
 
 The Roj^al Society of London, whose existence dates 
 from 164-5, thongh not definitely chartered until 1662, 
 began the publication of its "Philosophical Transac- 
 tions" in 1665 and has continued it practically unbroken 
 to the present time ; this is a unique record. Following 
 this, other early — but in most cases not continuous — 
 publications were those of Paris (1699) ; Berlin (171U) ; 
 Upsala (1720); Petrograd, 1728; Stockholm (1739); 
 and Copenhagen (1743). 
 
 For the latter half of the eighteenth century, Avhen the 
 foundations of our modern science were being rapidly 
 laid, a considerable list might be given of early publica- 
 tions of similar scientific bodies. Some of the prominent 
 ones are: Gottingen (1750), Munich (1759), Brussels 
 (1769), Prague (1775), Turin (1784), Dublin (1788), etc. 
 The early years of the nineteenth century saw the begin- 
 nings of many others, particularly in northern Italy. It 
 is to be noted that, as stated, only rarely were the publi- 
 cations of these learned societies even approximately 
 continuous. In the majority of cases the issue of trans- 
 actions or proceedings was highly irregular and often 
 interrupted. 
 
 In this country the earliest scientific bodies are the 
 following : 
 
 Philadelphia. American Philosophical Society, founded in 
 1743. Transactions were published 1771-1809 ; then inter- 
 rupted until 1818 et seq. 
 
 Boston. American Academy of Arts and Sciences, founded 
 in 1780. Memoirs, 1785-1821 ; and then 1833 et seq. 
 
 New Haven. Connecticut Academy of Arts and Sciences, 
 begun in 1799. Memoirs, vol. 1, 1810-16 ; Transactions, 1866 
 et seq. 
 
 Philadelphia. Academv of Natural Sciences, begun in 1812. 
 Journal, 1817-1842 ; and from 1847 et seq. 
 
 New York. Lyceum of Natural History, 1817; later (1876) 
 became the New York Academy of Sciences. Annals from 1823 ; 
 Proceedings from 1870. 
 
22 A CENTURY OF SCIENCE 
 
 The situation is somewhat similar as to independent 
 scientific journals. A list of the names of those started 
 onl}^ to find an early death would be a very long one, but 
 interesting only historically and as showing a spasmodic 
 but unsustained striving after scientific growth. 
 
 It seems worth while, however, to give here the names 
 of the periodicals embracing one or more of the sub- 
 jects of the American Journal, which began at a very 
 early date and most of which have maintained an unin- 
 terrupted existence down to 1915. It should be added 
 that certain medical journals, not listed here, have also 
 had a long and continued existence.^ 
 
 Earlij Scientific Journals. 
 
 1771-1823. Journal de Physique, Paris ; title changed several 
 times. 
 
 1787-. Botanical Magazine. (For a time known as Curtis 's 
 Journal.) 
 
 1789-1816. Annales de Chimie, Paris. Continued from 1817 
 on as the Annales de Chimie et de Physique. 
 
 1790. Journal der Physik, Halle (by Gren) ; from 1799 on 
 became the Annalen der Physik (und Chemie), Halle, Leipzig. 
 The title has been somewhat changed from time to time though 
 publication has been continuous. Often referred to by the name 
 of the editor-in-chief, as Gren, Gilbert, Poggendorff, Wiedemann, 
 etc. 
 
 1795-1815. Journal des Mines, Paris, continued from 1816 
 as the Annales des Mines. 
 
 1796-1815. Bibliotheque Britannique, Geneva. From 1816- 
 1840, Bibliotheque Universelle, etc. 1846-1857, Archives des 
 Sci. phys. nat. Since 1858 generally known as the Bibliotheque 
 Universelle. 
 
 1797. Journal of Natural Philosophy, Chemistry and the 
 Arts (Nicholson's Journal) London; united in 1814 with the 
 Philosophical Magazine (Tilloch's Journal). 
 
 1798-. The Philosophical Magazine (originally by Tilloch). 
 This absorbed Nicholson's Journal (above) in 1814; also the 
 Annals of Philosophy (Thomson, Phillips) in 1827 and Brew- 
 sters' Edinburgh Journal of Science in 1832. 
 
 1798-1803. Allgemeines Journal de Chemie (Scherer's 
 Journal). 1803-1806; continued as Neues Allg. J. etc. (Geli- 
 len's Journal.) Later title repeatedly changed and finally 
 (1834 et seq.) Journal fiir praktische Chemie. 
 
 1816-18. Journal of Science and the Arts, London. 1819- 
 
AMERICAN JOURNAL OF SCIENCE 23 
 
 30, Quarterly J. etc. 1830-31, Journal of the Eoyal Institution 
 of Great Britain. 
 
 1818. American Journal of Science and Arts until 1880, 
 when "the Arts" was dropped, New Haven, Conn. First 
 Series, 1-50, 1818-1845 ; Second Series, 1-50, 1846-1870 ; Third 
 Series, 1-50, 1871-1895; Fourth Series, 1-45, 1896-June, 1918. 
 
 1818. Flora, or Allgemeine botanische Zeitung. Regensburg, 
 Munich. 
 
 1820-1867. London Journal of Arts and Sciences (after 
 1855, Newton's Journal). 
 
 1824—. Annales des sciences naturelles. Paris. 
 
 1826-. LinniEa, Berlin, Halle ; from 1882 united with Jahrb. 
 d. K. botan. Gartens. 
 
 1828-1840. Magazine of Natural History, London; united 
 1838 with the Annals of Natural History, and known since 1841 
 as the Annals and Magazine of Natural History 
 
 1828-. Journal of the Franklin Institute, Philadelphia, from 
 1826; earlier (1825) the American Mechanics Magazine. 
 
 1832-. Annalen cler Ghemie (und Pharmacie) often known 
 as Liebig's Annalen. Leipzig, Lemgo. 
 
 Tlie Founder of the American <Tour7ial of Science. 
 
 The establishment of a scientific journal in this countrj^ 
 in 1818 was a pioneer undertaking, requiring of its 
 founder a rare degree of energy, courage, and confidence 
 in the future. It was necessary, not only to obtain the 
 material to fill its pages and the money to carry on the 
 enterprise, but, before the latter end could be accom- 
 plished, an audience must be found among those who had 
 hitherto felt little or no interest in the sciences. This 
 great work was accomplished by Benjamin Silliman, 
 "the guardian of American Science," whose influence 
 was second to none in the early development of science in 
 this country. Before speaking in some detail of the 
 early years of this Journal and of its subsequent history, 
 it is proper that some words should be given to its 
 founder. 
 
 Benjamin Silliman, son of a general prominent in the 
 Revolutionary War, was born in Trumbull, Connecticut, 
 on August 8, 1779. He was a graduate of Yale College 
 of the class of 1796. Though at first a student of law and 
 accepted for the bar in Connecticut, he was called in 1802 
 by President Timothy Dwight — a man of rare breadth of 
 
24 A CENTUEY OF SCIENCE 
 
 mind — to occupy the newly-made chair of chemistry, min- 
 eralogy (and later geology) in Yale College at New 
 Haven. To fit himself for the work before him he 
 carried on extensive studies at home and in Philadelphia 
 and spent the year 1805 in travels and study at London 
 and Edinburgh, and also on the Continent. His active 
 duties began in 1806 and from this time on he was in the 
 service of Yale College until his resignation in 1853. 
 From the first, Silliman met with remarkable success as a 
 teacher and public lecturer in arousing an interest in 
 science. His breadth of knowledge, his enthusiasm for 
 his chosen subjects and power of clear presentation, com- 
 bined with his fine presence and attractive personality, 
 made him a great leader in the science of the country and 
 gave him a unique position in the history of its develop- 
 ment. 
 
 Much might be said of the man and his work, but, the 
 best tribute is that of James Dwight Dana, given in his 
 inaugural address upon the occasion of his beginning his 
 duties as Silliman professor of geology in Yale College. 
 This was delivered on February 18, 1856, in what was 
 then known as the "Cabinet Building." Dana says 
 in part : 
 
 "In entering upon the duties of this place, my thoughts turn 
 rather to the past than to the subject of the present hour. I 
 feel that it is an honored place, honored by the labors of one 
 who has been the guardian of American Science from its child- 
 hood; who here first opened to the country the wonderful 
 records of geology ; whose words of eloquence and earnest truth 
 were but the overflow of a soul full of noble sentiments and 
 warm sympathies, the whole throwing a peculiar charm over 
 his learning, and rendering his name beloved as well as illus- 
 trious. Just fifty years since, Professor Silliman took his sta- 
 tion at the head of chemical and geological science in this college. 
 Geology was then hardly known by name in the land, out of 
 these walls. Two years before, previous to his tour in Europe, 
 the whole cabinet of Yale was a half-bushel of unlabelled stones. 
 On visiting England he found even in London no school public 
 or private, for geological instruction, and the science was not 
 named in the English universities. To the mines, quarries, and 
 cliffs of England, the crags of Scotland, and the meadows of 
 Holland he looked for knowledge, and from these and the teach- 
 ings of Murray, Jameson, Hall, Hope, and Playfair, at Edin- 
 burgh, Professor Silliman returned, equipped for duty,— albeit 
 
AMEEICAN JOURNAL OF SCIENCE 25 
 
 a great duty, — that of laying the foundation, and creating 
 almost out of nothing a department not before recognized in any 
 institution in America. 
 
 He began his work in 1806. The science was without books — ■ 
 and, too, without system, except such as its few cultivators had 
 each for himself in his conceptions. It was the age of the first 
 beginnings of geology, when Wernerians and Huttonians were 
 arrayed in a contest. . . . Professor Silliman when at Edin- 
 burgh witnessed the strife, and while, as he says, his earliest 
 predilections were for the more peaceful mode of rock-making, 
 these soon yielded to the accumulating evidence, and both views 
 became combined in his mind in one harmonious whole. The 
 science, thus evolved, grew with him and by him; for his ot^ti 
 labors contributed to its extension. Every year was a year of 
 expansion and onward development, and the grandeu.r of the 
 opening views found in him a ready and appreciative response. 
 
 And while the sciences and truth have thus made progress 
 here, through these labors of fifty years, the means of study in 
 the institution have no less increased. Instead of that half- 
 bushel of stones, which once went to Philadelphia for names, in 
 a candle-box, you see above the largest mineral cabinet in the 
 country, which but for Professor Silliman, his attractions and 
 his personal exertions together, would never have been one of 
 the glories of old Yale. . . . 
 
 Moreover, the American Journal of Science, — now in its 
 thirty-seventh year and seventieth volume [1856], — projected 
 and long-sustained solely by Professor Silliman, while ever dis- 
 tributing truth, has also been ever gathering honors, and is one 
 of the laurels of Yale. 
 
 We rejoice that in laying aside his studies, after so many 
 years of labor, there is still no abated vigor. . . . He retires 
 as one whose right it is to throw the burden on others. Long 
 may he be with vis, to enjoy the good he has done, and cheer us 
 by his noble and benign presence." 
 
 In addition to these words of Dana, much, of vital 
 interest in regard to Silliman and his work will be 
 gathered from what is given in the pages immediately 
 following, quoted from his personal statements in the 
 early volumes of the Journal. 
 
 The Early Years of the Joxirnal. 
 
 In no direction did Silliman 's enthusiastic activities in 
 science produce a more enduring result than in the found- 
 
; •i—^ MORE ESPECIALLY OF 
 
 ^ MI^ERALOGY^ GEOLOGY^ ^ 
 
 Z^^ AND THE 
 
 ^^'^ OTHER BRANCHES OF NATURAL HISTORY 
 
 INCLUDING AL80 
 AND THE 
 
 ORNAMENTAL AS WELL AS USEFUL 
 
 CONDUCTED BY 
 
 BUXJJIMIX SILLJM.iJV, 
 
 PROCESSOR O? CUEMJSTR7. MINKF.ALOOT. ETC IN TALF. COLLEGE, AOTHOR 0? 
 TRAVELS IS ENGLdNn. SCOI LAND. ASD UOLLdND, ETC 
 
AMERICAN JOURNAL OF SCIENCE 27 
 
 ing and carrying on of the Journal. The first sugges- 
 tion in regard to the enterprise was made to Silliman by 
 his friend, Colonel George Gibbs, from whom the famous 
 Gibbs collection of minerals was bought by Yale College 
 in 1825. Silliman says (25, 215, 1834) : 
 
 "Col. Gibbs was the person who first suggested to the Editor 
 the project of this Journal, and he urged the topic with so much 
 zeal and with such cogent arguments, as prevailed to induce the 
 effort in a case then viewed as of very dubious success. The 
 subject was thus started in November, 1817 ; proposals for the 
 Journal were issued in January, 1818, and the first number 
 appeared in July of that year." 
 
 He adds further (50, p. iii, 1847) that the conversation 
 here recorded took place "on an accidental meeting on 
 board the steamboat Fulton in Long Island Sound." 
 This was some ten years after Robert Fulton's steam- 
 boat, the Clermont, made its pioneer trip on the Hudson 
 river, already alluded to. The incident is not without 
 significance in this connection. The deck of the "Ful- 
 ton" was not an inappropriate place for the inauguration 
 of an enterprise also great in its results for the country. 
 
 In the preface to the concluding volume of the First 
 Series (loc. cit.) Silliman adds the following remarks 
 which show his natural modesty at the thought of under- 
 taking so serious a work. He says : 
 
 Although a different selection of an editor would have been 
 much preferred, and many reasons, public and personal, con- 
 curred to produce diffidence of success, the arguments of Col. 
 Gibbs, whose views on subjects of science were entitled to the 
 most respectful consideration, and had justly great weight, 
 being pressed with zeal and ability, induced a reluctant assent; 
 and accordingly, after due consultation with many competent 
 judges, the proposals were issued early in 1818, embracing the 
 whole range of physical science and its applications. The 
 Editor in entering on the duty, regarded it as an affair for life, 
 and the thirty years of experience which he has now had, have 
 proved that his views of the exigencies of the service were not 
 erroneous. 
 
 The plan with which the editor began his work and the 
 lines laid down by him at the outset can only be made 
 clear by quoting entire the "Plan of the Work" which 
 
28 A CENTURY OF SCIENCE 
 
 opens the first number. It seems desirable also to give 
 this in its original form as to paragraphs and typog- 
 raphy. The first page of the cover of the opening nmn- 
 ber has also been reproduced here. It will be seen that 
 the plan of the young editor was as wide as the entire 
 range of science and its applications and extended out to 
 music and the fine arts. This seems strange to-day, but 
 it must be remembered how few were the organs of pub- 
 lication open to contributors at the time. If the plan 
 was unreasonablj^ extended, that fact is to be taken not 
 onlj^ as an expression of the enthusiasm of the editor, as 
 yet inexperienced in his work, but also of the time when 
 the sciences were still in their infancy. 
 He says (1, pp. v, vi) : 
 
 "PLAN OF THE WOEK. 
 
 This Journal is intended to embrace the circle of The Phys- 
 ical SciENOEs, with their application to The Arts, and to every 
 useful purpose. 
 
 It is designed as a deposit for original American communica- 
 tions; but will contain also occasional selections from Foreign 
 Journals, and notices of the progress of science in other coun- 
 tries. Within its plan are embraced 
 
 Natural History, in its three great departments of Miner- 
 alogy, Botany, and Zoology; 
 
 Chemistry and Natural Philosophy, in their various 
 branches : and Mathematics, pure and mixed. 
 
 It will be a leading object to illustrate American Natural 
 History, and especially our Mineralogy and Geology. 
 
 The Applications' of these sciences are obviously as numer- 
 ous as physical arts, and physical ivants; for no one of these 
 arts or wants can be named which is not connected with them. 
 
 While Science will be cherished for its own sake, and with a 
 due respect for its own inherent dignity; it will also be 
 employed as the handmaid to the Arts. Its numerous applica- 
 tions to Agriculture, the earliest and most important of them ; 
 to our Manufactures, both mechanical and chemical; and 
 to^ our Domestic Economy, will be carefully sought out, and 
 faithfully made. 
 
 It is also within the design of this Journal to receive communi- 
 cations on Music, Sculpture, Engraving, Painting, and gener- 
 ally on the fine and liberal, as well as useful arts ; 
 
 On Military and Civil Engineering, and the art of Navis'ation. 
 
2^.i ^.^4' ^^'■^^^C 
 
AMERICAN JOURNAL OF SCIENCE 29 
 
 Notices, Reviews, and Analyses of new scientific works, and 
 of new Inventions, and Specifications of Patents ; 
 
 Biograpliieal and Obituary Notices of scientific men; essays 
 on Comparative Anatomy and Physiology, and generally on 
 such other branches of medicine as depend on scientific prin- 
 ciples ; 
 
 Meteorological Registers, and Reports of Agricultural Experi- 
 ments : and we would leave room also for interesting miscellane- 
 ous things, not perhaps exactly included under either of the 
 above heads. 
 
 Communications are respectfully solicited from men of 
 science, and from men versed in the practical arts. 
 
 Learned Societies are invited to make this Journal, occasion- 
 ally, the vehicle of their communications to the Public. 
 
 The editor will not hold himself responsible for the sentiments 
 and opinions advanced by his correspondents ; but he will con- 
 sider it as an allowed liberty to make slight verbal alterations, 
 where errors may be presumed to have arisen from inadver- 
 tency. ' ' 
 
 In tlie "Advertisement" which precedes the above 
 statement in the first number, the editor remarks some- 
 what naively that he "does not pledge himself that all the 
 subjects shall be touched upon in every number. This is 
 plainly impossible unless every article should be very 
 short and imperfect. . ." 
 
 The whole subject is discussed in all its relations in 
 the "Introductory Remarks" which open the first vol- 
 ume. No apologj^ is needed for quoting at considerable 
 length, for only in this way can the situation be made 
 clear, as seen by the editor in 1818. Further we gain 
 here a picture of the intellectual life of the times and, not 
 less interesting, of the mind and personality of the writer. 
 With a frank kindliness, eminently characteristic of the 
 man, as -will be seen, he takes the public fully into his 
 confidence. In the remarks made in subsequent vol- 
 umes, — also extensively quoted — the vicissitudes in the 
 conduct of the enterprise are brought out and when suc- 
 cess was no longer doubtful, there is a tone of quiet 
 satisfaction which was also characteristic and which the 
 circumstances fully justified. 
 
 The Inteoductoey Remaeks begin as follows : 
 
 The age in which we live is not less distinguished by a vigorous 
 and successful cultivation of physical science, than by its numer- 
 
30 A CENTURY OF SCIENCE 
 
 ous and important applications to the practical art-s, and to the 
 common purposes of life. 
 
 In every enlightened country, men illustrious for talent, worth 
 and Imowledge, are ardently engaged in enlarging the boiind- 
 aries of natural science ; and the history of their labors and 
 discoveries is communicated to the v/orld chiefly through the 
 medium of scientific journals. The utility of such journals has 
 thus become generally evident ; they are the heralds of science ; 
 they proclaim its toils and its achievements ; they demonstrate 
 its intimate connection as well with the comfort, as with the 
 intellectual and moral improvement of our species ; and they 
 often procure for it enviable honors and substantial rewards. 
 
 Mention is then made of the journals existing in 
 England and France in 181S "which Iiave long enjoyed a 
 high and deserved rej^utation. ' ' He then continues : 
 
 From these sources our country reaps and will long continue 
 to reap, an abundant harvest of information : and if the light 
 of science, as well as of day, springs from the East, we will wel- 
 come the rays of both ; nor should national pride induce us to 
 reject so rich an offering. 
 
 But can we do nothing in return? 
 
 In a general diffusion of useful information through the vari- 
 ous classes of society, in activity of intellect and fertility of 
 resource and invention, producing a highly intelligent popula- 
 tion, we have no reason to shrink from a comparison with any 
 country. But the devoted cultivators of science in the United 
 States are comparatively few: they are, however, rapidly 
 increasing in number. Among them are persons distinguished 
 for their capacity and attainments, and, notwithstanding the 
 local feelings nourished by our state sovereignties, and the rival 
 claims of several of our larger cities, there is evidently a predis- 
 position towards a concentration of effort, from which we may 
 hope for the happiest results, with regard to the advancement 
 of both the science and reputation of our country. 
 
 Is it not, therefore, desirable to furnish some rallying point, 
 some object sufficiently interesting to be nurtured by common 
 efforts, and thus to become the basis of an enduring, common 
 interest? To produce these efforts, and to excite this interest, 
 nothing, perhaps, bids fairer than a Scientific Journal. 
 
 The valuable work already accomplished by various 
 medical journals is then spoken of and particularly that 
 of the first scientific periodical in the United States, 
 Bruce 's Mineralogical Journal. This, as Silliman says' 
 
AMERICAN JOURNAL OF SCIENCE 31 
 
 (1, p. 3, 1818), although "both in this country and in 
 Europe received in a very flattering manner," did not 
 survive the death of its founder, and only a single vol- 
 ume of 270 pages appeared (1810-1813). 
 Silliman continues : 
 
 No one, it is presumed, will doubt that a journal devoted to 
 science, and embracing a sphere sufficiently extensive to allure 
 to its support the principal scientific men of our country, is 
 greatly needed; if cordially supported, it will be successful, 
 and if successful, it will be a great public benefit. 
 
 Even a failure, in so good a cause, (unless it should arise from 
 incapacity or unfaithfulness,) cannot be regarded as dishonour- 
 able. It may prove only that the attempt was premature, and 
 that our country is not yet ripe for such an undertaking; for 
 without the efficient support of talent, knowledge, and money, 
 it cannot long proceed. No editor can hope to carry forward 
 such a work without the active aid of scientific and practical 
 men ; but, at the same time, the public have a right to expect 
 that he will not be sparing of his own labour, and that his work 
 shall be generally marked bj' the impress of his own hand. To 
 this extent the editor cheerfully acknowledges his obligations 
 to the public ; and it will be his endeavour faithfully to redeem 
 his pledge. 
 
 Most of the periodical works of our country have been short- 
 lived. This, also, may perish in its infancy; and if any degree 
 of confidence is cherished that it will attain a maturer age, it is 
 derived from the obvious and intrinsic importance of the under- 
 taking; from its being built upon permanent and momentous 
 national interests ; from the evidence of a decided approbation 
 of the design, on the part of gentlemen of the first eminence, 
 obtained in the progress of an extensive correspondence ; from 
 assurance of support, in the way of contributions, from men of 
 ability in many sections of the union ; and from the existence 
 of such a crisis in the affairs of this country and of the world, 
 as appears peculiarly auspicious to the success of every wise and 
 good undertaking. 
 
 An interesting discussion follows (pp. 5-8) as to the 
 claims of the different branches of science, and the extent 
 to which they and their applications had been already 
 developed, also the spheres still open to discovery. 
 
 The Introductory Remarks close, as follows : 
 
 In a word, the whole circle of physical science is directly 
 applicable to human wants and constantly holds out a light to 
 
32 A CENTURY OF SCIENCE 
 
 the practical arts; it thus polishes and benefits society and 
 everywhere demonstrates both supreme intelligence and harmony 
 and beneficence of design in the Creator. 
 
 The science of mathematics, both pure and mixed, can never 
 cease to be interesting and important to man, as long as the 
 relations of quantity shall exist, as long as ships shall traverse 
 the ocean, as long as man shall measure the surface or heights 
 of the earth on which he lives, or calculate the distances and 
 examine the relations of the planets and stars ; and as long as 
 the iron reign of war shall demand the discharge of projectiles, 
 or the construction of complicated defences. 
 
 The closing part of the paragraph shows the mflnence 
 exerted upon the mind of the editor by the serious wars 
 of the years preceding 1818, a subject alluded to again at 
 the close of this chapter. 
 
 In February, 1822, with the completion of the fourth 
 volume, the editor reviews the situation which, though 
 encouraging is bv no means fully assuring. He says 
 (preface to'vol. 4," dated Feb. 15, 1822) : 
 
 Two years and a half have elapsed, since the publication of 
 tlie first volume of this Journal, and one year and ten mouths 
 since the Editor assumed the pecuniary responsibility. . . . 
 
 The work has not, even yet, reimbursed its expenses, (we 
 speak not of editorial or of business compensation,) we intend, 
 that it has not paid for the paper, printing and engraving ; the 
 proprietors of the first volume being in advance, ou those 
 accounts, and the Editor on the same score, with respect to the 
 aggregate expense of the three last volumes. This deficit is, 
 however, no longer increasing, as the receipts, at present, just 
 about cover the expense of the physical materials, and of the 
 manual labour. A reiterated disclosure of this kind is not 
 grateful, and would scarcely be manly, were it not that the 
 public, who alone have the power to remove the difficulty, have 
 a right to a frank exposition of the state of the case. As the 
 patronage is, however, growing gradually more extensive, it is 
 believed that the work will be eventually sustained, although 
 it may be long before it will command any thing but gratuitous 
 intellectual labour. ... 
 
 These facts, with the obvious one, — that its pages are supplied 
 with contributions from all parts of the Union, and occasionally 
 from Europe, evince that the work is received as a national and 
 not as a local undertaking, and that the community consider it 
 as having no sectional character. Encouraged by \his view of 
 
AMERICAN JOURNAL OF SCIENCE 33 
 
 the subject, and by the favour of many distingTiishecl men, both 
 at home and abroad, and supported by able contributors, to 
 whom the Editor again tenders Ids grateful acknowledgments, 
 he will still persevere, in the hope of contributing something 
 to the advancement of our science and arts, and towards the 
 elevation of our national character. 
 
 In the autumn of the same jear, tlie editor closes the 
 fifth volume with a more confident tone (Sept. 25, 1822) ; 
 
 A trial of four years has decided the point, that the American 
 Public will support this Journal. Its pecuniary patronage is 
 now such, that although not a lucrative, it is no longer a hazard- 
 ous enterprise. It is now also decided, that the intellectual 
 resources of the countrj^ are sufficient to afford an unfailing 
 supply of valuable original communications and that nothing 
 but perseverance and eit'ort are necessarj^ to give perpetuity to 
 the undertaking. 
 
 The decided and uniform expression of public favour which 
 the Journal has received both at home and abroad, affords the 
 Editor such encouragement, that he cannot hesitate to per- 
 severe — and he now renews the expression of his thanks to the 
 friends and correspondents of the work, both in Europe and the 
 United States, requesting at the same time a continuance of their 
 friendly influence and efforts. 
 
 Still again in the preface to the sixth volume (1823) he 
 takes the reader more fully into his confidence and shows 
 that he regards the enterprise as no longer of doubtful 
 success. He says : 
 
 The conclusion of a new volume of a work, involving so much 
 care, labour and responsibility, as are necessarily attached, at 
 the present day, to a Journal of Science and the Arts, natur- 
 ally produces in the mind, a state of not ungrateful calmness, 
 and a disposition, partaking of social feeling, to say something 
 to those who honour such a production, by giving to it a small 
 share of their money, and of their time. The Editor's first 
 impression was, that the sixth volume should be sent into the 
 world without an introductory note, but he yields to the impulse 
 already expressed, and to the established usages of respectful 
 courtesy to the public, which a short preface seems to imply. 
 He has now persevered almost five years, in an undertaking, 
 regarded by many of the friends whom he originally consulted, 
 as hazardous, and to which not a few of them prophetically 
 alloted onl_y an ephemeral existence. It has been his fortune to 
 
3i A CENTURY OF SCIENCE 
 
 prosecute this work without, (till a very recent period,) returns, 
 adequate to its indispensable responsibilities ; — under a heavy 
 pressure of professional and private duty ; with trying fluctua- 
 tions of health, and amidst severe and reiterated domestic 
 afiSictions. The world are usually indulgent to allusions of this 
 nature, when they have any relation to the discharge of public 
 duty; and in this view, it is with satisfaction, that the Editor 
 adds, that he has now to look on formidable difficulties, onlj^ in 
 retrospect, and witli something of the feeling of him, who sees 
 a powerful and vanquished foe, slowly retiring, and leaving a 
 field no longer contested. 
 
 This Journal which, from the first, was fully supplied with 
 original communications, is now sustained by actual pajnnent, 
 to such an extent, that it may fairly be considered as an estab- 
 lished work ; its patronage is regularly increasing, and we trust 
 it M'ill no longer justify such remarks as some of the following, 
 from the pen of one of the most eminent scientific men in 
 Europe. "Nothing surprises me more, than the little encourage- 
 ment which j'our Journal," ("which I always read with very 
 great interest, and of which I make great use,") "experiences 
 in America — this must surely arise from the present depressed 
 condition of trade, and cannot long continue." 
 
 Six years more of uninterrupted editorial work passed 
 by, the sixteenth volume was completed, and the editor 
 was now in a position to review the wdiole situation up to 
 1829. This preface (dated July 1, 1829), which is quoted 
 nearly in full, cannot fail to be found particularly inter- 
 estino- and from several standpoints, not the least" for the 
 insight it gives into the writer's mind. It is also note- 
 worthy that at this early date it was found possible to 
 pay for original contributions, a privilege far beyond 
 the means of the editor of to-day. 
 
 Wlien this Journal was first projected, very few believed that 
 it would succeed. 
 
 Among others. Dr. Dorsey wrote to the editor; "I predict a 
 short life for you, although I wish, as the Spaniards say, that 
 you may live a thousand years." The work has not lived a 
 thousand years, but as it has survived more than the hundredth 
 part of that period, no reason is apparent why it may not con- 
 tinue to exist. To the contributors, disinterested and arduous 
 as have been their exertions, the editor's warmest thanks are 
 due; and they are equally rendered to numerous personal 
 friends for their unwavering support: nor ought those sub- 
 
AMERICAN JOURNAL OF SCIENCE 35 
 
 scribers to be forgotten who, occiipied iii the common pursuits 
 of life, have aided, by their money, in sustaining the hazardous 
 novelty of an American Journal of Science. A general appro- 
 bation, sufBciently decided to encourage effort, where there was 
 no other reward, has supported the editor ; but he has not been 
 inattentive to the voice of criticism, whether it has reached him 
 in the tones of candor and liindness, or in those of severity. 
 We must not look to our friends for the full picture of our 
 faults. He is unwise who neglects the maxim — 
 
 — fas est ab hoste doceri, 
 
 and we may be sure, that those are quite in earnest, whose 
 pleasure it is, to place faults in a strong light and bold relief; 
 and to throw excellencies into the shadow of total eclipse. 
 Minds at once enlightened and amiable, viewing both in their 
 proper proportions, will however render the equitable verdict; 
 
 Non ego paucis offendar maculis, — • 
 
 It is not pretended that this Journal has been faultless ; there 
 may be communications in it which had been better omitted, and 
 it is not doubted that the power to command intellectual effort, 
 by suitable pecuniary reward, would add to its purity, as a 
 record of science, and to its richness, as a repository of dis- 
 coveries in the arts. 
 
 But the editor, even now, offers payment, at the rate adopted 
 by the literary Journals, for able original communications, con- 
 taining especially important facts, investigations and discoveries 
 in science, and practical inventions in the useful and ornamental 
 Arts. 
 
 As however his means are insufficient to pay for all the copy, 
 it is earnestly requested, that those gentlemen, who, from other 
 motives, are still willing to write for this Journal, should con- 
 tinue to favor it with their communications. That the period 
 when satisfactory compensation can be made to all writers whose 
 pieces are inserted, and to wliom payment will be acceptable, is 
 not distant, may perhaps be hoped, from the spontaneous expres- 
 sion of the following opinion, by the distinguished editor of one 
 of our principal literary journals, whose letter is now before 
 me. "The character of the American Journal is strictly 
 national, and it is the only vehicle of communication in which 
 an inquirer may be sure to find what is most interesting in the 
 wide range of topics, which its design embraces. It has become 
 in short, not more identified with the science tlian the literature 
 of the countrj^. " It is believed that a strict examination of 
 its contents will prove that its character has been decidedly 
 scientific ; and the opinion is often expressed to the editor, tliat 
 
36 A CENTUEY OF SCIENCE 
 
 in common with the journals of our Academies, it is a work of 
 reference, indispensable to him who would examine the progress 
 of American science during the period which it covers. That it 
 might not be too repulsive to the general reader, some miscel- 
 laneous pieces have occasionally occupied its pages; but in 
 smaller proportion, than is common with several of the most 
 distinguished British Journals of Science. 
 
 Still, the editor has been frequently solicited, both in public 
 and private, to make it more miscellaneous, that it might be 
 more acceptable to the intelligent and well educated man, who 
 does not cultivate science; but he has never lost sight of his 
 great object, which was to produce and concentrate original 
 American effort in science, and thus he has foregone pecuniary 
 returns, which by pursuing the other course, might have been 
 rendered important. Others would not have him admit any 
 thing that is not strictly and technically scientific ; and would 
 make this journal for mere professors and amateurs ; especially 
 in regard to those numerous details in natural history, M'hich 
 although important to be registered, (and which, when pre- 
 sented, have always been recorded in the American Journal,) 
 can never exclusively occupy the pages of any such work without 
 repelling the majority of readers. 
 
 If this is true even in Great Britain it is still more so in this 
 country ; and our savants, unless they would be, not only the 
 exclusive admirers, but the sole purchasers of their own works, 
 must permit a little of the graceful drapery of general literature 
 to flow around the cold statvies of science. The editor of this 
 Journal, strongly inclined, both from opinion and habit, to 
 gratify the cultivators of science, will still do everything in his 
 power to promote its high interests, and as he hopes in a better 
 manner than heretofore ; but these respectable gentlemen will 
 have the courtesy, to yield something to the reading literary, as 
 well as scientific public, and will not, we trust, be disgl^sted, 
 if now and then an Oasis relieves the eye, and a living stream 
 refreshes the traveller. Not being inclined to renew the abortive 
 experiment, to please every body, which has been so long 
 renowned in fable; the editor will endeavor to pursue, the 
 even tenor of his way; altogther inclined to be courteous and 
 useful to his fellow travellers, and hoping for their kindness 
 and services in return. 
 
 T/te Close of the First Series. 
 
 The "First Series," as it was henceforth to be kno^vn, 
 closed with the fiftieth volume (1847, pp. xx -f 347). 
 This final volume is devoted to an exhaustive index to the 
 
'iM £. ff-UJ 
 
 I 
 
AMERICAN JOURNAL OF SCIENCE 37 
 
 forty-nine volumes preceding. In the preface (dated 
 April 19, 1847) the elder Silliman, now the senior editor, 
 reviews the work that had been accomplished with a 
 frank expression of his feeling of satisfaction in the vic- 
 tory won against great obstacles ; with this every reader 
 must sympathize. He quotes here at length (but in 
 slightly altered form) the matter from the hrst volume 
 (1818), which has been already reproduced almost 
 entire, and then goes on as follows (pp. xi et seq.) : 
 
 Sucli was the pledge wliich, on entering upon our editorial 
 labors in 1818, we gave to the public, and such were the views 
 which we theu eutertained, regarding science and the arts as 
 connected with the interests and honor of our country and of 
 mankind. In the retrospect, we realize a sober hut grateful 
 feeling of satisfaction, in having, to the extent of our power, 
 discharged these self-imposed obligations ; this feeling is chas- 
 tened also by a deep sense of gratitude, first to God for life and 
 power continued for so high a purpose ; and next, to our noble 
 band of contributors, whose labors are recorded in half a century 
 of volumes, and in more than a quarter of a century of years. 
 "We need not conceal our conviction, that the views expressed 
 in these "Introductory Remarks," have been fully sustained 
 by our fellow laborers. 
 
 Should we appear to take higher ground than becomes us, 
 we find our vindication in the fact, that we have heralded 
 chiefly the doings and the fame of others. The work has indeed 
 borne throughout "the impress" of editorial unity of design, 
 and much that has flowed from one pen, and not a little from 
 the pens of others, has been without a name. The materials 
 for the pile, have however been selected and brought in, chiefly 
 by other hands, and if the monument which has been reared 
 should prove to be "aere perennius," the honor is not the sole 
 property of the architect; those who have quarried, hewn and 
 polished the granite and the marble, are fully entitled to the 
 enduring record of their names already deeply cut into the 
 massy blocks, which themselves have furnished. 
 
 If a retrospective survey of the labors of thirty .vears on this 
 occasion has rekindled a degree of enthusiasm, it is a natural 
 result of an examination of all our volumes from the contents 
 of which we have endeavored to make out a summary both of 
 the laborers and their works. . . . 
 
 The series of volumes must ever form a work of permanent 
 interest on account of its exhibiting the progress of American 
 science during the long period which it covers. Comparing 
 
38 A CENTURY OF SCIENCE 
 
 1817 with 1847, we mark on this subject a very gratifj^ng change. 
 The cultivators of science in the United States were then few — 
 now they are numerous. Societies and associations of various 
 names, for the cultivation of natural history, have been insti- 
 tuted in very many of our cities and towns, and several of them 
 have been active and efficient in making original observations 
 and forming collections. 
 
 A summary follows presenting some facts as to the 
 growth of scientific societies and scientific collections in 
 this country during the period involved: Then the 
 striking contrast between 1818 and 1847 in the matter of 
 organized effort toward scientific exploration is dis- 
 cussed, as follows (pp. xvi et seq.) : 
 
 When we began our Journal, not one of the States had been 
 .surveyed in relation to its geology and natural history; now 
 those that have not been explored are few in number. State 
 collections and a United States j\Iuseum hold forth many allure- 
 ments to the young naturalist, as well as to the archsologist and 
 the student of his own race. The late Exploring Expedition 
 [Wilkes] with the National Institute, has enriched the capital 
 with treasures rarely equalled in any country, and the Smith- 
 sonian Institution recently organized at Washington, is about 
 to begin its labors for the increase and diffusion of knowledge 
 among men. 
 
 It must not be forgotten that the American Association of 
 Geologists and Naturalists — composed of individuals assembled 
 from widely separate portions of the Union — by the seven ses- 
 sions which it has held, and by its rich volume of reports, has 
 produced a concentration and harmony of effort which promise 
 happy results, especially as, like the British Association, it 
 visits different towns and cities in its annual progress. 
 
 Astronomy now lifts its exploring tubes from the observatories 
 of many of our institutions. Even the Ohio, which within the 
 memory of tlie oldest living men, rolled along its dark waters 
 through interminable forests, or received the stains of blood 
 from deadly Indian warfare, now beholds on one of its most 
 beautiful hills, and near its splendid city, a permanent obser- 
 vatory with a noble telescope sweeping the heavens, by the hand 
 of a zealous and gifted observer. At Washington also, under 
 the powerful patronage of the general government, an excellent 
 observatory has been established, and is furnished with superior 
 instruments, under the direction of a vigilant and well instructed 
 astronomer — seconded by able and zealous assistants. 
 
 Here also (in Tale College) successful observations have been 
 
AMERICAN JOUENAL OF SCIENCE 39 
 
 made with good instruments, although no permanent building 
 has been erected for an Observatory. 
 
 We only give single examples by way of illustration, for the 
 history of the progress of science in the United States, and of 
 institutions for its promotion, during the present generation, 
 would demand a volume. It is enough for our purpose that 
 science is understood and valued, and the right methods of 
 prosecuting it are known, and the time is at hand when its moral 
 and intellectual use will be as obvious as its physical applica- 
 tions. Nor is it to be forgotten that we have awakened an 
 European interest in our researches: general science has been 
 illustrated by treasures of facts drawn from this country, and 
 our discoveries are eagerly sought for and published abroad. 
 
 "While with our co-workers in many parts of our broad land, 
 we rejoice in this auspicious change, we are far from arrogating 
 it to ourselves. Multiplied labors of many hands have produced 
 the great results. In the place which we have occupied, we 
 have persevered despite of all discouragements, and may, with 
 our numerous coadjutors, claim some share in the honors of the 
 daj^ We do not say that our work might not have been better 
 done — but we may declare with truth that we have done all in 
 our power, and it is something to have excited many others to 
 effort and to have chronicled their deeds in our annals. Let 
 those that follow us labor with like zeal and perseverance, and 
 the good cause will continue to advance and prosper. It is the 
 cause of truth — science is only embodied and sympathized truth 
 and in the beautiful conception of our noble Agassiz — "it tells 
 the thought of God." 
 
 The preface closes "\vitli some personal remarks : 
 
 In tracing back the associations of many gone-by years, a 
 host of thoughts rush in, and pensive remembrance of the dead 
 who have labored with us casts deep shadows into the vista 
 through which we view the past. 
 
 Anticipation of the hour of discharge, when our summons 
 shall arrive, gives sobriety to thought and checks the confidence 
 which health and continued power to act might naturally inspire, 
 were we not reproved, almost every day, by the death of some 
 co-eval, co-worker, companion, friend or patron. This very hour 
 is saddened by such an event, — but we will continue to labor 
 on, and strive to be found at our post of duty, until there is 
 nothing more for us to do ; trusting our hopes for a future life 
 in the hands of Him who placed us in the midst of the splendid 
 garniture of this lower world, and who has made not less ample 
 provision for another and a better. 
 
40 A CENTURY OF SCIENCE 
 
 Editorial and fiiunwial-^Tlie editorial labors on the 
 Journal were carried by the elder Silliman alone for 
 t^venty years from 1818 to 1838. As has been clearly 
 shown in his statements, already quoted, he was, after the 
 first beginning, personally responsible also for the finan- 
 cial side of tiie enterprise. With volume 34 (1838) the 
 name of Benjamin Silliman, Jr., is added as co-editor on 
 the title page. He was graduated from Tale College the 
 j^ear preceding and at this date was only twenty-one 
 years old. His aid was unquestionably of much service 
 from the beginning and increased rapidly with years and 
 experience. The elder Silliman introduces him in the 
 preface to vol. 34 (1838) and comes back to the subject 
 again in the preface to vol. 50 (1847). The whole edi- 
 torial situation is here presented as follows : 
 
 "During twenty years from the inception of this Journal, the 
 editor laliored alone, ahhoug^h overtures for editorial co-opera- 
 tion had been made to him by gentlemen commanding his con- 
 fidenee and esteem, and who would personally have been very- 
 acceptable. It was, however, his opinion that the unity of 
 purpose and action so essential to the success of such a work 
 were best secured by individuality ; but he made every effort, 
 and not without success, to conciliate the good will and to secure 
 tlie assistance of gentlemen eminent in particular departments 
 of knowledge. On the title page of No. 1, vol. 34, published in 
 July, 1888, a new name is introduced: the individual to whom 
 it belongs liaving been for several j'ears more or less concerned 
 in the management of the Journal, and from his education, 
 position, pursuits and taste, as well as from affinity, being almost 
 identified with the editor, he seemed to be quite a natural ally, 
 and his adoption into the editorship was scarcely a violation of 
 individual unity. His assistance has proved to "be very import- 
 ant: — his near relation to the senior editor prevents him from 
 saying more, while justice does not permit him to say less." 
 
 As is distinctly intimated in the preceding paragraph 
 the elder Silliman was fortunate in obtaining the assist- 
 ance in his editorial labors of numerous gentlemen inter- 
 ested in the enterprise. Their cooperation provided 
 many of the scientific notices, liook reviews and the like 
 contained in the JMiscellany with which each number 
 closed. It is impossible, at this date, to render the credit 
 due to Silliman 's helpers or even to mention them by 
 
AMERICAN JOURNAL OF SCIENCE il 
 
 name. Very early Asa Graj^ was one of these as occa- 
 sional notes are signed by his initials. Dr. Levi Ives of 
 New Haven was another. Prof. J. Griscom of Paris also 
 sent numerous contributions even as early as 1825 (see 
 9, 154, 1825; 22, 192, 1S32; 24, ;J12, 1833, and others). 
 
 Some statements have already been quoted from the 
 early volumes as to the business part of Silliman's enter- 
 prise. The subject is taken up more fully in the preface 
 to volume 50 (1847). No one can fail to marvel at the 
 energy and optimism required to push the Journal for- 
 ward when conditions must have been so difficult and 
 encouragement so scanty. He says (pp. iii, iv) : 
 
 This Journal first appeared in Julj', 1818, and in June, 1819, 
 the first volume of four numbers and 448 pages was completed. 
 This scale of publication, originallj' deemed sufficient, was found 
 inadequate to receive all the communications, and as the receipts 
 proved insufficient to sustain the expenses, the work, having but 
 three hundred and fifty subscribers, was, at the end of the year, 
 abandoned by the publishers. 
 
 An unprofitable enterprise not being attractive to the trade, 
 ten months elapsed before another arrangement could be carried 
 into effect, and, therefore, No. 1 of vol. 2 was not published until 
 April, 1820. The new arrangement was one of mutual responsi- 
 bility for the expenses, but the Editor was constrained neverthe- 
 less to pledge his own personal credit to obtain from a bank the 
 funds necessaiy to begin again, and from this responsibility he 
 was, for a series of years, seldom released. The single volume 
 per annum being found insufficient for the communications, 
 two volumes a year were afterward published, commencing with 
 the second volume. 
 
 The publishers whose names appear on the title page 
 of the four numbers of the first volume are ' ' J. Eastburn 
 & Co., Literary Rooms, Broadway, New York" and Howe 
 & Spalding, New Haven." For the second volume and 
 those immediately following the corresponding state- 
 ment "printed and published by S. Converse [New 
 Haven] for the Editor. " 
 
 Silliman adds (p. iv) : 
 
 At the conclusion of vol. 10, in Februarj'-, 1826, the work was 
 again left upon the hands of its Editor; all its receipts had been 
 absorbed by the expenses, and it became necessary now to pay 
 a heavy sum to the retiring publisher, as an equivalent for his 
 
42 A CENTURY OF SCIENCE 
 
 copies of previous volumes, as it was deemed necessary either 
 to eoutrol the work entirely or to abandon it. The Editor was 
 not willing to think of the latter, especially as he was encouraged 
 by public approbation, and was cheered onward in his labors by 
 eminent men both at home and abroad, and he saw distinctly 
 that the Journal was rendering service not only to science and 
 the arts, but to the reputation of his country. He reflected, 
 moreover, that in almost every valuable enterprise perseverance 
 in effort is necessary to success. He being now sole proprietor, 
 a new arrangement was made for a single year, the publishers 
 being at liberty, at the end of that time, to retire, and the Editor 
 to resume the Journal should he prefer that course. 
 
 The latter alternative he adopted, taking upon himself the 
 entire concern, including both the business and the editorial 
 duties, and of course, all the correspondence and accounts. 
 From that time the work has proceeded without interruption, 
 two volumes per annum having been published for the last 
 twenty years; and its pecuniary claims ceased to be onerous, 
 although its means have never been large. . . . 
 
 Later in the same preface lie adds (p. siv) : 
 
 It may be interesting to our readers to know something of the 
 patronage of the Journal. It has never reached one thousand 
 paying subscribers, and has rarely exceeded seven or eight 
 hundred — for many years it fluctuated between six and seven 
 hundred. 
 
 It has been far from paying a reasonable editorial compensa- 
 tion; often it has paid nothing, and at present it does little 
 more than pay its bills. The number of engravings and the 
 extra labor in printer's composition, cause it to be an expensive 
 work, while its patronage is limited. 
 
 It is difficult at this date to give any adequate state- 
 ment of the amount of encouragement and active assist- 
 ance given to Silliman by his scientific coUeagties in New 
 Haven and elsewhere — a subject earlier alluded to. It 
 is fortunately possible, however, to acknowledge the gen- 
 erous aid received by the Journal in the early days from 
 a source near at hand. It has already been noted in 
 another place that the dawning activitj^ of science at New 
 Haven was recognized by the founding of the "Connecti- 
 cut Academy of Arts and Sciences," formally estab- 
 lished at New Haven in 1799 and the third scientific body 
 to be organized in this country. From the beginnino- of 
 
AMERICAN JOURNAL OF SCIENCE 43 
 
 the Journal in 1818, the Connecticut Academy freely 
 gave its support hoth in papers for pnhlication and at 
 least on one occasion later it gave important financial aid. 
 Upon the occasion of the celebration of the centennial 
 anniversary of the Academy on October 11, 1899, Pro- 
 fessor, later Governor, Baldwin, the president of the 
 Academy, discusses this subject in some detail. He says 
 in part : 
 
 To support his [Sillinian's] luidertaking, a vote had been 
 passed in February [1818], "that the Committee of PubUcation 
 may allow such of the Academy's papers as they think proper, 
 to be published in Mr. Sillinian's Seientific Journal." 
 
 Free use was made of this authority, and a large part of the 
 contents of the Journal was for many years drawn from this 
 source. In some cases this fact was noted in publication f but 
 in most it was not. . . . 
 
 In 1826, when the Journal was in great need of financial sup- 
 port, the Academy further voted to pay for a year the cost of 
 printing such of its papers as might be published in it. In 
 Baldwin's Annals of Yale College, published in 1831, it is 
 described as a publication "honorable to the science of our 
 common country, ' ' and having ' ' an additional value as being 
 adopted as the acknowledged organ of the Connecticut Academy 
 of Arts and Sciences." 
 
 Many active campaigns were carried on over the 
 country through paid agents to obtain new subscribers 
 for the Journal and it was doubtless due to these efforts 
 that the nominal subscription list was, at times, as 
 already noted, relatively large as compared with that of a 
 later date. The new subscribers in many cases, however, 
 did not remain permanently interested, often failed to 
 pay their bills, and the uncertain and varying demand 
 upon the supply of printed copies was doubtless one 
 reason why many single numbers became early out of 
 print. 
 
 An interesting sidelight is thrown upon the efforts of 
 Silliman to interest the public in his work, at its begin- 
 ning, by a letter to the editor from Thomas Jefferson, 
 then seventy-five years of age. The writer is indebted to 
 Mr. Robert B. Adam of Buffalo for a copy of this letter 
 and its interest justifies its being reproduced here entire. 
 The letter is as follows : 
 
44 A CENTURY OF SCIENCE 
 
 Monticello, Apr. 11. '18. 
 Sir 
 
 Tlie unlueky displacement of your letter of Mar 3 has been 
 the cause of delay in my answer, altlio' I have very generally 
 withdrawn from subscribing to or reading periodical publica- 
 tions from the love of rest which age produces, yet I willingly 
 subscribe to the journal you propose from a confidence that the 
 talent with which it will be edited will entitle it to attention 
 among the things of select reading for which alone I have time 
 now left, be so good as to send it by mail, and the receipt of 
 the 1st number will be considered as announcing tliat the work 
 is commenced and the subscription money for a year shall be 
 forwarded. Accept the assurance of my great esteem and 
 respect. 
 
 Th. Jefferson 
 
 Professor Silliman. 
 
 Contributors. — An interesting summary is also gi^^n 
 by Silliman of tlie contributors to the Journal and tlie 
 extent of their work (vol. 50, pp. xii, xiii) ; he says : 
 
 We find that there have been about 600 contributors of orig- 
 inal matter to the Journal, and we have the unexpected satis- 
 faction of believing that probably five-sixths of them are still 
 living; for we are not certain that more than fifij^ are among 
 the dead ; of perhaps fifty more we are without information, 
 and if that additional number is to be enrolled among the ' ' stel- 
 ligeri," we have still 500 remaining. Among them are not a 
 few of the veterans with whom we began our career, and several 
 of these are still active contributors. Shall we then conclude 
 that the peaceful pursuits of knowledge are favorable to long 
 life ? This we think is, cccteris paribus, certainly true : but in 
 the present instance, another reason can be assigned for the 
 large amount of survivorship. As the Journal has advanced 
 and death has removed its scientific contributors, younger men 
 and men still younger, have recruited the ranks, and volunteers 
 have enlisted in numbers constantly increasing, so that the 
 flower of the host are now in the morning and meridian of life. 
 
 We have been constantly advancing, like a traveller from the 
 equinoctial towards the colder zones, — as we have increased our 
 latitude, stars have set and new stars have ris;cn, while a few 
 planetary orbs visible in every zone, have contiiuied to cheer us 
 on our course. 
 
 The number of articles, almost exclusively original, contained 
 in the Journal is about 1800, and the Index will show' how many 
 
AMERICAN JOURNAL OF SCIENCE 45 
 
 have been contributed by each individual; we have doubtless 
 included in this number some feiv articles republished from 
 foreign Journals — but we think they are even more than coun- 
 terbalanced by original communications without a name and by 
 editorial articles, both of which have been generally omitted in 
 the enumeration. 
 
 Of smaller articles and notices in the Miscellany, we have not 
 made any enumeration, but they evidently are more numerous 
 than the regidar articles, and we presume that they may amount 
 to at least 2500. 
 
 Of party, either in politics or religion, there is no trace in 
 our work; of personalities there are none, except those that 
 relate to priority of claims or other rights of individuals. Of 
 these vindications the number is not great, and we could heartily 
 have wished that there had been no occasion for anj^ 
 
 General Scope of Articles. — Many references will be 
 found in the chapters following which throw light upon 
 the character and scope of the papers published in the 
 Journal, particularly in its early years ; a few additional 
 statements here may, however, prove of interest. 
 
 One feature that is especially noticeable is the frequent 
 publication of articles planned to place before the read- 
 ers of the Journal in full detail subjects to which they 
 might not otherwise have access. These are sometimes 
 translations; sometimes republications of articles that 
 had already appeared in English periodicals; again, 
 they are exhaustive and critical reviews of important 
 memoirs or books. The value of this feature in the early 
 history of the Journal, when the distribution of scientific 
 literature had nothing of the thoroughness characteristic 
 of recent years, is sufficiently obvious. 
 
 It is also interesting to note the long articles of geo- 
 logical description and others giving lists of mineral or 
 botanical localities. Noteworthy, too, is the attempt to 
 keep abreast of occurring phenomena as in the many 
 notes on tornadoes and storms by Redfield, Loomis, etc. ; 
 on auroras at different localities ; on shooting stars by 
 Herrick, Olmstead and others. 
 
 The wide range of topics treated of is quite in accord- 
 ance with the plan of the editor as given on an earlier 
 page. Some notes, taken more or less at random, may 
 serve to illustrate this point. An extended and quite 
 
46 A CENTURY OF SCIENCE 
 
 teelmical discussion of "Musical Temperament" opens 
 the first number (1, pp. 9-35) and is concluded in the same 
 volume (pp. 176-199) . An article on ' ' Mystery" is given 
 by Mark Hopkins, A.M., "late a tutor of Williams Col- 
 lege" (13, 217, 1828). There is an essay on "Gj^sies" 
 by J. Grriscom (from the Eevue Encyclopedique) in vol- 
 ume 24 (pp. 342-.345, ] 833), while some notes on American 
 gypsies are added in vol. 26 (p. 189, 1834). The "divin- 
 ing rod" is described at length in vol. 11 (pp. 201-212, 
 1826), but without giving any comfort to the credulous; 
 on the contrary the last paragraph states that "the pre- 
 tensions of diviners are worthless, etc." A long article 
 by J. Finch on the forts of Boston harbour appeared 
 in 1824 (8, 338-348) ; the concluding paragraph seems 
 worthy of quotation : 
 
 "Many centuries hence, if despotism without, or anarchy 
 within, should cause the republican institutions of America to 
 fade, then these fortresses ought to be destroyed, because they 
 would be a constant reproach to the people ; but until that 
 period, they should be preserved as the noblest monuments of 
 liberty. ' ' 
 
 The promise to include the fine arts is kept by the pub- 
 lication of various papers, as of the Trumbull paintings 
 (16, 163, 1829) ; also by a series of articles on "architec- 
 ture in the United States" (17, 99, 1830; 18, 218, 220, 
 1830) and others. Quite in another line is the paper by 
 J. W. Gibbs (33, 324, 1838) on "Arabic words in 
 English. ' ' A number of related linguistic papers by the 
 same author are to be found in other volumes. Papers 
 in pure mathematics are also not infrequent, though 
 now not considered as falling Avithin the field of the 
 Journal. 
 
 Applied science takes a prominent place through all the 
 volume of the First Series. An interesting paper is that 
 on Eli Whitney, containing an account of the cotton gin ; 
 this is accompanied by an excellent portrait (21, 201-264, 
 1832). The steam engine and its application are repeat- 
 edly discussed and in the early volumes brief accounts 
 are given of the early steamboats in use; for example, 
 between Stockholm and St. Petersburg (2, 347, 1820) ; 
 Trieste and Venice (4, 377, 1822) ; on the Swiss Lakes 
 
AMERICAN JOURNAL OF SCIENCE 47 
 
 (6, 385, 1823). The voyacje of the first Athantic steam- 
 boat, the "Savannah," Avhich crossed from Savannah 
 to Liverpool in 1819, is described (38, 155, 1840) ; men- 
 tion is also made of the "first iron boat" (3, 371, 1821; 
 5, 396, 1822). A nnmber of interestinft' letters on 
 "Steam Navigation" are given in vol. 35, 160, 162, 332, 
 333, 336; some of the suggestions seem very quaint, 
 viewed in the light of the experience of to-day. 
 
 A very early form of explosive engine is described at 
 length by Samuel IMorey (11, 104, 1826) ; this is an article 
 that deserves mention in these days of gasolene motors. 
 Even more interesting is the description by Charles Gris- 
 wold (2, 94, 1820) of the first suhmarine invented by 
 David Bushnell and used in the Revolutionary War in 
 August, 1776. An account is also given of a dirigible 
 balloon that may be fairly regarded as the original ances- 
 tor of the Zeppelin (see 11, 346, 1826). The whole sub- 
 ject of aerial navigation is treated at length by H. Strait 
 (25, pp. 25, 26, 1834) and the expression of his hopes for 
 the future deserve quotation : 
 
 "Conveyance by air can be easily rendered as safe as by 
 water or land, and more cheap and speedy, while the universal 
 and uniform diffusion of the air over every portion of the 
 earth, will render aerial navigation preferable to any otlier. To 
 carry it into effect, there needs only an immediate appeal on a 
 sufficiently large scale, to experiment ; reason has done her part, 
 when experiment does hers, nature will not refuse to sanction the 
 whole. Aerial navigation will present the works of nature in 
 all their charms; to commerce and the diffusion of knowledge, 
 it will bring the most efficient aid, and it can thus be rendered 
 serviceable to the whole human family." 
 
 A subject of quite another character is the first discus- 
 sion of the properties of chloroform (chloric ether) and 
 its use as an anassthetic (Guthrie, 21, 64, 405, 1832; 
 22, 105, 1832; Levi Ives, 21, 406). Further interesting 
 communications are given of the first analyses of the gas- 
 tric juice and the part played by it in the process of 
 digestion. Dr. William Beaumont of St. Louis took 
 advantage of a patient who through a gun-shot wound 
 Avas left with a permanent opening into his stomach 
 through which the gastric juice could be drawn off. The 
 
48 A CENTURY OF SCIENCE 
 
 results of Dr. Beaumont and of Professor Robley Dungli- 
 son, to whom samples were submitted, are given in full 
 in the life of Beaumont by Jesse S. Myer (St. Louis, 
 1912). The interest of the matter, so far as the Journal 
 is concerned, is chiefly because Dr. Beaumont selected 
 Professor Silliman as a chemist to whom samples for 
 examination were also submitted. An account of Silli- 
 man 's results is given in the Beaumont volume referred 
 to (see also 26, 193, 1834). Desiring the support of a 
 chemist of wider experience in organic analysis, he also 
 sent a sample through the Swedish consul to Berzelius in 
 Stockholm. After some months the sample was received 
 and it is interesting to note in a perfectly fresh condi- 
 tion; it is to be regretted, however, that the Swedish 
 chemist failed to add anvthing to the results already 
 obtained in this country (27, 40b, 1835). 
 
 The above list, which might be greatly extended, seems 
 to leave little ground for the implied criticism replied to 
 by Silliman as follows (16, p. v, 1829) : 
 
 A celebrated scholar, while himself an editor, advised me, in 
 a letter, to introduce into this Journal as much " readcible" 
 matter as possible : and there was, pretty early, an earnest but 
 respectful recommendation in a Philadelphia paper, that Litera- 
 ture, in imitation of the London Quarter!}' Journal of Science, 
 &c. should be in form, inscribed among the titles of the work. 
 
 The Second, Third and Fourth Series. 
 
 The Second Series of the Journal, as already stated, 
 began with January, 1846. Up to this time the publica- 
 tion had been a quarterly or two volumes annually of two 
 numbers each. Prom 1846 until the completion of an 
 additional fifty vohmies in 1871, the Journal was made a 
 bimonthly, each of the tAvo yearly volumes having three 
 numbers each. Furthermore, a general index was given 
 for each period of five years, that is for everj^ ten 
 volumes. 
 
 Much more important than this cliange was the addi- 
 tion to the editorial staff of James Dwight Dana, Silli- 
 man 's son-in-law. Dana returned from the four-years 
 cruise of the AVilkes Exploring Expedition in 1842; he 
 settled in New Haven, was married in 1844, and in 1850 
 
'atu>^..A-^ ^ 
 
 cuu.ye'^^^ 
 
AMERICAN JOURNAL OF SCIENCE 49 
 
 was appointed Silliman professor of Geology in Yale 
 College. He was at this time actively engaged in writ- 
 ing Ms three quarto reports for the Expedition and 
 hence did not begin his active professional duties in Yale 
 College until 1856. Part of his inaugural address was 
 quoted on an earlier page. 
 
 Dana had already performed the severe labor of pre- 
 paring the complete index to the First Scries, a volume 
 of about 350 pages, finally issued in 1847. From the 
 beginning of the Second Scries he was closely associated 
 with his brother-in-law, the younger Silliman. Later the 
 editorial labor devolved more and more upon him and the 
 larger part of this he carried until about 1890. His work, 
 was, however, somewhat interrupted during periods of ill 
 health. This was conspicuously true during a year's 
 absence in Europe in 1859-60, made necessary in the 
 search for health; during these periods the editorial 
 responsibility rested entirely upon the younger Silliman. 
 Of Dana's contributions to science in general this is not 
 the place to speak, nor is the present writer the one to 
 dwell in detail upon his work for the Journal. This sub- 
 ject is to such an extent involved in the history of geology 
 and zoology, the subjects of several succeeding chapters, 
 that it is adequately presented in them. 
 
 It may, however, be worth stating that in the bibliog- 
 raphv accompanving the obituary notice of Dana (49, 
 329-356, 1895) some" 250 titles of articles in the Journal 
 are enumerated; these aggregate approximately 2800 
 pages. The number of critical notes, abstracts, book 
 reviews, etc., could be also given, were it worth while, but 
 what is much more significant in this connection, than 
 their number or aggregate length, is the fact that these 
 notices are in a large number of cases — like those of Gray 
 in botany — minutely critical and original in matter. 
 They thus give the writer's own opinion on a multitude 
 of different subjects. It was a great benefit to Dana, as 
 it was to science also, that he had this prompt means at 
 hand of putting before the public the results of his active 
 brain, which continued to work unceasingly even in times 
 of health prostration. 
 
 This may be the most convenient place to add that as 
 Dana became gradually less able to carry the burden of 
 
50 A CENTURY OF SCIENCE 
 
 the details involved in editing the Journal in addition to 
 his more important scientific labors, particularly from 
 1890 on, this work devolved more and more upon his son, 
 the present editor, whose name was added to the editorial 
 staff in 1875, with volume 9, of the Third Series. The' 
 latter has served continuously until the present time, 
 with the exception of absences, due to ill health, in 1893-94 
 and in 1903 ; during the first of these Professor Henry S. 
 Williams and during the second Professor H. E. Greg- 
 ory occupied the editorial chair. 
 
 The Third Seeies began in 1871, after the completion 
 of the one-hundredth volume from the beginning in 1818. 
 At this date the Journal was made a monthly and as such 
 it remains to-day. Fifty volumes again completed this 
 series, which closed in 1895. 
 
 The FouETH Seeies began with January, 1896, and the 
 present number for July, 1918, is the opening one of the 
 forty-sixth volume or, in other words, — the one hundred 
 and ninety-sixth volume of the entire issue since 1818. 
 The Fourth Series, according to the precedent estab- 
 lished, will end with 1920. 
 
 Associate Editors. — In 1851 the new policy was intro- 
 duced of adding "Associate Editors" to the staff. The 
 first of these was Dr. Wolcott Gibbs of Cambridge. He 
 began his duties with the eleventh volume of the Second 
 Series in 1851 and continued them with unceasing care 
 and thoroughness for more than twenty vears. In a note 
 dated Jan.'l, 1851 (11, 105), he says: " 
 
 It is my intention in future to prepare for the columns of this 
 Journal abstracts of the more important pliysieal and eliemieal 
 memoirs contained in foreign scientific journals, accompanied 
 by references, and hy such critical observations as tlie occasion 
 may demand. Contributions of a similar character from others 
 will of course not be excluded by this arrangement, but I shall 
 hold myself responsible only for those notices which appear 
 over my initials. 
 
 The departments covered by Dr. Gibbs, in his excellent 
 monthly contributions, embraced chemistrj^ and physics, 
 and these subjects were carried together until 1873 "when 
 they were separated and the plwsical notes were fur- 
 
AMERICAN JOURNAL OF SCIENCE 51 
 
 nislied, first by Alfred M. Mayer and later successively 
 by E. C. Pickering (from 1874), J. P. Cooke (from 1877), 
 and John Trowbridge (from 1880). The first instalment 
 of the long series of notes in chemistry and chemical 
 physics by George F. Barker was printed in volume 50, 
 1870. He came in at first to occasionally relieve Dr. 
 Gibbs, but soon took the entire responsibility. His name 
 was placed among the associate editors on the cover in 
 1877 and two years later Dr. Gibbs formally retired. It 
 may be added that from the beginning in 1851 to the 
 present time, the notes in "Chemistry and Physics" have 
 been continued almost without interruption. 
 
 The other departments of science have been also fully 
 represented in the notes, abstracts of papers pub- 
 lished, book notices, etc., of the successive numbers, but 
 as with the chemistry and physics the subject of botany 
 was long treated in a similar formal manner. For the 
 notes in this department, the Journal was for many years 
 indebted to Dr. Asa Gray, who became associate editor in 
 1853, two years after Gibbs, although he had been a 
 not infrequent contributor for many years previously. 
 Gray's contributions were furnished with great regu- 
 larity and were always critical and original in matter. 
 They formed indeed one of the most valuable features 
 of the Journal for many years ; as botanists well appre- 
 ciate, and, as Professor Goodale has emphasized in his 
 chapter on botany, Gray's notes are of vital importance 
 in the history of the development of his subject. With 
 Gray's retirement from active duty, his colleague, 
 George "W. Goodale, took up the work in 1888 and in 1895 
 William G. Farlow, also of Cambridge, was added as an 
 associate editor in cr^-ptogamic botany. At this time, 
 however, and indeed earlier, the sphere of the Journal 
 had unavoidably contracted and botany perforce ceased 
 to occupy the prominent place it had long done in the 
 Journal pages. 
 
 This is not the place to present an appreciation of the 
 truly magnificent Avork of Asa Gray. It may not be out 
 of place, however, to call attention to the notice of Gray 
 written for the Journal bv his life-long friend, James D. 
 Dana (35, 181, 1888). The opening paragraph is as 
 follows : 
 
r,'), 
 
 A CENTURY OF SCIENCE 
 
 "Our friend and associate, Asa Gray, the eminent botanist 
 of America, the broad-minded student of nature, ended his life 
 of unceasing and fruitful work on the 30th of January last. 
 For thirty -five years he has been one of the editors of this Jour- 
 nal, and for more than fifty years one of its contributors ; and 
 through all his communications there is seen the profound and 
 always delighted student, tlie accomplished writer, the just and 
 genial critic, and as Darwin has well said, ' The lovable man. 
 
 The tliird associate editor, following Gray, was Louis 
 Agassiz, whose •worli for science, particularly in his 
 adopted home in this country, calls for no praise here. 
 His term of service extended from 1853 to 1866 and, par- 
 ticularly in the earlier j^ears, his contributions were nu- 
 merous and important. The next gentleman in the list 
 was Waldo I. Burnett, of Boston, who served one year 
 only, and then followed four of Dana's colleagues in New 
 Haven, of whose generosity and able assistance it would 
 be impossible to say too much. These gentlemen were 
 Brush in mineralogy ; Johnson in chemistry, particularly 
 on the agricultural side ; New'ton in mathematics and 
 astronomy, whose contributions will be spoken of else- 
 where ; and Verrill — a student of Agassiz — in zoology. 
 
 All of these gentlemen, besides their frequent and 
 important original articles, were ever ready not only to 
 give needed advice, but also, to furnish brief communi- 
 cations, abstracts of papers and book reviews, and other- 
 wise to aid in the work. Verrill particularly furnished 
 the Journal a long list of original and important papers, 
 chiefly in systematic zoology, extending from 1865 
 almost down to the present year. His abstracts and 
 book notices also were numerous and trenchant and it is 
 not too much to say that without him the Journal never 
 could have tilled the place in zoology which it so long 
 held. LIuch later the list of New Haven men was 
 increased by the addition of Henry S. Williams (1894), 
 andO. C. Marsh (1895). 
 
 Of the valuable work of those more or less closely asso- 
 ciated in the conduct of the Journal at the present time, 
 it would not be appropriate to speak in detail. It must 
 suffice to say that the services rendered freely by them 
 have been invaluable, and to their aid is due a large part 
 of the success of the Journal, especially since the Fourth 
 
^^tA^^'M^ 
 
AMERICAN JOURNAL OF SCIENCE 53 
 
 Series began in 1896. But even this statement is inade- 
 quate, for the editor-in-chief has had the generous assist- 
 ance of otlier gentlemen, whose names have not been 
 placed on the title page, and who have also played an 
 important part in the conduct of the Journal. This 
 policy, indeed, is not a matter of recent date. Very 
 early in the First Series, Professor Griscom of Paris, as 
 already noted, furnished notes of interesting scientific 
 discoveries abroad. Other gentlemen have from time to 
 time acted in the same capacity. The most prominent of 
 them was Professor Jerome Nicldes of Nancy, France, 
 who regularly furnished a series of valuable notes on 
 varied subjects, chiefly from foreign sources, extending 
 from 1852 to 1869. On the latter date he met an untimely 
 death in his laboratory in connection with experiments 
 upon hydrofluoric acid (47, 434, 1869). 
 
 It may be added, further, that one of the striking 
 features about the Journal, especially in the earlier half 
 century of its existence, is the personal nature of many 
 of its contributions, which were verj^ frequently in the 
 form of letters written to Benjamin Silliman or J. D. 
 Dana. This is perhaps but another reflection of the 
 extent to which the growth of the magazine centered 
 around these two men, whose wide acquaintance and 
 broad scientific repute made of the Journal a natural 
 place to record the new and interesting things that were 
 being discovered in science. 
 
 The following list gives the names and dates of ser- 
 vice, as recorded on the Journal title pages, of the gen- 
 tlemen formally made Associate Editors : 
 
 Wolcott Gibbs (2) 11, 1R51 to (3) 18, 1879 
 
 Asa Gray " 15, 1853 " " 34, 1887 
 
 Louis Agassiz " 16, 1853 " (2) 41, 1866 
 
 Waldo I. Burnett " 16, 1853 " " 17, 1853 
 
 George J. Brush " 35, 1863 " (3) 18, 1879 
 
 Samuel W. Johnson " 35, 1863 " " 18, 1879 
 
 Hubert A. Newton (2) 38, 1864 to (4) 1, 1896 
 
 Addison E. Verrill " 47, 1869 
 
 Alfred M. Mayer (3) 5, 1873 to (3) 6, 1873 
 
 Edward C. Pickering " 7, 1874 " " 13, 1877 
 
 George F. Barker " 14, 1877 " (4) 29, 1910 
 
 Josiah P. Cooke " 14, 1877 " (3) 47, 1894 
 
54 A CENTURY OF SCIENCE 
 
 John Trowbridge (3) 19, 1880 
 
 George W. Goodale 
 Henry S. "Williams 
 
 Henry P. Bowditch 
 
 William G. Farlow 
 
 Othniel C. Marsh 
 
 Henry A. Rowland (4) 1, 1896 " " 10, 1900 
 
 Joseph S. Diller 
 Louis V. Pirsson . . . 
 William M. Davis . . 
 Joseph S. Ames . . . . 
 Horace L. Wells . . . . 
 Herbert E. Gregory 
 Horace S. Uliler . . . . 
 
 ao, 1888 
 47, 1894 
 49, 1895 to (4) 8, 1899 
 
 49, 1895 
 
 49, 1895 to (4) 6, 1899 
 
 1, 1896 
 7, 1899 
 9, 1900 
 12, 1901 
 18, 1904 
 18, 1904 
 33, 1912 
 
 Present and Future Conditions. 
 
 The field to be occupied by the "American Journal of 
 Science and Arts," as seen by its founder in 1818 and 
 presented by him in the first number, as quoted entire on 
 an earlier page, was as broad as the entire sphere of 
 science itself. It thus included all the departments of 
 both pure and applied science and extended even to music 
 and fine arts also. As the j^ears went by, however, and 
 the practical applications of science greatly increased, 
 technical journals started up, and the necessity of culti- 
 vating this constantly expanding field diminished. It 
 was not, however, until January, 1880, that "the Arts" 
 ceased to be a part of the name by which the Journal 
 was known. 
 
 About the same date also — or better a little earlier — 
 began an increasing development of scientific research, 
 particularly as fostered by the graduate schools of our 
 prominent universities. The full i^resentation of this 
 subject would require much space and is indeed unneces- 
 sary as the main facts must be distinct in the mind of the 
 reader. It is only right, however, that the large part 
 played in this movement by the Johns Hopkins Univer- 
 sity (founded in 1876) should be mentioned here. 
 
 As a result of this movement, which has been of great 
 benefit in stimulating the growth of science in the 
 country, many new journals of specialized character have 
 come into existence from time to time. Further local- 
 ization and specialization of scientific publication have 
 
AMERICAN JOURNAL OF SCIENCE 
 
 55 
 
 resulted from the increased activity of scientific societies 
 and academies at numerous centers and the springing 
 into existence thereby of new organs of publication 
 through them, as also through certain of the Government 
 Departments, the Carnegie Institution, and certain uni- 
 versities and museums. 
 
 As bearing upon this subject, the following list of the 
 more prominent scientific periodicals started in this 
 country since 1867 is not without interest : 
 
 1867- . American Naturalist. 
 
 1875- . Botanical Bulletin ; later Botanical Gazette. 
 
 1879-1913. American Cliemical Journal. 
 
 1880-1915. School of Mines Quarterly. 
 
 1883- . Science. 
 
 1885- . Journal of Heredity. 
 
 1887- . Journal of Morphology. 
 
 1887-1908. Technology Quarterly. 
 
 1888-1905. American Geologist. 
 
 1891- . Journal of Comparative Neurology. 
 
 1893- . Journal of Geology. 
 
 1893- . Physical Review. 
 
 1895- . Astrophysical Journal. 
 
 1896- . Journal of Physical Chemistry. 
 1896- . Terrestrial Magnetism. 
 1897-1899. Zoological Bulletin; followed by 
 
 1900- . Biological Bulletin. 
 
 1901- . American Journal of Anatomy. 
 1901r- . Journal of Experimental Zoology. 
 
 1905- . Economic Geology. 
 
 1906- . Anatomical Record. 
 
 1907- . Journal of Economic Entomology. 
 1911- . Journal of Animal Behavior. 
 1914- . American Journal of Botany. 
 1916- . Genetics. 
 
 1918- . American Journal of Physical Anthropology. 
 
 The result of the whole movement has been of neces- 
 sity to narrow, little by little, the sphere of a general 
 scientific periodical such as the Journal has been from 
 the beginning. The exact change might be studied in 
 detail by tabulating as to subjects the contents of succes- 
 sive volumes, decade by decade, from 1870 down. It is 
 sufficient, here, however, to recognize the general fact 
 that while the number of original papers published in the 
 
56 A CENTURY OF SCIENCE 
 
 periodicals of tliis countrj^, in 1910, for example, was very 
 many times what it was in 1825, a large part of these 
 have naturally found their home in periodicals devoted 
 to the special subject dealt with in each case. That this 
 movement will continue, though in lessened degree now 
 that the immediate demand is measurably satisfied, is to 
 be expected. At the same time it has not seemed wise, at 
 any time in the past, to formally restrict the pages of the 
 Journal to any single group of subjects. The future is 
 before us and its problems will be met as they arise. At 
 the moment, however, there seems to be still a place for a 
 scientific monthly sufficiently broad to include original 
 papers of important general bearing even if special in 
 immediate subject. In this way it would seem that 
 "Silliman's Journal" can best continue to meet the 
 ideals of its honored founder, modified as they must be to 
 meet the change of conditions which a century of scien- 
 tific investigation and growth have wrought. Incident- 
 ally it is not out of place to add that a self-supporting, 
 non-subsidized scientific periodical may hope to find a 
 larger number of subscribers from among the workers in 
 science and the libraries if it is not too restricted in scope. 
 
 The last subject touched upon introduces the essential 
 matter of financial support without which no monthly 
 publication can survive. With respect to the periodicals 
 of recent birth, listed above, it is safe to say that some 
 form of substantial support or subsidy — often very gen- 
 erous — is the rule, perhaps the universal one. This has 
 never been the case with the American Journal. The 
 liberality and broad-minded attitude of Yale College in 
 the early days, and of the Yale University that has devel- 
 oped from it, have never been questioned. At the same 
 time the special conditions have been such as to make it 
 desirable that the responsibility of meeting the financial 
 requirements should be carried by the editors-in-chief. 
 At present the Yale Library gives adequate payment for 
 certain publications received by the Journal in exchange, 
 though for many 3^ears they were given to it as a matter 
 of course, free of charge. Beyond this there is nothing 
 approaching a subsidy. 
 
 The difficulties on the financial side met with by the elder 
 Silliman have been suggested, although not adequately 
 
AMERICAN JOURNAL OF SCIENCE 67 
 
 presented, in tlie various statements quoted from early 
 volumes. The same problems in varying degree have 
 continued for the past sixty years. Since 1914"they have 
 been seriously aggravated for reasons that need not be 
 enlarged upon. Prior to that date the subscription list 
 had, for reasons chiefly involved in the development of 
 special journals, been much smaller than the number 
 estimated by Silliman, for example, in volume 50 (p. xiv), 
 although there has been this partial compensation that 
 the considerable number of well-established libraries on 
 the subscription list has meant a greater degree of sta- 
 bility and a smaller proportion of bad accounts. The 
 past four years, however, the Journal, with all simi- 
 lar undertakings here and elsewhere, has been compelled 
 to bear its share of the burden of the world war in dimin- 
 ished receipts and greatly increased expenses. It is 
 gratifying to be able to acknowledge here the generosity 
 of the authors, or of the laboratories with which they 
 have been connected, in their willingness not infrequently 
 to give assistance, for example, in the payment of more 
 or less of the cost of engravings, or in a few special cases 
 a large portion of the total cost of publication. In this 
 way the problem of ways and means, constantly before 
 the editor who bears the sole responsibility, has been 
 simplified. 
 
 It should also be stated that as those immediately 
 interested have looked forward to the present anniver- 
 sary, it has been with the hope that this occasion might be 
 an appropriate one for the establishment of a "Silliman 
 Fund" to commemorate the life and work of Benjamin 
 Silliman. The income of such a fund would lift from 
 the University the burden that must unavoidably fall 
 upon it when the responsibility for the conduct of the 
 Journal can no longer be carried by members of the fam- 
 ily including tlie editor and — as in years long past — a 
 silent partuer whose aid on the business side has been 
 essential to the efficiency and economy of the enterprise. 
 Present conditions are not favorable for such a move- 
 ment, although something has been already accomplished 
 in the desired direction. At the present time every 
 patriotic citizen must feel it his first duty to give his sav- 
 ings as well as his spare income to the support of the 
 
58 A CENTURY OF SCIENCE 
 
 National Government in tlie world struggle for freedom 
 in -which it is taking part. But, whatever the exact con- 
 dition of the future may be, it cannot be questioned that 
 the Journal founded by Benjamin Sillinian in 1S18 will 
 survive and will continue to play a vital part in the sup- 
 port and further development of science. 
 
 The present year of 1918 finds the world at large, and 
 with it the world of science, painfully crushed beneath the 
 overwhelming weight of a world war of unprecedented 
 severity. The four terrible years now nearly finished 
 have seen a fearful destruction of life and property which 
 must have a sad influence on the progress of science for 
 many years to come. Only in certain restricted lines has 
 there been a partial compensation in the stimulating 
 influence due to the immediate necessities connected with 
 the great conflict. One hundred years ago "the reign of 
 war" was keenly in the mind of the editor in beginning 
 his work, but for him, happily, the long period of the 
 Napoleonic wars was already in the past, as also the brief 
 conflict of 1812, in which this country was engaged and in 
 wliicli Silliman himself played a minor part. We, too, 
 must believe, no matter how serious the outlook of the 
 present moment, that a fundamental change will come in 
 the not distant future; the nations of the world must 
 sooner or later turn once more to peaceful pursuits and 
 the scientific men of ditferent races must become again 
 not enemies but brothers engaged in the common cause 
 of uplifting human life. The peace that we look forward 
 to to-day is not for this country alone, but a peace which 
 shall be a permanent blessing to the entire world for 
 ages to come. 
 
 Note. — The portrait on the next leaf has been repro- 
 duced from the plate in volume 50 (1847) of the Journal. 
 The original painting was made by 11. Willard in 1835, 
 when Silliman was in Boston engaged in delivering the 
 Lowell lectures ; he was then nearly fifty-six years of age. 
 The engraving, as he states elsewhere, was made from 
 this painting for the Yale Literary Llagazine, and was 
 published in the number for December, 1S39. 
 

 (yV. rJ^A^^^d.-'^-l'^t^^i^-l^ 
 
AMERICAN JOURNAL OF SCIENCE 59 
 
 It is interesting- to quote the remarl^s with wliicli tlie 
 editor introduces the portrait (50, xviii, 1847). He says : 
 
 The iDortrait prefixed to this volume was engraved for a very 
 different purpose and for others than the patrons of this Jour- 
 nal. It has been suggested by friends, whose judgment we are 
 accustomed to respect, that it ought to find a place here, since it 
 is regarded as an authentic, although, perhaps, a rather austere 
 resemblance. In yielding to this suggestion, it may be sufficient 
 to quote the sentiment of Cowper on a similar occasion, who 
 remarked — "that after a man has, for many years, turned his 
 mind inside out before the world, it is only affectation to attempt 
 to hide his face." 
 
 Notes. 
 
 ' The statements given are necessarily much condensed, "without an 
 attempt to follow all changes of title ; furthermore, the dates of actual 
 publication for the academies given above are often somewhat vaguely 
 recorded. For f iiller information see Scudder 's ' ' Catalogue of Scientific 
 Serials, 1633-1S76," Cambridge, 1876; also H. Carrington Bolton's 
 "Catalogue of Scientific and Technical Periodicals, 166.5-1882" (Smith- 
 sonian Institution, 1885). The writer is much indebted to Mr. C. J. Barr, 
 Assistant Librarian of Tale University Library, for his valuable assistance 
 in this connection. 
 
 " The following footnote accompanies the opening article of the first 
 volume of the Journal. "From the MS. papers of the Connecticut Acad- 
 emy, now published by permission." Similar notes appear elsewhere. 
 Ed. 
 
II 
 
 A CENTURY OF GEOLOGY.— THE PROGRESS 
 
 OF HISTORICAL GEOLOGY IN NORTH 
 
 AMERICA 
 
 By CHARLES SCHUCHEBT 
 
 Intr^oduction. 
 
 THE American Journal of Science, "one of the 
 greatest influences in American geology," founded 
 in 1818, has published a little more than 92,000 
 pages of scientific matter. Of geology, including min- 
 eralogy, there appear to be upward of 20,000 pages. 
 What "a vast treasure house of geologic knowledge is 
 stored in these 191 volumes, and how well the editors 
 have lived up to their proposed "plan of work" as 
 stated in the opening volume, where Silliman says: "It 
 is designed as a deposit for original American communi- 
 cations" in "the physical sciences . . . and especially 
 our mineralogy and g^eology" (1, v, 1818)] Not only is 
 it the oldest continuously published scientific journal of 
 this country, but it has proved itself to be "perhaps the 
 most important geological periodical in America" (Mer- 
 rill). It is impossible to adequately present in this 
 memorial volume of the Journal the contents of the 
 articles on the geological sciences. 
 
 Editor Silliman was not only the founder of the Jour- 
 nal, but the generating center for the making of 
 geologists and promoting geology during the rise of this 
 science in America. For nearly three decades, the work- 
 ers came to him for counsel and help, and he had a kind 
 paternal word for them all. This influence is also shown 
 in the many letters which were addressed to him, and 
 which he published in the Journal. A similar influence, 
 paternal care, and constructive criticism were continued 
 
HISTOEICAL GEOLOGY 61 
 
 by James D. Dana, and especially in his earlier career 
 as editor. 
 
 Not including mineralogy, there are in the Journal 
 upward of 1500 distinct articles on geology. Of these, 
 over 400 are on vertebrate paleontology, about 325 on 
 invertebrate paleontology, and 90 on paleobotany. Of 
 articles bearing on historical geology there are about 160, 
 and on stratigraphic geology more than 360. In addition 
 to all this, there are more than 2000 pages of geologic 
 matter relating to books and of letters communicated to 
 the editors Silliman and Dana. "We may summarize with 
 Doctor Merrill's statement in his well-known Contribu- 
 tions to the History of American Geology : 
 
 "From its earliest inception geological notes and papers 
 occupied a prominent place in its pages, and a perusal of the 
 numbers from the date of issue down to the present time will, 
 alone, afi'ord a fair idea of the gradual progress of American 
 geology." 
 
 Before presenting a synopsis of the more important 
 steps in the progress of historical geology in America, it 
 will be well to introduce a rapid survey of the rise of 
 geology in Europe, for, after all, American geology grew 
 out of that of England, France and Germany. This 
 dependence was conspicuously true during the first 
 four decades of the previous century. With the rise of 
 the first New York State Survey (1836-1843) and that 
 of Pennsylvania (1836-1844, 1858), American geology 
 became more or less independent of Europe. Finally, 
 this article will conclude with a survey of the rise of 
 paleometeorology, paleogeography, evolution, and inver- 
 tebrate paleontology. 
 
 The Hise of Geologij in Europe. 
 
 Mineral Geology. — The geological sciences had their 
 rise in the study of minerals as carried on by the German 
 chemist and physician George Bauer (1494-1555), better 
 known as Agricola. Bauer originated the critical study 
 of minerals, but did not distinguish his "fossilia," the 
 remains of organisms, from the inorganic crystal forms. 
 Mineral geology endured until the close of the eighteenth 
 century. 
 
62 A CENTURY OF SCIENCE 
 
 Cosniogonists. — Then came the expounders of the 
 earth's origin, the cosmogonists of the sixteenth to the 
 end of the eighteenth centuries. The fashion of this 
 time was to write histories of the earth derived out of 
 the imagination. 
 
 Earliest Historical Geology. — Even though Giovamii 
 Arduino (1713-1795) of Padua was not the first to 
 classify the rocks into three series according to their 
 age, he did this more clearly than any one else before his 
 time. The rocks about Verona he grouped in 1759 into 
 Primary, Secondary, Tertiary, and Volcanic. This 
 three-fold classification came into general use, though 
 modified with time. 
 
 Early in the nineteenth century it had become plain 
 that formations of very varying ages were included in 
 each one of the three series. Through the study of the 
 fossils and the recognition of the fact that mountain 
 ranges have been raised at various times, causing 
 younger fossiliferous strata to take on the characters of 
 the Primary, it was seen that these terms of Arduino had 
 lost their original significance. 
 
 The first one to describe in detail a local stratigraphic 
 sequence was Johann Gottlob Lehmann (died 1767). 
 In 1756 he iDublished "one of the classics of geological 
 literature," distinguishing clearly thirty su^ccessive sedi- 
 mentary deposits, some of which he said had fossils, but 
 he did not use them to distinguish the strata. 
 
 What Lehmann did for the Permian system, George 
 Christian Fiichsel (1722-1773) did even better for the 
 Triassic of Thuringia, in 1762 and 1773. He pointed out 
 not only the sequence, but also how the gently inclined 
 strata rest upon the older upturned masses of the moun- 
 tains ; also that some formations have only marine fos- 
 sils, while others have only terrestrial forms and thus 
 indicate the proximity of land. The deformed strata he 
 thought had fallen into the hollows within the earth, 
 great caverns that had also consumed much of the 
 oceanic waters and had in so doing greatly lowered 
 the sea-level. It was Fiichsel who first introduced the 
 theory of universal formations, and who defined the term 
 formation, using it as we now do, system or period. 
 Even though Lehmann and Fiichsel showed that there 
 
HISTORICAL GEOLOGY 63 
 
 was a definite order and process in the formation of the 
 earth's crust, their example was barren of followers until 
 the beginning of the eighteenth century. 
 
 Wernerian Geology or Geoqnosy. — We come now to 
 the time of Abraham Gottlob '^AVerner (1749-1817), who 
 from 1775 to 1817 was professor of mining and mineral- 
 ogy in the Freiberg Academy of Mines. Geikie, in his 
 most interesting Founders of Geology, says that Werner 
 "bulks far more largely in the history of geology than 
 any of those with whom up to the present we have been 
 concerned — a man who wielded an enormous author- 
 ity over the mineralogy and geology of his day." 
 "Although he did great service by the precision of his 
 lithological characters and by his insistence on the doc- 
 trine of geological succession, yet as regards geological 
 theory, whether directly by his own teaching, or indi- 
 rectly by the labors of his pupUs and followers, much of 
 his influence was disastrous to the higher interests of 
 geology." 
 
 Werner arranged the crust of the earth into a series of 
 formations, as had been done previously by Lehmann 
 and Fiichsel, and one of his fundamental postulates was 
 that all rocks were chemically precipitated in the ocean 
 as "universal formations." For this reason Werner's 
 school were called the Neptunists. Nowhere, however, 
 did he explain how and where the deep and primitive 
 ocean had disappeared. 
 
 According to Werner, the first formed or oldest rocks 
 were the chemically deposited Primitive strata, including 
 granite and other igneous and metamorphic rocks. On 
 these followed the Transition rocks, the earliest sedi- 
 ments of mechanical origin, and above them the Floetz 
 rocks, a term for the horizontal stratified rocks. These 
 last he said were partly of chemical but chiefly of mechan- 
 ical origin. Last of all came the Alluvial series. 
 
 The existence of volcanoes had been pointed out long 
 before Werner's time by the Italian school of geologists, 
 but as for "the universality and potency of what is now 
 termed igneous action," all was "brushed aside by the 
 oracle of Freiberg." Reactions between the interior 
 and exterior of our earth "were utterly antagonistic to 
 Werner's conception of the structure and history of the 
 
64 A CENTURY OF SCIENCE 
 
 earth." To him, volcanoes were "burning mountains" 
 that arose from the combustion of subterranean beds of 
 coal, spontaneously ignited. 
 
 The breaking down of the Wernerian doctrines began 
 with two of Werner's most distinguished pupils, D'Au- 
 huisson de Voisins (1769-1819) and Von Buch. _The 
 former in 1803 had accepted Werner's aqueous origin of 
 basalt, but after studying the celebrated and quite recent 
 volcanic area of Auvergne he recanted in 1804. Here he 
 saw the basaltic rocks lying upon and cutting through 
 granite, and in places more than 1200 feet thick. "If 
 these basaltic rocks were laA'as," says Geilde, "they 
 must, according to the Wernerian doctrine, have resulted 
 from the combustion of beds of coal. But how could coal 
 be supposed to exist under granite, which was the first 
 chemical precipitate of a primeval ocean?" 
 
 Leopold von Buch (1774-1853), "the most illustrious 
 geologist that Germany has produced," after two years 
 spent in Norway was satisfied "that the rocks in the 
 Christiania district could not be arranged according to 
 the Wernerian plan, which there completely broke down. 
 Von Buch found a mass of granite lying among 
 fossiliferous limestones which were manifestly meta- 
 morphosed, and were pierced by veins of granite, por- 
 phyry, and syenite." Even so, he was not ready to 
 abandon the teachings of his master. After a study 
 of the mountain systems of Germany, however, "he 
 declared that the more elevated mountains had never 
 been covered by the sea, as Werner had taught, but were 
 produced by successive ruptures and uplifts of the ter- 
 restrial crust" (Geikie). 
 
 Rise of Geology and Conformlsm. — Modern geology 
 has its rise in James Hutton (1726-1797) of Edinburgh, 
 Scotland. In 1785 and 1795, Hutton published his 
 Theory of the Earth, with Proofs and Illustrations. His 
 "immortal theory" is his only work on geology. "For- 
 tunately for Hutton 's fame and for the onward march of 
 geology, the philosopher numbered among his friends the 
 illustrious mathematician and natural philosopher, John 
 Playfair (1748-1819), who had been closely associated 
 with him in his later years, and was intimately con- 
 versant with his geological opinions." In 1802, Play- 
 
HISTORICAL GEOLOGY 65 
 
 fair published lais Illustrations of the Huttonian Theory 
 of the Earth, of which Geilde says, "Of this great classic 
 it is impossible to speak too highly," as it is at the basis 
 of all modern geology. 
 
 One of Hutton's fundamental doctrines is that the 
 earth is internally hot and that in the past large masses 
 of molten material, the granites, have been intruded into 
 the crust. It was these igneous views that led to his 
 followers being called the Plutonists. Another of his 
 great doctrines was that "the ruins of an earlier world 
 lie beneath the secondary strata," and that they are sep- 
 arated by what is now known as unconformity. He 
 clearly recognized a lost interval in the broken relation 
 of the structures, and that the ruins, the detrital mate- 
 rials, of one world after another are superposed in the 
 structure of the earth. 
 
 Hutton also held that the deformation of once horizon- 
 tally deposited strata was probably brought about at dif- 
 ferent periods by great convulsions that shook the very 
 foundations of the earth. After a convulsion, there was 
 a long time of erosion, represented by the unconformity. 
 Geikie says, "The whole of the modern doctrine of 
 earth sculpture is to be found in the Huttonian theory. ' ' 
 
 The Lyellian doctrine of metamorphism had its origin 
 in Hutton, for he showed that invading igneous granite 
 had altered, through its heat and expanding power, the 
 originally water-laid sediments, and that the schists of 
 the Alps had been born of the sea like other strati- 
 fied rocks. 
 
 Hutton is the father of the Uniformitarian principle, 
 for he "started with the grand conception that the past 
 history of our globe must be explained by what can be 
 seen to be happening now, or to have happened only 
 recently. The dominant idea in his philosophy is that 
 the present is the key to the past." This principle has 
 been impressed on all later geologists by Sir Charles 
 Lyell, and is the chief cornerstone of modern geology. 
 
 The principle of uniformitarianism has underlain 
 geologic interpretation since the days of Hutton, Play- 
 fair, and Lyell. However, it is often applied too rigidly 
 in interpretations based upon the present conditions, 
 because in the past there were long times when the topo- 
 
66 A CENTURY OF SCIENCE 
 
 graphic features of the earth were very different from 
 those of to-day. Throughout the Paleozoic, and, less 
 markedly, the Mesozoic, the oceans flooded the lands 
 widely (at times over 60 per cent of the total area), high- 
 lands were inconspicuous, sediments far scarcer, and 
 climates warm and equable throughout the world. High- 
 land conditions, and especially the broadly emergent con- 
 tinents of the present, were only periodically present in 
 the Paleozoic and then for comparatively short intervals 
 between the periods. Therefore rates of denudation, 
 solution, sedimentation, and evolution have varied 
 greatly throughout the geological ages. These differ- 
 ences, however, relate to degrees of operation, and not to 
 kinds of processes ; but the differences in degree of 
 operation react mightily on our views as to the age of 
 the earth. 
 
 Geologic time had, for Hutton, no "vestige of a begin- 
 ning, no prospect of an end." In other words, geologic 
 time is infinite. He did not, however, discover a method 
 by which the chronology of the earth could be determined. 
 
 First Important Text-books. — In 1822 a^Dpeared the 
 ablest text-book so far published, and the pattern for 
 most of the later ones. Outlines of the Geology of Eng- 
 land and Wales, bv W. D. Conybeare (1787-1857) and W. 
 Phillips (1775-1828). "In this excellent volume all that 
 was then known regarding the rocks of the country, from 
 the youngest formations down to the Old Red Sandstone, 
 was summarized in so clear and methodical a manner as 
 to give a powerful impulse to the cultivation of geology 
 in England" (Geikie). This book is reviewed at great 
 length by Edward Hitchcock in the Journal (7, 203,1824), 
 
 To indicate how far historical geology had progressed 
 up to 1822 in England, a digest of the geological column 
 as presented in this text-book is given in the following 
 table, along with other information. 
 
 A text-book writer of yet greater influence was Charles 
 Lyell (1797-1875), whose Principles of Geology appeared 
 in three volumes between 1830 and 1833. This and his 
 other boolfs were kept up to date through many editions, 
 and his Elements of Geology is, as Geikie says, "the hand 
 book of every English geologist" working with the fos- 
 siliferous formations. 
 
HISTORICAL GEOLOGY 67 
 
 Tlie Rise of Geology in North America. 
 
 _ The Generating Centers. — In America, geology had its 
 rise independently in three places : in the two scientific 
 societies of Boston and Philadelphia, and dominantly in 
 Benjamin Silliman of Yale College. Stated in another 
 way, we may say that geology in America had its origin 
 in the following pioneers and founders : first, in William 
 Maclure at Philadelphia, and next in Benjamin Silliman 
 at New Haven. Through the influence of the latter, 
 Amos Eaton, the botanist, became a geologist and taught 
 geology at Williams College and later at the Rensselaer 
 School in Troy, New York. Through the same influence 
 Rev. Edward Hitchcock also became a geologist and 
 taught the subject after 1825 at Amherst College. 
 
 Silliman was the first to take up actively the teach- 
 ing of mineralogy and geology based on collections of 
 specimens. He spread the knowledge in popular lectures 
 throughout the Eastern States, graduated many a stu- 
 dent in the sciences, making of some of them professional 
 teachers and geologists, provided all with a journal 
 wherein they could publish their research, organized the 
 first geological society and through his students the first 
 official geological surveys, and by kind words and acts 
 stimulated, fostered, and held together American scien- 
 tific men for fifty years. Of him it has been truly said 
 that he was "the guardian of American science from its 
 childhood." 
 
 The American Academy in Boston. — The second oldest 
 scientific society, but the first one to publish on geological 
 subjects, was the American Academy of Arts and 
 Sciences of Boston, instituted and publishing since 1780. 
 Up to the time of the founding of this Journal, there had 
 appeared in the publications of the American Academy 
 about a dozen papers of a geologic character, none of 
 which need to be mentioned here excepting one liy S. L. 
 and J. F. Dana, entitled "Outlines of the Mineralogy and 
 Geology of Boston," published in 1818. This is an early 
 and important step in the elucidation of one of the most 
 intricate geologic areas, and is further noteworthy for its 
 geologic map, the third one to appear, the .older ones 
 being by Maclure and Hitchcock (Merrill). 
 
The Geological Column in 1822 
 
 Present American 
 
 
 C.&P. 
 
 Wer- 
 
 Other 
 
 
 classification 
 
 Conybeare and Phillips 1822 
 
 orders 
 
 nerian 
 orders 
 
 writ- 
 ers 
 
 Ps 
 
 ychozoic or Recent 
 
 Alluvial 
 
 
 O) 
 
 
 
 
 
 ^. 
 
 C3 
 
 
 
 
 
 0) 
 
 '2 
 
 3 
 
 § 
 
 
 Pleistocene 
 
 Diluvial 
 
 
 
 
 
 
 o 
 
 Sl=}^-gene 
 
 Upper Marine formation (Crag, 
 
 .2 
 
 
 
 £? ■ 
 
 o 
 
 Bagshot sand, and Isle of Wight) 
 
 't^ 
 
 ,g 
 
 G 
 
 Freshwater formations 
 
 G. 
 
 en 
 
 
 6 
 
 STl^^i-s- 
 
 London Clay 
 Plastic Clay 
 
 C» 
 
 
 H 
 
 
 Cretaceous 
 
 Chalk 
 
 Beds between Chalk and Oolite 
 
 
 
 
 
 Comanchian 1887 
 
 Series (Chalk Marie, Green Sand, 
 Weald Clay, Iron Sand) 
 
 
 
 
 
 - 
 
 Upper Oolitic division (Purbeck 
 
 u 
 
 
 ro 
 
 .s^ 
 
 
 beds, Portland Oolite, Kimmer- 
 
 ^ 
 
 w 
 
 
 
 
 idge Clay) 
 
 
 
 1 
 
 « 
 
 g 
 
 
 Middle Oolitic division (Coral Rag, 
 
 ^ 
 
 rf 
 
 3 
 
 O- 
 
 
 Oxford Clay) 
 
 ci 
 
 
 
 i>i 
 
 r^ 
 
 Jurassic 1829 
 
 Lower Oolitic division (Cornbrash, 
 
 cd 
 
 13 
 
 
 
 
 Stonesfield Slate, Forest ISIarble, 
 
 a 
 
 
 
 ;2 
 
 
 
 Great Oolite, Fullers' Earth, In- 
 
 a 
 
 E 
 
 
 
 
 
 ferior Oolite, Sand and Marie- 
 
 3 
 
 
 1 
 
 
 
 stone 
 
 
 
 
 
 - 
 
 Lias 
 
 
 
 
 
 Triassic 1834 
 
 New Red Sandstone 
 
 
 ^ 
 
 
 
 
 13 
 
 
 rermian 1841 
 
 Magnesian Limestone 
 
 
 c 
 
 C3 
 
 03 
 
 
 Coal Measures 
 
 ^ 
 
 1-..^ jj 
 
 
 O 
 
 Pennsylvanian 1891 
 
 
 -?'S? 
 
 
 
 'o 
 
 Mississippian 1869 
 
 Millstone Grit and Shale 
 
 2 oO 
 
 ^ 
 
 -2 
 
 O 
 
 Devonian 1839 
 Silurian 1835 
 
 Old Red Sandstone 
 
 aj i3 3 
 
 So2 
 
 ^0 
 
 .2 
 
 
 
 
 k^ 
 
 
 Ordovician 1879 
 
 
 
 ^ 
 H 
 
 a 
 
 
 (=Lower .Silurian 1835) 
 
 
 
 
 Cambrian 1833 
 
 Unresolved 
 Submedial 
 
 
 <D 
 
 
 o 
 
 "o 
 
 Keweenawan 1 3 
 Animilvian '2 ,'g 
 Jluronian 2 3 
 Sudburian J 3, 
 
 a) 
 
 o 
 
 
 
 l> 
 
 > 
 
 1 
 Ah 
 
 o 
 
 and 
 
 Inferior Orders 
 
 
 'u 
 
 o o 
 
 1 CO 
 
 Keewatin 1 £| S 
 
 
 f1 
 
 CoutcliiehinE (2s 
 
 
 
 
 
HISTORICAL GEOLOGY C9 
 
 Earli/ Geology in Philadelphia. — The oldest scientific 
 society is tlie American Philosopliical Society of Phila- 
 delphia, started by the many-sided Benjamin Franklin in 
 1769, and -which has published since 1771. Up to the time 
 of the founding' of the Journal in 1818, there had 
 appeared in the publications of this society thirteen 
 papers of a geologic nature, nearly all small building 
 stones in the rising geologic story of North America. 
 The only fundamental ones were Maclure 's Observations 
 of 1809 and 1817. Later, in this same city, there was 
 organized another scientific society that came to be for 
 a long time the most active one in America. This was 
 the Academy of Natural Sciences, started in 1812 with 
 seven members, but it was not until 1817 and the election 
 of William Maclure as its first president that the work 
 of the Academy was of a far-reaching character. Here 
 was built up not only a society for the advancement of the 
 natural sciences and publications for the dissemination 
 of such knowledge, but, what is equally important, the 
 first large library and general museum. 
 _ William Maclure (1763-1840), correctly named by Sil- 
 liman the "father of American geology," was born and 
 educated in Scotland, and died near Mexico City. A 
 merchant of London until 1796, when he had already 
 amassed "a considerable fortune," he made a first short 
 visit to New York City in 1782. In 1796 he again came 
 to America, this time to become a citizen of this country 
 and a liberal patron of science. 
 
 About 180.3, single-handed and unsustained by gov- 
 ernment patronage, Maclure interested himself most 
 zealously and efficiently in American geology. In 1809 
 he published his Observations on the Geology of the 
 United States, Explanatory of a Geological Map. This 
 work he revised "on a yet more extended scale," issuing 
 it in 1817 with 130 pages of text, accompanied by a large 
 colored geological map. 
 
 SiUiman, the Pioneer Promoter of Geolofiy. — In 1806 
 when Benjamin Silliman (1779-1864) began actively to 
 teach chemistry and mineralogy, all the sciences in Amer- 
 ica were in a very backward state, and the earth sciences 
 were not recognized as such in the curricula of any of our 
 colleges. Silliman gave his first lecture in chemistry on 
 
TO A CENTURY OF SCIENCE 
 
 April 4, 1804. In the summer of that year, Yale College 
 asked him to go to England to purchase material for the 
 College, and great possibilities for broadening his 
 knowledge now loomed before him. As Silliman himself 
 (43, 225, 1842) has told the interesting story of his 
 sojourn in England and Scotland, it is worth while to 
 restate a part of it here. 
 
 "Passing over to England in the spring of 1805, and fixing 
 my residence for six months in London, I found there no school, 
 public or private, for geological instruction, and no association 
 for the cultivation of the science, which was not even named in 
 the English universities." In geology "Edinburgh was then 
 far in advance of London . . . Prof. Jameson having recently 
 returned from the school of Werner, fully instructed in the doc- 
 trines of his illustrious teacher, was ardently engaged to maintain 
 them, and his eloquent and acute friend, the late Dr. John Mur- 
 ray, was a powerful auxiliary in the same cause; both of these 
 philosophers strenuously maintaining the ascendancy of the 
 aqueous over the igneous agencies, in the geological phenomena 
 of our planet. 
 
 On the other hand, the disciples and friends of Dr. Hutton 
 were not less active. He died in 1797, and his mantle fell upon 
 Sir James Hall, who, with Prof. Playfair and Prof. Thomas 
 Hope, maintained with signal ability, the igneous theory of 
 Hutton. It did not become one who was still a youth and a 
 novice, to enter the arena of the geological tournament where 
 such powerful champions waged war ; but it was very interest- 
 ing to view the combat, well sustained as it was on both sides, 
 and protracted, without a decisive issue, into a drawn battle . . . 
 
 The conflicts of the rival schools of Edinburgh — the Neptun- 
 ists and the Vulcanists, the Wernerians and the Huttonians, 
 were sustained with great zeal, energy, talent, and science ; they 
 were indeed marked too decidedly by a partisan spirit, but this 
 very spirit excited untiring activity in discovering, arranging, 
 and criticising the facts of geologj--. It was a transition period 
 between the epoch of geological hypotheses and dreams, which 
 had passed by, and the era of strict philosophical induction, in 
 which the geologists of the present day are trained . . . 
 
 I was a diligent and delighted listener to the discussions of 
 both schools. Still the igneous philosophers appeared to me to 
 assume more than had been proved regarding internal heat. 
 In imagination we were plunged into a fiery Phlegethon, and I 
 was glad to find relief in the cold bath of the Wernerian ocean, 
 where my predilections inclined me to linger." 
 
HISTORICAL GEOLOGY Tl 
 
 Silliman's Students and Their Publications. — Silli- 
 man's first student to take up geology as a profession was 
 Denison Olmstead (1791-1859), educator, chemist, and 
 geologist, Avho was graduated from Yale in 1813. Four 
 years later he was under special preparation with Silli- 
 man in mineralogy and geology, and in that year was 
 appointed professor of chemistry in the University of 
 North Carolina. In 1824-1825 Olmstead issued a Report 
 on the Geology of North Carolina, which is the first offi- 
 cial geological report issued by any state in America, 
 "a conspicuous and solitary instance," according to 
 Hitchcock's review of it (14, "230, 1828), "in which any 
 of our state governments have undertaken thoroughly to 
 develop their mineral resources." 
 
 Amos Eaton (1776-1842), lawyer, botanist, surveyor, 
 and one of the founders of American geology, was a 
 graduate of Williams College in the class of 1799. He 
 studied with Silliman in 1815, attending his lectures on 
 chemistry, geology, and mineralogy. He also enjoyed 
 access to the libraries of Silliman and of the bot- 
 anist, Levi Ives, in which works on botany and materia 
 medica were prominent, and was a diligent student of the 
 College cabinet of minerals. He settled as a la"W3^er and 
 land agent in Catskill, Ncav York, and here in 1810 he 
 gave a popular course of lectures on botany, believed to 
 have been the first attempted in the United States. 
 
 In 1818 appeared Eaton's first noteworthy geological 
 publication, the Index to the Geology of the Northern 
 States, a text-book for the classes in geology at "Williams- 
 town. The controlling- principle of this book was Wer- 
 nerism, a .false doctrine from which Eaton was never 
 able to free himself. This book was "written over 
 anew" and published in 1820. 
 
 While at Albany in 1818, Governor He Witt Clinton 
 asked Eaton to deliver a course of lectures on chemistry 
 and geology before the members of the legislature of 
 New York. It is believed that Eaton is the only Ameri- 
 can having this distinction, and because of it he became 
 acquainted with many leading men of the state, inter- 
 esting them in geology and its application to agriculture 
 by means of surveys. In this way was so\vn the idea 
 
72 A CENTURY OF SCIENCE 
 
 which eventually was to fructify in that great official 
 work: The Natural History of New York. (See 43, 215, 
 1842; and Youmans' sketch of Eaton's life, Pop. Sci. 
 Monthly, Nov. 1890.) 
 
 Edward Hitchcock (1793-1864), reverend, state geolo- 
 gist, college president, and another of the founders of 
 American geology, was largely self-taught. Previous to 
 1825, when he entered the theological department of Yale 
 College, he had met Amos Eaton, who interested him 
 in botany and mineralogy, and between 1815 and 1819 
 he had made lists of the plants and minerals found about 
 his native town, Deerfield, Massachusetts. Therefore, 
 while studying theology at Yale it was natural for him 
 also to take up mineralogy and geology with Silliman, 
 whose acquaintance he had made at least as early as 1818. 
 
 Hitchcock, who was destined to be one of the most 
 prominent figures of his time, was appointed in 1825 to 
 the chair of chemistry and natural history at Amherst 
 College. His first geologic paper, one of five pages, 
 appeared in 1815. Three years later appeared his more 
 important paper on the Geology and Mineralogy of a 
 Section of Massachusetts, New Hampshire, and Vermont 
 (1, 105, 4.36, 1818). This is also noteworthy for its 
 geological map, the next one to be published after those 
 of ]\Iaclure of 1809 and 1817, In 1823 came a stHl 
 greater work, A Sketch of the Geology, Mineralogy, and 
 Scenery of the Regions contiguous to the River Connecti- 
 cut (6, 1, 200, 1823; 7, 1, 1824). Here the map above 
 referred to was greatly improved, and the survey was 
 one of the most important of the older publications. 
 
 Youmans in his account of Hitchcock (Pop. Sci. 
 Monthly, Sept. 1895) says: 
 
 "The State of Massachusetts commissioned him to make a 
 geological survey of her territory in 1830. Three years were 
 spent in the explorations, and the work was of such a high char- 
 acter that other States were induced to follow the example of 
 Massachusetts . . . The State of New York sought his advice 
 in the organization of a survey, and followed his suggestions, 
 particnlai'ly in the division of the territory into four parts, and 
 appointed him as the geologist of the first district. He entered 
 upon the work, but after a few daj^s of labor he found that he 
 must necessarily be separated from his family, much to his dis- 
 
HISTORICAL GEOLOGY 13 
 
 inclination. He also conceived, the idea of urging a more thor- 
 ough survey of his own State ; hence he resigned his commission 
 and returned home. The effort for a resurvey of Massachusetts 
 was successful, and he was recommissioned to do the work. The 
 results appeared in 1841 and 1844." 
 
 Oliver P. Hubbard was assistant to SlUiman in 1831- 
 1836, and then up to 1866 taught chemistry, mineralogy, 
 and geology at Dartmouth College. James G. Percival 
 was graduated at Yale in 1815, and in 1835 he and C. U. 
 Shepard of Amherst College were appointed state geol- 
 ogists of Connecticut. Their report was issued in 1842. 
 
 James Dwight Dana (1813-1895) was undoubtedly the 
 ablest of all of Silliman's students. Graduated at Yale 
 in 1833, he spent fifteen months in the United States 
 Na'^^ as instructor in mathematics, cruising off France, 
 Italy, Greece, and Turkey. In 1836 he was assistant to 
 Silliman, and in 1837, at the age of twenty-four years, 
 he published his widely used System of Mineralogy. 
 Two years later Dana joined the AVilkes Exploring Expe- 
 dition as mineralogist, returning to America in 1842 ; his 
 geological results of this expedition were published in 
 1849. In 1863, during the Rebellion, he published his 
 Manual of Geology, and through four editions it 
 remained for forty years the standard text-book for 
 American geologists. 
 
 First American Geological Society. — The founding in 
 1807 of the Geological Society of London, the parent of 
 geological societies, undoubtedly had its stimulating 
 effect on Silliman, and with his marked organizing ability 
 he began to think of forming an American society of the 
 same kind. This he brought about the year following 
 the appearance of the Journal, that is, in 1819. The 
 American Geological Society, begun in 1819 (1, 442, 
 1819), was terminated in 1830 (17, 202, 1830). The first 
 meeting (September 6, 1819) and all the subsequent ones 
 were held in the cabinet of Yale College. The brief 
 records of the doings of this society are printed in vol- 
 umes 1, 10, 15, and 18 of the Journal. Silliman was the 
 attraction at the meetings, surrounded by his mineral 
 cabinet, and he gave "the true scientific dress to all the 
 naked mineralogical subjects" discussed. 
 
n A CENTURY OF SCIENCE 
 
 Wernerian Geology in North America. 
 
 Tlie Father of American Geology. — Historical Geology 
 begins in America with William Maclure's Observations 
 on the Geology of the United States, issued in 1809. 
 This was the first important original work on North 
 American geology, and its colored geological map was the 
 first one of the area east of the Mississippi Eiver. The 
 classification was essentially the Wernerian sj'stem. All 
 of the strata of the Coastal Plain, now known to range 
 from the Lower Cretaceons to Recent, were referred to 
 the Alluvial. To the west, over the area of the Piedmont, 
 were his Primitive rocks, while the older Paleozoic 
 formations of the- Appalachian ranges were referred to 
 the Transition. West of the folded area, all was Floetz 
 or Secondary, or what we now know as Paleozoic sedi- 
 mentaries. The Triassic of the Piedmont area and that 
 of Connecticut he called the Old Red Sandstone, and the 
 coal formations of the interior region he said rested upon 
 the Secondar}^ The second edition of the work in 1817 
 was much improved, along with the map, which was also 
 printed on a more correct geographic base. (For greater 
 detail, see Merrill, Contributions to the History of 
 American Geology, 1906.) 
 
 Even though Maclure's geologic maps are much gen- 
 eralized, and the scheme of classification adopted a very 
 broad one, they are in the main correct, even if they do 
 emphasize unduly the rather simple geologic structure 
 of North America. This fact is patent all through 
 Maclure's description. Cleaveland also refers to it in 
 his treatise of 1816, and Silliman in the opening volume 
 of the Journal (1, 7, 1818) says : "The outlines of Amer- 
 can geology appear to be particularly grand, simple, and 
 instructive. ' ' Then, all the kinds of rocks were compre- 
 hended under four classes, Primitive, Transition, Allu- 
 vial, and Volcanic. It is also interesting to note here 
 that in 1822 Maclure had lost faith in the aqueous origin 
 of the igneous rocks and writes of the Wernerian system 
 as "fast going out of fashion" (5, 197, 1822), "while 
 Hitchcock said about the same thing in 1825 (9, 146). 
 
 The Work of Eaton. — Amos Eaton, after traveling 
 10,000 miles and completing his Erie Canal Report in 
 
HISTOEICAL GEOLOGY 75 
 
 1824, "reviewed the whole line several times," and pub- 
 lished^ in 1828 in the Journal (14, 145) a paper on Geolog- 
 ical Nomenclature, Classes of Rocks, etc. The broader 
 classification is the Wernerian one of Primitive, Transi- 
 tion, and Secondary classes. Under the first two he has 
 fossiliferous early Paleozoic formations, but does not 
 know it, because he pays no attention any^vhere to the 
 detail of the entombed fossils, and all of his Secondary 
 is what we now call Paleozoic. The correlations of the 
 latter are faulty throughout. 
 
 Then came his paper of 1830, Geological Prodromus 
 (17, 63), in which he says: "I intend to demonstrate 
 . . . that all geological strata are arranged in five analo- 
 gous series ; and that each series consists of three forma- 
 tions; viz., the Carboniferous [meaning mud-stones], 
 Quartzose, and Calcareous." We seem to see here 
 expressed for the first time the idea of "cycles of sedi- 
 mentation," but Eaton does not emphasize this idea, and 
 the localities given for each "formation" of "analogous 
 series" demonstrate beyond a doubt that he did not have 
 a sedimentary sequence. The whole is simply a jumble 
 of rinrelated formations that happen to agree more or 
 less in their physical characters. 
 
 "I intend to demonstrate," he says further, "that 
 the detritus of New Jersey, embracing the marie, which 
 contains those remarkable fossil relics, is antediluvial, or 
 the genuine Tertiary formation." This correlation had 
 been clearly sho'wn. by Pinch in 1824 (7, 31) and yet both 
 are in error in that they do not distinguish the included 
 Cretaceous marls and greensands as something apart 
 from the Tertiary. 
 
 One gets impatient with the later writings of Eaton, 
 because he does not become liberalized with the progres- 
 sive ideas in stratigraphic geology developing first in 
 Europe and then in America, especially among the geolo- 
 gists of Philadelphia. Therefore it is not profitable to 
 follow his work further. 
 
 Early American Text-hoohs of Geolofiy. — The first 
 American text-book of geology bears the date of Boston 
 1816 and is entitled An Elementary Treatise on Mineral- 
 ogy and Geology, its author being Parker Cleaveland of 
 Bowdoin College. The second edition appeared in 1822. 
 
76 A CENTUEY OF SCIENCE 
 
 It also had a geologic map of the United States, practi- 
 cally a copy of Maclure 's. To mineralogy were devoted 
 585 pages, and to geology 55, of which 37 describe rocks 
 and 5 the geology of the United States. The chronology 
 is Wernerian. Of "geological systems" there are two, 
 "primitive and secondary rocks." 
 
 In 1818 appeared Amos Eaton's Index to the Geology 
 of the Northern States, having 54 pages,_ and in 1820 
 came the second edition, "wholly written over anew," 
 with 286 pages. The theory of the later edition is still 
 that of Werner, with "improvements of Cuvier and 
 Bakcwell," and yet one sees nowadays but little in it of 
 the far better English text-book. Eaton did very little 
 to advance philosophic geology in America. What 
 is of most value here are his personal observations in 
 regard to the local geology of western Massachusetts, 
 Connecticut, southwestern Vermont, and eastern New 
 York (1, 69, 1819; also MerrUl, p. 234). 
 
 We come now to the most comprehensive and advanced 
 of the early text-books used in America. This is the 
 third English edition of Robert Bakewell's Introduction 
 to Geology (400 pages, 1829), and the first American edi- 
 tion "with an Appendix Containing an Outline of his 
 Course of Lectures on Geology at Yale College, by Ben- 
 jamin Silliman" (128 pages). Bakewell's good book is 
 in keeping with the time, and while not so advanced as 
 Conybeare and Phillips's Outlines of 1822, yet is far 
 more so than Silliman 's appendix. The latter is general 
 and not specific as to details ; it is still decidedly Wer- 
 nerian, though in a modified form. Silliman saj^s he is 
 "neither Wernerian nor Tluttonian," and yet his sum- 
 mary on pages 120 to 126 shows clearly that he was not 
 only a Wernerian but a pietist as well. 
 
 Unearfhing of the Ceuozoie and Mesozoic 
 in North AmeHca. 
 
 The Discerning of the Tertiary. — The New England 
 States, with their essentially igneous and metamorphic 
 formations, could not furnish the proper geologic envi- 
 ronment for the development of stratigraphers and 
 paleontologists. So in America we see the rise of such 
 geologists first in Philadelphia, where they had easy 
 
HISTORICAL GEOLOGY 77 
 
 access to the horizontal and highly fossiliferous strata of 
 the coastal plain. The first one to attract attention was 
 Thomas Say, after him came John Finch, followed by 
 Lardner Vanuxem, Isaac Lea, Samuel G. Morton, and 
 T. A. Conrad. These men not only worked out the 
 succession of the Cenozoic and the upper part of the 
 Mesozoic, but blazed the way among the Paleozoic strata 
 as well. 
 
 Thomas Say (1787-1834), in 1819, was the first Ameri- 
 can to point out the chronogenetic value of fossils in his 
 article, Observations on some Species of Zoophytes, 
 Shells, etc., principally Fossil (1, 381). He correctly 
 states that the progress of geology "must be in part 
 founded on a knowledge of the different genera and 
 species of reliquise, which the various accessible strata of 
 the earth present." Say fully realizes the difficulties in 
 the study of fossils, because of their fragmental charac- 
 ter and changed nature, and that their correct interpre- 
 tation requires a knowledge of similar living organisms. 
 
 The application of what Say pointed out came first in 
 John Finch's Geological Essay on the Tertiary Forma- 
 tions in America (7, 31, 1824). Even though the paper 
 is still laboring under the mineral system and does not 
 discern the presence of Cretaceous strata among his Ter- 
 tiary formations, yet Finch also sees that "fossils con- 
 stitute the medals of the ancient world, by which to ascer- 
 tain the various periods." 
 
 Finch now objects to the wide misuse in America of 
 the term alluvial and holds that it is applied to what is 
 elsewhere known as Tertiary. He says : 
 
 "Geology will achieve a triumph in America, when the term 
 alluvial shall be banished from her Geological Essays, or con- 
 fined to its legitimate domain, and then her tertiary formations 
 will be seen to coincide with those of Europe, and the formations 
 of London, Paris, and the Isle of Wight, will find kindred asso- 
 ciations in Virginia, the Carolinas, Georgias, the Floridas, and 
 Louisiana. ' ' 
 
 The formations as he has them from the bottom 
 upwards are: (1) Ferruginous sand, (2) Plastic clay, 
 (3) Calcaire Silicieuse of the Paris- Basin, (4) London 
 Clay, (5) Calcaire Ostree, (6) Upper marine formation, 
 (7) Diluvial. 
 
78 A CENTURY OF SCIENCE 
 
 The grandest of these early stratigraphic papers, 
 however, is that by Lardner Vanuxem (1?92-1848]_, of 
 only three pages, entitled "Remarks on the Characters 
 and Classification of Certain American Rock Forma- 
 tions" (16, 254, 1829). Vanuxem, a cautions man and a 
 profound thinker, had been educated at the Paris School 
 of Mines. James Hall told the writer in a conversation 
 that while the first New York State Survey was in oper- 
 ation, all of its members looked to Vanuxem for advice. 
 
 In the paper above referred to, Vanuxem points out in 
 a very concise manner that : 
 
 "The alluvial of Mr. Maclure . . . contains not only well 
 characterized alluvion, but products of the tertiary and second- 
 ary classes. Littoral shells, similar to those of the English and 
 Paris basins, and pelagic shells, similar to those of tlie chalk 
 deposition or latest secondary, abound in it. These two kinds 
 of shells are not mixed with each other ; they occur in different 
 earthy matter, and, in the southern states particularly, are at 
 different levels. The incoherency or earthiness of the mass, and 
 our former ignorance of the true position of the shells, have been 
 the sources of our erroneous views." 
 
 The second error of the older geologists, according to 
 Vanuxem, was the extension of the secondary rocks over 
 "the western country, and the back and upper parts of 
 New York. " They are now called Paleozoic. Some had 
 even tried to show the presence of Jurassic here because 
 of the existence of oolite strata. "It was taken for 
 granted, that all horizontal rocks are secondarj^, and as 
 the rocks of these parts of the United States are horizon- 
 tal in their position, so they were supposed to be second- 
 ary." He then shows on the basis of similar Ordovician 
 fossils that the rocks of Trenton Falls, New York, recur 
 at Frankfort in Kentucky, and at Nashville in Tennessee. 
 
 "It is also certain that an uplifting or downf ailing 
 force, or both, have existed, but it is not certain that 
 either or both these forces have acted in a uniform man- 
 ner. . . . Innumerable are the facts, which have fallen 
 under my observation, which show the fallacy of adopt- 
 ing inclination for the character of a class," such as the 
 Transition class of strata. He then goes on to say that 
 in the interior of our country the so-called secondary 
 rocks are horizontal and in the mountains to the east the 
 
HISTOEICAL GEOLOGY 79 
 
 same strata are liigiily inclined, ' ' Tlie analogy, or iden- 
 tity of rocks, I determine by their fossils in the first 
 instance, and their position and mineralogical characters 
 in the second or last instance." 
 
 It appears that Isaac Lea (1792-1886) in his Contri- 
 butions to Geology, 1833, was the first to transplant to 
 America Lyell's terms. Pliocene, Miocene, and Eocene, 
 proposed the previous year. The celebrated Claiborne 
 locality was made known to Lea in 1829, and in the work 
 here cited he describes from it 250 species, of which 200 
 are new. The horizon is correlated with the London 
 Clay and with the Calcaire Grossier of France, both of 
 Eocene time (25, 413, 1834). 
 
 Tunothy A. Conrad began to write about the Ameri- 
 can Tertiary in 1830, and his more important publica- 
 tions were issued at Philadelphia. His papers in the 
 Journal begin with 1833 and the last one on the Tertiary 
 is in 1846. 
 
 The Tertiary faunas and stratigraphy have been 
 modernized by William H. Dall in his monumental work 
 of 1650 pages and 60 plates entitled "Contributions to 
 the Tertiary Fauna of Florida ' ' ( 1885-1903 ) . Here more 
 than 3160 forms of the Atlantic and Gulf deposits are 
 described, but in order to understand their relations to 
 the fossil faunas elsewhere and to the living world, the 
 author studied over 10,000 species. Since then, many 
 other workers have interested themselves in the Tertiary 
 problems. Much good work is also being done in 
 the Pacific States where the sequence is being rapidly 
 developed. 
 
 The Discerning of the Eastern Cretaceous. — The Cre- 
 taceous sequence was first determined bv that "active 
 and acute geologist," Samuel G. Morton (1799-1851), but 
 that these rocks might be present along the Atlantic 
 border had been surmised as early as 1824 by Edward 
 Hitchcock (7, 216). Vanuxem, as above pointed out, 
 indicated the presence of the Cretaceous in 1829. In 
 this same year Morton proved its presence before the 
 Philadelphia Academy of Natural Sciences. 
 
 Between 1830 and 1835 Morton published a series of 
 papers in the Journal under the title "Synopsis of the 
 Organic Remains of the Ferruginous Sand Formation of 
 
80 A CENTURY OF SCIENCE 
 
 the United States, with Geological Eemarks" (17, 274, et 
 seq.). In these he describes the Cretaceous fossils and 
 demonstrates that the "Diluvial" and Tertiary strata of 
 the Atlantic border also have a long sequence of Creta- 
 ceous formations. In the opening paper he writes : "I 
 consider the marl of New Jersey as referable to the great 
 ferruginous sand series, which in Prof. Bucldand's 
 arrangement is designated by the name of green sand. 
 . . . On the continent this series is called the ancient 
 chalk . . . lower chalk," etc. Again, the marls of New 
 Jersey are "geologically equivalent to those beds which 
 in Europe are interposed between the white chalk and 
 the Oolites." This correlation is with the European 
 Lower Cretaceous, but we now know the marls to be of 
 Upper Cretaceous age. Although Eaton objected stren- 
 uously to Morton's correlation, we find M. Dufresnoy of 
 France saying, "Your limestone above green sand 
 reminds me verv much of the Mtestricht beds," a correla- 
 tion which stands to this day (22, 94, 1832). In 1833 Mor- 
 ton announces that the Cretaceous is known all along the 
 Atlantic and Gulf border, and in the Mississippi valley. 
 "The same species of fossils are found throughout," and 
 none of them are known in the Tertiary. He now 
 arranges the strata of the former "Alluvial" as follows: 
 
 Modem 
 
 I Alluvial. 
 
 ] Diluvial. 
 
 r Upper Tertiary (Upper Marine). 
 Tertiary 4 Middle Tertiary (London Clay). 
 
 l^Lower Tertiary (Plastic Clay), 
 q -, j Calcareous Strata / Cretaceous group, or Perrugi- 
 
 beconaary ^ ferruginous Sand \ nous Sand series (24, 128). 
 
 Western Cretaceous.— In 1841 and 1843 J. N. Nicollet 
 announced the discovery of Cretaceous in the Rocky 
 Mountain area. Of 20 species of fossils collected by 
 him, 4 were said to occur on the Atlantic border, and of 
 the 200 forms of the Atlantic slope only 1 was found in 
 Europe. Here we see pointed out a specific dissimilarity 
 between the continents, and a similarity between the 
 American areas of Cretaceous deposits (41, 181; 45, 153). 
 
 The Cretaceous of the Rocky JMountains was clearly 
 
HISTORICAL GEOLOGY 81 
 
 developed by F. V. Hayden in 1855-1888 and by F. B. 
 Meek (1857-1876). Other workers in this iield were 
 Charles A. AVhite (1869-1891), and R. P. "\Aniitfield (1877- 
 1889) . Since 1891 T. W. Stanton has been actively inter- 
 preting its stratigraphy and faunas. 
 
 Cretaceous and Comanche of Texas. — The broader 
 outlines of the Cretaceous of Texas bad been described 
 by Ferdinand Roomer in 1852 in his good work, Kreide- 
 bildungen von Texas, but it was not until 1887 that 
 Robert T. Hill showed in the Journal (33, 291) that it 
 included two great series, the Gulf series, or what we now 
 call Upper Cretaceous, and a new one, the Comanche 
 series. This was a very important step in the right 
 direction. Since then the Comanche scries has been 
 regarded by some stratigraphers as of period value, 
 while others call it Lower Cretaceous; the rest of the 
 Texas Cretaceous is divided by Hill into Middle and 
 Upper Cretaceous. On the other hand, Lower Creta- 
 ceous strata had been proved even earlier in the state of 
 California, for here in 1869 W. M. Gabb (1839-1878) and 
 J. D. Whitney (1819-1896) had defined their Shasta 
 group, which was wholly distinct faunally from the 
 Comanche of Texas and the southern part of the Great 
 Plains country. 
 
 Jurassic and Triassic of the West. — In 1864, the Geo- 
 logical Survey of California proved the presence of 
 marine Upper Triassic in that State, and since then it 
 has been shown that not only is all of the Triassic present 
 in Idaho (where it has been known since 1877), Oregon, 
 Nevada, and California, but that the Upper Triassic is 
 of very wide distribution throughout western North 
 America. Jurassic strata, on the other hand, were not 
 shown to be present in California until 1885, while in the 
 Rocky Mountain area of the United States there was 
 long kno"wn an unresolved series of "Red Beds" sit- 
 uated between the Carboniferous and Cretaceous. This 
 .gave rise to the "Red Bed problem," the history of 
 which is given by C. A. Wliite in the Journal (17, 214, 
 1879). In 1869, F. V. Hayden announced the discovery 
 of marine Jurassic fossils in this series, and since then 
 they have come to be known as the Sundance fauna, 
 extending from southern Utah and Colorado into Alaska. 
 
82 A CENTURY OF SCIENCE 
 
 Above lie the dinosaur-bearing fresh-water deposits, 
 since 1894 Imown as the Morrison beds. In 1896, O. C. 
 Marsh (1831-1899) announced the presence of Jurassic 
 fresh-water strata along the Atlantic coast (2, 433), but 
 to-day only a small part of them are regarded as of the 
 age of the Morrison, while the far greater part are 
 referred to the Comanche or Lower Cretaceous. The 
 red beds below the Jurassic of the Rocky Mountain area 
 have during the past twenty years been shown to be in 
 part of Upper Triassic age and of fresh-water origin, 
 while the greater lower part is connected with the Car- 
 boniferous series and is made up of brackish- and fresh- 
 water deposits of probable Permian time. 
 
 Triassic of Atlantic States. — The fresh-water Triassic 
 of the Atlantic border states was first mentioned by 
 Maclure (1817), who regarded it as the equivalent of the 
 Old Red Sandstone of Europe. In this he was followed 
 by Hitchcock in 1823 (6, 39), the latter saying that above 
 it lies "the coal formation," which is true for Europe, 
 but in America the coal strata are older than these red 
 beds, now known to be of Triassic age. 
 
 The first one to question this correlation was Alex- 
 andre Brongniart, who had received from Hitchcock rock 
 specimens and a fossil fish which he erroneously identi- 
 fied with a Permian species, and accordinglv referred 
 the strata to the Permian (3, 220, 1821 ; 6, 76,^1- 9, figs. 1, 
 2, 1823). The discerning Professor Finch in 1826 
 remarked that the red beds of Connecticut appear to 
 belong "to the new or variegated sandstone," because of 
 eight different criteria that he mentions. Of these, but 
 two are of value in correlation, their "geological posi- 
 tion" and the presence of bones other than fishes. In 
 the Connecticut area, however, the geological position 
 cannot be determined even to-day, and in Finch's time 
 the bones of dinosaurs were unknown. Finch then goes 
 on to point out the occurrences of Old Red Sandstone in 
 Pennsylvania, but all of the places he refers to are either 
 younger or older in time. Here we again see the fatality 
 of trying to make positive correlations on the basis of 
 lithology and color (10, 209, 1826), In 1835, however, 
 Hitchcock showed that the bones that had been found in 
 1820 were those of a saurian, and accordingly referred 
 
HISTOEICAL GEOLOGY 83 
 
 the strata of the Connecticut valley to the New Red 
 Sandstone, a term that then covered both the Permian 
 and the Triassic. In 1842, W. B. Rogers referred the 
 beds to the Jurassic, on the basis of plants from Virginia. 
 In 1856, W. C. Redfield (1789-1857), because of the fishes, 
 advocated a Lias, or Jurassic age, and proposed the 
 name Newark group for all the Triassic deposits of 
 the Atlantic border. More recently, on the basis of the 
 plants studied by Newberry, Fontaine, Sturr, and Ward, 
 and the vertebrates described by Marsh and Lull, the 
 age has been definitely fixed as Upper Triassic (see 
 Dana's Manual of Geology, 740, 1895). 
 
 Unearthing of the Paleozoic in North America. 
 
 Permian of the United States. — In Europe, previous to 
 1841, the formations now classed as Permian were 
 included in the New Red Sandstone, and with the Car- 
 boniferous were referred to the Secondary. In that 
 year Murchison proposed the period term Permian. In 
 1845 came the classic Geology of Russia in Europe and 
 the Ural Mountains, by Murchison, Keyserling, and De 
 Verneuil. In this great work the authors separated out 
 of the New Red the Magnesian Limestone of Great Brit- 
 ain and the Rothliegende marls, Kupferschiefer, and 
 Zechstein of Germany, and with other formations of the 
 Urals in Russia, referred them to the Permian system. 
 This step, one of the most discerning in historical geol- 
 ogy, was all the more important because they closed the 
 Paleozoic era with the Permian, beginning the Second- 
 ary, or Mesozoic, with the New Red Sandstone or the 
 Triassic period. There is a good review of this work by 
 D. D. Owen (1807-1860) in the Journal for 1847 (3, 153). 
 
 Owen, though accepting the Permian system, is not 
 satisfied with "its reference to the Paleozoic, and he sets 
 the matter forth in the Journal (3, 365, 1847). He 
 doubts "the propriety of a classification which throws 
 the Permian and Carboniferous systems into the Paleo- 
 zoic period." This is mainly because there is no "evi- 
 dence of disturbance or unconformability" between the 
 Permian and Triassic systems. Rather "there is so 
 complete a blending of adjacent strata" that it is only 
 
84 A CENTUEY OF SCIENCE 
 
 in Eussia that the Permian has been distinguished from 
 the Triassic. This view of Owen 's was not only correct 
 for Eussia but even more so for the Alps and for India, 
 and it has taken a great deal of work and discussion to 
 tix upon the disconformable contact that distinguishes 
 the Paleozoic from the Mesozoic in these areas. In 
 other w^ords, there was here at this time no mountain 
 making. Then Owen goes on to state that because the 
 Permian of Europe has reptiles, he sees in them decisive 
 ]\Iesozoic evidence. "These are certainly strong argu- 
 ments in favor of placing, not only the Permian, but also 
 the Carboniferous groujo in the Mesozoic period, and ter- 
 minating the Paleozoic division with the commencement 
 of the coal measures." To this harking backwai'd the 
 geologists of the world have not agreed, but have fol- 
 lowed the better views of Murchison and his associates. 
 
 In 1855 G. G. Shumard discovered, and in 1860 his 
 brother B. F. Shumard (1820-1869) announced, the 
 presence of Permian strata in the Guadalupe Mountains 
 of Texas, and in 1902 George H. Girty (14, 363) con- 
 firmed this. Girty regards the faunas as younger than 
 any other late Paleozoic ones of America, and says: 
 "For this reason I propose to give them a regional name, 
 which shall be employed in a force similar to Mississip- 
 pian and Pennsylvanian. . . . The term Guadalupian is 
 suggested." 
 
 G^. C. Swallow (1817-1899) in 1858 was the first to 
 announce the presence of Permian fossils in Kansas, and 
 this led to a controversy between himself and F. B. Meek, 
 both claiming the discovery. It is only in more recent 
 years that it has been generally admitted that there is 
 Permian in that state, in Oklahoma, and in Texas. This 
 admission came the more readily through the discovery 
 of manv reptiles in the red beds of Texas, and through 
 the work of C. A. Wliite, published in 1891, The Texan 
 Permian and its Mesozoic Tj^dcs of Fossils (Bull. U. S. 
 Geological Survey, No. 77). 
 
 Carboniferous Formations. — The coal formations are 
 noted in a general way throughout the earliest volumes 
 of the Journal.' The first accounts of the presence of 
 coal, in Ohio, are bv Caleb Atwater (1, 227 239 1819) 
 and S. P. Hildreth (13, 38, 40, 1828). The first coal 
 
HISTORICAL GEOLOGY 85 
 
 plants to be described and illustrated were also from 
 Ohio, in an article by Ebenezer Granger in 1821 (3, 5-7). 
 The anthracite field was first described in 1822 by Zach- 
 ariah Cist (4, 1) and then by Benjamin Silliman (10, 
 331-351, 1826) ; that of western Pennsylvania was 
 described by William Meade in 1828 (13, 32). 
 
 The Lower Carboniferous was first recognized by W. 
 W. Mather in 1838 (34, 356). Later, through the work 
 of Alexander Winchell (1824-1891), beginning in 1862 
 (33, 352) and continuing until 1871, and through the 
 surveys of Iowa (1855-1858), Illinois (essentially the 
 work of A. H. Worthen, 1858-1888), Ohio (1838, Mather, 
 etc.), and Indiana (Owen, etc., 1838), there was even- 
 tually worked out the following succession: 
 
 Permian period. 
 
 Upper Barren series. 
 Dunkard group. 
 Washington group. 
 Pennsjdvanian period. 
 
 Upper Productive Coal series. Monongahela series. 
 Lower Barren Coal Measures. Conemaugh series. 
 Lower Productive Coal Measures. Allegheny series. 
 Pottsville series. 
 
 The Netv York System. — We now come to the epochal 
 survej" of the State of New York, one that established 
 the principles of, and put order into, American strati- 
 graphy from the Upper Cambrian to the top of the 
 Devonian. No better area could have been selected for 
 the establishing of this sequence. This survey also 
 developed a stratigraphic nomenclature based on New 
 York localities and rock exposures, and made full use of 
 the entombed fossils in correlation. Incidentally it devel- 
 oped and brought into prominence James Hall, who con- 
 tinued the stratigraphic work so well begun and \yho 
 also laid the foundation for paleontology in America, 
 becoming its leading invertebrate worker. 
 
 This work is reviewed at great length in the Journal 
 in the volumes for 1844-1847 by D. D. Owen. Evidently 
 it followed too new a plan to receive fulsome praise from 
 conservative Owen, as it should have. He remarks that 
 the volumes ' ' are not a little prolix, are voluminous and 
 
8G A CENTURY OF SCIENCE 
 
 expensive, and do not give as clear and connected a view 
 of tlie geological features of the state as could be wished. 
 . . . We are of the opinion that before this work can 
 become generally useful and extensively circulated, it 
 must be condensed and arranged into one compendious 
 volume" (46, 144, 1844). This was never done and yet 
 the work was everywhere accepted at once, and to this 
 end undoubtedly Owen's detailed review helped much. 
 
 The Natural History Survey of New York was organ- 
 ized in 1836 and completed in 1843. The state was 
 divided into four districts, and to these were finally 
 assigned the following experienced geologists. The 
 southeastern part was named the First District, with W. 
 W. Mather (1804-1859) as geologist; the northeastern 
 quarter was the Second District, with Ebenezer Emmons 
 (1799-1863) in charge ; the central portion was the Third 
 District, under Lardner Vanuxem (1792-1848) ; while 
 the western part was James Hall's (1811-1898) Fourth 
 District. Paleontology for a time was in charge of T. A. 
 Conrad (1830-1877) ; the mineralogical and chemical work 
 was in the hands of Lewis C. Beck; the botanist was 
 John Torre}' ; and the zoologist James DeKay. 
 
 The New York State Survey published six annual 
 reports of 1675 pages octavo, and four final geological 
 reports with 2079 pages quarto. Finally in 1846 
 Emmons added another volume on the soils and rocks 
 of the state, in which he also discussed the Taconic and 
 New York systems ; it has 371 pages. With the com- 
 pletion of the first survey. Hall took up his life work 
 under the auspices of the state — his monumental work. 
 Paleontology of New York, in fifteen quarto volumes of 
 4539 pages and 1081 plates of fossils. In addition to all 
 this, there are his annual and other reports to the 
 Regents of the State, so that it is safe to say that he 
 pul3lislied not less than 10,000 pages of printed matter 
 on the geology and paleontology of North America. 
 
 In regard to this great series of works, all that can be 
 presented here is a table of formations as developed by 
 the New York State Survey. Practically all of its 
 results and formation names have come into general use, 
 with the exception of the Taconic system of Emmons and 
 the division terms of the New York sj^stem. (See p. 88.) 
 
HISTORICAL GEOLOGY 87 
 
 The New York State Survey, begun in 1836, was con- 
 tinued by James Hall from 1843 to 1898. During this 
 time he was also state geologist of Iowa (1855-1858) and 
 Michigan (1862). Since 1898, John M. Clarke has ably 
 continued the Geological Survey of New York, the state 
 which continues to be, in science and more especially in 
 geology and paleontology, the foremost in America. 
 
 Western Extension of the Neiu York system. — Before 
 Hall finished his final report, we find him in 1841 on "a 
 tour of exploration through the states of Ohio, Indiana, 
 Illinois, a part of Michigan, Kentucky, and Missouri, and 
 the territories of Iowa and Wisconsin." This tour is 
 described in the Journal (42, 51, 1842) under the caption 
 "Notes upon the Geology of the Western States." His 
 object was to ascertain how far the New York system as 
 the standard of reference "was applicable in the western 
 extension of the series." In a general way he was very 
 successful in extending the sj^stem to the Mississippi 
 River, and he clearly saw "a great diminution, first of 
 sandy matter, and next of shale, as we go westward, and 
 in the whole, a great increase of calcareous matter in the 
 same direction." He also clearly noted the warped 
 nature of the strata, the "anticlinal axis," since known 
 as the Cincinnati and Wabash uplifts and the Ozark 
 dome. 
 
 Hall, however, fell into a number of flagrant errors 
 because of a too great reliance on lithologic correlation 
 and supposedlj^ similar sequence. For instance, the 
 Coal Measures of Pennsylvania were said to directly 
 overlap the Chemung group of southern New York, and 
 now he finds the same condition in Ohio, Indiana, and 
 Illinois, failing to see that in most places between the 
 top of the New York system and the Coal Measures lay 
 the extensive Mississippian series, one that he generally 
 confounded with the Chemung, or included in the ' ' Car- 
 boniferous group. ' ' He states that the Portage of New 
 York is the same as the Waverly of Ohio, and at Louis- 
 ville the Middle Devonian waterlime is correlated with 
 the similar rock of the New York Silurian. Hall was 
 especially desirous of fixing the horizon of the Middle 
 Ordovician lead-bearing rocks of Illinois, Wisconsin, and 
 Iowa, but unfortunately correlated them with the Niag- 
 
88 
 
 A CENTURY OF SCIENCE 
 
 The Geological Column of the New York Geologists of 1842-1843, 
 according to W. W. Mather 1842. 
 
 C Alluvial division. 
 Quaternary sj'stem -< Quaternary division. 
 
 I Drift division. 
 
 Tertiary system 
 
 Upper Secondary 
 system 
 
 These strata are included in the next 
 lower division. 
 
 Long Island division. Equals the Ter- 
 tiary and Cretaceous marls, sands, 
 and clays of the coastal plain of New 
 Jersey. 
 
 New Ked system 
 of Emmons and 
 Hall. 
 
 Trappean division. 
 
 The Palisades 
 Eed Sandstone 
 division. 
 
 Coal system of Mather, and Carboniferous system of Hall. 
 Old Eed sj^stem of Catskill Mountains of Emmons ; Catskill 
 division of Mather and Hall ; and Catskill group of Vanuxem. 
 
 According to Hall 1843, and essentially Yanuxem 1842. 
 
 ' Chemung, Portage or Nunda (divided 
 into Cashaqua, Gardeau, Portage), 
 Genesee, Tully, Hamilton (divided 
 into Ludlowville, Enerinal, Moscow), 
 and Mareellus. 
 
 Corniferous, Onondaga, Schoharie, Cau- 
 da-galli, Oriskany, Upper Pentame- 
 rus, Enerinal, Delthyris, Pentamerus, 
 Waterlime, Onondaga salt group. 
 
 Niagara, Clinton, and Medina. 
 
 Oneida or Shawangunk, Grey sandstone, 
 Hudson Eiver group, Utica, Trenton, 
 Black Eiver including Birdseye and 
 Chazy, Calciferous sandrock, and 
 Potsdam. 
 
 Erie division 
 [Devonian] 
 
 Helderberg series 
 [Devonian- 
 Silurian] 
 
 Ontario division 
 [Silurian] 
 
 Champlain division 
 [ Silurian-Ordovi- 
 cian-Upper 
 Cambrian] 
 
 According to Emmons 1842, Mather 1843, Yanuxem 1842, 
 Hall 1843. 
 
 Taconic system f ^ , ^ cu -, -, ■ -, 
 
 [Ordovician and \ G^nular quartz Stockbridge Innestone, 
 Lower Cambrian] 1 ^agnesian slate, and Taconic slate. 
 
 Primary or Hypo- 
 gene system 
 
 Metamorphic and Primary rocks. 
 
lilSTORICAL GEOLOGY 89 
 
 aran, while the IMiddle Devonian about Cohimbus, Ohio, 
 and Louisville, Kentucky, he referred to the same 
 horizon. The Galena-Niagaran error was corrected in 
 1855, but the Devonian and Mississippian ones remained 
 unadjusted for a long time, and in Iowa until toward the 
 close of the nineteenth century. 
 
 Correlations u-'dli Europe. — The first effort toward 
 correlating the New York system with those of Europe 
 was made by Conrad in his Notes on American Geology 
 in 1839 (35, 243). Here he compares it on faunal 
 grounds with the Silurian system. A more sustained 
 effort was that of Llall in 1843 (45, 157), when he said 
 that the Silurian of Murchison was equal to the New 
 York system and embraced the Cambrian, Silurian, and 
 Devonian, which he considered as forming but one sys- 
 tem. Hall in 1844 and Conrad earlier were erroneously 
 regarding the Aliddle Devonian of New York (Hamilton) 
 as "an equivalent of the Ludlow rocks of Mr. Murchi- 
 son" (47, 118, 1844). 
 
 In 1846 E. P. De Verneuil spent the summer in Amer- 
 ica with a view to correlating the formations of the New 
 York system with those of Europe. At this time he had 
 had a wide field experience in France, Germany, and 
 Russia, was president of the Geological Society of 
 France, and "virtually the representative of European 
 geology" (2, 153, 1846). Hall says, "No other person 
 could have presented so clear and perfect a coup d'oeil. " 
 De Verneuil's results were translated by Hall and with 
 his own comments were published in the Journal in 1848 
 and 1849 under the title "On the Parallelism of the 
 Paleozoic Deposits of North America with those of 
 Europe." De Verneuil was especially struck with the 
 complete development of American Paleozoic deposits 
 and said it was the best anywhere. On the other hand, 
 he did not agree with the detailed arrangement of the 
 formations in the various divisions of the New York 
 system, and Hall admitted altogether too readily that the 
 terms were proposed "as a matter of concession, and it is 
 to be regretted that such an artificial classification was 
 adopted." De Verneuil's correlations are as follows: 
 
 The Lower Silurian system begins with the Potsdam, 
 the analogue of the Obolus sandstone of Russia and 
 
90 A CENTURY OF SCIENCE 
 
 Sweden. The Black River and Trenton hold the position 
 of the Orthoceras limestones of Sweden and Russia, 
 while the Utica and Lorraine are represented by the 
 Graptolite beds of the same countries. Both porrelations 
 are in partial error. He unites the Chazy, Birdseye, and 
 Black River in one series, and in another the Trenton, 
 Utica, and Lorraine. Of species common to Europe and 
 America he makes out seventeen. 
 
 In the Upper Silurian system, the Oneida and 
 Shawangunk are taken out of the Champlain division, 
 and, witii the Medina, are referred to the Silurian, along 
 with all of the Ontario division plus the Lower Helder- 
 berg. The Clinton is regarded as highest Caradoc or as 
 holding a stage between that and the Wenlock. The 
 Niagara group is held to be the exact equivalent of the 
 Wenlock, "while the live inferior groups of the Helder- 
 berg division represent the rocks of Ludlow." We now 
 know that these Helderberg formations are Lower Devo- 
 nian in age. De Verneuil unites in one series the 
 Waterlime, Pentamerus, Delthyris, Encrinal, and Upper 
 Pentamerus. Of identical species there are forty com- 
 mon to Europe and America. 
 
 The Devonian system De Verneuil begins, "after 
 much hesitation," with the Oriskany and certainly with 
 the five upper members of Hall 's Helderberg division, all 
 of the Erie and the Old Red Sandstone. He also adjusts 
 Hall's error by placing in the Devonian the Upper Cliff 
 limestone of Ohio and Indiana, regarded by the former 
 as Silurian. The Oriskany is correlated with the grau- 
 wackes of the Rhine, and the Onondaga or Corniferous 
 with the lower Eifelian. Cauda-galli, Schoharie, and 
 Onondaga are united in one series ; Marcellus, Hamilton, 
 TuUy, and Genesee in another; and Portage and 
 Chemung in a third. Of species common to Europe and 
 America there are thirty-nine. 
 
 The Waverly of Ohio and that near Louisville, Ken- 
 tucky, which Hall had called Chemung, De Verneuil cor- 
 rectly refers to the Carboniferous, but to this Hall does 
 not consent. De Verneuil points out that there are 
 thirty-one species in common between Europe and Amer- 
 ica. "And as to plants, the immense quantity of terres- 
 trial species identical on the two sides of the Atlantic, 
 
HISTORICAL GEOLOGY 91 
 
 proves that the coal was formed in the neighborhood of 
 lands already emerged, and placed in similar phj^sical 
 conditions. ' ' 
 
 An analysis of the Paleozoic fossils of Europe and 
 America leads De Vernenil to ' ' the conviction that identi- 
 cal species have lived at the same epoch in America and 
 in Europe, that they have had nearly the same duration, 
 and that they succeeded each other in the same order." 
 This he states is independent of the depth of the seas, 
 and of "the upheavings which have affected the surface 
 of the globe." The species of a period begin and drop 
 out at different levels, and toward the top of a system 
 the whole takes on the character of the next one. "If it 
 happens that in the two countries a certain number of 
 systems, characterized by the same fossils, are superim- 
 posed in the same order, whatever may be, otherwise, 
 their thickness and the number of physical groups of 
 which they are composed, it is philosophical to consider 
 these systems as parallel and synchronous." 
 
 Because of the dominance of the sandstones and shales 
 in eastern New York, De Vernenil holds that a land lay 
 to the east. The many fucoids and ripple-marks from 
 the Potsdam to the Portage indicated to him shallow 
 water and nearness to a shore. 
 
 The Oldest Geologic Eras. — We have seen in previous 
 pages how the Primitive rocks of Arduino and of Werner 
 had been resolved, at least in part, into the systems of 
 the Paleozoic, but there still remained many areas of 
 ancient rocks that could not be adjusted into the accepted 
 scheme. One of the most extensive of these is in Canada, 
 where the really Primitive formations, of granites, 
 gneisses, schists, and even undetermined sediments, 
 abound and are developed on a grander scale than else- 
 where, covering more than two million square miles and 
 overlain unconformably by the Paleozoic and later rocks. 
 The first to call attention to them was J. I. Bigsby, a 
 medical staff officer of the British Army, in 1821 (3, 
 254). It was, however, William E. Logan (1798-1875), 
 the "father of Canadian geolo,gy," who first unravelled 
 their historical sequence. At first he also called them 
 Primary, but after much work he perceived in them par- 
 allel structures and metamorphosed sediments, under- 
 
92 A CENTURY OF SCIENCE 
 
 lain by and associated with pink granites. For the 
 oldest masses, essentially the granites, he proposed the 
 term Laurentian system (1853,"l863) and for the altered 
 and deformed strata, the name Huronian series (1857, 
 18G3). Overlying these unconformably was a third 
 series, the copper-bearing rocks. Since his day a great 
 host of Canadian and American geologists have labored 
 over this, the most intricate of all geology, and now we 
 have the following tentative chronology (Schu chert and 
 Barren, 38, 1, 1914) : 
 
 Late Proterozoic era. 
 
 Keweenawan, Animikian and Huronian periods. 
 Early Proterozoic era. 
 
 Sudburian period or older Huronian. 
 Archeozoic era. 
 
 Granville series, etc. 
 Cosmic history. 
 
 Tlie Taconic System Resurrected. 
 
 The Taconic system Avas first announced by Ebenezer 
 Emmons in 1841, and clearly defined in 1842. It started 
 the most bitter and most protracted discussion in the 
 annals of American geology. After Emmons's subse- 
 quent publications had put the Taconic system through 
 three phases, Barrande of Bohemia in 1860-1863 shed a 
 great deal of new and correct light upon it, affirming in a 
 series of letters to Billings that the Taconic fossils are 
 like those of his Primordial system, or what we now call 
 the Middle Cambrian (31, 210, 1861, et seq.). 
 
 In a series of articles published b;^ S. W. Ford in the 
 Journal between 1871 and 1886, there was developed the 
 further new fact that in Rensselaer and Columbia coun- 
 ties, New York, the so-called Hudson River group 
 abounds in "Primordial" fossils wholly unlike those of 
 the Potsdam, and which Ford later on spoke of as 
 belonging to "Lower Potsdam" time. 
 
 James D. Dana entered the field of the Taconic area in 
 1871 and demonstrated that the system also abounds in 
 Ordovician fossiliferous formations. Then came the 
 far-reaching work of Charles D. Walcott, beginning in 
 1886, which showed that all through eastern New York 
 and into northern Vermont the Hudson River group and 
 
HISTORICAL GEOLOGY 93 
 
 the Taconic system abound not only in Ordovician but 
 also in Cambrian fossils. Finally in 1888 Dana pre- 
 sented a Brief History of Taconie Ideas, and laid away 
 the system with these words (36, 27) : 
 
 "It is almost fifty years since the Taconic system made its 
 abrupt entrance into geological science. Notwithstanding some 
 good points, it has been through its greater errors, long a hin- 
 drance to progress here and abroad . . . But, whether the evil 
 or the good has predominated, we may now hope, while heartily 
 honoring Professor Emmons for his earnest geological labors and 
 his discoveries, that Taconic ideas may be allowed to be and 
 remain part of the past. ' ' 
 
 As an epitaph Dana placed over the remains of the 
 Taconic system the black-faced numerals 1841-1888. 
 That the remains of the system, however, and the term 
 Taconic are still alive and demanding a rehearing is 
 apparent to all interested stratigraphers. This is not 
 the place to set the matter right, and all that can be done 
 at the present time is to point out what are the things 
 that still keep alive Emmons's system. 
 
 In the tj'^oical area of the Taconic system, i. e., in Rens- 
 selaer County, Emmons in 1844-1846 produced the fossils 
 Atops trilineafus and Elliptoce'pliala asaphoides. S. W. 
 Ford, as stated above, later produced from the same gen- 
 eral area many other fossils that he demonstrated to be 
 older than the Potsdam sandstone. To this time he gave 
 the name of Lower Potsdam, thus proving on paleon- 
 tological grounds that at least some i^art of the Taconic 
 system is older than the New York system, and therefore 
 older than the Hudson River group of Ordovician age. 
 
 In 1888 Walcott presented his conclusions in regard to 
 the sequence of the strata in the tjioical Taconic area and 
 to the north and south of it. He collected Lower Cam- 
 brian fossils at more than one hundred localities 
 "within the typical Taconic area," and said that the 
 thickness of his "terrane No. 5" or "Cambrian (Geor- 
 gia)," now referable to the Lower Cambrian, is "14,000 
 feet or more." He demonstrated that the Lower Cam- 
 brian is infolded with the Lower and Middle Ordovician, 
 and confirmed Emmons's statement that the former rests 
 upon his Primary or Pre-Cambrian masses. Elsewhere, 
 he writes: "To the west of the Taconic range the sec- 
 
94 A CENTURY OF SCIENCE 
 
 tion passes clown thi^ough the limestone (3) [of Lower 
 and Middle Ordovician age] to the hydromica schists (2) 
 [whose age may also be of early Ordovician] , and thence 
 to the great development of slates and shales with their 
 interhedded sparry limestones, calcif erous and arenaceous 
 strata, all of which contain more or less of the Olenellus 
 . . . fauna. ' ' He then knew thirty-five species in Wash- 
 ington County, New York (35, 401, 1888). 
 
 Finally in 1915 Walcott said that in the Cordilleran 
 area of America there was a movement that brought 
 about changes "in the sedimentation and succession of 
 the faunas which serve to draw a boundary line between 
 the Lower and Middle Cambrian series. . . . The 
 length of this period of interruption must have been con- 
 siderable . . . and when connection with the Pacific was 
 resumed a new fauna that had been developing in the 
 Pacific was then introduced into the Cordilleran sea and 
 constituted the Middle Cambrian fauna. The change 
 in the species from the Lower to the Middle Cambrian 
 fauna is very great." He then goes on to show that in 
 the Appalachian geosyncline there was another move- 
 ment that shut out the Middle Cambrian Paradoxides 
 fauna of the Atlantic realm from this trough, and all 
 deposition as well. 
 
 Conclusions. — Accordingly it appears that everywhere 
 in America the Lower Cambrian formations are sep- 
 arated by a land interval of long duration from those of 
 Middle Cambrian time. These formations therefore 
 unite into a natural sj^stem of rocks or a period of time. 
 Between Middle and Upper Cambrian time, however, 
 there appears to be a complete transition in the Cordil- 
 leran trough, binding these two series of deposits into 
 one natural or diastrophic system. Hence the writer 
 proposes that the Lower Cambrian of America be known 
 as the Taconic system. The Middle and Upper Cam- 
 brian series can be continued for the present under the 
 term Cambrian system, a term, however, that is by no 
 means in good standing for these formations, as will be 
 demonstrated under the discussion of the Silurian con- 
 troversy. 
 
HISTORICAL GEOLOGY 95 
 
 The Silurian Conf rovers ij. 
 
 Just as in America tlie base of the Paleozoic was 
 involved in a protracted controversy, so in England the 
 Cambrian-Silurian succession was a subject of long 
 debate between Sedgwick and Murchison, and among the 
 succeeding geologists of Europe. The history of the 
 solution is so well and justly stated in the Journal by 
 James D. Dana under the title "Sedgwick and Murchi- 
 son: Cambrian and Silurian" (39, 167, 1890), and by Sir 
 Archibald Geikie in his Text-book of Geology, 1903, that 
 all that is here required is to briefly restate it and to 
 bring the solution up to date. 
 
 Adam Sedgwick (1785-1873) and R. I. Murchison 
 (1792-1871) each began to work in the areas of Cam- 
 bria (Wales) and Siluria (England) in 1831, but the 
 terms Cambrian and Silurian were not published until 
 1835. Murchison was the first to satisfactorily work out 
 the sequence of the Silurian system because of the 
 simpler structural and more fossiliferous condition of 
 his area. Sedgwick, on the other hand, had his academic 
 duties to perform at Cambridge University, and being an 
 older and more conservative man, delaj^ed publishing his 
 final results, because of the further fact that his area 
 was far more deformed and less fossiliferous. In 1834 
 they were working in concert in the Silurian area, and 
 Sedgwick said: "I was so struck by the clearness of the 
 natural sections and the perfection of his workmanship 
 that I received, I might say, with implicit faith every- 
 thing which he then taught me. . . . The whole ' Silurian 
 system' was by its author placed above the great undu- 
 lating slate-rocks of South Wales." At that time Mur- 
 chison told Sed.g^vick that the Bala group of the latter, 
 now known to be in the middle of the Lower Silurian, 
 could not be brought within the limits of the Silurian 
 system, and added, "I believe it to plunge under the true 
 Llandeilo-flags," now placed next below the Bala and 
 above the Arenig, which at the present is regarded as at 
 the base of the Ordovician. 
 
 The Silurian system was defined in print by Murchison 
 in July, 1835, the Upper Silurian embracing the Ludlow 
 and Wenlock, while the Lower Silurian was based on the 
 
96 A CENTURY OF SCIENCE 
 
 Caradoc and Llandeilo. Murchison's monumental work, 
 The Silurian System, of 100 pages and many plates of 
 fossils, appeared in 1838. 
 
 The Cambrian system was described for the first time 
 by Sedgwick in August, 1835, but the completed work — a 
 classic in geology — S3^nopsis of the Classification of the 
 British Palaeozoic Eocks, along with M 'Coy's Descriptions 
 of British PaltTozoic Fossils, did not appear until 1852- 
 1855. Sedgwick's original Upper Cambrian included the 
 greater part of the chain of the BerA\'yns, where he said 
 it was connected with the Llandeilo flags of the Silurian. 
 The Middle Cambrian comprised the higher mountains of 
 Caernarvonshire and Merionethshire, and the Lower 
 Cambrian was said to occupy the southwest coast of 
 Cfernarvonshire, and to consist of chlorite and mica 
 schists, and some serpentine and granular limestone. In 
 1853 it was seen that the fossiliferous Upper Cambrian 
 included the Arenig, Llandeilo, Bala, Caradoc, Coniston, 
 Hirnant, and Lower Llandovery. On the other hand, it 
 was not until long after Murchison and Sedgwick passed 
 away that the Middle and Lower Cambrian were shown 
 to have fossils, but few of those that characterize what 
 is now called Lower, Middle, and Upper Cambrian time. 
 
 Not until long after the original announcement of the 
 Cambrian system did Sedgwick become aware "of the 
 unfortunate mischief-involving fact" that the most fos- 
 siliferous portion of the Cambrian — the Upper Cambrian 
 — and at that time the only part jdelding determinable 
 fossils, when compared with the Lower Silurian was 
 seen to be an equivalent formation but with very dif- 
 ferent lithologic conditions. He began to see in 1842 
 that his Cambrian was in conflict with the Silurian sys- 
 tem, and four years later there were serious divergencies 
 of views between himself and Murchison. The climax 
 of the controversy was attained in 1852, when Sedgwick 
 was extending his Camlnnan system upwards to include 
 the Bala, Llandeilo, and Caradoc, a proceeding not unlilve 
 that of Murchison, who earlier had been extending his 
 Silurian downward through all of the fossiliferous Cam- 
 brian to the base of the Ling-ula flags. 
 
 Dana in his review of the Silurian-Cambrian contro- 
 versy states : ' ' The claim of a worker to affix a name to a 
 
HISTORICAL GEOLOGY 97 
 
 series of rocks first studied and defined by him cannot be 
 disputed." We have seen that Murchison had priority 
 of publication in his term Silurian over Sedgwick's Cam- 
 brian, but that in a complete presentation, both strati- 
 graphically and faunally, the former had years of prior 
 definition. What has even more weight is that geologists 
 nearly everywhere had accepted ]\iurchison's Silurian 
 system as founded upon the Lower and Upper Silurian 
 formations. A nomenclature once widely accepted is 
 almost impossible to dislodge. However, in regard to 
 the controversy it should not be forgotten that it was 
 only Murchison's Loiuer Silurian that was in conflict 
 with Sedgwick's Upper Cambrian. As for the rest of 
 the Cambrian, that was not involved in the controversy. 
 
 Dana goes on to state that science may accept a name, 
 or not, according as it is, or is not, needed. In the prog- 
 ress of geology, he thought that the time had finally been 
 reached when the name Cambrian was a necessity, and 
 he included both Cambrian and Silurian in the geologi- 
 cal record. The ' ' Silurian, ' ' however, included the Lower 
 and Upper Silurian — not one system of rocks, but two. 
 
 It is now twenty-seven years since Dana came to this 
 conclusion, at a time when it was believed that there was 
 more or less continuous deposition not only between the 
 formations of a system but between the systems them- 
 selves as well. To-day many geologists hold that in the 
 course of time the oceans pulsate back and forth over 
 the continents, and accordingly that the sequence of 
 marine sedimentation in most places must be much 
 broken, and to-day we know that the breaks or land inter- 
 vals in the marine record are most marked between the 
 eras, and shorter between all or at least most of the 
 periods. Furthermore, in North America, we have 
 learned that the breaks between the systems are most 
 marked in the interior of the continent and less so on or 
 toward its margins. 
 
 Hardly any one now questions the fact of a long land 
 interval between the Lower Silurian and Upper Silurian 
 in England, and it is to Sedgwick's credit that he was the 
 first to point out this fact and also the presence of an 
 unconformity. It therefore follows that we cannot con- 
 tinue to use Silurian system in the sense proposed by 
 
9S A CENTURY OF SCIENCE 
 
 Murcliison, since it includes two distinct systems or 
 periods. Dana, in the last edition of his Manual of 
 Geology (1895), also recognizes two systems, but 
 curiously he saw nothing incongruous in calling them 
 "Lower Silurian era" and "Upper Silurian era." It 
 certainly is not conducive to clear thinking, however, to 
 refer to two systems by the one name of Silurian and to 
 speak of them individually as Lower and Upper Silurian, 
 thus giving the impression that the two systems are but 
 parts of one — the Silurian. Each one of the parts has its 
 independent faunal and physical characters. 
 
 We must digress a little here and note the work of 
 Joachim Barrande (1799-1883) in Bohemia. In 1846 he 
 published a short account of the "Silurian system" of 
 Bohemia, dividing it into etages lettered C to H. 
 Between 1852 and 1883 he issued his ' ' Systeme Silurien 
 du Centre de la Boheme," in eighteen quarto volumes 
 with 5568 pages of text and 798 plates of fossils — a mon- 
 umental work unrivalled in paleontology. In the first 
 volume the geology of Bohemia is set forth, and here we 
 see that etages A and B are Azoic or pre-Cambrian, and 
 C to H make up his Silurian sj'stem. Etage C has his 
 "Primordial fauna," now known to be of Paradoxides or 
 Middle Cambrian time, while D is Lower Silurian, E is 
 Upper Silurian, F is Lower Devonian, and G and H are 
 Middle Devonian. From this it appears that Barrande 's 
 Silurian system is far more extensive than that of Murclii- 
 son, embracing twice as many periods as that of England 
 and Wales. 
 
 About 1879 there was in England a nearly general 
 agreement that Cambrian should embrace Barrande 's 
 Primordial or Paradoxides faunas, and in the North 
 Wales area be continued up to the top of the Tremadoc 
 slates. To-day we would include Middle and Upper 
 Cambrian. Lower Cambrian in the sense of containing 
 the Olenellus faunas was then unknown in Great Britain. 
 
 Lapworth, recognizing the distinctness of the Lower 
 Silurian as a system, proposed in 1879 to recognize it as 
 such, and named it Ordovician, restricting Silurian to 
 Murchison's Upper Silurian. This term has not been 
 widely used either in Great Britain or on the Continent, 
 but in the last twenty years has been accepted more and 
 
HISTORICAL GEOLOGY 99 
 
 more widely in America. Even here, however, it is in 
 direct conflict witli the term Champhiin, proposed by the 
 New York State Geologist in 1842. 
 
 In 1897 the International Geological Congress pub- 
 lished E. Renevier's Chronographie Geologique, wherein 
 we find the following : 
 
 O 
 
 03 
 
 Upper or Silurian f Ludlowian (Murchison 1839). 
 
 (Murcliison, re- X Wenlockian (Murchison 1839). 
 
 stricted, 1835). |^ Landoverian (Murcliison). 
 
 ■],«-• 1-11 „ „ ri.n„ ■ •„ f Caradocian (Murcliison 1839). 
 Middle or Ordovician ^ , .,• /,^ ,. mon/ 
 
 ,T ., -\Q^n\ -s Landeilian (Murchison 1839). 
 
 (LapWOrth lb/9). ] . • ■ /o i ■ \ ^Q^^\ 
 
 ^ ^ ' l^ Arenigian (Sedgwick 1847). 
 
 Lower or Cambrian f Potsdamian (Emmons 1838). 
 
 (Sedgwick, re- X ilenevian (Salter and Hicks 1865) 
 
 stricted, 1835). |^ Georgian (Hitchcock 1861). 
 
 Regarding this period, which, by the way, is not very 
 unlike that of Barrande, Renevier remarks that it is "as 
 important as the Cretaceous or the Jurassic. Lapworth 
 even gives it a value of the first order equal to the Pro- 
 tozoic era." 
 
 In the above there is an obvious objection in the double 
 usage of the term Silurian, and this difficulty was met 
 later on in Lapparent's Traite by the proposal to substi- 
 tute Gothlandian for Silurian. Of this change Geikie 
 remarks : ' ' Such an arrangement . . . might be adopted 
 if it did not involve so serious an alteration of the nomen- 
 clature in general use." On the other hand, if dias- 
 trophism and breaks in the stratigraphic and fauna! 
 sequence are to be the basis for geologic time divisions, 
 we cannot accept the above scheme, for it recognizes 
 but one period where there are at least four in nature. 
 
 Conclusions. — We have arrived at a time when our 
 knowledge of the stratigraphic and faunal sequence, plus 
 the orogenic record as recognized in the principle of 
 diastrophism, should be reflected in the terminology of 
 the geologic time-table. It would be easy to offer a satis- 
 factory nomenclature if we were not bound by the law of 
 priority in publication, and if no one had the geologic 
 chronology of his own time ingrained in his memory. 
 In addition, the endless literature, with its accepted 
 nomenclature, bars our way. Therefore with a view of 
 
100 A CENTURY OF SCIENCE 
 
 creating the least change in geologic nomenclature, and 
 of doing the greatest justice to our predecessors that the 
 present conditions of our knowledge will allow, the fol- 
 lowing scheme is offered: 
 
 Sihirian period. Llandovery to top of Ludlow in Europe. 
 Alexandrian-Cataract-Medina to top of Manlius in America. 
 
 Cliamplain (1842) or Ordovician (1879) period Arenig to top 
 of Caradoc in Europe. Beekmantown to top of Kiclnnondian 
 in America. 
 
 Cambrian period. In the Atlantic realm, begins with the ' 
 Paradoxides, and in the Pacific, with the Bathyuriscus and 
 Ogygopsis faunas. The close is involved in Ulrich's provi- 
 sionally defined Ozarkian system. When the latter is estab- 
 lished, the Ozarkian period will hold the time between the 
 Ordovician and the Cambrian. 
 
 Taeonic period. For the world-wide Olenellus or Mesonacids 
 faunas. 
 
 Paleogeography. 
 
 When geologists began to perceive the vast significance 
 of Button 's doctrine that ' ' the ruins of an earlier world 
 lie beneath the secondary strata," and that great masses 
 of bedded rocks are separated from one another by 
 periods of mountain making and by erosion intervals, it 
 was natural for them to look for the lands that had fur- 
 nished the debris of the accumulated sediments. In this 
 way paleogeography had its origin, but it was at first of 
 a descriptive and not of a cartographic nature. 
 
 The word paleogeography was proposed by T. Sterry 
 Hunt in 1872 in a paper entitled "The Paleogeography 
 of the North American Continent," and published in the 
 Journal of the American Geographical Society for that 
 year. It has to do, he says, with the ' ' geographical his- 
 tory of these ancient geological periods." It was again 
 prominently used by Robei't Etheridge in his presidential 
 address before the Geological Society of London in 188L 
 Since Canu's use of the term in 1896, it has been fre- 
 quently seen in pi'int, and now is generally adopted to 
 signify the geography of geologic time. 
 
 The French were the first to make paleogeographic 
 maps, and Jules Marcou relates in 1866 that Elie de 
 Beaumont, as early as March, 1831, in his course in the 
 College of France and at the Paris School of Mines, used 
 
HISTOKICAL GEOLOGY 101 
 
 to outline tlie relation of the lands and the seas in the 
 center of Europe at the different great geologic periods. 
 His first printed paleogeographic map appeared in 1833, 
 and was of early Tertiary time. Other maps by Beau- 
 mont were published by Beudant in 1841-1842. The 
 Sicilian geologist Gemmellaro published six maps of his 
 country in 1834, and the Englishman De La Beche had 
 one in the same year. In America the first to show such 
 maps was Arnold Guyot in his Lowell lectures of 1848. 
 James D. Dana published three in the 1863 edition of his 
 Manual of Geology. Of world paleogeographic maps, 
 Jules Marcou produced the first of Jurassic time, pub- 
 lishing it in France in 1866, but the most celebrated of 
 these early attempts was the one by Neumayr published 
 in 1883 in connection with his Ueber klimatische Zonen 
 wahrend der Jura- und Kreidezeit. 
 
 The first geologist to produce a series of maps showing 
 the progressive geologic geography of a given area was 
 Jukes-Brown, who in the volume entitled "The Building 
 of the British Isles," 1888, included fifteen such maps. 
 Karpinsky published fourteen maps of Russia, and in 
 1896 Canu in his Essai de paleogeographie has fifty-seven 
 of France and Belgium. Lapparent's Traite of 1906 is 
 famous for paleogeographic maps, for he has twenty- 
 three of the world, thirty-four of Europe, twenty-five of 
 Prance, and ten taken from other authors. Schuchert in 
 1910 published fifty-two to illustrate the paleogeography 
 of North America, and also gave an extended list of such 
 published maps. Another article on the subject is by Th. 
 Arldt, "Zur Geschichte der Palaogeographischen Eekon- 
 structionen, " published in 1914. Edgar Dacque in 1913 
 also produced a list in his Palaogeographischen Karten, 
 and two years later appeared his book of 500 pages, 
 Grundlagen und IMethoden der Palaogeographie, where 
 the entire subject is taken up in detail. 
 
 Conclusions. — Since 1833 there have been published 
 not less than 500 different paleogeographic maps, and of 
 this number about 210 relate to North America. Never- 
 theless paleogeography is still in its infancy, and most 
 maps embrace too much geologic time, all of them tens 
 of thousands, and some of them millions of years. The 
 geographic maps of the present show the conditions of 
 
102 A CENTURY OF SCIENCE 
 
 the strand-lines of to-day, and those made fifty years ago 
 have to be revised again and again if they are to be of 
 value to the mariner and merchant. Therefore in our 
 future paleogeographic maps the tendency must ever be 
 toward smaller amovmts of geologic time, if we are to 
 show the actual relation of water to land and the move- 
 ments of the periodic floodings. Moreover, the ancient 
 shore lines are all more or less hj'pothetic and are drawn 
 in straight or sweeping curves, unlike modern strands 
 with their bays, deltas, and headlands, and the ancient 
 lands are featureless plains. We must also pay more 
 attention to the distribution of brackish- and fresh-water 
 deposits. The periodically rising mountains will be the 
 first topographic features to be shown upon the ancient 
 lands, and then more and more of the drainage and the 
 general climatic conditions must be portrayed. In the 
 seas, depth, temperature, and currents are yet to be 
 deciphered. Finally, other base maps than those of the 
 geography of to-day will have to be made, allowing for 
 the compression of the mountainous areas, if we are to 
 show the true geographic configurations of the lands and 
 seas of any given geologic time. 
 
 Faleometeorology, 
 
 In accordance with the Laplacian theory, announced at 
 the beginning of the nineteenth century, all of the older 
 geologists held that the earth began as a hot star, and 
 that in the course of time it slowly cooled and finally 
 attained its present zonal cold to tropical climatic condi- 
 tions. That the earth had very recently passed through 
 a much colder climate, a glacial one, came into general 
 acceptance only during the latter half of the previous 
 century. 
 
 Rise. — Our knowledge of glacial climates had its origin 
 in the Alps, that wonderland of mountains and glaciers. 
 The rise of this knowledge in the Alps is told in a charm- 
 ing and detailed manner by that erratic French- 
 American geologist, Jules Marcou (1824-1898), in his 
 Life, Letters, and Works of Louis Agassiz, 1896. He 
 relates that the Alpine chamois hunter JPerraudin in 1815 
 directed the attention of the engineer De Charpentier to 
 the fact "that the large boulders perched on the sides of 
 
HISTORICAL GEOLOGY 103 
 
 the Alpine valleys were carried and left there by gla- 
 ciers. ' ' For a long time the latter thought the conclusion 
 extravagant, and in the meantime Perraudin told the 
 same thing to another engineer, Venetz. He, in 1829, 
 convinced of the correctness of the chamois hunter's 
 views, presented the matter before the Swiss naturalists 
 then meeting at St. Bernard's. Venetz ' ' told the Society 
 that his observations led him to believe that the whole 
 Valais has been formerly covered by an immense glacier 
 and that it even extended outside of the canton, covering 
 all the Canton de Vaud, as far as the Jura Mountains, 
 carrying the boulders and erratic materials, which are 
 now scattered all over the large Swiss valley." Eight 
 years earlier, in 1S21, similar views had been presented 
 by the same modest naturalist before the Helvetic 
 Society, but it was not until 1833 that De Charpentier 
 found the manuscript and had it published. Venetz 's 
 conclusions were that all of the glaciers of the Bagnes 
 valley "have very recognizable moraines, which are 
 about a league from the present ice." "The moraines 
 . . . date from an epoch which is lost in the night of 
 time." Then in 1834 De Charpentier read a paper 
 before the same society, meeting at Lucerne. "Seldom, 
 if ever, has such a small memoir so deej^ly excited the 
 scientific world. It was received at first with incredulity 
 and even scorn and mockery, Agassiz being among its 
 opponents." The paper was published in 1835, first at 
 Paris, then at Geneva, and finally in Germany. It 
 "attracted much attention, and the smile of incredulity 
 with which it Avas received when read at Lucerne soon 
 changed into a desire to know more about it." 
 
 Louis Agassiz (1807-1873), who had long been ac- 
 quainted with his countryman, De Charpentier, spent 
 several months with him in 1836, and together they 
 studied the glaciers of the Alps. Agassiz was at first 
 "adverse to the h^'pothesis, and did not believe in the 
 great extension of glaciers and their transportation of 
 boulders, but on the contrary, was a partisan of Lyell's 
 theory of transport by icebergs and ice-cakes . . . but 
 from being an adversary of the glacial theory, he 
 returned to Neuchatel an enthusiastic convert to the 
 views of Venetz and De Charpentier. . . . With his 
 
104 A CENTUEY OF SCIENCE 
 
 power of quick perception, liis unmatched memory, his 
 perspicacity and acuteness, his way of classifying, judg- 
 ing and marshalling facts, Agassiz promptly learned the 
 whole mass of irresistible arguments collected patiently 
 during seven years by De Charpentier and Venetz, and 
 with his insatiable appetite and that faculty of assimila- 
 tion which he possessed in such a wonderful degree, he 
 digested the whole doctrine of the glaciers in a few 
 weeks. ' ' 
 
 In Julji', 1837, Agassiz presented as his presidential 
 address before the Helvetic Society his memorable ' ' Dis- 
 cours de Neuchatel," which was "the starting point of 
 all that has been written on the Ice-age," — a term coined 
 at the time by his friend Schimper, a botanist. The first 
 part of this address is reprinted in French in Marcou's 
 book on Agassiz. The address was received with aston- 
 ishment, much incredulity, and indifference. Among the 
 listeners was the great German geologist Von Bucli, who 
 "was horrified, and with his hands raised towards the 
 sky, and his head bowed to the distant Bernese Alps, 
 exclaimed: '0 Sancte de Saussure, ora pro nobis!'" 
 Even De Charpentier "was not gratified to see his glacial 
 theory mixed with rather uncalled for biological prob- 
 lems, the connection of which with the glacial age was 
 more than problematic." Agassiz was then a Cuvierian 
 catastrophist and creationist, and advanced the idea of 
 a series of glacial ages to explain the destruction of the 
 geologic succession of faunas ! Curiously, this theory 
 was at once accepted by the American paleontologist 
 T. A. Conrad (35, 239, 1839). 
 
 The classics in glacial geology are Agassiz 's Etudes 
 sur les Glaciers, 1840, and De Charpentier 's Essai sur les 
 Glaciers, 1841. Of the latter book, Marcou states that 
 it has been said: "It is impossible to be truly a geologist 
 without having read and studied it." In the English 
 language there is Tjmdall's Glaciers of the Alps, 18(50. 
 
 The progress of the ideas in regard to Pleistocene 
 glaciation is presented in the following chapter by H. E. 
 Gregory. 
 
 Older Glacial Climates. — Hardly had the Pleistocene 
 glacial climate been proved, when geologists began to 
 point out the possibility of even earlier ones. An enthu- 
 
HISTORICAL GEOLOGY 105 
 
 siastic Scotch writer, Sir Andrew Ramsay, in 1855 
 described certain late Paleozoic conglomerates of middle 
 England, which he said were of glacial origin, but his 
 evidence, though never completely gainsaid, has not been 
 generally accepted. In the following year, an English- 
 man, Doctor W. T. Blanford, said that the Talchir con- 
 glomerates of central and southern India were of glacial 
 origin, and since then the evidence for a Permian glacial 
 climate has been steadily accumulating. Africa is the 
 land of tillites, and here in 1870 Sutherland pointed out 
 that the conglomerates of the Karroo formation were of 
 glacial origin. Australia also has Permian glacial 
 deposits, and they are known widely in eastern Brazil, 
 the Falkland Islands, the vicinity of Boston, and else- 
 where. So convincing is this testimony that all geolo- 
 gists are now ready to accept the conclusion that a 
 glacial climate was as wide-spread in early Permian time 
 as was that of the Pleistocene.^ 
 
 In South Africa, beneath the marine Lower Devonian, 
 occurs the Table Mountain series, 5000 feet thick. The 
 series is essentially one of quartzites, with zones of shales 
 or slates and with striated pebbles up to 15 inches long. 
 The latter occur in pockets and seem to be of glacial origin. 
 There are here no typical tillites, and no striated under- 
 grounds have so far been found. While the evidence of 
 the deposits appears to favor the conclusion that the 
 Table Mountain strata were laid down in cold waters with 
 floating ice derived from glaciers, it is as yet impossible 
 to assign these sediments a definite geologic age. They 
 are certainly not younger than the Lower Devonian, but 
 it has not yet been established to what period of the 
 early Paleozoic they belong. 
 
 In southeastern Australia occur tillites of wide distri- 
 bution that lie conformably beneath, but sharply sep- 
 arated from the fossiliferous marine Lower Cambrian 
 strata. David (1907), Howchin (1908), and other Aus- 
 tralian geologists think they are of Cambrian time, but 
 to the writer they seem more probably late Protei'ozoic 
 in age. In arctic Norway Reusch discovered unmistak- 
 able'tillites in 1891, and this occurrence was confirmed by 
 Strahan in 1897. It is not yet certainly known what 
 their age is, but it appears to be late Proterozoic rather 
 
106 A CENTURY OF SCIENCE 
 
 than early Paleozoic. Other undated Proterozoic tillites 
 ocour in China (Willis and Blackwelder 1907), Africa 
 (Schwarz 1906), India (Vredenburg 1907), Canada 
 (Coleman 1908), and possibly in Scotland. 
 
 The oldest known tillites are described by Coleman in 
 1907, and occur at the base of the Lower Huronian or in 
 early Proterozoic time. They extend across northern 
 Ontario for 1000 miles, and from the north shore of Lake 
 Huron northward for 750 miles. 
 
 Fossils as Climatic Indexes. — Paleontologists have 
 long been aware that variations in the climates of the 
 past are indicated by the fossils, and Neumayr in 1883 
 brought the evidence together in his study of climatic 
 zones mentioned elsewhere. Plants, and corals, cepha- 
 lopods, and foraminifers among marine animals, have 
 long been recognized as particularly good "life ther- 
 mometers." In fact, all fossils are climatic indicators 
 to some extent, and a good deal of evidence concerning 
 paleometeorology has been discerned in them. This evi- 
 dence is briefly stated in the paper by Schuchert already 
 alluded to, and in W. D. Matthew's Climate and Evolu- 
 tion, 1915. 
 
 Sediments as Climatic Indexes. — Johannes Walther in 
 the third part of his Einleitung — Lithogenesis der 
 Gegenwart, 1894 — is the first one to decidedly direct 
 attention to the fact that the sediments also have within 
 themselves a climatic record. In America Joseph Bar- 
 rell has since 1907 written much on the same subject. 
 On the other hand, the periodic floodings of the con- 
 tinents by the oceans, and the making of mountains, 
 due to the periodic shrinkage of the earth, as expressed 
 in T. C. Chamberlin's principle of diastrophism and in 
 his publications since 1897, are other criteria for estimat- 
 ing the climates of the past. 
 
 Conclusions. — In summation of this subject Schuchert 
 says : 
 
 "The inarine 'life thermometer' indicates vast stretches of 
 time of mild to warm and equable temperatures, with but slight 
 zonal differences between the equator and the poles. The great 
 bulk of inarine fossils are those of the shallow seas, and the evo- 
 lutionary changes recorded in these 'medals of creation' are 
 slight throughout vast lengths of time that are punctuated by 
 
HISTORICAL GEOLOGY 107 
 
 short bnt decisive periods of cooled waters and great mortality, 
 followed by quick evolution, and the rise of new stocks. The 
 times of less warmth are the miotherm and those of greater 
 heat the pUothcrm periods of Ramsay. 
 
 On the land the story of the climatic changes is different, but 
 in general the equability of the temperature simulates that of 
 the oceanic areas. In other words, the lands also had long- 
 enduring times of mild to warm climates. Into the problem 
 of land climates, however, enter other factors that are absent 
 in the oceanic regions, and these have great influence upon the 
 climates of the continents. Most important of these is the peri- 
 odic warm-water inundation of the continents by the oceans, 
 causing insular climates that are milder and moister. With the 
 vanishing of the floods somewhat cooler and certainly drier 
 climates are produced. The effects of these periodic floods must 
 not be underestimated, for the North American continent was 
 variably submerged at least seventeen times, and over an area 
 of from 154.000 to 4,000.000 square miles. 
 
 When to these factors is added the effect upon the climate 
 caused by the periodic rising of mountain chains, it is at once 
 apparent that the lands must have had constantly varyuig 
 climates. In general the temperature fluctuations seem to have 
 been slight, but geographically the climates varied between mild 
 to warm pluvial, and mild to cool arid. The arid factor has 
 been of the greatest import to the organic world of the lands. 
 Further, when to all of these causes is added the fact that dur- 
 ing emergent periods the formerly isolated lands were connected 
 by land bridges, permitting intermigration of the land floras 
 and faunas, with the introduction of their parasites and parasitic 
 diseases, we learn that while the climatic environment is of fun- 
 damental importance it is not the only cause for the more rapid 
 evolution of terrestrial life . . . 
 
 Briefly, then, we may conclude that the markedly varying 
 climates of the past seem to be due primarily to periodic changes 
 in the topographic form of the earth's surface, plus variations 
 in the amount of heat stored by the oceans. The causation for 
 the warmer interglacial climates is the most difficult of all to 
 explain, and it is here that factors other than those mentioned 
 may enter. 
 
 Granting all this, there still seems to lie back of all these 
 theories a greater question connected with the major changes in 
 paleometeorology. This is: What is it that forces the earth's 
 topography to change with varying intensity at irregularly 
 rhythmic intervals ? . . . Are we not forced to conclude that 
 the earth's shape changes periodically in response to gravitative 
 forces that alter the body-form?" 
 
108 A CENTURY OF SCIENCE 
 
 Evolution, 
 
 ]\Iodern evolution, or the theory of life continuously 
 descending from life with change, may be said to have 
 had its tirst marked development in Comte de Buffon 
 (1707-1788), a man of wealth and station, yet an indus- 
 trious compiler, a brilliant writer, and a popularizer of 
 science. He was not, however, a true scientific investi- 
 gator, and his monument to fame is his Histoire Nat- 
 urelle, in forty-four volumes, 1749-1804. A. S. Packard 
 in his book on Lamarck, his Life and AVork, 1901, con- 
 cludes in regard to Buffon as follows : 
 
 "The impression left on the mind, after reading Buffon, is 
 that even if he threw out these suggestions and then retracted 
 them, from fear of annoyance or even persecution from the 
 bigots ot his time, he did not himself always take them seriously, 
 but rather jotted them down as passing thoughts . . . They 
 appeared thirty-four years before Lamarck's theory, and though 
 not epoch-making, they are such as will render the name of 
 Buffon memorable for all time." 
 
 Chevalier de Lamarck (1744-1829) may justly be 
 regarded as the founder of the doctrine of modern evo- 
 lution. Previous to 1794 he was a believer in the fixity 
 of species, but by 1800 he stood definitely in favor of 
 evolution. Loc)^ in his Biology and its Makers, 1908, 
 states his theories in the following simplified form : 
 
 "Variations of organs, according to Lamarck, arise in animals 
 mainly through use and disuse, and new organs have their origin 
 in a physiological need. A new need felt by the animal [due 
 to new conditions in its life, or the environment] expresses 
 itself on the organism, stimulating growth and adaptations in a 
 particular direction." 
 
 To Lamarck, "inheritance was a simple, direct trans- 
 mission of those superficial changes that arise in organs 
 within the lifetime of an individual owing to use and 
 disuse." This part of his theory has come to be known 
 as "the inheritance of ncrpiircd characters." 
 
 Georges Cuvier (17G9-1832), a peer of France, was a 
 decided believer in the fixity of species and in their crea- 
 tion through divine acts. In 1796 he began to see that 
 among the fossils so plentiful about Paris many were of 
 
HISTORICAL GEOLOGY 109 
 
 3xtmct forms, and later on that there was a succession 
 af wholly extinct faunas. This at first puzzling phenom- 
 3non he finally came to explain by assuming that the 
 jarth had gone through a series of catastrophes, of which 
 the Deluge was the most recent but possibly not the last. 
 With each catastrophe all life was blotted out, and a new 
 though improved set of organisms was created by divine 
 acts. The Cuvierian theory of catastrophism was widely 
 accepted during the first half of the nineteenth century, 
 and in America Louis Agassiz was long its greatest 
 exponent. It was this theory and the dominance of the 
 brilliant Cuvier, not only in science but socially as well, 
 that blotted out the far more correct views of the more 
 philosophical Lamarck, who held that life throughout the 
 ages had been continuous and that through individual 
 effort and the inheritance of acquired characters had 
 evolved the wonderful diversity of the present living 
 world. 
 
 In 1830 there was a public debate at Paris between 
 Cuvier and Geoffroy Saint-Hilaire, the one holding to the 
 views of the fixity of species and creation, the other that 
 life is continuous and evolves into better adapted forms. 
 Cuvier, a gifted speaker and the greatest debater zoology 
 ever had, with an extraordinary memory that never 
 failed him, defeated Saint-Hilaire in each day's debate, 
 although the latter was in the right. 
 
 A book that did a great deal to prepare the English- 
 speaking people for the coming of evolution was "Ves- 
 tiges of Creation," published in 1844 by an unknown 
 author. In Darwin's opinion, "the work, from its power- 
 ful and brilliant style . . . has done excellent service 
 ... in thus preparing the ground for the reception of 
 analogous views." This book was recommended to the 
 readers of the Journal (48, 395, 1845) with the editorial 
 remark that "we cannot subscribe to all of the author's 
 views." 
 
 We can probably best illustrate the opinions of Amer- 
 icans on the question of evolution just before the appear- 
 ance of Darwin's great work bv directing attention to 
 James D. Dana's Thoughts on Species (24, 305, 1857). 
 A.fter reading this article and others of a similar nature 
 by Agassiz, one comes to the opinion that unconsciously 
 
110 A CENTURY OF SCIENCE 
 
 both men are proving evolution, but consciously tliey 
 are firm creationists. It is astonishing that with their 
 extended and minute knowledge of living organisms and 
 their philosophic type of mind neither could see the true 
 significance of the imperceptible transitions between 
 some species, which if they do not actually pass into, at 
 least shade towards, one another. 
 
 Dana speaks of "the endless diversities in individu- 
 als" that compose a species, and then states that a living 
 species, like an inorganic one, "is based on a specific 
 amount or condition of concentered force defined in the 
 act or law of creation." Species, he says, are perma- 
 nent, and hybrids "cannot seriously trifle with the true 
 units of nature, and at the best, can only make tempo- 
 rary variations." "We have therefore reason to believe 
 from man's fertile intermixture, that he is one in species : 
 and that all organic species are divine appointments 
 which cannot be obliterated, unless by annihilating the 
 individuals representing the species." 
 
 Through the activities of the French the world was 
 prepared for the reception of evolution, and now it was 
 already in the minds of many advanced thinkers. In 
 1860 Asa Gray sent to the editor of the Journal (29, 1) 
 an article by the English botanist, Joseph D. Hooker, 
 entitled "On the Origination and Distribution of 
 Species," with these significant remarks: 
 
 "The essay cannot fail to attract the immediate and profound 
 attention of scientific men ... It has for some time been 
 manifest that a re-statement of the Lamarckian hypothesis is 
 at hand. We have this, in an improved and truly scientific 
 form, in the theories which, recently propounded by Mr. Dar- 
 win, followed by Mr. Wallace, are here so ably and altogether 
 independently maintained. When these views are fully laid 
 before them, the naturalists of this country will be able to 
 take part in the interesting discussion which they will not fail 
 to call forth." 
 
 Hooker took up a study of the flora of Tasmania, of 
 which the above cited article is but a chapter, with a 
 view to trying out Darwin's theory, and he now accepts 
 it. He says, "Species are derivative and mutable." 
 "The limits of the majority of species are so undefina- 
 ble that few naturalists are agreed upon them." 
 
HISTORICAL GEOLOGY 111 
 
 Asa Gray had received from Darwin an advance copy 
 of the book that Avas to revolutionize tlie thous'ht of the 
 world, and at once wrote for the Journal a Review of 
 Darwin's Theory on the Origin of Species by means of 
 Natural Selection (29, 153, 1860). This is a splendid, 
 critical but just, scientific review of Darwin's epoch- 
 making book. Evidently views similar to those of the 
 English scientist had long been in the mind of Gray, for 
 he easily and quickly mastered the work. He is easy on 
 Dana's Thoughts on Species, which were idealistic and 
 not in harmony with the naturalistic views of Darwin. 
 On the other hand, he contrasts Darwin's views at length 
 with those of the creationists as exemplified by Louis 
 Agassiz, and says "The widest divergence appears." 
 
 Gray says in part : 
 
 "The gist of Mr. Darwin's work is to show that such varieties 
 are gradually diverged into species and genera through natural 
 selection ; that natural selection is the inevitable result of the 
 struggle for existence which all living things are engaged in ; 
 and that this struggle is an unavoidable conseciuenee of several 
 natural causes, but mainly of the high rate at which all organic 
 beings tend to increase. 
 
 Darwin is confident that intermediate forms must have 
 existed; that in the olden times when the genera, the families 
 and the orders diverged from their parent stocks, gradations 
 existed as fine as those which now connect closely related species 
 with varieties. But they have passed and left no sign. The 
 geological record, even if all displayed to view, is a book from 
 which not only many pages, but even whole alternate chapters 
 have been lost out, or rather which were never printed from the 
 autographs of nature. The record was actually made in fossil 
 litliography only at certain times and under certain conditions 
 (i. e., at periods of slow subsidence and places of abundant sedi- 
 ment) ; and of these records all but the last volume is out of 
 print; and of its pages only local glimpses have been obtained. 
 Geologists, except Lyell, will object to this, — some of them 
 moderately, others with vehemence. Mr. Darwin himself admits, 
 with a candor rarely displayed on such occasions, that he should 
 have expected more geological evidence of transition than he 
 finds, and that all the most eminent paleontologists maintain the 
 immutability of species. 
 
 The general fact, however, that the fossil fauna of each period 
 as a whole is nearly intermediate in character between the 
 preceding and the succeeding faunas, is much relied on. "We 
 
112 A CENTURY OF SCIENCE 
 
 are brought one step nearer to the desired inference by the similar 
 'fact,' insisted on by all paleontologists, that fossils from two 
 consecutive formations are far more closely related to each other, 
 than are the fossils of two remote formations. 
 
 It is well said that all organic beings have been formed on two 
 great laws ; Unity of type, and Adaptation to the conditions of 
 existence . . . Mr. Darwin harmonizes and explains them 
 naturally. Adaptation to the conditions of existence is the 
 result of Natural Selection ; Unity of type, of unity of descent. ' ' 
 
 Gray's article was soon followed by another one from 
 Agassiz on Individuality and Specific Differences among 
 Acalephs, but the running title is "Prof. Agassiz on the 
 Origin of Species" (30, 142, 1860). Agassiz stoutly 
 maintains his well known views, and concludes as 
 follows : 
 
 "Were the transmutation theory true, the geological record 
 should exhibit an uninterrupted succession of types blending 
 gradually into one another. The fact is that throughout all 
 geological times each period is characterized by definite specific 
 types, belonging to definite genera, and these to definite families, 
 referable to definite orders, constituting definite classes and 
 definite branches, built upon definite plans. Until the facts of 
 Nature are shown to have been mistaken by those who have col- 
 lected them, and that they have a different meaning from that 
 now generally assigned to them, I shall therefore consider the 
 transmutation theory as a scientific mistake, untrue in its facts, 
 unscientific in its method, and mischievous in its tendency." 
 
 Dana, in reviewing Huxley's well known book, Man's 
 Place in Nature (35, 451, 1863), holds that man is apart 
 from brute nature because man exhibits "extreme ceph- 
 alization" in that he has arms that no longer are used 
 in locomotion but go rather with the head, and because 
 he has a far higher mentality and speech. As for the 
 Darwinian theory, the evidence, he says, "comes from 
 lower departments of life, and is acknowledged by its 
 advocates to be exceedingly scanty and imperfect." 
 
 The growth of evolution is set forth in the Journal in 
 Asa Gray's article on Charles Darwin (24, 453, 1882), 
 which speaks of the latter as "the most celebrated man of 
 science of the nineteenth century," and, in addition, as 
 "one of the most kindly and charming, unaffected s'im- 
 ple-hearted, and lovable of men. ' ' In regard to the rise 
 
HISTORICAL GEOLOGY 113 
 
 of evolution in America, more can be had from Dana's 
 paper on Asa Gray (35, 181, 1888). Here we read, as a 
 sequel to his Thoughts on Species, that the "paper may 
 be taken, perhaps, as a culmination of the past, just as 
 the new future was to make its appearance." Finally, 
 in this connection there should be mentioned 0. C. 
 Marsh's paper on Thomas Henry Huxley (50, 177, 1895), 
 wherein is recorded the latter 's share in the upbuilding 
 of the evolutionary theory. 
 
 We have seen that originally Dana was a creationist, 
 but in the course of his long and fruitful life he gradually 
 became an evolutionist, and rather a Neo-Lamarckian 
 than a Darwinian. This change may be traced in the 
 various editions of his Manual of Geology, and in the last 
 edition of 1895 he says his "speculative conclusions" of 
 1852 in regard to the origin of species are not ' ' in accord 
 with the author's present judgment." "The evidence in 
 favor of evolution by variation is now regarded as essen- 
 tially complete." On the other hand, while man is 
 "unquestionably" closely related in structure to the 
 man-apes, yet he is not linked to them but stands apart, 
 through "the intervention of a Power above Nature. 
 . . . Believing that Nature exists through the will and 
 ever-acting power of the Divine Being, and . . . that the 
 whole Universe is not merely dependent on, but actually 
 is, the Will of one Supreme Intelligence, Nature, with 
 Man as its culminant species, is no longer a mystery." 
 
 In America most of the paleontologists are Neo- 
 Lamarckian, a school that was developed independently 
 by E. D. Cope (1840-1897) through the vertebrate evi- 
 dence, and by Alpheus Hyatt (1838-1902) mainly on the 
 evidence of the ammonites. They hold that variations 
 and acquired characters arise through the effects of the 
 environment, the mechanics of the organism resulting 
 from the use and disuse of organs, etc. One of the lead- 
 ing exponents of this school is A. S. Packard, whose book 
 on Lamarck, His Life and Work, 1901, fully explains the 
 doctrines of the Neo-Lamarckians. 
 
 The Grotvth of Invertebrate Paleontology. 
 
 How and by whom paleontology has been developed 
 has been fully stated in the Journal in a very clear man- 
 
114 A CENTURY OF SCIENCE 
 
 ner by Professor Marsh in his memorable presidential 
 address of 1879, History and Methods of Palajontological 
 Discovery (18, 323, 1879), and by Karl von Zittel in his 
 most interesting book, History of Geology and Palffion- 
 tology, 1901. In this discussion we shall largely follow 
 Marsh. 
 
 The science of paleontology has passed through four 
 periods, the first of them the "long Mystic period extend- 
 ing up to the beginning of the seventeenth century, when 
 the idea that fossils were once living things was only 
 rarely perceived. The second period was the Diluvial 
 period of the eighteenth century, when nearly everyone 
 regarded the fossils as remains of the Noachian deluge. 
 With the beginnings of the nineteenth century there 
 arose in western Europe the knowledge that fossils are 
 the "medals of creation" and that they have a chrono- 
 genetic significance ; also that life had "been periodically 
 destroyed through world-wide convulsions in nature. 
 From about 1800 to 1860 was the time of the creationists 
 and catastrophists, which may be known as the Catas- 
 trophic period. The fourth period began in 1860 with 
 Darwin's Origin of Species. Since that time the theory 
 of evolution has pervaded all work in paleontology, and 
 accordingly this time may be known as the Evolutionary 
 period. 
 
 Mystic Period. — The Mystic period in paleontology 
 begins with the Greeks, five centuries before the present 
 era, and continues down to the beginning of the seven- 
 teenth century of our time. Some correctly saw that the 
 fossils were once living marine animals, and that the sea 
 had been where they now occur. Others interpreted fos- 
 sil mammal bones as those of human giants, the Titans, 
 but the Aristotelian view that they were of spontaneous 
 generation through the hidden forces of the earth domi- 
 nated all thought for aliout twenty centuries. 
 
 In the sixteenth century canals were being dug in 
 Northern Italy, and the many fossils so revealed led to a 
 fierce discussion as to their actual nature. Leonardo da 
 Vinci (1452-1519) opposed the commonly accepted view 
 of their spontaneous generation and said that they were 
 the remains of once living animals and that the sea had 
 been where they occur. "You tell mo," he said, "that 
 
HISTORICAL GEOLOGY 115 
 
 Nature and the influence of the stars have formed these 
 shells in the mountains ; then show me a place in the 
 mountains where the stars at the present day make shelly 
 forms of different ages, and of different species in the 
 same place." However, nothing came of his teachings 
 and those of his countryman Fracastorio (1483-1558), 
 who further ridiculed the idea that they were the 
 remains of the deluge. The first mineralogist, Agricola, 
 described them as minerals — fossilia — and said that they 
 arose in the ground from fatty matter set in fermenta- 
 tion by heat. Others said that they were freaks of 
 nature. Martin Lister (1638-1711) figured fossils side 
 by side with living shells to show that they were extinct 
 forms of life. In the seventeenth century, and especially 
 in Italy and Germany, many books were published on 
 fossils, some with illustrations so accurate that the 
 species can be recognized to-day. Finally, toward 
 the close of this century the influence of Aristotle and the 
 scholastic tendency to disputation came more or less to 
 an end. Fossils were already to many naturalists once 
 living plants and animals. Marsh states : ' ' The many 
 collections of fossils that had been brought together, and 
 the illustrated works that had been published about them, 
 were a foundation for greater progress, and, with the 
 eighteenth century, the second period in the history of 
 paleontology began." 
 
 Diluvial Period. — During the eighteenth century many 
 more books on fossils were published in western Europe, 
 and now the prevalent explanation was that they were 
 the remains of the Noachian deluge. For nearly a cen- 
 tury theologians and laymen alike took this view, and 
 some of the books have become famous on this account, 
 but the diluvial views sensibly declined with the close 
 of the eighteenth century. 
 
 The true nature of fossils had now been clearty deter- 
 mined. They were the remains of plants and animals, 
 deposited long before the deluge, part in fresh water and 
 part in the sea. ' ' Some indicated a mild climate, and some 
 the tropics. That any of these were extinct species, was 
 as yet only suspected." Yet before the close of the cen- 
 tury there were men in England and France who pointed 
 out that different formations had different fossils and 
 
116 A CENTURY OF SCIENCE 
 
 that some of them were extinct. These views then led to 
 many fantastic theories as to how the earth was formed — 
 dreams, most of them have been called. Marsh says : 
 
 "The dominant idea of the first sixteen centuries of the 
 present era was, that the universe was made for Man. This was 
 the great obstacle to the correct determination of the position 
 of the earth in the universe, and, later, of the age of the earth. 
 . . . In a superstitious age, when every natural event is 
 referred to a supernatural cause, science cannot live . . . 
 Scarcely less fatal to the growth of science is the age of Author- 
 ity, as the past proves too well. With freedom of thought, came 
 definite knowledge, and certain progress; — but two thousand 
 years was long to wait. ' ' 
 
 One of the most significant publications of this period 
 was Linnffius 's Systema Nature, which appeared in 1735. 
 In this work was introduced binomial nomenclature, or 
 the system of giving each plant and animal species a, 
 generic and specific name, as Felis leo for the lion. The 
 system was, however, not established until the tenth 
 edition of the work in 1758, which became the starting 
 point of zoological nomenclature. Since then there has 
 been added another canon, the law of priority, which 
 holds that the first name applied to a given form shall 
 stand against all later names given to the same organism. 
 
 Catastrophic Period. — With the beginning of the nine- 
 teenth century there started a new era in paleontology, 
 and this was the time when the foundations of the science 
 were laid. The period continued for six decades, or until 
 the time of the Origin of Species. Marsh says that now 
 "method replaced disorder, and systematic study super- 
 seded casual observation." Fossils were accurately 
 determined, comparisons were made with living forms, 
 and the species named according to the binomial system. 
 However, every species, recent and extinct, was regarded 
 as a separate creation, and because of the usually sharp 
 separation of the superposed fossil faunas and floras, 
 these were held to have been destroyed through a series 
 of periodic catastrophes of which the Noachian deluge 
 was the last. 
 
 Lamarck between 1802 and 1806 described the Tertiary 
 shells of the Paris basin. Comparing them with the liv- 
 
HISTORICAL GEOLOGY 117 
 
 ing forms, he saw that most of the fossils were of extinct 
 species, and in this way he came to be the founder of 
 modern invertebrate paleontology. He also maintained 
 after 1801 that life has been continuous since its origin 
 and that nature has been uniform in the course of its 
 development. Marsh adds : 
 
 "His researches on the invertebrate fossils of the Paris Basin, 
 although less striliing, were not less important than those of 
 Cuvier on the vertebrates ; while the conclusions he derived from 
 them form the basis of modern biology." 
 
 ' ' Lamarck was the prophetic genius, half a century in advance 
 of his time." 
 
 Cuvier established comparative anatomy and verte- 
 brate paleontology, and was one of the first to point out 
 that fossil animals are nearly all extinct forms. He 
 came to the latter conclusion in 1796 through a study of 
 fossil elephants found in Europe. "Cuvier enriched 
 the animal kingdom by the introduction of fossil forms 
 among the living, bringing all together into one compre- 
 hensive system." This opened to him entirely new 
 "^dews respecting the theory of the earth, and he devoted 
 more than twenty-five years to developing the theories 
 of special creation and catastrophism, described in his 
 Discourse on the Revolutions of the Surface of the Globe. 
 "With all his knowledge of the earth, he could not free 
 himself from tradition, and believed in the universality 
 and power of the Mosaic deluge. Again, he refused to 
 admit the evidence brought forward by his distinguished 
 colleagues against the permanence of species, and used 
 all his great influence to crush out the doctrine of evolu- 
 tion, then first proposed" (Marsh). 
 
 In England it was William Smith (1769-1839) who 
 independently discovered the chronogenetic significance 
 of fossils, and in their stratigraphic superposition indi- 
 cated the way for the study of historical geology. He 
 first published on this matter in 1799, but his completed 
 statements came in works entitled "Strata identified by 
 Organized Fossils," 1816-1820, and " Stratigraphical 
 System of Organized Fossils," 1817. 
 
 Invertebrate paleontology in America during the 
 Catastrophic period had its beginning in Lesueur, who 
 
118 A CENTURY OF SCIENCE 
 
 in 1818 described tlie Ordovician gastropod Maclurites 
 magna. All of the paleontologists of this time were sat- 
 istied to describe species and genera and to ascertain in a 
 broad way the stratigraphic significance of the fossil 
 faunas and floras. James Hall in 1854 (17, 312) knew of 
 1588 species, described and undescribed, in the New York 
 system, while in England Morris listed in that year 8300 
 Paleozoic forms. In 1856 Dana recites the known fossil 
 species as follows (22, 333): The whole number of 
 known American species of animals of the Permian to 
 Recent is about 2000; while in Britain and Europe, there 
 were over 20,000 species. In the Permian we have none, 
 while Europe has over 200 species. In the Triassic we 
 have none, Europe 1000 species ; Jurassic 60, Europe 
 over 4000; Cretaceous 350 to 400, Europe about 6000; 
 Tertiary hardly 1500, Europe about 8000. Since that 
 time nearly all of the larger American Paleozoic faunas 
 have been developed, but there are thousands of species 
 yet to be described. Who the more prominent American 
 paleontologists of this period were has been told in the 
 section on the development of the geological column. 
 
 The grander paleontologic results of the Catastrophic 
 period have been so well stated by Marsh that it is worth 
 our while to repeat them here : 
 
 "It had now liccn proved beyond question that portions at 
 least of the earth's surface had been covered many times by the 
 sea, with alternations of fresh water and of land ; that the strata 
 thus deposited were formed in succession, the lowest of the series 
 being the oldest ; that a distinct succession of animals and 
 plants had inhabited the earth during the different geological 
 periods; and that the order of succession found in one part of 
 the earth was essentially the same in all. More than 30,000 new 
 species of extinct animals and plants had now been described. 
 It had been found, too, that from the oldest formations to the 
 most recent, there had been an advance in the grade of life, both 
 animal and vegetable, the oldest forms being among the simplest 
 and the higher forms successively naaking their appearance. 
 
 It had now become clearly evident, moreover, tliat the fossils 
 from the older formations were all extinct species, and that only 
 in the most recent deposits were there remains of forms still 
 living . . . Another important conclusion reached, mainly 
 through the labors of Lyell, was, that the earth had not been 
 subjected in the past to sudden and violent revolutions; but the 
 
HISTORICAL GEOLOGY 119 
 
 great changes wrought had been gradual, differing in no essen- 
 tial respect from those still in progress. Strangely enough, the 
 corollary to this proposition, that life, too, had been continuous 
 on the earth, formed at that date no part of the common slock 
 of knowledge. In the physical world, the great law of 'cor- 
 relation of forces' had been announced, and widely accepted; 
 but in the organic world, the dogma of the miraculous creation 
 of each separate species still held sway." 
 
 Evolutionary Period. — This period begins with 1860 
 and the publication of Darwin's Origin of Species (late 
 in 1859). It is the period of modern paleontology, and is 
 dominated by the belief that universal laws pervade not 
 only inorganic matter, but all life as well. Louis Agas- 
 siz had been in America fourteen years when Darwin's 
 book appeared, and his wonderful influence in bringing 
 the zoology of our country to a high stand and the 
 further influence he exerted through his students was 
 bound to react beneficially on invertebrate paleontology. 
 Shortly after the beginning of this period, or in 1867, 
 Alpheus Hyatt, one of Agassiz's students, began to apply 
 the study of embryology to fossil cephalopods, showing 
 clearly that these shells retain a great deal of their 
 growth stages or ontogeny. This method of study was 
 then followed by R, T. Jackson, C. E. Beecher, and J, 
 P. Smith, and has been productive of natural classifica- 
 tions of the Cephalopoda, Brachiopoda, Trilobita, and 
 Echinoidea. 
 
 The dominant invertebrate paleontologist of this 
 period was of course James Hall, who described about 
 5000 species of American Paleozoic fossils. He also 
 built up the New York State Museum, while around his 
 private collections of fossils have been developed the 
 American Museum of Natural History in New York City 
 and the Walker Museum at the University of Chicago. 
 In his most important laboratory of paleontology at 
 Albany, there have been trained either wholly or in 
 part the following paleontologists: F. B. Meek, C. A. 
 White, R. P. Wliitfiekl, C. D. Walcott, C. E. Beecher, 
 John M. Clarke, and Charles Schuchert. 
 
 In Canada, through the work of the Geological Survey 
 of the Dominion, came the paleontologists Elkanala 
 Billings and, later on, J. F. "V'\^iiteaves. The "father of 
 
120 A CENTURY OP SCIENCE 
 
 Canadian paleontology," Sir William Dawson, who 
 developed independently, was active in all branches of 
 the science and did much to unravel the geology of 
 eastern Canada. No organism has been more discussed 
 and more often rejected and accepted as a fossil than his 
 "dawn animal of Canada," Eozoon canadense, first 
 described in 1865. His son, George M. Dawson, was one 
 of the directors of the Geological Survey of Canada. 
 Finally the extensive paleontology of the Cambrian of 
 Canada was worked out by another self-made paleontolo- 
 gist, G. F. Matthew. 
 
 Paleobotany. — American paleobotany was developed 
 during this, the fourth period, through the state and 
 national surveys, first in Leo Lesquereux, a Swiss stu- 
 dent induced by Agassiz to come to America, and in J. S. 
 Newberry. The second generation of paleobotanists is 
 represented by Lester F. Ward and W. N. Fontaine, 
 and the third generation, the present workers, includes 
 F. H. Knowlton, David White, Arthur HoUick, and E. W. 
 Berry. A new line of paleobotanical work, the histology 
 of woody but pseudomorphous remains, has been devel- 
 oped by G. R. Wieland. 
 
 The grander results of the studj^ of paleontology dur- 
 ing the evolutionary loeriod may be summed up with the 
 conclusions of Marsh : 
 
 "One of the main characteristics of this epoch is the belief 
 that all life, living and extinct, has been evolved from simple 
 forms. Another prominent feature is the accepted fact of the 
 great antiquity of the human race. These are quite sufficient 
 to distinguish this period sharply from those that preceded it. 
 
 Cliarles Darwin's work at once aroused attention, and brought 
 about in scientific thought a revolution which "has influenced 
 paleontology as extensively as any other department of science 
 ... In the [previous period] species were represented inde- 
 pendently by parallel lines; in the present period, they are 
 indicated by dependent, branching lines. The former was the 
 analytic, the latter is the sjaathetic period." 
 
 Synthetic PerfoJ.— What is to be the next trend in 
 paleontology? Clearly it is to be the Sjaithetic period, 
 one that Marsh in 1879 indicated in these words: "But 
 if we are permitted to continue in imao-ination the rap- 
 idly converging lines of research pursued to-day, they 
 
HISTORICAL GEOLOGY 121 
 
 seem to meet at the point where organic and inorganic 
 nature become one. That this point will yet be reached, 
 I cannot doubt. ' ' 
 
 This Synthetic period, foreshadowed also in Herbert 
 Spencer's Synthetic Philosophy, has not yet arrived, but 
 before long another great leader will appear. We have 
 the prophecy of his coming in such books as The Fitness 
 of the Environment, by Lawrence J. Henderson, 1913 ; 
 The Origin and Nature of Life, by Benjamin Moore, 
 1913; The Organism as a AMiole, by Jacques Loeb, 1916; 
 and The Origin and Evolution of Life, by Henry F. 
 Osborn, 1917. 
 
 In all nature, inorganic and organic, there is continuity 
 and consistency, beauty and design. We are beginning 
 to see that there are eternal laws, ever interacting and 
 resulting in progressive and regressive evolutions. The 
 realization of these scientific revelations kindles in us a 
 desire for more knowledge, and the grandest revelations 
 are yet before us in the synthesis of the sciences. 
 
 Notes. 
 
 ' For more detail in regard to these tillites and the older ones see Climatea 
 of Geologic Time, by Charles Schuchert, being Chapter XXI in Hunting- 
 ton's Climatic Factor as Illustrated in Arid America, Publication No. 
 192 of the Carnegie Institution of Washington, 1914. Also Arthur P. 
 Coleman's presidential address before the Geological Society of America 
 in 1915, Dry Land in Geology, published in the Society 's Bulletin, 27, 
 175, 1916. 
 
Ill 
 
 A CENTURY OF GEOLOGY STEPS OF PROG- 
 RESS IN THE INTERPRETATION OF 
 LAND FORMS 
 
 By HERBERT E. GREGORY 
 
 THE essence of physiography is the belief that land 
 forms represent merely a stage in the orderly devel- 
 opment of the earth's surface features; that the 
 various dynamic agents perform their characteristic work 
 throughout all geologic time. The formulation of prin- 
 ciple and processes of earth sculpture was, therefore, 
 impossible on the hypothesis of a ready-made earth 
 whose features were substantially unchangeable, except 
 when modified by catastrophic processes. In 1821, J. W. 
 Wilson wrote in the Journal: "Is it not the best theory 
 of the earth, that the Creator, in the beginning, at least 
 at the general deluge, formed it with all its present grand 
 characteristic features?"^ If so, a search for causes is 
 futile, and the study of the work performed by streams 
 and glaciers and wind is unprofitable. The belief in the 
 Deluge as the one great geological event in the history of 
 the earth has brought it about that the speculations of 
 Aristotle, Herodotus, Strabo, and Ovid, and the illus- 
 trious Arab, Avicenna (980-1037), unchecked by appeal 
 to facts but also unopposed by priesthood or popular 
 prejudice, are nearer to the truth than the intolerant con- 
 troversial writings of the intellectual leaders whose 
 touchstone was orthodoxy. A few thinkers of the six- 
 teenth century revolted against the interminable repeti- 
 tion of error, and Peter Severinus (1571) advised his 
 students: "Burn up your books . . . buy yourselves 
 stout shoes, get away to the mountains, search the valleys, 
 the deserts, the shores of the seas. ... In this way and no 
 
INTERPRETATION OF LAND FORMS 1 23 
 
 other will you arrive at a Imowledge of things." But 
 the thorough-going "diluvialist" who believed that a 
 million species of animals could occupy a 450-foot 
 Ark, but not that pebbles weathered from" rock or that 
 rivers erode, had no use for his powers of observation. 
 
 Sporadic germs of a science of land forms scattered 
 through the literature of the seventeenth and eighteenth 
 centuries found an unfavorable environment and pro- 
 duced inconspicuous growths. Even their sponsors did 
 little to cultivate them. Steno (1631-1687) mildly sug- 
 gested that surface sculpturing, particularly on a small 
 scale, is largely the work of running water, and Guettard 
 (1715-1786), a truly great mind, grasped the fundamental 
 principles of denudation and successfully entombed his 
 views as well as his reputation in scores of books and vol- 
 umes of cumbrous diffuse writing. 
 
 At the beginning of the nineteenth century a sufficient 
 body of principles had been established to justify the 
 recognition of an earth science, geology, and the 195 vol- 
 umes of the Journal thus far published carry a large part 
 of the material which has won approval for the new 
 science and given prominence to American thought. 
 From the pages in the Journal, the progress of geology 
 may be illustrated by tracing the fluctuation in the devel- 
 opment of fact and theory as relates to valleys and gla- 
 cial features, the subjects to which this chapter is devoted. 
 
 The Interpretation of Valleys. 
 The Pioneers. 
 
 Desmarest (1725-1815) might be styled the father of 
 physiography. By concrete examples and sound induc- 
 tion he established (1774) the doctrine that the valleys of 
 central France are formed by the streams which occupy 
 them. He also made the first attempt to trace the his- 
 tory of a landscape through its successive stages on the 
 basis of known causes. His methods and reasoning are 
 practically identical with those of Dutton working in the 
 ancient lavas of New Mexico; and Whitney's description 
 of the Table Mountains of California might well have 
 appeared in Desmarest 's memoirs.- The teachings of 
 Desmarest were strengthened and expanded by DeSaus- 
 
124 A CENTURY OF SCIENCE 
 
 sure (1740-1799), the sponsor for the term, "Geology," 
 (1779) who saw in the intimate relation of Alpine 
 streams and valleys the evidence of erosion by running 
 water (1786). 
 
 The work of these acknowledged leaders of geological 
 thought attracted singularly little attention on the Con- 
 tinent, and Lamarck's volume on denudation (Hydro- 
 geologie), which appeared in 1802, although an important 
 contribution, sank out of sight. But the seed of the French 
 school found fertile ground in Edinburgh, the center of 
 the geological world during the first quarter of the nine- 
 teenth century. Button's "Theory of the Earth, with 
 Proofs and Illustrations," in which the guidance of 
 DeSaussure and Desmarest is gratefully acknowledged, 
 appeared in 1795. The original publication aroused only 
 local interest, but when placed in attractive form by Play- 
 fair 's "Illustrations of the Huttonian Theory" (1802), 
 the problem of the origin and development of land forms 
 assumed a commanding position in geological thought. 
 Hutton was peculiarly fortunate in his environment. He 
 had the support and assistance of a group of able scien- 
 tific colleagues as well as the bitter opposition of Jameson 
 and of the defenders of orthodoxy. His views were 
 discussed in scientific publications and found their way to 
 literary and theological journals. Hutton 's conception 
 of the processes of land sculpture — slow upheaving and 
 slow degradation of mountains, differential weathering, 
 and the carving of valleys by streams — has a very 
 modern aspect. Playf air's book would scarcely be out of 
 place in a twentieth century class room. The following 
 paragraphs are quoted from it :^ 
 
 " ... A river, of which the course is both serpentine and 
 deeply excavated in the rock, is among the phenomena, by 
 which the slow waste of the land, and also the cause of that 
 waste, are most directly pointed out. 
 
 The structure of the vallies among mountains, shews clearly to 
 what cause their existence is to be ascribed. Here we have first 
 a large valley, communicating directly with the plain, and wind- 
 ing between high ridges of mountains, while the river in the 
 bottom of it descends over a surface, remarkable, in such a 
 scene, for its uniform declivity. Into this, open a multitude of 
 transverse or secondary vallies, intersecting the ridges on either 
 
INTERPRETATION OF LAND FORMS 125 
 
 side of the former, each bringing a contribution to the main 
 stream, proportioned to its magnitude ; and, except where a 
 cataract now and then intervenes, all having that nice adjust- 
 ment in their levels, which is the more wonderful, the greater 
 the irregularity of the surface. Tliese secondary vallies have 
 others of a smaller size opening into them; and, among moun- 
 tains of the first order, where all is laid out on the greatest scale, 
 these ramifications are continued to a fourth, and even a fifth, 
 each diminishing in size as it increases in elevation, and as its 
 supply of water is less. Through them all, this law is in gen- 
 eral observed, that where a higher valley joins a lower one, of 
 the two angles which it makes with the latter, that which is 
 obtuse is always on the descending side ; . . . what else but the 
 water itself, working its way through obstacles of unequal 
 resistance, could have opened or kept up a communication 
 between the inequalities of an irregular and alpine surface . . . 
 
 . . . The probability of such a constitution [arrangement of 
 valleys] having arisen from another cause, is, to the probability 
 of its having arisen from the running of water, in such a pro- 
 portion as unity bears to a number infinitely great. 
 
 . . . With Dr. Hutton, we shall be disposed to consider those 
 great chains of mountains, which traverse the surface of the 
 globe, as cut out of masses vastly greater, and more lofty than 
 any thing that now remains. 
 
 From this gradual change of lakes into rivers, it follows, that 
 a lake is but a temporary and accidental condition of a river, 
 which is every day approaching to its termination ; and the 
 truth of this is attested, not only by the lakes that have existed, 
 but also by those that continue to exist" 
 
 Steps JBackwartl, 
 
 Even Hutton 's clear reasoning, firmly buttressed by 
 concrete examples, was insufficient to overcome the belief 
 in ready-made or violently formed valleys and original 
 corrugations and irregularities of mountain surface. 
 The pages of the Journal show that the principles laid 
 down by Playfair were too far in advance of the times to 
 secure general acceptance. In the first volume of the 
 Journal, the gorge of the Fi-ench Broad River is assigned 
 by Kain to "some dreadful commotion in nature which 
 probably shook these mountains to their bases,"' and 
 the gorge of the lower Connecticut is considered by 
 Hitchcock (1824)^ as a breach which drained a series of 
 lakes "not many centuries before the settlement of this 
 
126 A CENTURY OF SCIENCE 
 
 country. ' ' The prevailing American and Englisli view f or 
 the first quarter of the nineteentli century is expressed 
 in the reviews in tliis Journal, where the well-known 
 conclusions of Conybeare and Phillips that streams are 
 incompetent to excavate valleys are quoted with approval 
 and admiration is expressed for Buckland's famous 
 "Reliquiffi Diluviana;, " a 300-page quarto volume devoted 
 to proof of a deluge. The professor at Yale, Silliman, 
 and the professor at Oxford, Buckland, saw that an 
 acceptance of Button's views involved a repudiation of 
 the Biblical flood, and much space is devoted to combating 
 these "erroneous" and "unscientific" views. For exam- 
 ple, Buckland says -.^ 
 
 "... The general belief is, that existing streams, avalanches 
 and lakes, bursting their barriers, are sufficient to account for 
 all their phenomena, and not a few geologists, especially those 
 of the Huttonian school, at whose head is Professor Playfair, 
 have till recently been of this opinion. . . . But it is now very 
 clear to almost every man, who impartially examines the facts 
 in regard to existing vallies, that the causes now in action, men- 
 tioned above, are altogether inadecjuate to their production; 
 nay, that such a supposition would involve a phj^sical impossi- 
 bility. We do not believe that one-thousanclth part of our 
 present vallies were excavated by the power of existing streams. 
 ... In very many cases of large rivers, it is found, that so far 
 from having formed their own beds, they are actually in a grad- 
 ual manner filling them up. 
 
 Again ; how happens it that the source of a river is frequently 
 below the head of a valley, if the river excavated that valley? 
 
 The most powerful argument, however, in our opinion, 
 against the supposition we are combating, is the phenomena of 
 transverse and longitudinal valleys; both of which could not 
 possibly have been formed by existing streams." 
 
 Phillips writes in 1829:^ "The excavation of valleys 
 can be ascribed to no other cause than a great flood of 
 water which overtopped the hills, whose suimnits those 
 vallies descend." 
 
 Faith in Noah's flood as the dominant agent of erosion 
 rapidly lost ground through the teaching of Lyell after 
 1830, but the theory of systematic development of land- 
 scapes by rivers gained little. In fact, Scrope in 1830,** 
 in showing that the entrenched meanders of the Moselle 
 
INTERPRETATION OF LAND FORMS 127 
 
 prove gradual progressive stream work, was in advance 
 of his English contemporarJ^ Judged by contributions 
 to the Journal, Ly ell's teaching served to standardize 
 American opinion of earth sculpture somewhat as fol- 
 lows : The ocean is the great valley maker, but rivers 
 also make them ; the position of valleys is determined by 
 original or renewed surface inequalities or by faulting; 
 exceptional occurrences — earthquakes, bursting of lakes, 
 upheavals and depressions — have played an important 
 part. Hayes (1839)'^ thought that the surface of New 
 York was essentially an upraised sea-bottom modified by 
 erosion of waves and ocean currents. Sedgwick (1838)^" 
 considered high-lying lake basins proof of valleys which 
 were shaped under the sea. Many of the valleys in the 
 Chilian Cordillera were thought by Darwin (1844) to 
 have been the work of waves and tides, and water gaps 
 are ascribed to currents "bursting through the range at 
 those points where the strata have been least inclined 
 and the height consequently is less." Speaking of the 
 magnificent stream-cut canyons of the Blue Mountains 
 of New South Wales, gorges which lead to narrow exits 
 through monoclines, Darwin says : "To attribute these 
 hollows to alluvial action would be preposterous."" 
 
 The influence of structure in the formation of valleys 
 is emphasized by many contributors to the Journal. 
 Hildreth in 1836, in a valuable paper,'" which is perhaps 
 the first detailed topographic description of drainage in 
 folded strata, expresses the opinion that the West Vir- 
 ginia ridges and valleys antedated the streams and that 
 water gaps though cut by rivers involve pre-existing 
 lakes. Geddes {1826)i' denied that Niagara River cut its 
 channel and speaks of valleys which "were valleys e'er 
 moving spirit bade the waters flow." Conrad (1839)'* 
 discussed the structural control of the Mohawk, the 
 Ohio, and the Mississippi, and Lieutenant Warren 
 (1859)1^ concluded that the Niobrara must have orig- 
 inated in a fissure. According to Lesley (1862)'" 
 the course of the New River across the Great Val- 
 ley and into the Appalachians "striking the escarp- 
 ment in the face" is determined by the junction of 
 anticlinal structures on the north with faulted mono- 
 clines toward the south; a conclusion in harmony 
 
128 A CENTURY OF SCIENCE 
 
 with the views of Edward Hitchcock (1841)" that major 
 valleys and mountain passes are structural in origin and 
 that even subordinate folds and faults may determine 
 minor features. "Is not this a beautiful example of 
 prospective benevolence on the part of the Deity, thus, 
 by means of a violent fracture of primary moun- 
 tains, to provide for easy intercommunication through 
 alpine regions, countless ages afterwards!" The extent 
 of the wandering from the guidance of DeSaussure and 
 Playfair after the lapse of 50 years is shown by students 
 of "Switzerland. Alpine valleys to Murchison (1851) 
 were bays of an ancient sea; Schlaginweit (1852) found 
 regional and local complicated crustal movements a satis- 
 factory cause, and Forbes (1863) saw only glaciers. 
 
 T'allei/s Formed by Rivers. 
 
 One strong voice before 1860 appears to have called 
 Americans back to truths expounded by Desmarest and 
 Hutton. Dana in 1850'* amply demonstrated that val- 
 leys on the Pacific Islands owe neither their origin, 
 position or form to the sea or to structural factors. 
 They are the work of existing streams which have eaten 
 their way headwards. Even the valleys of Australia 
 cited b}' Darwin as tyqie examples of ocean work are 
 shown to be products of normal stream work. Dana 
 went further and gave a permanent place to the Hut- 
 tonian idea that many bays, inlets, and fiords are but the 
 drowned mouths of stream-made valleys. In the same 
 volume in which these conclusions appeared, Hubbard 
 (1850)''^ announced that in New Hampshire the "deepest 
 valleys are but valleys of erosion." The theory that 
 valleys are excavated by streams which occupy them 
 was all but universally accepted after F. V. Hayden's 
 description"" of Rocky Mountain gorges (1862) and New- 
 berry's interpretation of the canyons of Arizona (1862) ; 
 but the scientific world was poorly prepared for New- 
 berry's statement:-' 
 
 "Liko the great canons of the Colorado, the broad valleys 
 bounded by hifrli and perpendicular walls belong to a vast system 
 of erosion, and are wholly elite to the action of water. . . . The 
 first and most plausible explanation of the striking surface fea- 
 tures of this region will be to refer them to that embodiment of 
 
INTERPRETATION OF LAND FORMS 129 
 
 resistless power — the sword that cuts so many geological knots — • 
 volcanic force. The Great Canon of the Colorado would be 
 considered a vast fissure or rent in the earth's crust, and the 
 abrupt termination of the steps of the table lands as marking 
 lines of displacement. This theory though so plausible, and so 
 entirely adequate to explain all the striking phenomena, lacks 
 a single requisite to acceptance, and that is truth." 
 
 With such stupendous examples in mind, the dictum 
 of Hutton seemed reasonable : "there is no spot on which 
 rivers may not formerly have run." 
 
 Denudation by Rivers. 
 
 The general recognition of the competency of streams 
 to form valleys was a necessary prelude to the broader 
 view expressed by Jukes (1862)-- 
 
 "The surfaces of our present lands are as much carved and 
 sculptured surfaces as the medallion carved from the slab, or the 
 statue sculptured from the block. They have been gradually 
 reached by the removal of the rock that once covered them, and 
 are themselves but of transient duration, always slowly wasting 
 from decay." 
 
 Contributions to the Journal between 1850 and 1870 
 reveal a tendency to accept greater degrees of erosion 
 by rivers, but the necessary end-product of subaerial 
 erosion — a plain — is first clearly defined by Powell in 
 1875.-' In formulating his ideas Powell introduced the 
 term "base-level," which may be called the germ word 
 out of which has grown the "cycle of erosion," the 
 master key of modern physiographers. The original 
 definition of base-level follows : 
 
 "We may consider the level of the sea to be a grand base- 
 level, below which the dry lands cannot be eroded ; but we may 
 also have, for local and temporary purposes, other base-levels of 
 erosion, which are the levels of the iDeds of the principal streams 
 which carry away the products of erosion. (I take some liberty 
 in using the term 'level' in this connection, as the action of a 
 running stream in wearing its channel ceases, for all practical 
 purposes, before its bed has quite reached the level of the lower 
 end of the stream. What I have called the base-level would, in 
 fact, be an imaginary surface, inclining slightly in all its parts 
 toward the lower end of the principal stream draining the area 
 
130 A CENTURY OF SCIENCE 
 
 through which the level is supposed to extend, or having the 
 inclination of its parts varied in direction as determined by 
 tributary streams.) " 
 
 Analysis of Powell's view has given definiteness to the 
 distinction between "base-level," an imaginary plane, 
 and "a nearly featureless plain," the actual land surface 
 produced in the last stage of subaerial erosion. 
 
 Following their discovery in the Colorado Plateau 
 Province, denudation surfaces were recognized on the 
 Atlantic slope and discussed by McGee (1888),-"* in a paper 
 notable for the demonstration of the use of physiographic 
 methods and criteria in the solution of stratigraphic 
 problems. Davis (1889 )-■'"' described the upland of 
 southern New England developed during Cretaceous 
 time, introducing the term "peneplain," "a nearly fea- 
 tureless plain." The short-lived opposition to the 
 theory of peneplanation indicates that in America at least 
 the idea needed only formulation to insure acceptance. 
 
 It is interesting to note that surfaces now classed as 
 l^eneplains were fully described by Percival (1842),"'^ 
 who assigned them to structure, and by Kerr (1880),-'' 
 who considered glaciers the agent. In Europe "plains 
 of denudation" have been clearly recognized by Ramsay 
 (1846), Jukes (1862), A. Geilde (1865), Foster" and Top- 
 ley (1865), Maw (1866), W^mne (1867), Whitaker (1867), 
 Macintosh (1869), Green (1882), Richthofen (1882), but 
 all of them were looked upon as products of marine work, 
 and writers of more recent date in England seem reluc- 
 tant to give a subordinate place to the erosive power of 
 waves. Americans, on the other hand, have been think- 
 ing in terms of rivers, and the great contribution of the 
 American school is not that peneplains exist, but that 
 they are the result of normal subaerial erosion. More 
 precise field methods during the past decade have 
 revealed the fact that no one agent is responsible for the 
 land forms classed as peneplains ; that not only rivers 
 and ocean, but ice, wind, structure, and topographic 
 position must be taken into account. 
 
 The recognition of rivers as valley-makers and of the 
 final result of stream work necessarily preceded an 
 analysis of the process of subaerial erosion. The first 
 
INTERPRETATION OF LAND FORMS 131 
 
 and last terms were known, the intermediate terms and 
 the sequence remained to be established. A significant 
 contribution to this problem was made by Jukes (1862).-- 
 
 "... I believe that the lateral valleys are those which were 
 first formed by the drainage running directlj^ from the crests of 
 the chains, the longitudinal ones being subsequently elaborated 
 along the strike of the softer or more erodable beds exposed on 
 the flanks of those chains. ' ' 
 
 Powell's discussion of antecedent and consequent 
 drainage (1875) and Gilbert's chapter on land sculpture 
 in the Henry Mountain report (1880) are classics, and 
 McGee's contribution-* contains significant suggestions. 
 but the master papers are by Davis,-'-' who introduces an 
 analysis of land forms based on structure and age by the 
 statement : 
 
 "Being fully persuaded of the gradual and systematic evolu- 
 tion of topographical forms it is now desired ... to seek the 
 causes of the location of streams in their present courses ; to go 
 back if possible to the early date when central Pennsylvania was 
 first raised from the sea, and trace the development of the several 
 river systems then implanted upon it from their ancient begin- 
 ning to the present time." 
 
 That such a task could have been undertaken a quarter 
 of a century ago and to-day considered a part of every- 
 day field work shows how completely the lost ground of a 
 half-century has been regained and how rapid the 
 advance in the knowledge of land sculpture since the 
 canyons of the Colorado Plateau were interpreted. 
 
 Features Itestdfiug from Glaciation. 
 
 The Problem Stated. 
 
 Early in the nineteenth century when speculation 
 regarding the interior of the earth gave place in part to 
 observations of the surface of the earth, geologists were 
 confronted with perhaps the most difficult problem in the 
 history of the science. As stated by the editor of the 
 Journal in 1821 r° 
 
 "The almost universal existence of rolled pebbles, and boulders 
 of rock, not only on the margin of the oceans, seas, lakes, and 
 rivers ; but their existence, often in enormous quantities, in 
 
132 A CENTURY OF SCIENCE 
 
 situations quite removed from large waters ; inland, — in high 
 banks, imbedded in strata, or scattered, occasionally, in pro- 
 fusion, on the face of almost every region, and sometimes on the_ 
 tops and declivities of mountains, as well as in the vallies 
 between them ; their entire difference, in many cases, from the 
 rocks in the country where they lie — rounded masses and peb- 
 bles of primitive rocks being deposited in secondary and alluvial 
 regions, and vice versa; these and a multitude of similar facts 
 have ever struck us as being among the most interesting of 
 geological occurrences, and as being very inadequately accounted 
 for by existing theories. ' ' 
 
 The phenomena demanding explanation — jumbled 
 masses of "diluvium," polished and striated rock, 
 bowlders distributed with apparent disregard of topog- 
 raphy — were indeed startling. Even Lyell, the great 
 exponent of uniformitarianism, appears to have lost faith 
 in his theories when confronted with facts for which 
 known causes seemed inadequate. The interest aroused 
 is attested by 31 titles in tlie Journal during its first two 
 decades, articles which include speculations unsupported 
 by logic or fact, field observation unaccompanied by 
 explanation, field observation with fantastic explanation, 
 ex-catJiedra pronouncements by prominent men, sound 
 reasoning from insufficient data, and unclouded recogni- 
 tion of cause and effect by both obscure and prominent 
 men. With little knowledge of glaciers, areal geology, 
 or of structure and composition of drift, all known forces 
 were called in : normal weathering, catastrophic floods, 
 ocean currents, waves, icebergs, glaciers, wind, and even 
 depositions from a primordial atmosphere (Chabier, 
 1823). Human agencies were not discarded. Speak- 
 ing of a granite bowlder at North Salem, New York, 
 described by Cornelius (1820)-''i as resting on limestone, 
 Finch (1824)5- says: "it is a magnificent cromlech and 
 the most ancient and venerable monument which America 
 possesses." In the absence of a known cause, cata- 
 strophic agencies seem reasonable. 
 
 The Dcfiige. 
 
 In the seventh volimie of the Journal (1824)'" we read: 
 
 "After the production of these regular strata of sand, clay, 
 limeslone, &c. came a terrible irruption of water from the north, 
 
INTERPRETATION OF LAND FORMS 133 
 
 or north-west, whicli in many places covered the preceding 
 formations with diluvial gravel, and carried along with it those 
 immense masses of granite, and the older rocks, which attest to 
 the present day the destruction and ruin of a former world. ' ' 
 
 Another author remarks : 
 
 "We find a mantle as it were of sand and gravel indifferently 
 covering all the solid strata, and evidently derived from some 
 con%'Tilsion which has lacerated and partly hroken up those 
 strata. ..." 
 
 The catastrophe favored by most geologists was floods 
 of water violently released — "we believe," says the 
 editor, "that all geologists agree in imputing . . . the 
 diluvium to the agency of a deluge at one period or 
 another. "^^ Such conclusions rested in no small way 
 upon Hayden's well-known treatise on surficial deposits 
 (1821), 25 a volume which deserves a prominent place in 
 American geological literature. Hayden clearly dis- 
 tingTiished the topographic and structural features of the 
 drift but found an adequate cause in general wide-spread 
 currents which "flowed impetuously across the whole 
 continent . . . from north east to south west." In review- 
 ing Hayden's book Silliman remarks: 
 
 "The general cause of these currents Mr. Hayden concludes to 
 be the deluge of Noah. AVhile no one will object to the propriety 
 of ascribing very many, probably most of our alluvial features, 
 to that catastrophe, we conceive that neither Mr. Hayden, nor 
 any other man, is bound to prove the immediate phj'sical cause 
 of that vindictive infliction. 
 
 We would beg leave to suggest the following as a cause which 
 may have aided in deluging the earth, and wliich, were there 
 occasion, might do it again. 
 
 The existence of enormous caverns in the bowels of the earth, 
 (so often imagined by authors,) appears to be no very extrava- 
 gant assumption. It is true it cannot be proved, but in a sphere 
 of eight thousand miles in diameter, it would appear in no way 
 extraordinary, that many cavities might exist, wliich collectively, 
 or even singly, might well contain much more than all our 
 oceans, seas, and other superficial waters, none of wliich are 
 probably more than a few miles in depth. If these cavities com- 
 municate in any manner with the oceans, and are (as if they 
 exist at all, they probably are,) filled with water, there exist, we 
 
lU A CENTURY OF SCIENCE 
 
 conceive, agents very competent to expel the water of these cav- 
 ities, and thus to deluge, at any time, the dry land. 
 
 The teachings of Hayden were favorably received by 
 Hitchcock, Striider, and Hubbard, and many Europeans. 
 They found a champion in Jackson, who states (1839) r^" 
 
 "From the observations made upon Mount Ktaadn, it is 
 proved, that the current did rush over the summit of that lofty 
 mountain, and consequently the diluvial waters rose to the height 
 of more than 5,000 feet. Hence we are enabled to prove, that the 
 ancient ocean, which rushed over the surface of the State, was at 
 least a mile in depth, and its transporting power must have 
 been greatly increased by its enormous pressure. ' ' 
 
 Gibson, a student of western geology, reaches the same 
 conclusion (1836) :^'' 
 
 "That a wide-spread current, although not, as imagined, fed 
 from an inland sea, once swept over the entire region between 
 the Alleghany and the Rocky Mountains is established by 
 plenary proof." 
 
 Professor Sedgwick (1831) thought the sudden up- 
 heaval of mountains sufficient to have caused floods 
 again and again. The strength of the belief in the Bib- 
 lical flood, during the first quarter of the 19th century, 
 may he represented by the following remarks of Phil- 
 lips (1832) :''8 
 
 "Of many important facts which come under the consideration 
 of geologists, the 'Deluge' is, perhaps, the most remarkable; and 
 it is established by such clear and positive arguments, that if any 
 one point of natural history may be considered as proved, the 
 deluge must l)e admitted to have happened, because it has left 
 full evidence in plain and characteristic effects tq^on the surface 
 of the earth." 
 
 However, the theory of deluges, whether of ocean or 
 land streams, did not hold the field unopposed. In 18'23, 
 Granger,^-' an observer whose contributions to science 
 total only six pages, speaks of the striae on the shore of 
 Lake Erie as 
 
 "having been formed by the powerful and continued attrition of 
 some hard body. ... To me, it does not seem possible that water 
 under any circumstances, could have effected it. The flutings in 
 
INTEEPEETATION OF LAND FOEMS 135 
 
 width, depth, and direction, are as regular as if they had been 
 cut out by a grooving plane. This, running water could not 
 effect, nor could its operation have produced that glassy smooth- 
 ness, which, in many parts, it still retains." 
 
 Hayes and also Conrad expressed similar views in the 
 Journal 16 years later. 
 
 The idea that ice was in some way concerned with the 
 transportation of drift has had a curious history. The 
 first unequivocal statement, based on reading and keen 
 observation, was made in the Journal by Dobson in 
 1826 :« 
 
 "I have had occasion to dig up a great number of bowlders, of 
 red sandstone, and of the conglomerate kind, in erecting a cotton 
 manufactory ; and it was not uncommon to find them worn 
 smooth on the under side, as if done by their having been 
 dragged over rocks and gravelly earth, in one steady position. 
 On examination, they exhibit scratches and furrows on the 
 abraded part ; and if among the minerals composing the rock, 
 there happened to be pebbles of feldspar, or quartz, (which was 
 not uncommon,) they usuallj' appeared not to be worn so much 
 as the rest of the stone, preserving their more tender parts in a 
 ridge, extending some inches. When several of these pebbles 
 happen to be in one block, the preserved ridges were on the same 
 side of the pebbles, so that it is easy to determine which part of 
 the stone moved forward, in the act of wearing. 
 
 These bowlders are found, not only on the surface, but I have 
 discovered them a number of feet deep, in the earth, in the hard 
 compound of clay, sand, and gravel. . . . 
 
 I think we cannot account for these appearances, unless we 
 call in the aid of ice along with water, and that they have been 
 worn by being suspended and carried in ice, over rocks and 
 earth, under water." 
 
 In Dobson's day the h^-pothesis of "gigantic floods," 
 "debacles," "resistless world-wide currents," was so 
 firmly entrenched that the voice of the observant layman 
 found no hearers, and a letter from Dobson to Hitchcock 
 written in 1837 and containing additional evidence and 
 argument remained unpublished until ]\Iurchison, in 
 1842,*! paid his respects to the remarkable w^ork of a 
 remarkable man.* 
 
 * Peter Dobson (1784-1878) came to this country from Preston, England, 
 in 1809 and established a cotton factory at Vernon, Conn. 
 
136 A CENTUEY OF SCIENCE 
 
 ' ' I take leave of the glacial theory in congratulating American 
 science in having possessed the original author of the best 
 glacial theory, though his name had escaped notice ; and in 
 recommending to you the terse argument of Peter Dobson, a 
 previous acquaintance with which might have saved volumes of 
 disputation on both sides of the Atlantic." 
 
 Glaciers vs. Icebergs. 
 
 The glacial theory makes its way into geological lit- 
 erature with the development of Agassiz (1837) of the 
 views of Venetz (1833) and Charpentier (183-4), that the 
 glaciers of the Alps once had greater extent. The bold 
 assumption was made that the surface of Europe as far 
 south as the shores of the Mediterranean and Caspian 
 seas was covered by ice during a period immediately 
 preceding the present. The kernel of the present gla- 
 cial theory is readily recognizable in these early works, 
 but it is wrapped in a strange husk : it was assumed that 
 the Alps were raised by a great convulsion under the 
 ice and that the erratics slid to their i^laces over the 
 newly made declivities. The publication of the famous 
 "Etudes sur les Glaciers" (1840), remarkable alike for 
 its clarity, its sound inductions, and wealth of illustra- 
 tions, brought the ideas of Agassiz more into prominence 
 and inaugurated a 30-years' war with the proponents of 
 currents and icebergs. The outstanding objections to the 
 theory were the requirement of a frigid climate and the 
 demand for glaciers of continental dimensions ; very 
 strong objections, indeed, for the time when fossil evi- 
 dence was not available, the great polar ice sheets were 
 unexplored, and the distinction between till and water- 
 laid drift had not been established. 
 
 The glacial theory was cordially adopted by Buck- 
 land (1841)" and in part by Lyell in England but 
 viewed with suspicion by Sedgwick, "Wliewell, and Man- 
 tell. In America the response to the new idea was 
 immediate. Hitchcock (1841)''' concludes an able dis- 
 cussion with the statement: "So remarkably does it 
 solve most of the phenomena of diluvial action, "that I am 
 constrained to believe its fundamental principles to be 
 founded in truth." 
 
 The theory formed the chief topic of discussion at the 
 
INTERPRETATION OF LAND FORMS 137 
 
 third and fourth meetings of tlie Association of American 
 Geologists and Naturalists (1842, 1843) under the lead 
 of a committee on drift consisting of Emmons, W. B. 
 Rogers, Vanuxem, Nicollet, Jackson, and J. L. Hayes. 
 The result of these discussions was a curious reaction. 
 Hitchcock complained that he "had been supposed to be 
 an advocate for the unmodified glacial theory, but he had 
 never been a believer in it," and Jackson spoke for a 
 number of men when he stated :^^ 
 
 "This country exhibits no proofs of the glacial theory as taught 
 by Agassiz but on the contrary the general bearing of the facts 
 is against that theory. . . . Many eminent men incautiously 
 embraced the new theory, which within two or three years from 
 its promulgation, had been found utterly inadequate, and is now 
 abandoned by many of its former supporters." 
 
 Out of this symposium came also the strange contribu- 
 tion of H. D. Rogers (1844),"'* who cast aside the teach- 
 ings of deduction and observation and returned to the 
 views of the Medievalists. 
 
 "If we will conceive, then, a wide expanse of waters, less per- 
 haps than one thousand feet in depth, dislodged from some high 
 northern or circumpolar basin, by a general lifting of that region 
 of perhaps a few hundred feet, and an ec|ual subsidence of the 
 country south, and imagine this whole mass converted by earth- 
 quake pulsations of the breadth which such undulations have, 
 into a series of stupendous and rapid-moving waves of transla- 
 tion, helped on by the still more rapid flexures of the floor over 
 which they move, and then advert to the shattering and loosen- 
 ing power of the tremendous jar of the earthquake, we shall have 
 an agent adequate in every way to produce the results we see, to 
 float the northern ice from its moorings, to rip off, assisted with 
 its aid, the outcrops of the hardest strata, to grind up and strew 
 wide their fragments, to scour down the whole rocky floor, and, 
 gathering energy with resistance, to sweep up the slopes and over 
 the highest mountains." 
 
 Because of the prominence of their author, Rogers's 
 views exerted some influence and seemingly received 
 support from England through the elaborate mathematic 
 discussions of Whewell (1848), who considered the drift 
 as "irresistible proof of paroxysmal action," and Hop- 
 kins (1852), who contended for "currents produced by 
 repeated elevatory movements." 
 
138 A CENTURY OF SCIENCE 
 
 After his arrival in America (1846), Agassiz's influ- 
 ence was felt, and liis paper on the erratic phenomena 
 about Lake Superior (1850),-*^ in which he called upon 
 the advocates of water-borne ice to point out the barrier 
 which caused the current to subside, produced a salu- 
 tary effect; yet Desor (1852)-'° states that in the region 
 described by Agassiz "the assumption [of a general ice 
 cap] is no longer admissible," and that the bowlders on 
 Long Island "were transported on ice rafts along the sea 
 shore and stranded on the ridges and eminences which 
 were then shoals along the coast." Twenty years of 
 discussion were insufficient to establish the glacial theory 
 either in Europe or America. The consensus of opinion 
 among the more advanced thinkers in 1860 is expressed 
 by Dana •^'' 
 
 "In view of the whole subject, it appears reasonable to con- 
 clude that the Ghicier theory affords the best and fullest 
 explanation of the phenomena over the g:eneral surface of the 
 continents, and encounters the fewest difficulties. But icebergs 
 have aided beyond doubt in producing the results along the 
 borders of the continents, across ocean-channels like the German 
 Ocean and the Baltic, and possibly over great lakes like those of 
 North America. Long Island Sound is so narrow that a glacier 
 may have stretched across it." 
 
 Papers in the Journal of 1860-70 show a prevailing 
 belief in icebergs, but the evidence for land ice Avas 
 accumulating as the deposits became better known, and 
 in 1871 field workers speak in unmistakable tones :^^ 
 
 "It is still a mooted question in American geology whether the 
 events of the Glacial era were due to glaciers or iceiergs. . . . 
 American geologists are still divided in opinion, and some of the 
 most eminent have pronounced in favor of icebergs. 
 
 Since, then, icebergs cannot pick up masses tons in weight 
 from the bottom of a sea, or give a general movement southward 
 to the loose material of the surface ; neither can produce the 
 abrasion observed over the rocks under its various conditions; 
 and inasmuch as all direct evidence of the submergence of the 
 land required for an iceberg sea over New England fails, the 
 conclusion appears inevitable that icebergs had nothing to do 
 with the drift of the New Haven region, in the Connecticut 
 valley; and, therefore, that the Glacial era in central New Eng- 
 land was a Glacier era." 
 
INTERPRETATION OF LAND FORMS 139 
 
 Matthew (1871)"^' reached the same eoiiclusion for the 
 Lower Provinces of Canada. In spite of the increasing 
 clarity of the evidence, the battle for the glacial theory 
 was not yet won. The remaining opponents though few 
 in number were distinguished in attainments. Dawson 
 clung to the outworn doctrine until his death in 1899. 
 
 An interesting feature of the history of glacial theories 
 is the calculation by Maclaren (1842)^" that the amount 
 of water abstracted from the seas to form the hjqio- 
 thetical ice sheet would lower the ocean-level 350 feet — ■ 
 an early form of the glacial control hj^oothesis (see 
 Dalysi). 
 
 Extent of Glacial Drift. 
 
 By the middle of the nineteenth century, it was recog- 
 nized that the "drift," whatever its origin, was not of 
 world-wide extent. In America its characteristic features 
 were found best developed north of latitude 40 degrees ; 
 in Europe, the Alps, the Scottish Highlands, and Scandi- 
 navia were recognized as tj^^e areas. The limits were 
 unassigned, partly because the field had not been sur- 
 veyed, but largely because criteria for the recognition of 
 drift had not been established. The well-kno\\Ti hillocks 
 and ridges of "diluvium" and "alluvium" and "drift" 
 of New Jersey and Ohio, and the mounds of the Missouri 
 Cotou elaborately described by Catlin (1840)"'- bore 
 little resemblance to the walls of unsorted rock which 
 stand as moraines bordering Alpine glaciers. The 
 Orange sand of Mississippi was included in the drift by 
 Hilgard (1866),"^^ and the gravels at Philadelphia by 
 Hail (1876)." Stevens (187.3)" described trains of gla- 
 cial erratics at Richmond, Virginia, and William B. 
 Rogers (1876)''^*^ accounts for certain deposits in the Poto- 
 mac, James, and Roanoke rivers by the presence of 
 Pleistocene ice tongues or swollen glacial rivers, and 
 remarks: "It is highly probable that glacial action had 
 much to do with the original accumulation of the rocky 
 debris on the flanks of the Blue Ridge, and in the Appa- 
 lachian valleys beyond." Kerr (1881)" referred the 
 ancient erosion surface of the Piedmont belt in North 
 Carolina to glacial denudation, De la Becbe compared 
 
140 A CENTURY OF SCIENCE 
 
 the drift of Jamaica with that of New England, and 
 Agassiz interpreted soils of Brazil as glacial. 
 
 The tirst detailed description and unequivocal inter- 
 pretation of either terminal or recessional moraines is 
 from the pen of Gilbert (1871),^** geologist of the Ohio 
 Survey. In discussing the former outlet of Lake Erie 
 through the Fort Wayne channel, Gilbert writes : 
 
 "The page of history recorded in these phenomena is by no 
 means ambiguous. The ridges, or, more properly, the ridge 
 which determines the courses of the St. Joseph and St. Marys 
 rivers is a buried terminal moraine of the glacier that moved 
 southwestward through the Maumee valley. The overlying Erie 
 Clay covers it from sight, but it is shadowed forth on the surface 
 of that deposit, as the ground is pictured through a deep and 
 even canopy of snow. Its irregularly curved outline accords 
 intimately with the configuration of the valley, and with the 
 direction of the ice markings ; its concavity is turned toward 
 the source of motion ; its greatest convexity is along the line of 
 least resistance. 
 
 Soutli of the St. Marys river are other and numerous moraines 
 accompanied by glacial stria3. Their character and courses 
 have not yet been studied ; but their presence carries the mind 
 back to an epoch of the cold period, when the margin of the ice- 
 field was farther south, and the glacier of the Maumee valley was 
 merged in the general mass. As the mantle of ice grew shorter — ■ 
 and, in fact, at every stage of its existence — its margin must have 
 been variously notched and lobed in conformity with the contour 
 of the country, the higher lands being first laid bare by the 
 encroaching secular summer. Early in the history of this 
 encroachment the glacier of the Maumee valley constituted one of 
 these lobes, and has recorded its form in the two moraines that 
 I have described." 
 
 Three years after the recognition of moraines in the 
 Maumee valley, Chamberlin (1874)^=* showed that the 
 seemingly disorganized mounds and basins and ridges 
 known as the Kettle range of Wisconsin is the terminal 
 moraine of the Green Bay glacier. At an earlier date 
 (18G4) Whittlesey interprefed the kettles of the Wis- 
 consin moraine as evidence of ice blocks from a melting 
 glacier and presented a map showing the "southern 
 limit of boulders and coarse drift." In 1876 attention 
 was called to the terminal moraine of New England by G. 
 
INTERPEETATION OF LAND FORMS flil' 
 
 ■—.-^ 
 
 Frederick Wright, who assigns the honor of discovery to 
 Clarence King. 
 
 With the observations of Gilbert, Chamberlin, and 
 King in mind, the terminal moraine was traced by 
 various workers across the United States and into 
 Canada and the extent of glacial cover revealed. Fol- 
 lowing 1875 the pages of the Journal contain many con- 
 tributions dealing with the origin and structure of 
 moraines, eskers, kames, and drumlins. Before 1890 
 twenty-eight papers on the glacial phenomena of the Erie 
 and Ohio basin alone had appeared. By 1900 substantial 
 agreement had been reached regarding the significant 
 features of the drift, the outline history of the Great 
 Lakes had been written, and the way had been paved for 
 stratigraphic studies of the Pleistocene, which hulk large 
 in the pages of the Journal for the last two decades. 
 
 Epochs of Glaciafion, 
 
 For a decade following the general acceptance of the 
 glacial origin of "diluvium," the deposits were embraced 
 as "drift" and treated as the products of one long period 
 of glacial activity, and throughout the controversy of 
 iceberg and glacier the unity of the glacial period was 
 unquestioned. Beds of peat and fossiliferous lacustrine 
 deposits in Switzerland, England, and in America and 
 the recognition of an "upper" and a "lower" diluvium 
 by Scandinavian geologists suggested two epochs, and as 
 the examples of such deposits increased in number and 
 it became evident that the plant fossils represented forms 
 demanding a genial climate and that the phenomena 
 were seen in many countries, the belief grew that minor 
 fluctuations or gradual recession of an ice sheet were 
 inadequate to account for the phenomena observed. 
 
 It is natural that this problem should have found its 
 solution in America, where the Pleistocene is admirably 
 displayed, and where the State and Federal surveys were 
 actively engaged in areal mapping. In 188.3 Chamber- 
 lin"" presented his views under the bold title, "Prelim- 
 inary Paper on the Terminal Moraine of the Second 
 Glacial Epoch," and the existence of deposits of two or 
 more ice sheets and the features of intcrglacial periods 
 
112 A CENTURY OF SCIENCE 
 
 were substantially established by the interesting debate 
 in the Journal led by Chamberlin, "Wright, Upham and 
 Dana.'^^ Contributions since 1895 have been concerned 
 with the degree rather than the fact of complexity, and 
 continued study has resulted in the general recognition 
 of five glacial stages in North America and four in 
 Europe. 
 
 -*&^ 
 
 The Loess as a Glacial Deposit, 
 
 A curious side-product of the study of giaciation in 
 North America is the controversy over the origin of loess. 
 The interest aroused is indicated by scores of papers in 
 American periodicals and State reports of the last quar- 
 ter of the 19th century — papers which bear the names of 
 prominent geologists. 
 
 The "loess" in the valley of the Rhine bad long been 
 known, but the subject assumed prominence by the pub- 
 lication in 1866 of Pumpelly's Travels in China.''- Wide- 
 spread deposits 200 to 1,000 feet thick were described as 
 very fine-grained yellowish earth of distinctive structure 
 without stratification but penetrated by innumerable 
 tubes and containing land or fresh-water shells. Pum- 
 pelly considered these deposits lacustrine, a view which 
 found general acceptance though combated by Kingsmill 
 (1871),"" who argued for marine deposition. Baron Von 
 Richthofen's classic on China, which appeared in 1877, 
 amplifies the observations of Pumpelly and marshals the 
 evidence to support the hypothesis that the loess is wind- 
 laid both on dry land and within ancient salt lakes. The 
 conclusions of Von Richthofen were adopted by Pumpelly 
 whose knowledge of the Chinese deposits, supplemented 
 by studies in Missouri, of which State he was director of 
 the Geological Survey in 1872-73, placed him in position 
 to form a correct judgment. He says r*'* 
 
 "Recognizing from personal observation tlie full identity of 
 character of the loess of northern China, Europe and the Mis- 
 souri Valley, I am obliged to reject my own explanation of the 
 origin of the Chinese deposits, and to believe with Richthofen 
 that the true loess, wherever it occurs, is a sub-aerial deposit, 
 formed in a dry central region, and that it owes its structure to 
 the formative influence of a steppe vegetation. 
 
 The one weak point of Richthofen's theory is in the evident 
 
INTERPRETATION OF LAND FORMS li3 
 
 inadequacy of the current disintegration as a source of material. 
 When we consider the immense area covered by loess to depths 
 varying from 50 to 2,000 feet, and the fact that this. is only the 
 very finest portion of the product of rock-destruction, and again 
 that the accumulation represents only a very short period of 
 time, geologicallj' speaking, surely we must seek a more fertile 
 source of supply than is furnished by the current decomposition 
 of rock surface. 
 
 It seems to me that there are two important sources: I. The 
 silt brought by rivers, many of them fed by the products of 
 glacial attrition flowing from the mountains into the central 
 region. Where the streams sink away, or where the lakes which 
 receive them have dried up, the finer products of the erosion 
 of a large territory are left to be removed in dust storms. 
 
 II. The second . . . source is the residuary products of a 
 secular disintegration." 
 
 The evidence presented by Pumpelly for the eolian 
 origin of loess — structure, texture, composition, fossil 
 content and topographic position — is complete, and to him 
 belongs the credit for the correct interpretation of the 
 Mississippi valley deposits. Unfortunately his contribu- 
 tion came at a time when the geologists of the central 
 States were intent on tracing the paths and explaining 
 the work of Pleistocene glaciers, and the belief was 
 strong that loess was some phase of glacial work. Its 
 position at the border of the lowan drift so obviously 
 suggests a genetic relation that the fossil evidence of 
 steppe climate suggested by Binney in 1848*'^ was mini- 
 mized. Students of Pleistocene geology in Minnesota, 
 Iowa, Nebraska, Missouri, although less vigorous in 
 expression, were substantially in agreement with Hilgard 
 (1879)."" "The sum total of anomalous conditions 
 required to sustain the eolian hypothesis partakes 
 strongly of the marvellous." The last edition of Dana's 
 Manual, 1894, and of LeConte's Geology, 1896, the two 
 most widely used text books of their time, oppose the 
 eolian theory, and Chamberlin, in 1897,""^ states: "the 
 aqueous hypothesis seems best supported so far as con- 
 cerns the deposits of the Mississippi Valley and western 
 Europe" (p. 795). Shimek, in papers published since 
 1896 has shown that aquatic and glacial conditions can 
 not account for the loess fossils, and the return to the 
 views of Pumpelly that the loess was deposited on land 
 
Ui A CENTURY OF SCIENCE 
 
 by the agency of wind in a region of steppe vegetation is 
 now all but universal. 
 
 Glacial Sculpttire, 
 
 Within the present generation sculpture by glaciers has 
 received much attention and has involved a reconsidera- 
 tion of the ability of ice to erode which in turn involves 
 a crystallization of views of the mechanics of moving ice. 
 The evidence for glacier erosion has remained largely 
 physiographic and rests on a study of land forms. In 
 fact, the inadequacy of structural features or of river 
 corrasion to account for flat-floored, steep-walled gorges, 
 hanging valleys, and many lake basins, rather than a 
 knowledge of the mechanics of ice has led to the present 
 fairly general belief that glaciers are powerful agents of 
 rock sculpture. The details of the process are not yet 
 understood. 
 
 Erosion by glaciers enters the arena of active discus- 
 sion in 1862-63. The possibility had been suggested by 
 Esmark (1827) and by Dana (1849) in the description of 
 fiords and by Hind (1855) with reference to the origin 
 of the Great Lakes. It appears full-fledged in Ramsay's 
 classic, which was published simultaneously in England 
 and in America."'' The argument runs as follows : 
 There is a close association of ancient glaciers and lakes 
 especially in mountains ; glaciers are amply able to 
 erode ; evidences of faulting, special subsidence, river 
 erosion, and marine erosion are absent from the lake 
 basins of Switzerland and Great Britain. To quote 
 Ramsay : 
 
 "It required a solid body grinding steadily and powerfnlly in 
 direct and heavy contact witli and across the rocks to scoop out 
 deep hollows, the situations of which might either be determined 
 by unequal hardness of the rocks, hj extra weight of ice iu 
 special places, or by accidental circumstances, the clue to which 
 is lost from our inability perfectly to reconstruct the original 
 forms of the glaciers." 
 
 "I believe with the Italian geoloarists, that all that the glaciers 
 as a whole effected was only .slightly to deepen these valleys and 
 materially to modify their general outlines, and, further (a the- 
 ory I am alone responsible for), to deepen them in parts more 
 considerably when, from various causes, the grinding power of 
 
INTERPRETATION OF LAND FORMS 145 
 
 the ice was unusually powerful, especially where, as in the low- 
 lands of Switzerland, the Miocene strata are comparatively soft." 
 
 Whittlesey (1864)"^ considered that the rock-bound 
 lakes and narrow bays near Lake Superior were partly 
 excavated by ice. LeConte (1875)"" records some sig- 
 nificant observations in a pioneer paper on glacier 
 erosion Avhich has not received adequate recognition. 
 He says: 
 
 "... I am convinced that a glacier, by its enormous pressure 
 and resistless onward movement, is constantly breaking off large 
 blocks from its bed and bounding walls. Its erosion is not only a 
 grinding and scoring, but also a crushing and breaking. It 
 makes by its erosion not only rock-meal, but also large rock- 
 chips. ... Its erosion is a constant process of alternate rough 
 helving and planing. 
 
 If Yosemite were unique, we might suppose that it was 
 formed by violent cataclj'sms ; but Yosemite is not unique in 
 form and therefore probably not in origin. There are many 
 Yosemites. It is more philosophical to account for them by the 
 regular operation of known causes. I must believe that all these 
 deep perpendicular slots have been sawn out by the action of gla- 
 ciers; the peculiar verticality of the walls having been determined 
 by the perpendicular cleavage structure." ... A lake in Bloody 
 Canyon "is a pure rock basin scooped out by the glacier at this 
 place. . . . These ridges [separating Hope, Faith, and Charity 
 valleys] are in fact the lips of consecutive lake basins scooped 
 out by ice. 
 
 . . . Water tends to form deep V-shaped canons, while ice pro- 
 duces broad valleys with lakes and meadows. ... I know not 
 how general these distinctions may be, but certainly the Coast 
 range of this State is characterized by rounded summits and 
 ridges, and deep V-shaped canons, while the high Sierras are 
 characterized on the contrary by sharp, spire-like, comb-like 
 summits, and broad valleys; and this difference I am convinced 
 is due in part at least to the action of water on the one hand, 
 and of ice on the other." 
 
 King (1878)" assigned to glacial erosion a command- 
 ing position in mountain sculpture. In regard to the 
 Uintas, he says : 
 
 "Glacial erosion has cut almost vertically down through the 
 beds carving immense amphitheatres with basin bottoms con- 
 taining numerous Alpine lakes. . . . Post-glacial erosion has done 
 
146 A CENTUEY OF SCIENCE 
 
 an absolutely trivial work. There is not a particle of direct 
 evidence, so far as I can see, to warrant the belief that these 
 U-shaped canons were given their peculiar form by other means 
 than the actual ploughing erosion of glaciers. ..." 
 
 These contributions from the Cordilleras corroborat- 
 ing the conclusions of Ramsay (1862), Tyndall (1862), 
 Jukes (1862), Hector (1863), Logan (1863), Close (1870), 
 and James Geikie (1875), made little impression. The 
 views of Lyell (1833), Ball (1863), J. W. Dawson (1864), 
 Falconer (1864), Studer (1864), Murchison (1864, 1870), 
 Euskin (1865), Rutimeyer (1869), Whymper (1871), 
 Bonney (1873), Pfaff (1874), Gurlt (1874), Judd (1876), 
 prevailed, and the conclusions of Davis in 1882^^ fairly 
 expressed the prevailing belief in Europe and in 
 America : 
 
 "The amount of glacial erosion in the central districts has 
 been very considerable, but not greatly in excess of pre-glacial 
 soils and old talus and alluvial deposits. Most of the solid rock 
 that was carried away came from ledges rather than from val- 
 leys ; and glaciers had in general a smoothing rather than a 
 roughening effect. In the outer areas on which the ice advanced 
 it only rubbed down the projecting points ; here it acted more 
 frequently as a depositing than as an eroding agent." 
 
 During the past quarter-century the cleavage in tlie 
 ranks of geologists, brought about by Ramsay's classic 
 paper, has remained. Fairchild and others in America, 
 Heim, Bonney, and Garwood in Europe argue for insig- 
 nificant erosion by glaciers ; and Gannet, Davis, Gilbert, 
 Tarr in America followed by Austrian workers present 
 evidence for erosion on a gigantic scale. A perusal of 
 the voluminous literature in the Journal and elsewhere 
 shows that the difference of opinion is in part one of 
 terms, the amount of erosion rather than the fact of 
 erosion ; it also arises from failure to differentiate the 
 work of mountain glaciers and continental ice sheets, of 
 Pleistocene glaciers and their present diminished repre- 
 sentatives. The irrelevant contribution of physicists has 
 also made for confusion. 
 
 It is interesting to note that the criteria for erosion 
 of valleys by glaciers has long been established and 
 by workers in different countries. Ramsay (1862) in 
 
INTERPRETATION OF LAND FORMS 147 
 
 England outlined the problem and presented generalized 
 evidence. Hector (1863) in New Zealand pointed out 
 the significance of discordant drainage, the "hanging 
 valleys" of GUbert. The U-form, the broad lake-dotted 
 floor, and the presence of cirques and the process of 
 plucking were probably first described by LeConte 
 (1873) in America. The truncation of valley spurs by 
 glaciers pointed out by Studer in the Kerguelen Islands 
 (1878) was used by Chamberlin (1883) as evidence of 
 glacial scouring. 
 
 Conclusion. 
 
 During the past century many principles of land 
 sculpture have emerged from the fog of intellectual 
 speculation and unorganized observation and taken their 
 place among generally accepted truths. Many of them 
 are no longer subjects of controversy. Erosion has 
 found its place as a major geologic agent and has given 
 a new conception of natural scenery. Lofty mountains 
 are no longer "ancient as the sun," they are youthful 
 features in process of dissection; valleys and canyons 
 are the work of streams and glaciers ; fiords are erosion 
 forms ; waterfalls and lakes are features in process of 
 elimination ; many plains and plateaus owe their form 
 and position to long-continued denudation. Modern 
 landscapes are no longer viewed as original features or 
 the product of a single agent acting at a particular time, 
 but as ephemeral forms which owe their present appear- 
 ance to their age and the particular forces at work upon 
 them as weU as to their original structure. 
 
 It is interesting to note the halting steps leading to the 
 present viewpoint, to find that decades elapsed between 
 the formulation of a theory or the recording of signifi- 
 cant facts and their final acceptance or rejection, and to 
 realize that the organization of principles and observa- 
 tions into a science of physiography has been the work 
 of the present generation. Progress has been condi- 
 tioned by a number of factors besides the intellectual 
 ability of individual workers. 
 
 The influence of locality is plainly seen. Convincing 
 evidence of river erosion was obtained in central France, 
 the Pacific Islands, and the Colorado Plateau — regions 
 
148 A CENTURY OF SCIENCE 
 
 in which other causes were easily eliminated. Sculpture 
 by glaciers passed beyond the theoretical stage when the 
 simple forms of the Sierras and New Zealand Alps were 
 described. The origin of loess was first discerned in a 
 region where glacial phenomena did not obscure the 
 vision. The complexity of the Glacial period asserted by 
 geologists of the Middle West was denied by eastern 
 students. The work of waves on the English coast 
 impressed British geologists to such an extent that plains 
 of denudation and inland valleys were ascribed to 
 ocean work. 
 
 In the establishment of principles, the friendly inter- 
 change of ideas has yielded large returns. Many of the 
 fundamental conceptions of earth sculpture have come 
 from groups of men so situated as to facilitate criticism. 
 It is impossible, even if desirable, to award individual 
 credit to Venetz, Charpentier, and Agassiz in the formu- 
 lation of the glacial theory ; and the close association of 
 Agassiz and Dana in New England and of Chamberlin 
 and Irving in Wisconsin was undoubtedly helpful in 
 establishing the theory of continental glaciation. From 
 the intimate companionship in field and laboratory of 
 Hutton, Playfair and Hope, arose the profound influence 
 of the Edinburgh school, and the sympathetic cooperation 
 of Powell, Gilbert, and Button has given to the world its 
 classics in the genetic study of land forms. 
 
 The influence of ideas has been closely associated with 
 clarity, conciseness, and attractiveness of presentation. 
 Hutton is known through Playfair, Agassiz 's contribu- 
 tions to glacial geology are known to every student, while 
 Venetz, Charpentier, and Hugi are only names. Cuvier's 
 discourses on dynamical geology were reprinted and 
 translated into English and Gei'man, but Lamarck's 
 "H3"drogeologie" is known only to book collectors. The 
 verbose works of Guettard, although carrying the same 
 message as Playfair 's "Illustrations" and Desmarest's 
 "Memoirs," are practically unknown, as is also Horace 
 H. Hayden's treatise (1821) on the drift of eastern 
 North America. It has been well said that the world- 
 wide influence of American physiographic teaching is due 
 in no small part to the masterly presentations of Gilbert 
 and Davis. 
 
INTERPKETATION OF LAND FORMS 149 
 
 It is surprising to note the delays, the backward steps, 
 and the duplication of effort resulting from lack of 
 familiarity with the work of the pioneers. Sabine says 
 in 1864 :'3 
 
 "It often happens, not unnaturally, that those who are most 
 occupied with the questions of the day in an advancing science 
 retain but an imperfect recollection of the obligations due 
 to those who laid the first foundations of our subsequent 
 knowledge. ' ' 
 
 The product of intellectual effort appears to be con- 
 ditioned by time of planting and character of soil as well 
 as by quantity of seed. For example : Erosion by 
 rivers was as clearly shown by Desmarest as by Dana and 
 Newberry 50 years later. Criteria for the recognition of 
 ancient fiuviatile deposits were established by James 
 Deane in 1847 in a study of the Connecticut Valley 
 Triassic. Agassiz's proof that ice is an essential factor 
 in the formation of till is substantially a duplication of 
 Dobson's observations (1826). 
 
 The volumes of the Journal with their very large num- 
 ber of articles and reviews dealing with geology show 
 that the interpretation of land forms as products of 
 subaerial erosion began in France and French Switzer- 
 land during the later part of the eighteenth century as a 
 phase of the intellectual emancipation following the Rev- 
 olution. Scotland and England assumed the leadership 
 for the first half of the nineteenth century, and the first 
 100 volumes of the Journal show the profound influence 
 of English and French teaching. In America, independ- 
 ent thinking, early exercised by the few, became general 
 with the establishment of the Federal survey, the increase 
 in university departments, geological societies and peri- 
 odicals, and has given to Americans the responsibilities 
 of teachers. 
 
 Bibliography. 
 
 (In the following list "this Journal" refers to the American Journal 
 of Science.) 
 
 ' Wilson, J. W., Bursting of lakes through mountains, this Journal, 3, 
 253, 1821. 
 
 ^ Whitney, J. D., Progress of the Geological Survey of California, this 
 Journal, 38, 263-264, 1864. 
 
 "Playfair, John, Illustrations of the Huttonian theory of the earth, Edin- 
 burgh, 'l802. 
 
150 A CENTURY OF SCIENCE 
 
 'Kain, J. H., Remarks on the mineralogy and geology of northwestern 
 Virginia and eastern Tennessee, this Journal, 1, 60-67, 1819. 
 
 ' Hitchcock, Edward, Geology, etc., of regions contiguous to the Connect- 
 icut, this Journal, 7, 1-30, 1824. 
 
 " Buckland, Wm., Reliquiae diluvianae, this Journal, 8, 150, 317, 1824. 
 
 ' Phillips, John, Geology of Yorkshire, this Journal, 21, 17-20, 1832. 
 
 sgcrope, G. P., Excavation of valleys, Geol. Soc, London, No. 14, 1830. 
 
 • Hayes, G. E., Remarks on geology and topography of western New 
 York, this Journal, 35, 88-91, 1839. 
 
 '" Seventh Meeting of the British Association for the Advancement of 
 Science, this Journal, 33, 288, 1838. 
 
 " Darwin, Charles, Geological observations on the volcanic islands and 
 parts of South America, etc., second part of the Voyage of the "Beagle," 
 during 1832-1836. London, 1844. 
 
 '^ Hildreth, S, P., Observations, etc., vaDey of the Ohio, this Journal, 29, 
 1-148, 1836. 
 
 " Geddes, James, Observations on the geological features of the south 
 side of Ontario vaUey, this Journal, 11, 213-218, 1826. 
 
 " Conrad, T. A., Notes on American geology, this Journal, 35, 237-251, 
 1839. 
 
 '" Warren, G. K., Preliminary report of explorations in Nebraska and 
 Dakota, this Journal, 27, 380, 1859. 
 
 '° Lesley, J. P., Observations on the Appalachian region of southern 
 Virginia, this Journal, 34, review, 413-415, 1862. 
 
 "Hitchcock, Edward, First anniversary address before the Association 
 of American Geologists, this Journal, 41, 232-275, 1841. 
 
 "* Dana, J. D., On denudation in the Pacific, this Journal, 9, 48-62, 1850. 
 
 , On the degradation of the rocks of New South Wales and 
 
 formation of valleys, this Journal, 9, 289-294, 1850. 
 
 " Hubbard, 0. P., On the condition of trap dikes in New Hampshire an 
 evidence and measure of erosion, this Journal, 9, 158-171, 1850. 
 
 " Hayden, F, V., Some remarks in regard to the period of elevation of 
 the Rocky Mountains, this Journal, 33, 305-313, 1862. 
 
 "' Newberry, J. S., Colorado River of the West, this Journal, 33, review, 
 387-403, 1862. 
 
 ^ Jukes, J. B., Address to the Geological Section of the British Associa- 
 tion at Cambridge, Quart, Jour. Geol. Soc, 18, 1862, this Journal, 34, 439, 
 1862. 
 
 "^ Powell, J. W., Exploration of the Colorado River of the West, 1875. 
 For Powell's preliminary article see this Journal, 5, 456-465, 1873. 
 
 " McGee, W. J., Three formations of the Middle Atlantic slope, this 
 Journal, 35, 120, 328, 367, 448, 1888. 
 
 ^ Davis, W. M., Topographic development of the Triassic formation of 
 the Connecticut Valley, this Journal, 37, 423-434, 1889. 
 
 " Percival, J. G., Geology of Connecticut, 1842. 
 
 " Kerr, W. C, Origin of some new points in the topography of North 
 Carolina, this Journal. 21, 216-210, 1881. 
 
 ''McGee, W. J., The classification of geographic forms by genesis, Nat. 
 Geogr, Mag., 1, 27-36, 1888. 
 
 "Davis, W. M., The rivers and valleys of Pennsylvania, Nat. Geogr. 
 Mag,, 1, 183-253, 1889. 
 
 , The rivers of northern New Jersey with notes on the classi- 
 fication of rivers in general, ibid., 2, 81-110, 1890. 
 
 "SUliman, Benjamin, Notice of Horace H. Hayden 's geological essays, 
 this Journal, 3, 49, 1821, 
 
 " Cornelius, Elias, Account of a singular position of a granite rock, this 
 Journal, 2, 200-201, 1820. 
 
INTERPRETATION OF LAND FORMS 151 
 
 " Finch, John, On the Celtic antiquities of America, this Journal, 7, 149- 
 161, 1824. 
 
 " Finch, John, Geological essay on the Tertiary formations in America, 
 this Journal, 7, 31-43, 1824. 
 
 "Conybeare and Phillips, Outlines of the geology of England and Wales, 
 this Journal, 7, 210, 211, 1824. 
 
 " Hayden, Horace H., Geological essays, 1-412, 1821, this Journal, 3, 
 47-57, 1821. 
 
 "Jackson, C. T., Reports on the geology of the State of Maine, and on 
 the public lands belonging to Maine and Massachusetts, this Journal, 36, 
 153, 1839. 
 
 "Gibson, J. B., Remarks on the geology of the lakes and the valley of 
 the Mississippi, this Journal, 29, 201-213, 1836. 
 
 =* Phillips, John, Geology of Yorkshire, this Journal, 21, 14-15, 1832 
 
 " Granger, Ebenezer, Notice of a curious fluted rock at Sandusky Bay, 
 Ohio, this Journal, 6, 180, 1823. 
 
 "Dobson, Peter, Remarks on bowlders, this Journal, 10, 217-218, 1826. 
 
 " Murchison, R. I., Address at anniversary meeting of the Geological 
 Society of London, this Journal, 43, 200-201, 1842, 
 
 " Buckland, W., On the evidence of glaciers in Scotland and the north 
 of England, Proc. London Geol. Soc, 3, 1841. 
 
 " Third annual meeting of the Association of American Geologists and 
 Naturalists, this Journal, 43, 154, 1842; Abstract of proceedings of the 
 fourth session of the Association of American Geologists and Naturalists, 
 ibid., 45, 321, 1843. 
 
 ** Rogers, H. D., Address delivered before Association of American Geol- 
 ogists and Naturalists, this Journal, 47, 275, 1844. 
 
 " Agassiz, Louis, The erratic phenomena about Lake Superior, this 
 Journal, 10, 83-101, 1850. 
 
 *■ Desor, E., On the drift of Lake Superior, this Journal, 13, 93-109, 
 1852; Post-Pliocene of the southern States, etc., 14, 49-59, 1852. 
 
 " Dana, J. D., Manual of geology, 546, Philadelphia, 1863. 
 
 "Dana, J. D., on the Quaternary, or post-Tertiary of the New Haven 
 region, this Journal, 1, 1-5, 1871. 
 
 " Matthew, G. F., Surface geology of New Brunswick, this Journal, 2, 
 371-372, 1871. 
 
 °° Maclaren, Charles, The glacial theory of Prof. Agassiz, this Journal, 
 42, 365, 1842. 
 
 " Daly, R. A., Problems of the Pacific Islands, this Journal, 41, 153-186, 
 1916. 
 
 '^ Catlin, George, Account of a journey to the Coteau des Prairies, this 
 Journal, 38, 138-146, 1840. 
 
 "^ Hilgard, E. W., Remarks on the drift of the western and southern States 
 and its relation to the glacier and ice-berg theories, this Journal, 42, 343- 
 347, 1866. 
 
 " Han, C. E., Glacial phenomena along the Kittatinny or Blue Mountain, 
 Pennsylvania, this Journal, 11, review, 233, 1876. 
 
 " Stevens, R. P., On glaciers of the glacial era in Virginia, this Journal, 
 6, 371-373, 1873. 
 
 ^ Rogers, W. B., On the gravel and cobble-stone deposits of Virginia and 
 the Middle States, Proc. Boston Soc. Nat. Hist., 18, 1875; this Journal, 
 11, 60-61, 1876. 
 
 " Kerr, W. C, Origin of some new points in the topography of North 
 Carolina, this Journal, 21, 216-219, 1881. 
 
 "* Gilbert, G. K., On certain glacial and post-glacial phenomena of the 
 Maumee valley, this Journal, 1, 339-345, 1871. 
 
 ™Chamberlin, T. C, On the geology of eastern Wisconsin, Geol, of 
 Wisconsin, 2, 1877; this Journal, 15, 61, 406, 1878, 
 
152 A CENTURY OF SCIENCE 
 
 " Chamberlin, T. C, Preliminary paper on the terminal moraine of the 
 second glacial epoch, U. S. Geol. Survey, Third Ann. Kept., 291-402, 1883. 
 
 '" Wright, G. F., Unity of the glacial epoch, this Journal, ii, 351-373, 
 1892. 
 
 Upham, Warren, The diversity of the glacial drift along its boundary, 
 ibid., 47, 358-365, 1894. 
 
 Wright, G. F., Theory of an interglacial submergence in England, ibid., 
 43, 1-8, 1892. 
 
 Chamberlin, T. G., Diversity of the glacial period, ibid., 45, 171-200, 
 1893. 
 
 Dana, J. D., On New England and the upper Mississippi basin in the 
 glacial period, ibid., 46, 327-330, 1893. 
 
 Wright, G. F., Continuity of the glacial period, ibid., 47, 161-187, 1894. 
 
 Chamberlin, T. C. and Leverett, F., Further studies of the drainage 
 features of the upper Ohio basin, ibid., 47, 247-282, 1894. 
 
 "■' Pumpelly, Eaphael, Geological researches in China, Japan, and Mom 
 golia, Smithsonian Contributions, No. 202, 1866. 
 
 '"Kingsmill, T. W., The probable origin of "loess" in North China 
 and eastern Asia, Quart. Jour. Geol. Soc, 27, No. 108, 1871. 
 
 " Pumpelly, Raphael, The relation of secular rock-disintegration to loess, 
 glacial drift and rock basins, this Journal, 17, 135, 1879. 
 
 °° Binney, A., Some geologic features at Natchez on the Mississippi Eiver, 
 Proc. Boston Soc. Nat. Hist., 2, 126-130, 1848. 
 
 "" Hilgard, E. W., The loess of Mississippi Valley, and the eolian hypoth- 
 esis, this Journal, 18, 106-112, 1879. 
 
 "' Chamberlin, T. C, Supplementary hypothesis respecting the origin of 
 the loess of the Mississippi Valley, Jour. Geol., 5, 795-802, 1897. 
 
 '■' Ramsay, A. C, On the glacial origin of certain lakes in Switzerland, 
 the Black Forest, Great Britain, Sweden, North America, and elsewhere, 
 Quart. Jour. Geol. Soc, 1862; this Journal, 35, 324-345, 1863. Preliminary 
 statements of this theory appeared in 1859 and 1860. 
 
 '■' Whittlesey, Charles, Smithsonian Contributions, No. 197, 1864. 
 
 '"LeConte, Joseph, On some of the ancient glaciers of the Sierras, this 
 Journal, 5, 325-342, 1873, 10, 126-139, 1875. 
 
 ■' King, Clarence, V. S. Geol. Expl. 40th Par., 1, 459-529, 1878. 
 
 '- Davis, W. M., Glacial erosion, Proc. Boston Soc. Nat. Hist., 22, 58, 
 18S2. 
 
 '' Sabine, Sir Edward, Address of the president of the Eoyal Society, 
 this Journal, 37, 108, 1864. 
 
IV 
 
 A CENTURY OF GEOLOGY THE GROWTH OF 
 
 KNOWLEDGE OF EARTH STRUCTURE 
 
 By JOSEPH BARRELL 
 
 Introduction 
 The Intellectual Fiewpoint in 181S. 
 
 IN 1818, the year of the founding of the Journal, the 
 natural sciences were still in their infancy in Europe. 
 Geology was still subordinate to mineralogy, was 
 hardly recognized as a distinct science, and consisted in 
 little more than a description of the character and distri- 
 bution of minerals and rocks. America was remote from 
 the Old World centers of learning. The energy of the 
 young nation was absorbed in its own expansion, and but 
 a few of those who by aptitude were fitted to increase 
 scientific knowledge were even conscious of the existence 
 of such a field of endeavor. Under these circumstances 
 the educative field open to a journal of science in the 
 United States was an almost virgin soil. Original con- 
 tributions could most readily be based upon the natural 
 history of the New World, and the founder of the Journal 
 showed insight appreciative of the situation in stating in 
 the "Plan of the Work" in the introduction to the first 
 volume that "It will be a leading o])ject to illustrate 
 Ameeican" Natural Histoky, and especially our Min"- 
 ERALOGY and Geology. 
 
 At this time educated people were still satisfied that 
 the whole knowledge of the origin and development of 
 the earth so far as man could or should know it was 
 embraced in the Book of Genesis. They were inclined to 
 look with misgiving at attempts to directly interrogate the 
 earth as to its history. Philosophers such as Descartes 
 
154 A CENTURY OF SCIENCE 
 
 and Liebnitz, the cosmogonists de Mailiet_ and Buffon 
 had been less instrumental in developing science than m 
 fitting a few facts and many speculations to their systems 
 of philosophy. By the opening of the nineteenth cen- 
 tury, however, men of learning were coming to appre- 
 ciate that the way to advance science was to experiment 
 and observe, to collect facts and discourage unfounded 
 speculation. Silliman's insight into the needs of geologic 
 science is shown in the following quotation (1, pp. 6, 
 7, 1818) : 
 
 ' ' Our geology, also, presents a most interesting field of inquiry. 
 A grand outline has recently been drawn by Mr. Maclure, with 
 a masterly hand, and with a vast extent of personal observation 
 and labour : but to fill up the detail, both observation and labour 
 still more extensive are demanded ; nor can the object be 
 effected, till more good geologists are formed, and distributed 
 over our extensive territory. 
 
 To account for the formation and changes of our globe, by 
 excursions of the imagination, often splendid and imposing, but 
 usually visionary, and almost always baseless, was, till within 
 half a century, the business of geological speculations ; but this 
 research has now assumed a more sober character ; the science 
 of geology has been reared upon numerous and accurate obser- 
 vations of facts; and standing thus upon the basis of induc- 
 tion, it is entitled to a rank among those sciences which Lord 
 Bacon's Philosophy has contributed to create. Geological 
 researches are now prosecuted by actually exploring the struc- 
 ture and arrangement of districts, countries, and continents. 
 The obliquity of the strata of most rocks, causing their edges 
 to project in many places above the surface; their exposure, in 
 other instances on the sides or tops of hills and mountains; 
 or, in consequence of the intersection of their strata, by roads, 
 canals, and river-courses, or by the wearing of the ocean ; or 
 their direct perforation, by the shafts of mines ; all these causes, 
 and others, afford extensive means of reading the interior 
 structure of the globe. 
 
 The outlines of American geology appear to be particularly 
 grand, simple, and instructive ; and a knowledge of the import- 
 ant facts, and general principles of this science, is of vast prac- 
 tical use, as regards the interests of agriculture, and the research 
 for useful minerals. Geological and mineralogical descriptions, 
 and maps of particular states and districts, are very much 
 needed in the United States ; and to excite a spirit to furnish 
 them will form one leading object of this Journal." 
 
KNOWLEDGE OF EARTH STRUCTURE 155 
 
 The Prolonged Influence of Oufgroivn Ideas. 
 
 Those interested in any branch of science should, as a 
 matter of education, read the history of that special sub- 
 ject. A knowledge of the stages by which the present 
 development has been attained is essential to give a 
 proper perspective to the literature of each period. 
 Much of the existing terminology is an inheritance from 
 the first attempts at nomenclature, or may rest upon 
 theories long discarded. Popular notions at variance 
 with advanced teaching are often the forgotten inherit- 
 ance of a past generation. 
 
 Gneiss, trap, and Old Red Sandstone are names which 
 we owe to Werner. The "Tertiary period" and "drift" 
 are relics of an early terminology. The geology of 
 tourist circulars still speaks of canyons as made by "con- 
 vulsions of nature." Popular writers still attribute to 
 geologists a belief in a molten earth covered by a thin 
 crust. Within the present century the eighteenth cen- 
 tury speculations of Werner and his predecessors, postu- 
 lating a supposed capacity of water to seep through the 
 crust into the interior of the earth, resulting in a hypo- 
 thetical progressive desiccation of the surface, views long 
 abandoned by most modern geologists, have been revived 
 by an astronomer into a theory of "planetology." 
 
 A review of the literature of a century brings to light 
 certain tendencies in the growth of science. Each decade 
 has witnessed a larger accumulation of observed facts 
 and a fuller classification of these fundamental data, but 
 the pendulum of interpretative theory swings away from 
 the path of progress, now to one side, now to the other, 
 testing out the proper direction. For decades the under- 
 standing of certain classes of facts may be actually retro- 
 gressive. A retrospect shows that certain minds, keen 
 and unfettered by a prevailing theory, have in some 
 directions been in advance of their generation. But the 
 judgment of the times had not sufficient basis in knowl- 
 edge for the separation and acceptance of their truer 
 views from the contemporaneous tangle of false inter- 
 pretations. 
 
 An interesting illustration of these statements regard- 
 
156 A CENTURY OF SCIENCE 
 
 ing the slow settling of opinion may be cited in regard to 
 the significance of the dip of the Triassic formations of 
 the eastern United States. The strata of the Massachu- 
 setts-Connecticut basin possess a monoclinal easterly dip 
 which averages about 20 degrees to the east. Those of 
 the New Jersey-Pennsylvania-Virginia basin possess a 
 similar dip to the northwest. Both basins are cut by 
 great faults and the dip is now accepted by practically 
 all geologists as due to rotation of the crust blocks 
 away from a geanticlinal axis between the two basins. 
 Edward Hitchcock, whose work from the first shows an 
 interpretative quality in advance of his time, states in 
 182.3 (6, 7-1) regarding the dip of the Connecticut valley 
 rocks : 
 
 "There is reason to believe that Mount Toby, the strata of 
 which are almost horizontal, exhibits the original dip of these 
 rocks, and that those cases in which they are more highly inclined 
 are the result of some Plutonian con^ailsion. Such irregularity 
 in the dip of coal fields is no uncommon occurrence." 
 
 In Hitchcock's Geology of Massachusetts, published in 
 1S33, ten years later, geological structure sections of the 
 Connecticut Valley rocks are given, the facts are dis- 
 cussed in detail and the dip ascribed to the elevatory 
 foi'ces. He says (1. c, pp. 213, 223) : 
 
 "If it were possible to doubt that the new red sandstone 
 formation was deposited from water, the surface of some of the 
 layers of this shale would settle the question demonstrably. 
 For it exhibits precisely those gentle undulations, which the 
 loamy bottom of every river with a moderate current, presents. 
 (No. 198.) But such a surface could never have been formed 
 Avhile the layers had that high inclination to the horizon, which 
 many of them now present : so that we have here, also, decisive 
 evidence that they have been elevated subsecpiently to their 
 deposition. . . . 
 
 The objection of a writer in the American Journal of Science, 
 that such a height of waters as would deposit Mount Toby, must 
 have produced a lake nearly to the upper part of New Hamp- 
 shire, in the Connecticut Valley, and thus have caused the same 
 sandstone to be produced higher up that valley than Northfield, 
 loses its force, when it is recollected that this formation was 
 deposited before its strata were elevated. For the elevating 
 force undoubtedly changed the relative level of different parts 
 
Courtesy of Popular Srii-n<-c M'oiiihln. 
 
KNOWLEDGE OF EARTH STRUCTURE 157 
 
 of the country. In this case, the disturbing force must have 
 acted beneath the primary rocks. And besides, we have good 
 evidence which will be shown by and b}^, that our new red 
 sandstone was formed beneath the ocean. We cannot then 
 reason on this subject from present levels." 
 
 In 1840, H. D. Rogers, a geologist who has acquired a 
 more widely known name than Hitchcock, but who in 
 reality showed an inferior ability in interpretation, made 
 the following statements in explanation of the regional 
 monoclinal dip of the New Jersey Triassic rocks averag- 
 ing 15 to 20 degrees to the northwest :' 
 
 "Their materials give evidence of having been swept into this 
 estuary, or great ancient river, from the south and southeast, 
 by a current producing an almo.st universal dip of the beds 
 towards the northwest, a feature clearly not caused by any 
 uplifting agency, but assumed originally at the time of their 
 deposition, in consequence of the setting of the current from the 
 opposite or southeastern shore." 
 
 In 1842, at the third annual meeting of the Association 
 of American Geologists both H. D. and W. B. Rogers 
 argued (43, 170, 1842) against Sir Charles Lyell and E. 
 Hitchcock that the present dip of the Triassic was the 
 original slope of deposition, stating among other reasons 
 that the footprints impressed upon the sediments often 
 showed a slipping and a pushing of the soft clay in the 
 direction of the downhill slope. In 1858 H. D. Rogers 
 still held to the same views of original dip,^ notwithstand- 
 ing that a moderate amount of observation on the mud- 
 cracked and rain-pitted layers would have supplied the 
 proof that such must have dried as horizontal surfaces. 
 The idea of inclined deposition is not yet wholly dead as 
 it has been suggested more than once within the present 
 generation as a means of escaping from the necessity of 
 accepting the very great thicknesses of this and similar 
 formations. Thus, as Brogger has remarked in another 
 connection, — the ghosts of the old time stand ever ready 
 to reappear. 
 
 In the present essay on the rise of structural geology 
 as reflected through a century of publication in the 
 Journal, attention will be given especially to two fields, 
 that of structures connected with igneous rocks and that 
 
 10 
 
158 A CENTURY OF SCIENCE 
 
 of structures connected with mountain making, and 
 emphasis will be placed upon the growth of understand- 
 ing rather than upon the accumulating knowledge of 
 details. The growth in both of these divisions of struc- 
 tural geology is well illustrated in the volumes of the 
 Journal. 
 
 Structures and Relationships of Igtieous Rocks. 
 Opposed Interpretations of Plutonists and Nejytunists. 
 
 During the first quarter of the nineteenth century the 
 geologic controversy between the Plutonists and Nep- 
 tunists was at its height; the Plutonists, following the 
 Scotchman, Hutton, holding to the igneous origin of 
 basalt and granite, the Neptunists, after their German 
 master, Werner of Freiberg, maintaining that these 
 rocks had been precipitated from a primitive universal 
 ocean. The Plutonists, although time has shown them to 
 have been correct in all essential particulars, were for a 
 generation submerged under the propaganda carried for- 
 ward by the disciples of Werner. The "Illustrations of 
 the Huttonian Theory of the Earth," a remarkable clas- 
 sic, worthy of being studied to-day as well as a century 
 ago, was published in 1802 by John Playfair, professor of 
 mathematics in the University of Edinburgh and a friend 
 of Hutton, who had died five years previously. This 
 volume was opposed by Robert Jameson, professor of nat- 
 ural philosophy in the same university, who had absorbed 
 the ideas of the German school while at Freiberg 
 and published in 1808 a volume on the "Elements of 
 Geognosy," in which the philosophy of Werner is fol- 
 lowed throughout and even obsidian and pumice are 
 argued to be aqueous precipitates. The authority of the 
 Wernerian autocracy caused its nomenclature to be 
 adopted in the new world, but strong evidence against 
 its interpretations was to be found in the actual struc- 
 tural relations displayed by the igneous rocks. 
 
 Contributions on Volcanic and Intrusive Rocks. 
 
 The accumulation and study of facts constituted the 
 best cure for an erroneous theory. The publications of 
 the Journal contributed toward this end by articles along 
 
KNOWLEDGE OF EARTH STRUCTURE 159 
 
 several lines. The most original contributions were those 
 which dealt with the areal and structural geology of 
 eastern North America, but equally valuable at that 
 time for the broadening of scientific interest were 
 the studies on the volcanic activities of the Hawaiian 
 Islands, published through many years. Perhaps most 
 valuable from the educative standpoint were the exten- 
 sive republications in the Journal of the more important 
 European researches, making them accessible to Ameri- 
 can readers. In volume 13 (1828), for example, a digest 
 of Scrope's work on volcanoes is given, covering forty 
 pages ; and of Daubeny on active and extinct volcanoes, 
 running over seventy-five pages and extending into vol. 
 14. Through these comprehensive studies the nature of 
 volcanic action became generally understood during the 
 first half of the nineteenth century and the original pub- 
 lications in the Journal were valuable in giving a knowl- 
 edge of the activities of the Hawaiian volcanoes. 
 
 Early in the nineteenth century the whole of America 
 still remained to be explored lay the geologist. The 
 regions adjacent to the centers of learning were among 
 the first to receive attention and the Triassic basin of 
 Connecticut and Massachusetts yielded information in 
 regard to the nature of igneous intrusion. This basin, 
 of unmetamorphic shales and sandstones, is occupied by 
 the Connecticut River except at its southern end. The 
 Formation contains within it sills, dikes, and outflows of 
 basaltic rocks which because of their superior resistance 
 to erosion constitute prominent hills, in places bounded 
 by cliffs. 
 
 Silliman in 1806^ described East Rock, New Haven, 
 Connecticut, as a whinstone, trap, or basalt, and 
 accounted for its presence on the supposition that it had 
 
 "actually been melted in the bowels of the earth and ejected 
 among the superior strata by the force of subterraneous fire, 
 but never erupted like lava, cooling under the pressure of the 
 superincumbent strata and therefore compact or nonvesicular, 
 its present form being due to erosion." 
 
 In these conclusions Silliman was correct. With but a 
 limited amount of experience he was able to discriminate 
 between the intrusive and effusive rocks and saw that the 
 
160 A CENTURY OF SCIENCE 
 
 prominence of this hill was due to the erosion of the sedi- 
 ments which once surrounded it. 
 
 An extensive paper on the geology of this region was 
 published by Edward Hitchcock in 1823/ then just thirty 
 years of age. This paper shows the evidence of exten- 
 sive field observations, and his comments in regard to 
 the trap and granite are of interest. Hitchcock gives 
 five pages to tlie subject of "Greenstone Dykes in Old 
 Eed Sandstone" (6, 56-60. 1823) and makes the follow- 
 ing statements : 
 
 "Professor SiUiman conducted me to an interesting locality 
 of these in East-Haven. They occur on the main road from 
 New-Haven to East-Haven, less than half a mile from Tomlin- 
 son's bridge . . . (p. 56). 
 
 They are an interesting feature in our geology, and deserve 
 more attention ; and it is peculiarly fortunate that they should 
 be situated so near a geological school and the first mineral 
 cabinet in our country . . . (p. 58). 
 
 Origin of Greenstone. 
 
 Does the greenstone of the Connecticut afford evidence in 
 favour of the Wernerian or of the Huttonian theory of its 
 origin? Averse as 1 feel to taking a side m this controversy, I 
 cannot but say, that the man who maintains, in its length and 
 breadth, the original hypothesis of Werner in regard to the 
 aqueous deposition of trap, will find it for his interest, if he 
 wishes to keep clear of doubts, not to follow the example of 
 D'Aubuisson, by going forth to examine the greenstone of this 
 region, lest, like that geologist, he should be compelled, not only 
 to abandon his theory, but to write a book against it. Indeed, 
 when surveying particular portions of this rock, I have some- 
 times thought Bakewell did not much exaggerate when he said 
 in regard to Werner's hypothesis, that, 'it is hardly possible 
 for the human mmd to invent a sj'stem more repugnant to 
 existing facts.' 
 
 Ou the other hand, the Huttonian would doubtless have his 
 heart gladdened, and his faith strengthened by a survey of the 
 greater part of this rock. As he looked at the dikes of the old 
 red sandstone, he would almost see the melted rock forcing its 
 way through the fissures ; and when he came to the amj'gdaloi- 
 dal, especially to that variety which resembles lava, he might 
 even be tempted to apply his thermometer to it, in the suspicion 
 that it was not yet cpiite cool . . . (p. 59). 
 
 By treating the subject in this manner I mean no disrespect 
 to any of the distinguished men who have adopted either side of 
 
KNOWLEDGE OF EARTH STRUCTURE IGl 
 
 this question. To President Cooper especially, who regards the 
 greenstone of the Connecticut as volcanic, I feel much indebted 
 for the great mass of facts he has collected on the subject. And 
 were I to adopt any hypothesis in regard to the origin of our 
 greenstone, it would be one not much different from his" (p. 60). 
 
 By 1833 and more clearly in 1841 Hitchcock had come 
 to recognize the distinction between intrusive and extru- 
 sive basaltic sheets in the Connecticut valley. Dawson 
 also came to regard the Acadian sheets as extrusive, and 
 Emerson in 1882 recalled again the evidence for Massa- 
 chusetts (24, 195, 1882). Davis, however, went a step 
 further and by applying distinctive criteria not only sep- 
 arated intrusive and extrusive sheets throughout the 
 whole Triassic area, but by using basalt flows as strati- 
 graphic horizons unraveled for the first time the system 
 of faults which cut the Triassic system. His preliminary 
 paper (24, 345, 1882) was followed by many others. 
 
 From 1880 onward begins the period of precise struc- 
 tural field work. The older geologists mostly conceived 
 their work after reconnaissance methods. From 1870 to 
 1880 a group of younger men entered geology who paid 
 close attention to the solid geometry and mechanics of 
 earth structures. In their hands ph}'sical and dynamical 
 geology began to assume the standing of a precise and 
 quantitative science. In the field of intrusive rocks the 
 opening classic was by Gilbert, who in his volume on the 
 geology of the Henry Mountains, published in 1880, made 
 laccoliths known to the world. With the beginning of 
 this new period we may well leave the subject of intru- 
 sive rocks and turn to the progress of knowledge in 
 regard to those deeper and vaster bodies now known as 
 batholiths. These, since erosion does not expose their 
 bottoms, Daly separates from intrusives and classifies as 
 subjacent. The batholiths consist typically of granite 
 and granodiorite, and introduce us to the problem of 
 granite. 
 
 Vieivs on the Structural Relations of Granite. 
 
 Conscientious field observations were sufficient to 
 establish the true nature of the intrusive and extrusive 
 rocks. The case was very different, however, with the 
 
1G2 A CENTURY OF SCIENCE 
 
 nature and relations of the great bodies of granite, 
 which may be taken in the structural sense as including 
 all the visibly crystalline acidic and intermediate rocks, 
 known more specifically as granite, syenite, and diorite. 
 
 The large bodies of granite, structurally classified as 
 stocks, or batholiths, commonly show wedges, tongues, or 
 dike networks cutting into the surrounding rocks. The 
 relations, however, are not all so simple as this. Gran- 
 ites may cover vast areas, they are usually the older 
 rocks, they are generally associated with regional 
 metamorphism of the intruded formations, which meta- 
 morphism is now understood to be due chiefly to the heat 
 and mineralizers given off from the granite magma, asso- 
 ciated with mashing and shearing of the surrounding 
 rocks. The granite was often injected in successive 
 stages which alternated with the stages of regional mash- 
 ing. A parallel or gneissic structure is thus developed 
 which is in part due to mashing, in part to igneous injec- 
 tion. "V\71iere the ascent of heat into the cover is exces- 
 sive, or where blocks are detached and involved in the 
 magma, the latter may dissolve some of the older cover 
 rocks, even where these were of sedimentary origin. 
 
 Thus between mashing, injection, and assimilation the 
 genetic relationships of a batholith to its surroundings 
 are in many instances obscure. Nevertheless, attention 
 to the larger relations shows that the molten magma orig- 
 inated at great depths in the earth's crust, far below the 
 bottoms of geosynclines, and consists of primary igneous 
 material, not of fused sediments. From those depths it 
 has ascended by various processes into the outer crust, 
 where it crystallized into granite masses, to be later 
 exposed by erosion. The amount of material which can 
 be dissolved and assimilated must be small in compari- 
 son with the whole body of the magma. The original 
 composition of the magma was probably basic, nearer 
 that of a basalt than that of a granite. 'Differentiation 
 of the molten mass is thought to cause the upper and 
 lower parts of the chamber to become unlike, the lighter 
 and more acidic portion giving rise to the great bodies of 
 granite. With the exception of certain border zones the 
 whole, however, is regarded as igneous rock risen from 
 the depths. 
 
KNOWLEDGE OF EARTH STRUCTURE 163 
 
 The complex border relations, but more particularly 
 certain academic hypotheses, led to a period of misunder- 
 standing and retrogression in regard to the nature of 
 granites. It constitutes an interesting illustration of 
 the possibility of a wrong theory leading interpretation 
 astray, chiefly through the magnification of minor into 
 major factors. This history illustrates the dangers of 
 qualitative science as compared to quantitative, of a 
 single hypothesis as matched against the method of mul- 
 tiple working hypothesis. This flux of opinion in regard 
 to the nature of granites may be traced through the vol- 
 umes of the Journal. 
 
 E. Hitchcock in 1824 (6, 12) noted that in places gran- 
 ite appeared bedded, but in other places existed in veins 
 which cut obliquely across the strata. Silliman, although 
 careful not to deny the aqueous origin of some basalts, 
 yet held that the field evidence of New England indicates 
 for that region the igneous or Huttonian origin of trap 
 and granite (7, 238, 1824). 
 
 In 1832 the following article by Hitchcock appeared in 
 the Journal (22, 1, 70) : 
 
 Report on the Geology of Massachusetts ; examined under the 
 direction of the Government of that State, during the years 
 1830 and 1831 ; by Edward Hitchcock, Prof, of Chemistry and 
 Natural History in Amherst College. 
 
 A footnote adds that this is "published in this Journal by 
 consent of the Government of Massachusetts, and intended to 
 appear also in a separate form, and to be distributed among the 
 members of the Legislature of the same State, about the time 
 of its appearance in this work. It is, we believe, the first exam- 
 ple in this country, of the geological survey of an entire State." 
 
 This article includes a geological map of the state and 
 covers the subject of economic geology. The report 
 brought forth the following remarks from a French 
 reviewer in the Bevue Encyclopedique , Aug. 1832, quoted 
 in the Journal (23, 389, 1833) : 
 
 "A single glance at this report, is sufficient to convince any 
 one of the utility of such a work, to the state which has under- 
 taken it; and to regret that there is so very small a part of the 
 French territory, whose geological constitution is as well known 
 to the public, as is now the state of Massachusetts. Prance has 
 the greater cause to regret her being distanced in this race by 
 
164 A CENTUEY OF SCIENCE 
 
 America, from her having a corps of mining engineers, who 
 if they had the means, would, in a vei'y short time furnish a 
 work of the same kind, still more complete, of each of the 
 departments. ' ' 
 
 The complete report published in 1833 is a work of 700 
 pages. Pages 465 to 517 are devoted to the subject_ of 
 granite. Numerous detailed sketches are given showing 
 contact relations. Nine pages are given to theoretical 
 considerations and many lines of proof are given that 
 granite is an igneous rock, molten from the internal heat 
 of the earth, and intruded into the sedimentary strata. 
 His statement is the clearest published in the world, so 
 far as the writer is aware, np to that date, and marks 
 Edward Hitchcock as one of the leading geologists of his 
 generation in Europe as well as America._ Unfortu- 
 nately his views were largely lost to sight during the fol- 
 lowing generation. 
 
 In 1840 the first American edition of Mantell's Won- 
 ders of Geology gave currency to the idea that granite is 
 proved to be of all geological ages up to the Tertiary 
 (39, 6, 1840). In 1843 J. D. Dana pointed out (45, 104) 
 that schistosity was no evidence of sedimentary origin. 
 He regarded most granites as igneous as shown by their 
 structural relations, but considers that some may have 
 had a sedimentary origin. 
 
 Jtise and Decline of the 3Ietaniorphic Theory of Granite. 
 
 Up to 1860 granite was regarded on the basis 
 of the facts of the field as essentially an intrusive 
 rock, but gneiss as a metamorphic product mostly of sedi- 
 mentary origin. It seemed as though sound methods of 
 research and interpretation were securely established. 
 Nevertheless, a new era of speculation and a modified 
 Wernerism arose at that time with a paper by T. Sterry 
 Hunt, marking a retrogression in the theory of granite 
 which lasted until his death in 1892. 
 
 In November, 1859, Hunt read before the Geological 
 Society of London a paper on "Some Points in Chemical 
 Geology" in which he announced that igneous rocks are 
 in all cases simply fused and displaced sediments, the 
 fusion taking place by the rise of the earth's internal 
 
KNOWLEDGE OF EARTH STRUCTUEE 165 
 
 heat into deeply buried and water-soaked masses of sedi- 
 ments (see 30, 133, 1860). The germ of this idea of 
 aqueo-igneous fusion was far older, due to Babbage and 
 John Herschel, neither of them geologists, but such 
 sweeping extensions of it had never before been pub- 
 lished. Hunt had the advantage of a wide acquaintance- 
 ship with geological literature and chemistry. He wrote 
 plausibly on chemical and theoretical geology, but his 
 views were not controlled by careful field observations. 
 In fact he wrote confidently on regions which apparently 
 he had never seen and where a limited amount of field 
 work would have shown him to have been fundamentally 
 in error. A man of egotistical temperament, he sought 
 to establish priority for himself in many subjects and in 
 order to cover the field made many poorly founded asser- 
 tions. Building on to another Wernerian idea, he held 
 that many metamorphic minerals had a chronologic value 
 comparable to fossils — staurolite for example indicating 
 a pre-Silurian age — and on this basis divided the crystal- 
 line rocks into five series. Although there is much of 
 value buried in Hunt's work it is difficult to disentangle 
 it, with the result that his writings were a disservice to 
 the science of geology. Although carrying much weight 
 in his lifetime, they have passed with his death nearly 
 into oblivion. 
 
 Marcou, with a limited knowledge of American geol- 
 ogy, and but little respect for the opinions of others, had 
 published a geologic map of the United States containing 
 gross errors. In support of his views he read in Novem- 
 ber, 1861, a paper on the Taconic and Lower Silurian 
 Rocks of Vermont and Canada. In the following year 
 he was severelv reviewed bv "T," who states positively 
 in controverting Marcou (33, 282, 283, 1862) that "the 
 granites (of the Green Mountains) are evidently strata 
 altered in place." 
 
 "Mr. Marcou should further be informed that the granites 
 of the Alpine summits, instead of being, as was once supposed, 
 eruptive rocks, are now knowTi to be altered strata of newer 
 Secondary and Tertiary age. A simple structure holds good in 
 the British Islands, where as Sir Roderick Murchison has shown 
 in his recent Geological map of Scotland, Ben Nevis and Ben 
 Lawers are found to be composed of higher strata, lying in 
 
166 A CENTURY OF SCIENCE 
 
 synclinals. This great law of mountain structure would alone 
 lead us to suppose that the gneiss of the Green mountains, 
 instead of being at the base, is really at the summit of the series. 
 
 We cannot here stop to discuss Mr. Marcou's remark about 
 'the unstratified and oldest crystalline rocks of the White 
 mountains' which he places beneath the lower Taconic series. 
 Mr. Lesley has shown that these granites are stratified, and with 
 Mr. Hunt, regards them as of Devonian Age. (This Journal, 
 vol. 31, p. 403.) Mr. Marcou has come among us with notions 
 of mountains upheaved by intrusive granites, and similar anti- 
 quated traditions, now, happily for science, well nigh forgotten." 
 
 It is seen that Marcou, notwithstanding the general 
 character of his work, happened to be nearer right in 
 some matters than were his critics, and that "T" had 
 adopted to the limit the views of Hunt. 
 
 The recovery of geology from this period of confusion 
 was partly owing to the slow accumulation of opposed 
 facts ; especially to a recognition of the fact that the 
 overplaced relation of the granite gneisses in western 
 Scotland was due to great overthrusts ; also to the evi- 
 dence of the clearly intrusive nature of many of the 
 Cordilleran granites. The recovery of a sounder theory 
 was hastened, however, by the application of criticisms 
 by J. D. Dana in the Journal. In 1866 (42, 252) Dana 
 pointed out that sedimentary rocks in Pennsylvania, in 
 Nova Scotia, and other regions which had been buried to 
 a depth of at least 16,000 feet are not metamorphic. 
 Mere depth of burial of sediments was not sufficient 
 therefore to produce metamorphism and aqueo-igneous 
 fusion. The baseless and speculative character of the 
 use of minerals as an index of age and of Hunt's inter- 
 pretation of New England geology in general was shown 
 by_ Dana in 1872 (3, 91). The following year Dana 
 pointed out clearly that igneous eruptions in general 
 have been derived from a deep-seated source and did not 
 come from the aqueo-igneous fusion of sediments. As to 
 gradations between true igneous rocks and fused and 
 displaced sediments he makes the following statements 
 (6, 114, 1873) : 
 
 "Again, the plastic rock-material that may be derived from 
 the fusion or semifusion of the supercrust, (that is, of rocks 
 
KNOWLEDGE OF EARTH STRUCTURE 167 
 
 originally of sedimentary origin,) gives rise to "igneous" rocks 
 often not distinguishable from other igneous rocks, when it is 
 ejected through fissures far from its place of origin; while crys- 
 talline rocks are simply metamorphic if they remain in their 
 original relations to the associated rocks, or nearly so. 
 
 Between these latter igneous rocks and the metamorphic there 
 may be indefinite gradations, as claimed by Hunt. But if our 
 reasonings are right, the great part of igneous rocks can be 
 proved to have had no such supercrust origin. The argument 
 from the presence of moisture or of hydrous minerals in such 
 rocks in favor of their origin from the fusion of sediments has 
 been shown to be invalid." 
 
 The injected marginal rocks and tlie post-intrusive 
 metamorphism of most of the New England granites has, 
 however, obscured more or less their real igneous nature 
 so that the gradation from metamorphic sediments 
 through igneous gneisses to granites could be read in 
 either direction. These features misled Dana who 
 accepted the prevailing idea of the general metamorphic 
 origin of granite. Dana makes the following statement 
 (6,'^164, 1873) : 
 
 "But Hunt is right in holding that in general granite and 
 syenite (the quartz-bearing syenite) are undoubtedly meta- 
 morphic rocks where not vein-formations, as I know from the 
 study of many examples of them in New England ; and the 
 veins are results of infiltration through heated moisture from 
 the rocks adjoining some part of the opened fissures they fill." 
 
 Granite, although regarded at this time as the extreme 
 of the metamorphic series and originating from sedi- 
 ments, was looked upon as typically Archean in age, 
 though in some cases younger. Such a doctrine per- 
 mitted such extreme misinterpretations as that of 
 Clarence King and S. F. Emmons on the nature of the 
 intrusive granite of the Little Cottonwood canyon in the 
 Wahsatch Range. This body cuts across 30,000 feet of 
 Paleozoic rocks and to the careful observer, _ as later 
 admitted by Emmons, shows clear evidence of its trans- 
 gressive nature. But at that time it was generally con- 
 sidered that granite mountains were capable of resist- 
 ing the erosion of all geological time. Consequently it 
 did not seem incredible to King and his associates that 
 here a great granite range of Archean origin had stood 
 
168 A CENTURY OF SCIENCE 
 
 up through Paleozoic time until gradual subsidence had 
 permitted it to be buried beneath 30,000 feet of sedi- 
 ments.^ 
 
 It may seem to the present day reader that such a mis- 
 interpretation, doing violence to fundamental geologic 
 knowledge as now recognized, was inexcusable ; but m 
 the light of the history of geology as here detailed it is 
 seen to have been the interpretation natural to that time. 
 It is true that a careful examination of the facts of that 
 very field would have proved the post-Paleozoic and in- 
 trusive nature of that great granite body now known 
 as the Little Cottonwood batholith, but Emmons has 
 explained the rapid and partial nature of the observa- 
 tions which they were compelled to make in order to keep 
 up to their schedule of progress (16, 139, 1903). 
 
 Whitney had found some years earlier that the gran- 
 ites of the Sierra Nevada were igneous rocks intrusive 
 into the Triassic and Jurassic strata. The Lake Supe- 
 rior geologists began to show in the eighties that granite 
 was there an intrusive igneous rock. E. D. Irving and 
 "Wadsworth noted these relations. Lawson in 1887 
 pointed out emphatically (33, 473) that the granites of 
 the Rainy Lake region, although basal, were younger 
 than the schists which lay above them. The granite- 
 gneisses he held were of clearly the same igneous origin 
 as the granites and neither gave any field evidence of 
 being fused and displaced sediments. From this time 
 forward the truly igneous nature of granite became 
 increasingly accepted until now the notion of its being 
 made of sedimentary rocks softened and recrystallized by 
 the rise of the isogeothcrms through deep burial is as 
 obsolete as the still older doctrine of the Neptunists that 
 granite was laid down as a crystalline precipitate on the 
 floor of the primitive ocean. 
 
 The recognition of the truly igneous nature of granites 
 has been followed in the present generation by a series 
 of studies on their structural relations and mode of 
 genesis. A number of important initial articles on vari- 
 ous aspects of structure and contact relations have 
 appeared in the Journal, but this sketch of the history of 
 the subject may well stop with the introduction to this 
 modern period. 
 
KNOWLEDGE OF EARTH STRUCTURE 169 
 
 Orogenic Structures. 
 Views of Plutonists and N eptunists. 
 
 Orogenic structures are, as the name implies, those 
 connected witli the birth of mountains. Nearly synony- 
 mous terms are deformative or secondary structures. 
 On a small scale this division embraces the phenomena 
 exposed in the rock ledge or quarry face, or in the dips 
 and dislocations varj'ing from one exposure to another. 
 These structures include faults, folds, and foliation. On 
 a larger scale are included the relations of the differ- 
 ent ranges of a mountain system to each other, relations 
 to previous geologic history, relations to the earth as a 
 whole, and to the forces which have generated the struc- 
 tures. 
 
 In order to see the stage of development of this subject 
 in 1818 and its progress as reflected through the publica- 
 tions of a century, more particularly in the Journal, it 
 is desirable to turn again to those two treatises emanat- 
 ing from Edinburgh at the beginning of the nineteenth 
 century and representing two opposite schools of 
 thought, the Plutonists and Neptunists. 
 
 Playfair, in 1802, devotes nineteen pages to the subject 
 of the inflection and elevation of strata.^ He places 
 emphasis on the characteristic parallelism of the strike 
 of the folds throughout a region, as shown through the 
 intersection of the folds bj^ a horizontal plane of erosion. 
 He contrasts this with the arches shown in a transverse 
 section and enlarges on our ability to study the deeply 
 buried strata through the denudation of the folded struc- 
 ture. He argues from these relations that the struc- 
 tures can not be explained by the vague appeal of the 
 Neptunists to forces of crystallization, to slopes of orig- 
 inal deposition, or to sinking in of the roofs of caverns. 
 The causes he argues were heat combined with pressure. 
 As to the directions in which the pressure acted he is not 
 altogether clear, but apparently regards the pressure as 
 acting in upward thrusts against the sedimentary planes, 
 the latter yielding as warped surfaces. His method of 
 presentation is that of inductive reasoning from facts, 
 but he stopped short of the conception of horizontal com- 
 pression through terrestrial contraction. 
 
170 A CENTURY OF SCIENCE 
 
 Jameson, professor of natural history in the same uni- 
 versity, in 1808 contemptuously ignores the work of Hut- 
 ton and Playfair in what he calls the ''monstrosities 
 known under the name of Theories of the Earth." lu a 
 couple of pages he confuses and dismisses the whole sub- 
 ject of deformation. He states:^ 
 
 "It is therefore a fact, that all inclined strata, with a very 
 few exceptions, have been formed so originally, and do not owe 
 their inclination to a subsequent change. 
 
 When we examine the structure of a mountain, we must be 
 careful that our observations be not too micrological, otherwise 
 we shall undoubtedly fail in acquiring a distinct conception of 
 it. This will appear evident when we reflect that the geognostic 
 features of Nature are almost all on the great scale. In no case 
 is this rule to be more strictly followed than in the examination 
 of the stratified structure. 
 
 By not attending to this mode of examination, geognosts 
 have fallen into numberless errors, and have frequently given 
 to extensive tracts of country a most irregular and confused 
 structure. Speculators building on these errors have repre- 
 sented the whole crust of the globe as an irregular and unseemly 
 mass. It is indeed surprising, that men possessed of any knowl- 
 edge of the beautiful harmony that prevails in the structure of 
 organic beings could for a moment believe it possible, that the 
 great fabric of the globe itself, — that magnificent display of 
 Omnipotence, — should be destitute of all regularity in its struc- 
 ture, and be nothing more than a heap of ruins." 
 
 This was the attitude of a leader of British opinion 
 toward the subject of deformational geology from which 
 the infant science had to recover before progress could be 
 made. The early maps were essentially mineralogical 
 and lithological. The order of superposition and the 
 consequent sequence of age was regarded as settled by 
 Werner in Germany and not requiring investigation in 
 America. The early examples of structure were sections 
 drawn with exaggerated vertical scales and those of 
 Maclure do not show detail. 
 
 Itecofjnition of Appalachian Striicttires, 
 
 Following- the founding of the Journal in 1818 there is 
 observable a growth in the quality and detail of geologi- 
 cal mapping. Dr. Aiken, professor of natural philosophy 
 
KNOWLEDGE OF EARTH STRUCTURE 171 
 
 and chemistry in Mt. St. Mary's College, published in the 
 Journal in 1834 (26, 219) a vertical section extending 
 between Baltimore and Wheeling, a distance of nearly 
 250 miles, on a scale of about 7 miles per inch. The suc- 
 cession of rocks is carefully shown and the direction of 
 dip, but no attempt is made to show the underground 
 relations, the stratigraphic sequence, and the folded 
 structures which are so clear in that Appalachian section. 
 The text also shows that the author had not recognized 
 the folded structure. Furthermore, where the folds 
 cease at the Alleghany mountain front, the flat strata are 
 shown as resting unconformably on the folded rocks to 
 the east. 
 
 R. C. Taylor, geologist, civil and mining engineer, was 
 from 1830 to 1835 the leading student of Pennsylvanian 
 geology as shown by the publication in 1835 of four 
 papers aggregating over 80 pages in the Transactions of 
 the Geological Society of Pennsylvania. His work is 
 noticeable for accuracy in detail and no doubt was influ- 
 ential in setting a high standard for the state geological 
 survey which immediately followed. 
 
 H. D. and W. B. Rogers have been given credit in this 
 country, and in Europe also, as being the leading 
 expounders of Appalachian structure. Merrill speaks of 
 H. D. Rogers as unquestionably the leading structural 
 geologist of his time.* To the writer, this attributed 
 position appears to be due to his opportunities rather 
 than to scientific acumen. The magnificent but readily 
 decipherable folded structure of Pennsylvania, the rela- 
 tionships of coal and iron to this structure, the consid- 
 erable sums of money appropriated, and the work of a 
 corps of able assistants were factors which made it com- 
 paratively easy to reach important results. In ability to 
 weigh facts and interpret them Edward Hitchcock 
 showed much more insight than H. D. Rogers, while in 
 the philosophic and comprehensive aspects of the subject 
 J. D. Dana far outranks him. 
 
 H. D. Rogers in his first report on the geological sur- 
 vey of New Jersey, 1836, recognizes that the Cambro- 
 Silurian limestones (lower Secondary limestones) were 
 deposited as nearly horizontal beds and the ridges of 
 pre-Cambrian gneiss (Primary) had been pushed up as 
 
172 A CENTURY OF SCIENCE 
 
 anticlinal axes (p. 128). He also clearly recognized the 
 distinction between slaty cleavage and true dip as shown 
 in the Ordovician slates (p. 97). Between 1836 and 1840 
 he had learned a great deal on the nature of folds as is 
 shown in his Pennsylvania report for 1839 and the struc- 
 ture sections in his New Jersey report for 1840. 
 
 R. C. Taylor, who had now become president of the 
 board of directors of the Dauphin and Susquehanna Coal 
 Company, published in the Journal in 1841 (41, 80) an 
 important paper entitled "Notice of a Model of the 
 Western portion of the Schuylkill or Southern Coal 
 Field of Pennsylvania, in illustration of an Address to 
 the Association of American Geologists, on the most 
 appropriate modes for representing Geological Phe- 
 nomena." In this paper he calls attention to the value 
 of modeling as a means of showing true relations in three 
 dimensions. He condemns the custom prevalent among 
 geologists of showing structure sections with an exag- 
 gerated vertical scale with its resultant topographic and 
 structural distortions. Taylor was widely acquainted 
 with the structure of Pennsylvania, Maryland, and Vir- 
 ginia. 
 
 Nature of Forces Procliicinff Foldinff. 
 
 In 1825 Dr. J. H. Steele sent to Professor Silliman two 
 detailed drawings and description of an overturned fold 
 at Saratoga Lake, New York. As to the significance of 
 this feature Steele makes the following statement (9, 3, 
 1825) : 
 
 "It is impossible to examine this locality witliout being 
 strongly impressed with the belief that the position which the 
 strata here assume could not have been effected in any other 
 way than by a power operating from beneath upwards and at 
 the same time possessing a progressive force ; something analo- 
 gous to what takes place in the breaking up of the ice of large 
 rivers. The continued swelling of the stream first overcomes 
 the resistance of its frozen surface and having elevated it to a 
 certain extent, it is forced into a vertical position, or thrown 
 over upon the unbroken stratum behind, by the progressive 
 power of the current." 
 
 So far as the present writer is aware this is the first 
 recognition in geological literature of the evidence of a 
 
KNOWLEDGE OF EARTH STRUCTURE 173 
 
 horizontally compressive and overturning force as a 
 cause of folding. 
 
 To E. Hitchcock belongs the credit of being the first to 
 describe overturning and inversion of strata on a large 
 scale, but without clearly recognizing it as such. In 
 western Massachusetts metamorphism is extreme in the 
 lower Paleozoic rocks in the vicinity of the overthrust 
 mass of Archean granite-gneiss which constitutes the 
 Hoosic range. The Paleozoic rocks of the valley to the 
 west are overturned and appear to dip beneath the older 
 rocks. Farther west the metamorphism fades out and 
 the series assumes a normal position. Such an inverted 
 relation, up to that time unknown, is described in 1833 as 
 follows by Hitchcock in his Geology of Massachussetts 
 (pp. 297, 298) : 
 
 "But a singular anomaly in tlie superposition of the series of 
 rocks above described, presents a great difficulty in this case. 
 The strata of these rocks almost uniformly dip to the east : that 
 is, the newer rocks seem to crop out beneath the older ones ; so 
 that the saccharine limestone, associated with gneiss in the east- 
 ern part of the range, seems to occupy the uppermost place in 
 the series. Now as superposition is of more value in determin- 
 ing the relative ages of rocks than their mineral characters, must 
 we not conclude that the rocks, as we go westerly from Hoosac 
 mountain, do in fact belong to older groups ? The petrifactions 
 which some of them contain, and their decidedly fragmentary 
 character, will not allow such a supposition to be indulged for 
 a moment. It is impossible for a geologist to mistake the evi- 
 dence, which he sees at almost every step, that he is passing 
 from older to newer formations, just as soon as he begins to 
 cross the valley of Berkshire towards the west. We are driven 
 then to the alternative of supposing, either that there must be 
 a deception in the apparent outcrop of the newer rocks from 
 beneath the older, or that the whole series of strata has been 
 actualty thrown over, so as to bring the newest rocks at the bot- 
 tom. The latter supposition is so improbable that I cannot at 
 present admit it." 
 
 Hitchcock tried to reconcile the evidence by a series of 
 unconformities and inclined deposition, but finds the solu- 
 tion unsatisfactory. 
 
 In this same year, 1833, Elie de Beaumont, a dis- 
 tinguished French geologist, published his theory of the 
 origin of mountains. He advanced the idea that since 
 
 11 
 
174 A CENTURY OF SCIENCE 
 
 the globe was cooling it was condensing, and tlie crust, 
 already cool, must suffer compression in adjusting itself 
 to the shrinking molten interior. He concluded from the 
 evidence shown in Europe that the collapse of the crust 
 occurred violently and rapidly at widely spaced intervals 
 of time. This hjqiothesis introduced the idea of moun- 
 tain folding by horizontal compressive forces. The the- 
 oretical paper of de Beaumont, together with further 
 observations by Hitchcock and others, led the latter in 
 1841 to a final belief in the inversion of strata on a large 
 scale by horizontal compression. His conclusions are 
 expressed in an important paper published in the Journal 
 (41, 268, 1841) and given on April 8, 1841, as the First 
 Anniversary Presidential Address before the Associa- 
 tion of American Geologists. This comprehensive sum- 
 mary of American geology occupies 43 pages. Three 
 pages are given to the inverted structure of the Appa- 
 lachians from which the following paragraphs may be 
 quoted : 
 
 "We have all read of the enormous dislocations and inver- 
 sions of the strata of the Alps ; and similar phenomena are said 
 to exist in the Andes. Will it be believed, that we have an 
 example in the United States on a still more magnificent scale 
 than any yet described? . . . 
 
 Let lis suppose the strata between Hudson and Connecticut 
 rivers, while yet in the plastic state, (and the supposition may 
 be extended to any other section across this belt of country from 
 Canada to Alabama,) and while only slightly elevated, were 
 acted upon by a force at the two rivers, exerted in opposite 
 directions. If powerful enough, it might cause them to fold 
 up into several ridges ; and if more powerful along the western 
 than the eastern side, they might fall over so as to take an 
 inverted dip, without producing any remarkable dislocations, 
 while subsequent denudation would give to the surface its 
 present outline. . . . 
 
 Fourthly, we should readily admit that such a plication and 
 inversion of the strata might take place on a small scale. If for 
 instance, we were to press against the extremities of a series of 
 plastic layers two feet long, they could easily be made to assume 
 the position into which the rocks under consideration are thrown. 
 Why then should we not be equally ready to admit that this 
 might as easily be done, over a breadth of fifty miles, and a 
 length of twelve hundred, provided we can find in nature, forces 
 
KNOWLEDGE OF EARTH STRUCTUEE 175 
 
 sufficiently powerful? Finallj', such forces do exist in nature, 
 and have often been in operation." 
 
 The advanced nature of these conceptions may he 
 appreciated hy contrasting them with those put forth by 
 H. D. and W. B. Rogers on April 29, 1842, before the third 
 annual meeting of the same body (43, 177, 1842) and 
 repeated by them before the British Association at Man- 
 chester two months later. In their own words, the 
 Rogers brothers from their studies on the folds shown in 
 Pennsylvania and Virginia, conceived mountain folds in 
 general to be produced by much elastic vapor escaping 
 through many parallel fissures formed in succession, pro- 
 ducing violent propulsive wave oscillations on the sur- 
 face of the fluid earth beneath a thin crust. Thus actual 
 billows are assumed to have rolled along through the 
 crust. They did not think tangential pressure alone 
 could produce folds. Such pressures were regarded as 
 secondary, produced by the propagation of the waves and 
 the only expression of tangential forces which they 
 admitted was to fix the folds and hold them in position 
 after the violent oscillation had subsided (44, 360, 1843). 
 The leading British geologists De la Beche and Sedg- 
 wick criticized adversely this remarkable theory, stating 
 that they could see no such analogy in mountain folds to 
 violent earthquake waves and that in their opinion the 
 slow application of tangential force was sufficient to 
 account for the phenomena (44, 362-365, 1843). 
 
 H. D. Rogers in the prosecution of the geological sur- 
 vey of Pennsylvania displayed notable organizing ability 
 and persistence in accomplishment, even to advancing per- 
 sonally considerable sums of money, trusting to the state 
 legislature to later reimburse him. Finally, after many 
 delays by the state, the publication was placed directly 
 in his charge and he produced in 1858 a magnificent 
 quarto work of over 1,600 pages, handsomely illustrated, 
 and accompanied by an atlas. It is excellent from the 
 descriptive standpoint, standing in the first class. Meas- 
 ured as a contribution to the theory of dynamical geol- 
 ogy, the explanatory portions were, however, thirty years 
 behind the times. The same hypotheses are put forth 
 in 1858 as in 1842. There is no acceptance of the views 
 
176 A CENTURY OF SCIENCE 
 
 of Lyell concerning the uniformitarian principles ex- 
 pounded by this British leader in 1830, or of the nature 
 of orogenic forces as published by Elie de Beaumont in 
 1833. Rogers rejects the view that cleavage is due to 
 compression and suggests "that both cleavage and folia- 
 tion are due to the parallel transmission of planes or 
 waves of heat, awakening the molecular forces, and 
 determining their direction.^ Thus a mere maze of 
 words takes the place of inductive demonstrations 
 already published. 
 
 In following the play of these opposing currents of 
 geologic thought we reach now the point where a period 
 of brilliant progress in the knowledge of mountains and 
 of continental structures begins in the work of J. D. 
 Dana. In 1842 Dana returned from the Wilkes Explor- 
 ing Expedition and the following year began the publica- 
 tion of the series of papers which for the next half 
 century marked him as the leader in geologic theory in 
 America. His work is of course to be judged against 
 the background of his times. His papers mark distinct 
 advances in many lines and are characterized throughout 
 by breadth of conception and especially by clear and log- 
 ical thinking. His work was published very largely in 
 the Journal, of which after a few years he became chief 
 editor. His first contribution on the subject of moun- 
 tain structures, entitled "Geological results of the earth's 
 contraction in consequence of cooling," was published in 
 1847 (3, 176). The evidence of horizontal pressure was 
 first perceived in France as shown by the features of the 
 Alps. Elie de Beaumont connected it, by means of the 
 theory of a cooling and contracting globe, with the other 
 large fact of the increase of temperature with descent in 
 the crust. Dana credits the Rogers brothers with first 
 making known the folded structures of the Appalachians, 
 but objects to their interpretation of origin. He showed 
 by means of diagrams that the folds are to be explained 
 by lateral pressure, the direction of overturning indicat- 
 ing the direction from which the driving force proceeded. 
 
 The Rogers brothers and especially James Hall, in 
 working out the Appalachian stratigraphy, had noted 
 that the formations, although accumulating to a maxi- 
 
 jO,000 and 40,000 feet, showed 
 
KNOWLEDGE OF EAETH STRUCTURE 177 
 
 evidences that the successive formations were deposited 
 in shallow water. It suggested to them that the weight of 
 the accumulating sediments was the cause of subsidence, 
 each foot of sediment causing a foot of down sinking. 
 This idea has continued to run through various text 
 books in geology for half a century, yet Dana early 
 saw the fallacy and in 1863 in the first edition of 
 his Manual of Geology (p. 717) states "whether this 
 is an actual cause or not in geological dynamics is 
 questionable." In 1866 in an important article on 
 "Observations on the origins of some of the earth's 
 features," Dana deals more fuUj^ and finally with 
 this subject (42, 205, 252, 1866). He shows that such an 
 effect of accumulating sediment postulates a delicate 
 balance, a very thin crust and no resistance below. If 
 such a weakness were granted it would be impossible for 
 the earth to hold up mountains. Furthermore such sub- 
 sidence was not regular during its progress and finally 
 in the long course of geologic time gave place to a reverse 
 movement of elevation. 
 
 Hall had pointed out the fact that the sediments were 
 thickest on the east in the region of mountain folding and 
 thinned out to a fraction of this thickness in the broad 
 Mississippi basin. Hall argued that the mere subsidence 
 of the trough would produce the observed folding and 
 that the folding was unrelated to mountain making or 
 crustal shortening. In supposed proof he cited the fact 
 that the Catskills consist of unfolded rock, are higher 
 than the folded region to the south, and nearly as high as 
 the highest metamorphic mountains to the east.^" Hall 
 and all his contemporaries were handicapped in their 
 geological theories by a complete inappreciation of the 
 importance of subaerial denudation. For subscribing to 
 these errors of their time even the ablest men should not 
 be held responsible. Hall was the most forcible person- 
 ality in geology in his generation. His contributions to 
 paleontology w^ere superb. His perception of the rela- 
 tion existing between troughs of thick sediments and 
 folded structures was a contribution of the first import- 
 ance; yet in the structural field his argument as to the 
 production of the Appalachian folds by mere subsidence 
 during deposition indicates a remarkable inability to 
 
178 A CENTURY OF SCIENCE 
 
 apply the logical consequences of his hj^pothesis to the 
 nature of the folds as already made known by the Rogers. 
 Dana pointed out in reply to Hall that the folding did not 
 correspond to the requirements of Hall's hyjDothesis, 
 especially as the folding took place not during, but after 
 the close of the vast Paleozoic deposition. Dana states 
 in conclusion on Hall's hypothesis (42, 209, 1866) that 
 "It is a theory of the origin of mountains with the origin 
 of mountains left out." 
 
 The Theory of GeosyncHnes and Geanticlines, 
 
 The fact that S3'stems of folded strata lie along axes of 
 especially thick sediments and that this implied subsi- 
 dence during deposition was tiall's contribution to geo- 
 logic theory, but curiously enough he failed, as shown, to 
 connect it with the subsequent nature of mountain fold- 
 ing. He did not see why such troughs should be weak to 
 resist horizontal compression. The clear recognition of 
 this relationship was the contribution of Le Conte, who 
 in a paper on "A theory of the formation of the great 
 features of the earth's surface" (4, 345, 460, 1872), 
 reached the conclusion that "mountain chains are 
 formed by the mashing together and the up-swelling of 
 sea bottoms where immense thicknesses of sediment have 
 accumulated. ' ' 
 
 As to the cause why mashing should take place along 
 troughs of thick sediments Le Conte adopts the hypothe- 
 sis of aqueo-igneous fusion proposed independently long 
 before by Babbage and Herschel and elaborated into a 
 theory of igneous rocks by Hunt. Under this vievi^^ as the 
 older sediments became deeply buried, the heat of the 
 earth's interior ascended into them, and since they 
 included the water of sedimentation a softening and met- 
 amorphism resulted. Dana had shown, however, six 
 years previously (42, 252, 1866), as the following quota- 
 tion will indicate, that metamorphism of sediments 
 required more than deep burial and that no such weaken- 
 ing as was postulated by Herschel had occurred : 
 
 "The correctness of Herschel's principle cannot be doubted. 
 But the ciuestion of its actual agency in ordinary metamorphism 
 must be decided by an appeal to facts ; and on this point I would 
 here present a few facts for consideration. 
 
KNOWLEDGE OF EARTH STRUCTUEE 179 
 
 The numbers and boldness of the flexures in the rocks of most 
 metamorphic regions have always seemed to me to bear against 
 the view that the heat causing the change had ascended by the 
 very quiet method recognized in this theory. . . . 
 
 But there are other facts indicating a limited sufficiency to 
 this means of metamorphism. These are afforded by the great 
 faults and sections of strata open to examination. In the Appa- 
 lachian region, both of Virginia and Pennsylvania, faults occur, 
 as described by the Professors Rogers, and by Mr. J. P. Lesley, 
 which afford us important data for conclusions. Mr. Lesley, an 
 excellent geologist and geological observer, who has explored 
 personally the regions referred to, states that at the great fault 
 of Juniata and Blair Cos., Pennsylvania, the rocks of the Tren- 
 ton period are brought up to a level with those of the Chemung, 
 making a dislocation of at least 16,000, and probably of 20,000, 
 feet. And j^et the Trenton limestone and Hudson River shales 
 are not metamorphic. Some local cases of alteration occur there, 
 including patches of roofing slate ; but the greater part of the 
 shales are no harder than the ordinary shales of the Pennsyl- 
 vania Coal formation. 
 
 At a depth of 16,000 feet the temperature of the earth's crust, 
 allowing an increase of 1° F. for 60 feet of descent, would be 
 about 330° F.; or with 1° F. for 50 feet, about 380° F.— either 
 of which temperatures is far above the boiling point of water; 
 and with the thinner crust of Paleozoic time the temperature 
 at this depth should have been still higher. But, notwithstand- 
 ing this heat, and also the compression from so great an over- 
 lying mass, the limestones and shales are not crystalline. The 
 change of parts of the shale to roofing slate is no evidence in 
 favor of the efficiency of the alleged cause; for such a cause 
 should act uniformly over great areas." 
 
 The nest contribution to the theory of orogeny was a 
 series of papers published in 1873 by Dana, entitled ' ' On 
 some results of the earth's contraction from cooling, 
 including a discussion on the origin of mountains and 
 the nature of the earth's interior."" This contribution, 
 viewed as a whole, ranks among the first half dozen 
 papers on the science of mountains. The following- 
 quoted paragraphs give a view of the scope of this 
 article : 
 
 " Kinds and Structure of 3Iountains." 
 
 "While mountains and mountain chains all over the world, 
 and low lands, also, have undergone uplifts, in the course of 
 their long history, that are not explained on the idea that all 
 
180 A CENTURY OF SCIENCE 
 
 mountain elevating is simply what may come from plication 
 or crushing, the component parts of mountain chains, or those 
 simple mountains or mountain ranges that are the product of 
 one process of making — may have received, at the time of their 
 original making, no elevation beyond that resulting from 
 plication. 
 
 This leads us to a grand distinction in orography, hitherto 
 neglected, which is fundamental and of the highest interest in 
 dynamical geology ; a distinction between — 
 
 1. A simple or individual mountain mass or range, which is 
 the result of one process of making, like an individual in any 
 process of evolution, and which may be distinguished as a mono- 
 genetic range, being one in genesis; and 
 
 2. A composite or polygenetic range or chain, made up of 
 two or more monogenetic ranges combined. 
 
 The Appalachian chain — the mountain region along the 
 Atlantic border of North America — is a pioly genetic chain ; it 
 consists, like the Rocky and other mountain chains, of several 
 monogenetic ranges, the more important of which are: 1. The 
 Highland range (including the Blue Eidge or parts of it, and 
 the Adirondacks also, if these belong to the same process of 
 making) pre-Silurian in foi'mation ; 2. The Green Mountain 
 range, in western New England and eastern New York, com- 
 pleted essentially after the Lower Silurian era or during its 
 closing period; 3. The Alleghany range, extending from south- 
 ern New York southwestward to Alabama, and completed 
 immediately after the Carboniferous age. 
 
 The making of the Alleghany range was carried forward at 
 first through a long-continued subsidence — a geosynclinal (not 
 a true synclinal, since the rocks of the bending crust may have 
 had in them many true or simple synclinals as well as anti- 
 clinals), and a consequent accumulation of sediments, which 
 occupied the whole of Paleozoic time; and it was completed, 
 finally, in great breakings, faultings and foldings or plications 
 of the strata, along with other results of disturbance. 
 
 These examples exhibit the characteristics of a large class 
 of mountain masses or ranges. A geosynclinal accompanied by 
 sedimentary depositions, and ending in a catastrophe of plica- 
 tions and solidification, are the essential steps, while metamor- 
 phism and igneous ejections are incidental results. The process 
 is one that produces final stability in the mass and its annexation 
 generally to the more stable part of the continent, though not 
 stable against future oscillations of level of wider range, nor 
 against denudation. 
 
 It is apparent that in such a process of formation elevation 
 by direct uplift of the underlying crust has no necessary place. 
 The attending plications may make elevations on a vast scale 
 
KNOWLEDGE OF EARTH STRUCTURE 181 
 
 and so also may the shoves upward along the lines of fracture, 
 and crushing may sometimes add to the effect; but elevation 
 from an upward movement of the downward bent crust is only 
 an incidental concomitant, if it occur at all. 
 
 "We perceive thus where the truth lies in Professor Le Conte's 
 important principle. It should have in view alone monogenetic 
 mountains and these only at the time of their making. It will 
 then read, plication and shovings along fractures being made 
 more prominent than crushing : 
 
 Plication, shoving along fractures and crushing are the true 
 sources of the elevation that takes place during the making of 
 geosynclinal monogenetic mountains. 
 
 And the statement of Professor Hall may be made right if 
 we recognize the same distinction, and, also, reverse the order 
 and causal relation of the two events, accumulation and sub- 
 sidence ; and so make it read : 
 
 Regions of monogenetic mountains were, previous, and pre- 
 paratorj;-, to the making of the mountains, areas each of a slowly 
 progressing geosynclinal, and, consequently, of thick accumula- 
 tions of sediments. 
 
 The prominence and importance in orography of the moun- 
 tain individualities described above as originating through a 
 geosjmclinal make it desirable that they should have a distinc- 
 tive name ; and I therefore propose to call a mountain range 
 of this kind a synclinorium, from synclinal and the Greek opo?, 
 mountain. 
 
 This brings us to another important distinction in orographic 
 geology — that of a second kind of monogenetic mountain. The 
 synclinoria were made through a progressing geosynclinal. 
 Those of the second kind, here referred to, were produced by a 
 progressing geanticlinal. They are simply the upward bendings 
 in the oscillations of the earth's crust — the geanticlinal waves, 
 and hardly require a special name. Yet, if one is desired, the 
 term anticlinorium, the correlate of synclinorium, would be 
 appropriate. Many of them have disappeared in the course of 
 the oscillations ; and yet, some may have been for a time — • 
 perhaps millions of years — respectable mountains. 
 
 The geosynclinal ranges or synclinoria have experienced in 
 almost all cases, since their completion, true elevation through 
 great geanticlinal movements, but movements that embraced a 
 wider range of crust than that concerned in the preceding geo- 
 synclinal movements, indeed a range of crust that comes strictly 
 under the designation of a polygenetie mass." 
 
 " The Condition of the Earth's Interior." 
 
 "The condition of the earth's interior is not among the geo- 
 logical results of contraction from cooling. But these results 
 
182 A CENTURY OF SCIENCE 
 
 offer an argument of great weight respecting the earth's interior 
 condition, and make it desirable that the subject should be dis- 
 cussed in this connection. Moreover, the facts throw additional 
 light on the preceding topic — the origin of mountains. 
 
 It seems now to be demonstrated by astronomical and physical 
 arguments — arguments that are independent, it should be noted, 
 of direct geological observation — that the interior of our globe 
 is essentially solid. But the great oscillations of the earth's 
 surface, which have seemed to demand for explanation a liquid 
 interior, still remain facts, and present apparently a greater 
 difficulty than ever to the geologist. Professor Le Conte 's views, 
 in volume iv, were offered by him as a method of meeting this 
 difficulty; yet, as he admits in his concluding remarks, the 
 oscillations over the interior of a continent, and the fact of the 
 greater movements on the borders of the larger ocean, were 
 left by him unexplained. Yet these oscillations are not more 
 real than the changes of level or greater oscillations which 
 occurred along the sea border, where mountains were the final 
 result; and this being a demonstrated truth, no less than the 
 general solidity of the earth's interior, the question comes up, 
 how are the two truths compatible? 
 
 The geological argument on the subject (the only one within 
 our present purpose) has often been presented. But it derives 
 new force and gives clearer revelations when the facts are viewed 
 in the light of the principles that have been explained in the 
 preceding part of this memoir. 
 
 The Appalachian subsidence in the Alleghany region of 35,000 
 to 40,000 feet, going on through all the Paleozoic era, was due, 
 as has been shown, to an actual sinking of the earth's crust 
 through lateral pressure, and not to local contraction in the 
 strata themselves or the terranes iinderneath. But such a sub- 
 sidence is not possible, unless seven miles — that is, seven miles 
 in maximum depth and over a hundred in total breadth — unless 
 seven miles of something were removed, in its progress, from 
 the region beneath. 
 
 If the matter beneath was not aerial, then liquid or viscous 
 rock was pushed aside. This being a fact, it would follow that 
 there existed, underneath a crust of unascertained thickness, a 
 sea or lake of mobile (viscous or plastic) rock, as large as the 
 sinking region; and also that this great viscous sea continued 
 in existence through the whole period of subsidence, or, in the 
 case of the Alleghany region, through all Paleozoic time — an era 
 estimated on a previous page to cover at least thirty-five millions 
 of years, if time since the Silurian age began embraced fifty 
 millions of years. 
 
 The facts thus sustain the statement that lateral pressure 
 
KNOWLEDGE OF EARTH STRUCTURE 183 
 
 produced not only the subsidence of the Appalachian region 
 through the Paleozoic, but also, cotemporaneously, and as its 
 essential prerequisite, the rising of a sea-border elevation, or 
 geantielinal, parallel with it ; and that both movements demanded 
 the existence beneath of a great sea of mobile rock." 
 
 The recognition of regional ivarping as a major factor 
 in the larger structure of mountain systems, and the 
 expression of that factor in the terms geosyncline and 
 geanticline forms a notable advance in geologic thought. 
 Subsequent folding on a regional scale results in the 
 development of synclinoria and anticlinoria. Van Hise 
 has given these latter terms wide currency, but appar- 
 ently inadvertently has used synclinorium in a different 
 sense than that in which Dana defined it. Dana gave the 
 word to a mountain range made by the mashing and up- 
 lift of a geosyncline, Van Hise defines it as a downfold of 
 a large order of magnitude, embracing anticlines and 
 synclines within it; anticlinorium he uses for a corre- 
 sponding up fold.^- Rice has called attention to this 
 change of definition,^^ but Van Hise's usage is likely to 
 prevail, since they are needed terms for the larger moun- 
 tain structure and do not require a determination of the 
 previous limits of upwarp and downwarp, — of original 
 denudation and deposition. Furthermore, a geosyncline 
 in mountain folding may have one side uplifted, the other 
 side depressed and there are reasons for regarding the 
 folds of Pennsylvania, Dana's type sjmclinorium, as 
 representing but the western and downfolded side of the 
 Paleozoic geosyncline. Under that view the_ folded 
 Appalachians of Pennsylvania constitute a synclinorium 
 in both the sense of Dana and Van Hise. 
 
 The Ultimate Cause of Cfustal Coniiiression. 
 
 The next important advance in the theory of moun- 
 tains was made by C. E. Dutton who in 1874 published in 
 the Journal (8, 113-123) an article entitled "A criticism 
 upon the contractional hjTpothesis." Dutton gives rea- 
 sons for holding that the amount of folding and shorten- 
 ing exhibited in mountain ranges, especially those of 
 Tertiary date, is very much greater in magnitude and is 
 different in nature and distribution from that which 
 
184 A CENTURY OF SCIENCE 
 
 would be given by the surficial cooling of the globe._ The 
 following quotations cover the principal points in the 
 argument : 
 
 "The argument for the contraetional hypothesis presupposes 
 that the earth-mass may be considered as consisting of two por- 
 tions, a cooled exterior of undetermined (though probably com- 
 paratively small) depth, inclosing a hot nucleus. . . . The 
 secular loss of heat, it is assumed, would be greater from the 
 hot nucleus than from the exterior, and the greater consequent 
 contraction of the nucleus would therefore gradually withdraw; 
 the support of the exterior, which would collapse. The result- 
 ing strains upon the exterior would be mainly tangential. 
 Owing to considerable inequalities in the ability of different por- 
 tions to resist the strains thus developed, the yielding would take 
 place at the lines, or regions of least resistance, and the effects 
 of the yielding would be manifested chiefly, or wholly, at those 
 places, in the form of mountain chains, or belts of table-lands, 
 and in the disturbances of stratification. The primary division 
 of the surface into areas of land and water are attributed to the 
 assumed smaller conductivity of materials underlying the land, 
 which have been left behind in the general convergence of the 
 surface toward the center. Eegarding these as the main and 
 underlying premises of the contraetional argument, it is con- 
 sidered unnecessary to state the various subsidiary propositions 
 which have been advanced to explain the determination of this 
 action to particular phenomena, since the main proposition upon 
 which they are based is considered untenable. 
 
 There can be no reasonable doubt that the earth-mass consists 
 of a cooled exterior inclosing a hot nucleus, and a necessary 
 corollary to this must be secular cooling, probably accompanied 
 by contraction of the cooling portions. But when we apply the 
 known laws of thermal physics to ascertain the rate of this 
 cooling, and its distribution through the mass, the objectionable 
 character of the contraetional hypothesis becomes obvious. 
 
 That Fourier's theorem, under the general conditions given, 
 expresses the normal law of cooling, is admitted by all mathe- 
 maticians who have examined it. The only ground of contro- 
 versy must be upon the values to be assigned to the constants. 
 But there seem to be no values consistent with probability which 
 can be of help to the contraetional hypothesis. The applica- 
 tion of the theorem shows that below 200 or 300 miles the cool- 
 ing has, up to the present time, been extremely little. . . . 
 At present, however, the unavoidable deduction from this 
 theorem is that the greatest possible contraction due to secular 
 cooling is insufficient in amount to account for the phenomena 
 attributed to it by the contraetional hypothesis. 
 
KNOWLEDGE OF EARTH STRUCTURE 185 
 
 The determination of plications to particular localities pre- 
 sents difficulties in the way of the contractional hypothesis which 
 have been underrated. It has been assumed that if a contraction 
 of the interior were to occur, the yielding of the outer crust 
 would take place at localities of least resistance. But this could 
 be true only on the assumption that the crust could have a hori- 
 zontal movement in which the nucleus does not necessarily share. 
 A vertical section through the Appalachian region and west- 
 ward to the 100th meridian shows a surface highly disturbed 
 for about two hundred and fifty miles, and comparatively undis- 
 turbed for more than a thousand. No one would seriously argue 
 that the contraction of the nucleus had been confined to portions 
 underlying the disturbed regions : yet if the contraction was 
 general, there must have been a large amount of slip of some 
 portion of the undisturbed segment over the nucleus. Such a 
 proposition would be very difficult to defend, even if the pre- 
 mises were granted. It seems as if the friction and adhesion of 
 the crust upon the nucleus had been overlooked. Nor could this 
 be sm,all, even though the crust rested upon liquid lava. The 
 attempts which some eminent geologists have recently made to 
 explain surface corrugation by this method clearly show a neg- 
 lect on their part to analyze carefully the system of forces which 
 a contraction of the nucleus would generate in the crust. Their 
 discussions have been argumentative and not analytical. The 
 latter method of examination would have shown them certain 
 difficulties irreconcilable with their knowledge of facts. Adopt- 
 ing the argumentative mode, and in conformity with their view 
 regarding the exterior as a shell of insufficient coherence to 
 sustain itself when its support is sensibly diminished, the ten- 
 dency of corrugation to occur mainly along certain belts, with 
 series of parallel folds, is not explained by assuming that these 
 localities are regions of weakness. For a shrinkage of the 
 nucleus would throw each elementary portion of the crust into 
 a state of strain by the action of forces in all directions within 
 its own tangent plane. A relief by a horizontal yielding in one 
 direction would by no means be a general relief." 
 
 Button's criticisms robbed the current hypotliesis of 
 mountain-making- of its conventional basis witliout pro- 
 viding a new foundation. It was a quarter of a cen- 
 tury in advance of its time, has been seldom cited, and 
 seems to have had but little direct influence in shaping 
 subsequent thought. It, however, gave direction to But- 
 ton's views, and his later papers were far-reaching in 
 their influence. 
 
 If contraction from external cooling is not the cause 
 
186 A CENTURY OF SCIENCE 
 
 of the compressive forces it is necessary to seek anotlier 
 cause. Two years later, in 1876, Button attempted to 
 provide an answer to this open question.^"' A review of 
 this paper, evidently by J. D. Dana, is given in the Jour- 
 nal. The following explanations of Button's theory and 
 of Dana's comments upon it are contained in a few para- 
 graphs from this review (12, 142, 1876). 
 
 "Captain Button presents in this paper the views brought out 
 in his article in vohime viii of this Journal, with fuller illustra- 
 tions, and adds explanations of his theory of the origin of moun- 
 tains. The discussion should be read by all desiring to reach 
 right conclusions, it presenting many arguments from physical 
 considerations against the contraction-theory, or that of the 
 uplifting and folding of strata through lateral pressure. There 
 is much to be learned before any theory of mountain-making 
 shall have a sufficient foundation in observed facts to demand 
 full confidence, and Captain Button merits the thanks of geolo- 
 gists for the aid he has given them toward reaching right con- 
 clusions. His discussions are not free from misunderstandings 
 of geological facts, and if they fail to be finally received it will 
 be for this reason. 
 
 We here give in a brief form, and nearly in his own words, 
 the principal points in his theory of mountain-making as 
 explained in the later part of his memoir. 
 
 Accepting the proposition that there is a plastic condition of 
 rock beneath the earth's crust and that metamorphism is a 
 'hydrothermal process,' and believing that 'the penetration of 
 water to profound depths [in the earth's crust] is a well sus- 
 tained theory,' he says that great pressure and a temperature 
 approaching redness are essential conditions of metamorphism. 
 . . . 'The heaviest portion would sink into the lighter colloid 
 mass underneath, protruding it laterally beneath the lighter 
 portions where, by its lighter density, it tends to accumulate.' 
 He adds : ' The resulting movements would be determined, first, 
 by the amount of difference in the densities of the upper and 
 lower masses, and, second, by inequalities in the thickness of 
 the strata: the forces now become adequate to the building of 
 mountains and the plication of strata, and their modes of opera- 
 tion agree with the classes of facts already set forth as the 
 concomitants of those features.' 
 
 The views are next applied to a system of plications. ' It has 
 been indicated that plications occur where strata have rapidly 
 accumulated in great volume and in elongated narrow belts; 
 that the axes of plications are parallel to the axes of maximum 
 deposit; and that the movements immediately followed the 
 
KNOWLEDGE OF EARTH STRUCTURE 187 
 
 deposition' — the case of the Appalachians being an example in 
 which the accumulations averaged 40,000 feet. He observes : 
 'Wherever the load of sediments becomes heaviest, there they 
 sink deepest, protruding the colloid magma beneath them to the 
 adjoining areas, which are less heavily weighted, forming at 
 once both synclinals and antielinals.' 
 
 With regard to this new theory, we might reasonably question 
 the existence of the colloid magma — a condition fundamental to 
 the theory — and his evidence that water penetrates to profound 
 depths in the earth's crust sufficient to make hydrous rocks. 
 We might ask for evidence that the rocks beneath the Cretaceous 
 and Tertiary, and other underlying strata of the Uintahs, were 
 in such a colloid state, and this so near the surface, that the 
 'beds subsided by their gross weight as rapidly as they grew.' 
 
 Again, he saj's that the movements of mountain-making 
 'immediately followed the deposition.' 'Immediately' sounds 
 quick to one who appreciates the slowness of geological changes. 
 The Carboniferous age was very long; and somewhere in that 
 part of geological time, either Ijefore the age had fully ended, 
 or some time after its close, the epoch of catastrophe began." 
 
 We see foreshadowed in this paper the theory of 
 isostasy, or condition of vertical equilibrium in the crust 
 which Button published in 1889. This theory has borne 
 remarkable fruit, but Button attempted to link to it the 
 horizontally compressive forces which have produced 
 folding and over thrusting. Willis in 1907^^ and Hayford 
 in 1911, overlooking Dana's objections, have attempted 
 to make a lateral isostatic undertow the cause of all hori- 
 zontal movements in the crust, adopting the mechanism 
 of Button. The present writer, although accepting the 
 principle of isostasy as an explanation of broad vertical 
 movements, has published papers which go to show the 
 inadequacy of this hj-pothesis of lateral pressure ; inade- 
 quate in time relation, in amount, and in expression.!*^ 
 
 In 1903 it was determined by several physicists that 
 the materials of the earth's crust were radioactive and 
 must generate throughout geologic time a quantity of 
 heat which perhaps equalled that lost by radiation into 
 space. By 1907 this had become demonstrated. The 
 remarkable conclusion had been reached that the earth, 
 although losing heat, is not a cooling globe. Dut- 
 ton's contentions against mountain growth through 
 external cooling and contraction were thus unexpectedly, 
 
188 A CENTURY OF SCIENCE 
 
 tlirougla a wholly new branch of knowledge, demonstrated 
 to be true. 
 
 Nevertheless, all students of orogeny are agreed that 
 profound compressive forces have been the chief _ agents 
 in developing mountain structures. Chamberlin was 
 the first to arrive at the idea that the shrinkage may 
 originate in the deeper portions of the earth under the 
 urgency of the enormous pressures, apparently by giving 
 rise to slow recombinations of matter into denser 
 forms.^'^ 
 
 The New Era in the Interjn^efation of Mountain Structures. 
 
 In the meantime, between 1874 and 1904, another 
 advance in the knowledge of mountain structures was 
 taking place in Europe. Suess studied the distribution 
 of mountain arcs over the earth and dwelt upon the 
 prevalence of overthrust structures ; the backland being 
 thrust toward and over the foreland, the rise of the 
 mountain arc or geanticline depressing the foredeep or 
 geosjmcline. Bertrand and Lugeon from 1884 to 1900 
 were reinterpreting the Alpine structures on this basis. 
 They showed that the whole mountain system had been 
 overturned and overthrust from the south to an almost 
 incredible degree. Enormous denudation had later dis- 
 severed the northern outlying portions and given rise to 
 "mountains without roots," — isolated outliers, consist- 
 ing of overturned masses of strata which had accumu- 
 lated as sediments far to the southward in another por- 
 tion of the ancient geosyncline. 
 
 On a smaller scale similar phenomena are exhibited in 
 the Aiopalachians. Willis showed that the deep subsi- 
 dence of the center of the geosyncline gave an initial dip 
 which determined the position of yielding under compres- 
 sion. Laboratory experiments brought ou:t the weakness 
 of the stratigraphic structure to resist horizontal com- 
 pression. The nature of the stratigraphic series was 
 shown to determine whether the yielding would be by 
 mashing, competent folding, or breakage and overthrust. 
 The problem of mountain structures was thus brought 
 into the realm of mechanics. These results were pub- 
 lished in three sources in 1893, — the Transactions of the 
 
KNOWLEDGE OF EARTH STRUCTURE 189 
 
 American Institute of Mining Engineers, tlie thirteenth 
 annnal report of the United States Geological Survey, 
 and the Journal (46, 257, 1893). 
 
 Finally should be noted the contributions of the Lake 
 Superior school of geology, in which the work of Van 
 Hise stands preeminent. Under the economic stimulus 
 given by the discovery and development of enormously 
 rich bodies of iron ore, hidden under Pleistocene drift 
 and involved in the complex structures of vanished moun- 
 tain systems of ancient date, structural geology and met- 
 amorphism have become exact sciences to be drawn upon 
 in the search for mineral wealth and yielding also rich 
 returns in a fuller knowledge of early periods of earth 
 history. 
 
 Crust 3Iov€ments as Revealed by Physiography, 
 
 During the last quarter of the nineteenth century 
 another division of geology, dominantly American, was 
 taking form and growth, — the science of land forms, — 
 physiography. The history of that development is 
 treated by Gregory in the preceding chapter but some of 
 its bearings upon theory, in so far as they affect the sub- 
 ject of mountain origin, are necessarily given here. 
 
 Powell, Dutton, and Gilbert in their explorations of the 
 West saw the stupendous work of denudation which had 
 been carried to completion again and again during the 
 progress of geologic time. The mountain relief conse- 
 quently may be much younger than the folding of the 
 rocks, and may be largely or even wholly due to recurrent 
 plateau movement, a doctrine to which Dana had pre- 
 viously arrived. But the introduction of the idea of the 
 peneplain opened up a new field for exploration in the 
 nature and date of crust movements. Davis by this means 
 began to study the later chapters of Appalachian history, 
 the most important early paper being published in 1891.' '^ 
 Since then Davis, Willis, and many others have found 
 that, girdling the world, a large part of the mountainous 
 relief is due to vertical elevatory forces acting over 
 regions of previous folding and overthrust. In addition, 
 great plateau areas of unfolded rocks have been bodily 
 lifted one to two miles, or more, above their earlier levels. 
 
 13 
 
190 A CENTURY OF SCIENCE 
 
 They may be broad geanticlinal arches or bounded by the 
 walls of profound fractures. 
 
 The linear mountain systems made from deep troughs 
 of sediments have come then to be recognized as but one 
 of several classes of mountains. This class, from its 
 clear development in the Appalachians, and the fact that 
 many of the laws of mountain structure pertaining to it 
 were first worked out there, has been called by Powell the 
 Appalachian type (12, 414, 1876). A classification of 
 mountain systems was proposed by him in which moun- 
 tains are classified into two major divisions, those com- 
 posed of sedimentary strata altered or unaltered, and 
 those composed in whole or in part of extravasated mate- 
 rial. The first class he subdivides into six sub-classes 
 of which the folded Appalachians illustrate one. It 
 appears to the writer that Powell's classification gives 
 disproportionate importance to certain types which he 
 described; but nevertheless, the fact that such a classi- 
 fication was made, indicates the growth of a more com- 
 prehensive knowledge of mountains, — their origin, struc- 
 ture, and history. 
 
 Ilelations of Crnst 3Iovements to Density and Equilibrium. 
 
 A recent important development in the fields of geo- 
 physics and major crust movements consists in the incor- 
 poration into geology of the doctrine of isostasy. The 
 evidence was developed in the middle of the nineteenth 
 century by the geodetic survey of India which indicated 
 that the Himalayas did not exert the gravitative influence 
 that their volume called for. It was clear that the crust 
 beneath that mountain system was less dense than 
 beneath the plains of India and still less dense than the 
 crust beneath the Indian Ocean. This relation between 
 density and elevation indicated some approach to flota- 
 tional equilibrium in the crust, comparable in its nature 
 though not in delicacy of adjustment to the elevation of 
 the surface of an iceberg above the ocean level owing to 
 its depth and its density, less than that of the surround- 
 ing medium. This important geological conception was 
 kept within the confines of astronomy and geodesy, how- 
 ever, until Button in 1876, but especially in 1889, brought 
 
KNOWLEDGE OF EARTH STRUCTURE 191 
 
 it into. the geologic field. A test of isostasy was made for 
 the United States by Putnam and Gilbert in 1895 and 
 much more elaborate investigations have since been made 
 by Hayford and Bowie. These investigations demon- 
 strate the importance and reality of broad warping 
 forces acting vertically and related to the regional varia- 
 tions of density in the crust. 
 
 There are consequently two major and unrelated 
 classes of forces involved in the making of mountain 
 structures, — the irresistible horizontal compressive 
 forces, arising apparently from condensation deep within 
 the earth, and vertical forces originating in the outer 
 envelopes and tending toward a hydrostatic equilibrium. 
 In this latter field of investigation, America, since the 
 initial paper by Button, has taken the lead. 
 
 Conclusion on Contribution s of America to Theories of 
 Orogeny, 
 
 The sciences arose in Europe, but those which treated 
 of the earth were still in their infancy when transplanted 
 to America. The first comprehensive ideas on the nature 
 of mountain structures arose in Great Britain and 
 France. These ideas served as a guide and stimulus to 
 observation in the recognition of deformations in the 
 strata of the Appalachian system. Since 1840, however, 
 America has ceased to be a pupil in this field of research 
 but has joined as an equal with the two older countries. 
 New ideas have been contributed, new and striking illus- 
 trations cited, first by the scientists of one nation, next by 
 those of another. The composite mass of knowledge has 
 grown as a common possession. Nevertheless, a review 
 of the progress since 1840 as measured by the contribu- 
 tion of new ideas shows on the whole America at least 
 equal to its intellectual rivals, and at certain times 
 actually the leader. This is true of the science of geol- 
 ogy as a whole and also of the subdivision of orogeny. 
 
 Thus far no mention has been made of German geolo- 
 gists, with the exception of Suess, an Austrian. German 
 geology is voluminous and the names of many well-known 
 geologists could be cited. But this article has sought 
 to trace the origin and growth of fundamental ideas. 
 
192 A CENTURY OF SCIENCE 
 
 The Germans have been assiduous observers of detail; 
 preeminent as systematizers and classifiers, seldom orig- 
 inators. Even petrology, which might be regarded as 
 their especial field, was transplanted from Great Britain. 
 In the science of mountains they have followed in their 
 fundamental ideas especially the French. 
 
 Turning to the mediums of publication through which 
 this progress of knowledge in earth structures has been 
 recorded, the American Journal of Science stands fore- 
 most as the only continuous record for the wdiole century 
 in American literature, fulfilling for this country what the 
 Quarterly Journal of the Geological Society has done for 
 Great Britain since 1845, and the Bulletin de la Societe 
 Geologique for France since 1830. 
 
 Notes. 
 
 ^ H. D. Rogers, Geology of New Jersey, Final Report, p. 115, 1S40. 
 
 ' H. D. Rogers, Geology of Pennsylvaaiia, vol. 2, pt. II, pp. 761, 762, 1858. 
 
 ' Connecticut Academy of Arts and Sciences, 1810 ; quoted by G. P. 
 Merrill in Contributions to the History of North American geology, Ann. 
 Rpt. Smithsonian Institution for 1904, p. 216. 
 
 * A Sketch of the geology, mineralogy, and scenery of the regions con- 
 tiguous to the river Connecticut; with a geological map and drawings of 
 organic remains; and occasional botanical notices, the Journal, 6, 1-86, 
 201-236, 1823; 7, 1-30, 1824. 
 
 " Clarence King, D. S. Geol. Exploration of the Fortieth Parallel, vol. 
 1, pp. 16, 44-48, 1878. 
 
 " Illustrations of the Huttonian Theory of the Earth, pp. 219-238, 1802. 
 
 ' Robert Jameson, Elements of Geognosy, pp. 55-57, 1808. 
 
 " G. P. Merrill, Contributions to the History of American Geology. 
 Report of the U. S. National Museum for 1904, p. 328. 
 
 " H. D. Rogers, Geology of Pennsylvania, vol. 2, p. 916, 1858. 
 
 '° James Hall, Natural History of New York, Paleontology, vol. 3, pp. 
 51-73, 1859. 
 
 "The Journal, 5, 423-443, 474, 475; 6, 6-14, 104-115, 161-172, 304, 381, 
 382, 1873. 
 
 '- C. R. Van Hise, Principles of North American Pre-Cambrian Geology, 
 U. S. Geol. Surv., 16th Ann. Report, pt. I, pp. 607-612, 1896. 
 
 1' W. N. Rice, On the use of the words syuelinorium and anticlinorium, 
 Science, 23, 286, 287, 1906. 
 
 " C. E. Button, Critical observations on theories of the earth's physical 
 evolution. The Penn Monthly, May and June, 1876. 
 
 1' B. Willis, Research in China, vol. 2, 1907. 
 
 "Joseph Barrel!, Science, 39, 259, 260, 1909; Jour. Geol., 22, 672-683, 
 1914. 
 
 " T. C. Chamberlin, Geology, vol. 1, pp. 541, 542, 1904. 
 
 '=W. M. Davis, The geological dates of origin of certain topographic 
 forms on the Atlantic slope of the United States, Geol. Soe. Am Bull 2 
 541-542, 545-586, 1891. 
 
A CEIVTURY OF GOVERNMENT GEOLOGICAL. 
 
 SURVEYS 
 
 By GEORGE OTIS SMITH 
 
 Director of tbe United States Geological Surrey 
 
 EATHjST a Federal Bureau must be considered a 
 product of evolution : the past of the United States 
 Geological Survey far antedates March 3, 1879. 
 The scope of endeavor, the refinement of method, and 
 especially the personnel of the newly created service of 
 that day were largely inherited from pioneer organiza- 
 tions. Therefore a review of the country's record of 
 surveys under Government auspices becomes more than 
 a grateful acknowledgment by the present generation of 
 geologists of the credit due to those who blazed the way; 
 it shows the sequence and progress in the contributions 
 made by geelogic science to industry. 
 
 The earlier stages in industrial evolution mentioned by 
 Hess^ — exploitation, dcA^elopment, and maturity — deter- 
 mine a somewhat similar progressive development in 
 geologic investigation, so that geographic exploration 
 and geologic reconnaissance of the broadest type are the 
 normal contribution of exact science whenever and 
 wherever a nation is in the state of exploitation and 
 iilitial development of its mineral and agricultural 
 resources. The refinements of detailed surveys and 
 quantitative examinations belong rather to the next stage 
 of intensive utilization, or, indeed, they are the essentials 
 preliminary to full use. Thus regrets that the results of 
 present-day work were not available fifty years ago are 
 largely vain : the fathers may not have been without the 
 vision; they simply did the work as their day and gener- 
 ation needed it done. 
 
194 A CENTURY OF SCIENCE 
 
 Twenty years ago S. F. Emmons, in a presidential 
 address before the Geological Society of Washington, 
 divided the history of Governmental surveys m this 
 countrv into two periods, separated in a general way by 
 the Civil War. The first of these was the period of geo- 
 graphic exploration, the second that of geologic explora- 
 tion. Mr. Emmons of course regarded this subdivision 
 as not hard and fast, yet his dividing line seems logical, 
 for not only did the military activities in the East neces- 
 sarily suspend exploration in the West, but after the war 
 national, political, and economic considerations led nat- 
 urally to the demand for a more exact knowledge of the 
 vast national domain in the West. Geography and geol- 
 ogy are so closely related that Mr. Emmons's distinction 
 of the two periods is useful only with the limitations 
 iiiferentially set by himself — namely, that while geologic 
 investigation entered into most of the explorations of the 
 earlier period, the geologist was regarded as only an 
 accessory in these exploring expeditions ; on the other 
 hand, in the later surveys the topographic work was 
 developed because it was essential to the geologic 
 investigations. 
 
 The year 1818 was a notable one in American geology, 
 first of all in the appearance of the American Journal of 
 Science, itself so perfect a vehicle for geological thought 
 that, as is so well stated by Dr. G. P. Merrill, ' ' a perusal 
 of the numbers from the date of issue down to the present 
 time will alone afford a fair idea of the gradual progress 
 of American geology." The beginning of publications 
 on New England geology appeared that year in Edward 
 Hitchcock's first paper on the Connecticut Valley (1, 105, 
 1818) and the Danas' (S. L. and J. F.) detailed geologic 
 and mineralogic description of Boston and vicinity; and 
 the "Index" of Amos Eaton (noticed in this Journal, 1, 
 G9) was the first of that long list of notable contributions 
 to American stratigraphy that are to be credited to the 
 New York geologists. 
 
 In the present discussion, too, the year 1918 can be 
 regarded as in a way the centennial of Government geo- 
 logic surveys, for_it was in 1818 that Henry R. School- 
 craft began his trip to the Mississippi Valley — perhaps 
 the first geologic reconnaissance into the West — and it 
 
GOVERNMENT GEOLOGICAL SUEA^EYS 195 
 
 was his work in the lead region which served to make him 
 a member of the Cass expedition sent out by the Secre- 
 tary of War in 1820 to examine the metallic wealth of the 
 Lake Superior region. The earlier Government explora- 
 tions of Lewis and Clark, in 1803-7, and of Pike, in 1805-7, 
 were so exclusively geographic that geologic work under 
 Federal auspices must be regarded as beginning with 
 Schoolcraft and with Edwin James, the geologist of the 
 expedition of ]\Iajor Long in 1819-20 to the Rocky Moun- 
 tains. Both these observers published reports that are 
 valuable as contributions to the knowledge of little- 
 known regions. 
 
 Any description of geologic work under the Federal 
 Government that included no reference to the State 
 surveys would be inadequate, for in both date of 
 execution and stage of development the work of the State 
 geologists must be given precedence. In Merrill's Con- 
 tributions to the History of American Geology,- whose 
 modest title fails even to suggest that this work not only 
 furnishes the most useful chronologic record of the 
 progress of the science on the American continent but is 
 in fact a very thesaurus of incidents touching the per- 
 sonal side of geology, the author by his division of his 
 subject shows that four decades of the era of State sur- 
 veys elapsed before the era of national surveys began. 
 
 Thus the geologic survej'-s of some of the Eastern 
 States antedate by several decades any Federal organ- 
 ization of comparable geologic scope, and in investiga- 
 tions directed to local utilitarian problems these pioneer 
 geologists working in the older settled States of the 
 East were in fact already conducting work as detailed in 
 type as much of that attempted by the Federal geologists 
 of the later period. Even to-day it is true in a general 
 way that the State geologist can and should attack many 
 of his local problems with intensive methods and with 
 detail of results that are neither practicable nor desirable 
 for the larger interstate investigations or for examina- 
 tions in newer territory. All this relation of State and 
 Federal work must be looked upon as normal evolution- 
 ary development of geologic science in America. 
 
 One who reads the names of the Federal geologists of 
 the early days, beginning with Jackson and Owen and 
 
196 A CENTURY OF SCIENCE 
 
 following- with such leaders in Federal work as Gilbert, 
 Chamberlin, King, R. D. Irving, Pumpelly, Van Hise, 
 and Walcott, may note that these were all connected in 
 their earlier work with State surveys. Nor has the rela- 
 tion been one-sided, for among the State geologists 
 Whitney, Blake, Mather, Newberry, J. G. Norwood, Pur- 
 due, Bain, Gregory, Ashley, Kirk, W. H. Emmons, 
 DeWolf, Mathews, Brown, Landes, IMoore, and Crider 
 received their field training in part or wholly as members 
 of a Federal Survey. Moreover, under the present plan 
 of effective cooperation of several of the State surveys 
 with the United States Geological Survey, it is often dif- 
 ficult to differentiate between the two in either personnel 
 or results, for it even happens that the publishing organ- 
 ization may not have been the major contributor. The 
 full record of American geology, past and present, can 
 not be set forth in terms of Federal auspices alone. 
 
 The three decades preceding the Civil War, then, con- 
 stitute the era of State surveys, well described by Mer- 
 rill as at first characterized by a contagious enthusiasm 
 for beginning geologic work, later by a more normal 
 condition in which every available geologist seems to 
 have been quietly at work, and finally by renewed activity 
 in creating new organizations. The net result was that 
 Louisiana and Oregon seem to have been the only States 
 not having at least one geological survey. 
 
 The first specific appropriation by the Federal Govern- 
 ment for geologic investigation appears to have been 
 made in 1834, when a supplemental appropriation for 
 surveys of roads and canals under the War Department, 
 authorized in 1824, contained the item "of which sum 
 five thousand dollars shall be appropriated and applied 
 to geological and mineralogical survey and researches." 
 In July, 1834, Mr. G. W. Featherstonhaugh was appointed 
 United States geologist and employed under Colonel 
 Abert, U. S. Topographical Engineers, to "personally 
 inspect the mineral and geological character" of the pub- 
 lic lands of the Ozark Mountain region. Overlooking 
 the incidental fact that this Englishman — a man of 
 scientific attainment and large interest in public affairs — 
 was never naturalized,^ it must be placed to the credit of 
 this first of United States geologists that within seven 
 
From '^Contributions to the History of American <ieoIo^^y " 
 
 by '.Teor^e V. Merrills. 
 
GOVERNMENT GEOLOGICAL SURVEYS 197 
 
 months he completed his field work and returned to 
 Washington, and on February 17, 1835, his report was 
 transmitted to Congress. Two years earlier Feather- 
 stonhaugh had memorialized Congress for aid in the 
 preparation of a geologic map of the whole territory of 
 the United States, and in connection with this project he 
 suggested that geology as an aid to military engineering 
 should have a place in the curriculum at West Point. 
 This first United States geologist also appears to have 
 combined an appreciation of the practical worth of ' ' the 
 mineral riches of our country, their quality, quantity, 
 and the facility of procuring them," with an interest in 
 the more scientific side of geology, though his hypotheses 
 regarding both economic geology and stratigraphic and 
 structural geology have not won the endorsement of all 
 later workers in the same regions. In all these respects, 
 however, Featherstonhaugh may stand as a fairly good 
 prototype. His contributions to international affairs 
 subsequent to his scientific service to the United States 
 are of interest; he served as one of Her Majesty's com- 
 missioners in the settlement of the Canadian-United 
 States boundary question in 1839-40 and made an exam- 
 ination of the disputed area, and after the settlement of 
 this controversy he was appointed British Consul for the 
 Department of the Seine, France, where in 1848 he per- 
 sonally engineered the escape of Louis Philippe from 
 Havre. 
 
 The Federal geologic work thus started was soon con- 
 tinued in surveys of wider scope and more thorough 
 accomplishment. The position of the Government as the 
 proprietor of mineral lands in the Upper Mississippi 
 Valley led to their examination. These Government 
 lands containing lead had been reserved from sale for 
 lease since 1807, although no leases were issued until 1822. 
 The amount of illegal entry and consequent refusal of 
 smelters and miners to pay royalty after 1834 forced the 
 issue upon the attention of Congress, and in 1839 Presi- 
 dent Van Buren was requested to present to Congress a 
 plan for the sale of the public mineral lands. In carrying 
 out this policy Dr. David Dale Owen was selected to 
 make the necessary survey. 
 
 Owen had served as an assistant on the State Survey 
 
198 A CENTURY OF SCIENCE 
 
 of Tennessee and as the first State geologist of Indiana, 
 and he organized the new work promptly and effectively. 
 Although suffering from the handicap unfortunately 
 known by geologists of the present day — the receipt late 
 in the season (August 17, 1839) of authority to begin 
 work — within exactly a month he had his force of 139 
 assistants organized into 24 field parties, instructed in 
 "such elementary principles of geology as were neces- 
 sary to their performance of the duties required of 
 them." His plan of campaign provided for a northward 
 drive at a predetermined rate of traverse for each party, 
 with periodic reports to himself at appointed stations, 
 "to receive which reports and to examine the country in 
 person" he crossed the area under survey eleven times. 
 The result of such masterful leadership was the comple- 
 tion of the exploration of all the lands comprehended in 
 his orders in two months and six days, and his report on 
 this great area — about 11,000 square miles — bears date 
 of April 2, 1840. 
 
 Eight years later Doctor Owen made a survey of an 
 even larger area, continuing his examination northward 
 to Lake Superior. Again his report was published 
 promptlj'', and he continued for several years his exam- 
 ination of the Northwest Territory, submitting his final 
 report in 1851. It is interesting to note that in his 
 earlier report Doctor Owen subscribed himself as "Prin- 
 cipal Agent to explore the Mineral Lands of the United 
 States, ' ' but that in the later report he was " U. S. Greolo- 
 gist for Wisconsin." The two surveys together covered 
 57,000 square miles. 
 
 During the same period similar surveys were being 
 made in northern Michigan by Dr. Charles T. Jackson, 
 1847-48, and Foster and Whitney, 1849-51. These sur- 
 veys also had been hastened by the "copper fever" of 
 1844-46, with wholesale issue of permits and leases. Con- 
 gress in 1847 authorizing the sale of the mineral lands 
 and a geological surA^ey of the Lake Superior district. 
 The execution of these survej^s under Jackson and under 
 Foster and "Wliitney and the prompt publication in 1851 
 of the maps of the whole region materially helped to 
 establish copper mining on a more conservative basis. 
 
GOVERNMENT GEOLOGICAL SURVEYS 199 
 
 and the development of the Lake Superior region 
 was rapid.'' 
 
 These land-classification surveys, with their definite 
 purpose, represent the best geologic work of the time. 
 The plan necessitated thoroughgoing field work with con- 
 siderable detail and prompt publication of systematic 
 reports, and in the working up of the results specialists 
 like James Hall and Joseph Leidy contributed, while 
 F. B. Meek was an assistant of Owen. It is worthy of 
 note that had not Doctor Houghton, the State geologist of 
 Michigan, met an untimely death in 1847, effective coop- 
 eration of the State Surve^^ with the Federal officials 
 Avould have combined geologic investigation with the 
 execution of the linear surveys.® 
 
 Belonging to the same period of geologic exploration 
 was the service of J. D. Dana, as United States Geologist 
 on the Wilkes Exploring Expedition, the disaster to 
 which compelled his return from the Pacific Coast over- 
 land and resulted in his geologic observations on Oregon 
 and northern California. 
 
 The military expeditions during the decade 1850-60 
 and the earlier expeditions of Fremont add^d to the 
 geographic knowledge of the Western country and also 
 contributed to geologic science, largely through collec- 
 tions of rocks and fossils, usually reported on by the 
 specialists of the day. Thus the names of Hall, Con- 
 rad, Hitchcock, and Meek appear in the published 
 reports on these explorations, while Marcou, Blake, 
 Newberry, Gibbs, Evans, Hayden, Parry, Shumard, 
 Schiel, Antisell, and Engelmann were geologists attached 
 to the field expeditions. In 1852 geologic investigation 
 was seemingly so popular as to necessitate the statutory 
 prohibition "there shall be no further geological survey 
 by the Government unless hereafter authorized by law.". 
 
 Certain of these explorations had a specific pur- 
 pose: several of them sought a practical route for 
 a transcontinental railroad; another a new wagon 
 road across Utah and Nevada; and one under 
 Colonel Pope, with G. G. Shumard as geologist, Avas 
 sent out "for boring Artesian Wells along the line 
 of the 32d Parallel" in New Mexico. The pub- 
 
200 A CENTURY OF SCIENCE 
 
 lislied reports varied greatly in scientific value and m 
 carefulness of preparation, while the publication of at 
 least two reports was delayed until long after the war, 
 and the manuscript of another was lost. The report of 
 the expedition of Major Emory contained a colored 
 geologic map of the western half of the country, a pioneer 
 publication, for the map prepared by Marcou extended 
 only to the 106th meridian. 
 
 Thus in the first period of Government surveys, cover- 
 ing about forty years, the great West, with its wealth of 
 public lands, was well traversed hj exploratory surveys, 
 which furnished, however, only general outlines for a 
 comprehension of the stratigraphy and structure of 
 mountain and valley, plain and plateau. To an even less 
 degree was there any realization of the economic possi- 
 bilities of the vast territory west of the Mississippi. 
 President Jefferson, in planning the Lewis and Clark 
 expedition, had stated his special interest in the mineral 
 resources of the region to be traversed. Nearly forty 
 years later Doctor Owen was strongly impressed with 
 the commercial promise of the region he surveyed. His 
 reports contain analyses of ores and statistics of produc- 
 tion; he compared the lead output of Wisconsin, Iowa, 
 and Illinois with that of Europe and foretold the value 
 of the iron, copper, and zinc deposits of the area; he 
 outlined the extent of the Illinois coal field; and he laid 
 equal emphasis upon the agricultural possibilities of the 
 region. Indeed, so optimistic were Owen's general con- 
 clusions that he referred to his separate township plats, 
 with their detailed descriptions, as the basis for his san- 
 guine opinions, realizing that "the explorer is apt to 
 become the special pleader." With equal breadth of 
 view and thoroughness of execution the survej^s of Fos- 
 ter and Whitney laid the foundation for the development 
 of the copper and iron resources of the Lake Superior 
 region, and although these areas were largely wilderness 
 and not adapted to rapid traverse or easy observation 
 the reports on their explorations nevertheless compare 
 most favorably with the contributions of geologists work- 
 ing in the more hospitable regions in the older States. 
 
 The period following the Civil War naturally became 
 one of national expansion, the faces of many were turned 
 
GOVERNMENT GEOLOGICAL SURVEYS 201 
 
 westward, and exploration of the national domain for its 
 industrial possibilities took on fresh interest. Home- 
 seekers and miners largely made up this army of peace- 
 ful invasion, and the winning of the West began on a 
 scale quite different from that of the days of the military 
 path-finding expeditions of Fremont and other Army 
 officers. Thus the nation was aroused to the task of 
 investigating its public lands and Congress gave the sup- 
 port needed to make geologic exploration possible on a 
 large scale. 
 
 Geologic surveys of a high order were continued 
 in the older States, as shown by the contributions 
 during this period of J. P. Lesley and G. H. Cook in 
 the East, W. C. Kerr, E. W. Hilgard, and E. A. 
 Smith in the South, and J. S. Newberry, C. A. 
 White, Raphael Pumpelly, T. C. Chamberlin, Alex- 
 ander Winchell, and T. B. Brooks in the Central States. 
 To the north the Canadian Survey, organized in 1841 
 under Logan, had continued under the same sturdy 
 leadership until 1869, when the experienced and talented 
 Doctor Selwyn became Director. As contrasted with the 
 short careers of most of the State Surveys and with the 
 temporary character of all of the Federal undertakings 
 in geologic investigation, the continuance of the Cana- 
 dian Geological Survey for more than half a century 
 under two directors gave opportunity for continuity of 
 effort in making kno^vn to the people of the Dominion its 
 resources and at the same time contributing to the world 
 much pure science. 
 
 Passing with simple mention the two Government expe- 
 ditions into the Black Hills, which afforded opportunity 
 for geologic exploration by N. H. Winchell in 1874 and by 
 Jenney and Newton in 1875, the record of geologic work 
 under Government auspices in the period immediately 
 following the Civil War groups itself around the names 
 of four leaders — Hayden, King, Powell, and Wlieeler. 
 The four organizations, distinguished commonly by the 
 names of these four masterful organizers, occupied the 
 Western field more or less continuously from 1867 to 1878, 
 and the sum total of their contributions to geography 
 and geology was large indeed. In the words of Clarence 
 King,'' "Eighteen hundred and sixty-seven, therefore, 
 
202 A CENTUEY OF SCIENCE 
 
 marks, in the history of national geological work, a_ turn- 
 ing point, when the science ceased to l3e dragged in the 
 dust of rapid exploration and took a commanding posi- 
 tion in the professional work of the country. ' ' Together 
 these four expeditions covered half a million square 
 miles, or more than a third of the area of the United 
 States west of the one-hundredth meridian, and the cost 
 of all this work was approximately two million dollars, 
 which was a small fraction of its value to the nation 
 counting only the impetus given to settlement and utili- 
 zation. 
 
 As viewed from a distance of nearly half a century, 
 these four surveys differed much in plan of organization, 
 scope of purpose, and success of execution, so that com- 
 parison would have little value except as possibly bear- 
 ing upon the work of the larger organization which 
 followed them and became the heir not only to much that 
 had been attained by these pioneer surveys but also to 
 the great task uncompleted by them. So, if in the 
 earliest days of the present United States Geological 
 Survey there may have been a certain partisanship in 
 tracing derived characters in the new organization, it is 
 even now worth while to recognize the real origin of 
 much that is credited to present-day development. 
 
 Dr. F. V. Hayden was the first of these Survey leaders 
 to engage in geological exploration. He visited the Bad- 
 lands as early as 1853, and his connection with subse- 
 quent expeditions was interrupted only by his service as 
 a surgeon in the Federal Army during the war. In 1867, 
 however, Hayden resumed his geologic work as United 
 States Geologist in Nebraska, operating under direction 
 of the Commissioner of the General Land Office. In the 
 following eleven years the activities of the Hayden Sur- 
 vey — the "Geological and Geographical Survey of the 
 Territories" — extended into "Wyoming, Colorado, New 
 Mexico, Montana, and Idaho, covering with areal sur- 
 veys 107,000 square miles. This Survey, as might be 
 expected from the long experience of its leader, made 
 large contributions to stratigraphy, which involved 
 notable paleontologic work by Cope, Meek, and Les- 
 quereux. Next in importance wa!s the structural work of 
 A. C. Peale, W. H. Holmes, Capt. C. E. Button, and Dr. 
 
GOVERNMENT GEOLOGICAL SURVEYS 203 
 
 Hayden himself, and the influence of these expeditions in 
 popularizing geology should not be overlooked. The 
 expedition of 1871 into the geyser region on the upper 
 Yellowstone resulted in the creation of the first of the 
 national parks. W. H. Holmes began his artistic contri- 
 butions to geology in 1872 with this Survey. Topo- 
 graphic mapping was added to the geologic exploration, 
 James T. Gardner and A. D. Wilson joining the Hayden 
 Survey after earlier service on the King Survey and 
 Henry Gannett being a member of parties, first as astron- 
 omer and later as topographer in charge. The accom- 
 plishment of the Hayden Survey itself and the later work 
 of many of its members show that this organization pos- 
 sessed a corps of strong men. 
 
 The King Survey was a smaller organization, with 
 Congressional authorization of definite scope and a sys- 
 tematic plan of operation. The beginning of construc- 
 tion of the Union Pacific terminated the period of the 
 railroad surveys under the War Department and 
 afforded opportunity for geologic work that would be 
 more than exploratory: the opening up of the new 
 country made investigation of its resources logical. 
 This fact was recognized by Clarence King, who had 
 traversed the same route as a member of an emigrant 
 train with his friend James T. Gardner. His plan to 
 make a geological cross section of the Cordilleras, with a 
 study of the resources along the route of the Pacific rail- 
 roads, won the support of Congress, and the "Geological 
 Exploration of the Fortieth Parallel" was authorized in 
 1867, with Clarence King as geologist in charge, under 
 the Chief of Engineers of the Army. Field work was 
 begun in the summer of that year, and it is interesting to 
 note that Mr. King and his small force of geological 
 assistants — the two Hagues and S. F. Emmons — began 
 at the western end of this cross section, and in this 
 and subsequent years extended the survey from the east 
 front of the Sierra Nevada to Cheyenne, covering a belt 
 of territory about 100 miles in width. This comprehen- 
 sive plan was carried out in the field operations, and the 
 scientific and economic results were systematically 
 worked up in the reports, which appeared in 1870-80. 
 The only departure from this plan was a study of the 
 
204 A CENTURY OF SCIENCE 
 
 volcanic mountains Sliasta, Eainier, and Hood, in 1870, 
 occasioned by an unexpected and unsolicited appropria- 
 tion for field work, and that summer's work resulted in 
 the discovery of active glaciers, the first known within 
 the United States. 
 
 The Fortieth Parallel Survey is to be credited Avith 
 contributions to the knowledge of the stratigraphy of the 
 West, the region traversed being remarkably representa- 
 tive of the stratigraphic column, to which was added the 
 paleontologic work of Marsh, Meek, Hall, and Whitfield, 
 while the attempt was made to interpret the sedimentary 
 record in terms of Paleozoic, Mesozoic, and Tertiary 
 geography. King's plan of survey included large use of 
 topographic mapping with astronomic base and triangu- 
 lation control and contours based upon barometric eleva- 
 tions. The results were pronounced by an unfriendly 
 critic'^ as "very valuable, especially from a geological 
 point of view," but unfortunate in being the forerunner 
 of work in which Government geologists "have presumed 
 to arrogate the control of the fundamental operations of 
 a topographic survey." To the King Survey must be 
 credited the introduction of systematic contour mapping 
 and the iise of contour maps for purposes of geology. 
 In two other respects the King Survey contributed 
 largely to future Government work: microscopical 
 petrography in the United States may be said to have 
 begun with the visit of Professor Zirkel to this country as 
 a member of this Survey in 1875, and the report of J. D. 
 Hague on "Mining Industry" was the fitting expression 
 of the emphasis then put on the study of the mineral 
 resources of this newly opened territory, a subject of 
 investigation that was in large part the true basis of. 
 King's project rather than simply "the immediate 
 excuse for the SurveJ^" An earlier influence in the sci- 
 entific study of ore deposits had come from Von Riclit- 
 hofen's investigation of the Comstock Lode in 1865 and 
 his subsequent work Avith Wliitney in California. The 
 incident of King's relation to the diamond fraud in Ari- 
 zona in 1872 furnished a precedent for public servants of 
 a later day ; he investigated the reported find from scien- 
 tific interest but exposed it with all the zeal of a publicist 
 and truth lover. In a word, the Fortieth Parallel Sur- 
 
^J'V/^, 
 
GOVERNMENT GEOLOGICAL SURVEYS 205 
 
 vey commands our admiration for its brilliant plan, 
 thoroughgoing work in field and office, and high quality 
 of personnel. 
 
 Major J. W. Powell began his large contribution to 
 Government surveys with his exploration of the Grand 
 Canyon in 1869, the Congressional recognition of his 
 expedition being limited to an authorization for the issue 
 of rations by the War Department. Small appropria- 
 tions were made in the following years, and in 1874 full 
 authorization was given for the continuance of his survey 
 in Utah under the Secretary of the Interior and was 
 followed by the adoption of the name "United States 
 Geographical and Geological Survey of the Rocky Moun- 
 tain Region." This organization was the least preten- 
 tious of the four operating during this period — it covered 
 less area, expended less public money, and published much 
 less — but its contribution to American geology is not to be 
 measured by miles or pages but by ideas. Its physical 
 environment favored this survey, and in the work of 
 Powell, Dutton, and Gilbert can be seen the beginnings of 
 physiography on the heroic scale exemplified in the 
 Grand Canyon and the High Plateaus. The first use of 
 terms like "base level of erosion," "consequent and 
 antecedent drainage," and "laccolith" marked the intro- 
 duction of new ideas in the interpretation of land sculp- 
 ture and geologic structure. The daring boat trip of 
 Powell was no less brilliant than his simple explanation 
 of the Grand Canyon itself. 
 
 "The United States Geographical Surveys West of the 
 100th Meridian" was the title given to the explorations 
 made under Lieut. G. M. Wheeler, of the Engineer 
 Corps, which began with topographic reconnaissances in 
 Nevada, Utah, and Arizona, specifically authorized by 
 Congress in 1872. From the standpoint of American 
 geology this could be better known as the Gilbert Survey, 
 Mr. G. K. Gilbert serving for the three years 1871-73, the 
 later part of the time with the title of chief geological 
 assistant. Gilbert's contributions included his descrip- 
 tion of Basin Range structure, his first account of old 
 Lake Bonneville, and his discussion of the erosion phe- 
 nomena of the desert country. J. J. Stevenson also 
 served later as a geologist of this Survey, and A. R. Mar- 
 is 
 
206 A CENTURY OF SCIENCE 
 
 vine, E. E. Howell, E. D. Cope, Jules Marcou, and I. C. 
 Russell were connected with the field parties. Captain 
 ■\A^ieeler's own claim for the w^ork of his Survey empha- 
 sized its geographic side, for he regarded the results as 
 the partial completion of a systematic topographic sur- 
 vey of the country. 
 
 By 1878, when the Fortieth Parallel Survey had com- 
 pleted the work planned by its chief, three of these inde- 
 pendent surveys still contended for Federal support and 
 for scientific occupation of the most attractive portions 
 of the Western country. Unrestrained competition of 
 this kind, even in the public service, proves as wasteful as 
 unregulated competition in private business,^ and Con- 
 gress appealed to the National Academy of Sciences for a 
 plan for Government surveys to ' ' secure the best results 
 at the least possible cost." Under instructions by Con- 
 gress the National Academj^ considered all the work 
 relating to scientific surveys and reported to Congress 
 a plan prepared by a special committee, whose member- 
 ship included the illustrious names of Marsh, Dana, 
 Rogers, Newberry, Trowbridge, Newcomb, and Agassiz. 
 This report, which was adopted by the Academy with 
 only one dissenting vote, grouped all surveys — geodetic, 
 topographic, land parceling, and economic — under two 
 distinct heads, survej^s of mensuration and surveys of 
 geology. At that time five independent organizations in 
 three different departments were carrying on surveys of 
 mensuration, and the Academy recommended that all 
 such work be combined under the Coast and Geodetic 
 Survey with the new name Coast and Interior Survey. 
 For the investigation of the natural resources of the pub- 
 lic domain and the classification of the public lands a 
 new organization was proposed, the United States Geo- 
 logical Survey. The functions of these two surveys and 
 of a third coordinate bureau in the Interior Department, 
 the Land Office, were carefully defined and their inter- 
 relations fully recognized and provided for in the plan 
 presented to Congress. Viewed in the light of 39 years 
 of experience the National Academy plan would be 
 indorsed by most of us as eminently practical, and the 
 report stands as a splendid example of public service ren- 
 dered by America's leading scientists. The legislation 
 
GOVEENMENT GEOLOGICAL SURVEYS 207 
 
 which embodied the entire plan, however, failed of pas- 
 sage in Congress. 
 
 The natural activity behind the scenes of the conflicting 
 interests represented by those connected with the sev- 
 eral surveys may be seen in the legislative history of the 
 moves leading up to the creation of the United States 
 Geological Survey. In the last session of the 45th Con- 
 gress the special legislation embodying the recommenda- 
 tions of the National Academy was included in the 
 Legislative, Executive, and Judicial Appropriation bill 
 as it passed the House of Representatives, while the Sun- 
 dry Civil Appropriation bill carried an item simply mak- 
 ing effective the longer section in the other appropriation 
 bill. The item in the Legislative appropriation bill 
 created the office of the Director of the Geological Sur- 
 vey, provided his salary, and defined his duties, as well 
 as specifically terminating the operations of the three 
 older organizations. The item in the Sundry Civil bill as 
 it passed the House appropriated $100,000 for the new 
 Geological Survey, but when this appropriation bill was 
 reported to the Senate a committee amendment added 
 the words "of the Territories," and further amendments 
 offered on the floor changed the item so as to provide 
 specifically and exclusively for the continuation of the 
 Hayden Survey. Other amendments provided small 
 appropriations for the completion of the reports of the 
 Powell and Wheeler surveys, and the bill passed the Sen- 
 ate in this form. The Legislative Appropriation bill was 
 similarly pruned, while in the Senate, of all reference to 
 the proposed new organization. This bill, however, died 
 in conference, but in the last hours of the session the 
 conferees on the Sundry Civil bill took unto themselves 
 legislative powers and transferred from the dead bill to 
 the pending measure all the language which constitutes 
 the "organic act" of the United States Geological Sur- 
 vey. This action was denounced in the Senate as "a 
 wide departure from the authority that is possessed by 
 a conference committee," and it was further stated in 
 debate that the inserted provision which created a new 
 ofHce and discontinued the existing surveys was one 
 "which neither the Committee of the Senate nor the Sen- 
 ate itself ever saw." This assertion was perhaps par- 
 
208 A CENTURY OF SCIENCE 
 
 liamentarily sound in that the language was new to the 
 Sundry Civil bill, yet actually the Senate had only two 
 days before stricken the same proposed legislation from 
 the pending Legislative Appropriation bill. However, 
 the House conferees — Representatives Atkins of Tennes- 
 see, Hewett of New York, and Hale of Maine — had real- 
 ized their tactical advantage, and the Senate, after a 
 brief debate, voted on March 3 to concur in the report of 
 the committee of conference, thus reversing all their 
 earlier action, in which the friends of the Hayden and 
 Wheeler organizations apparently had commanded more 
 votes than the advocates of the National Academy plan, 
 
 Clarence King was appointed first Director of the 
 United States Geological Survey on April 3, 1879, and 
 began the work of organization. With his proven genius 
 for administration. King promptly resolved the doubt as 
 to the meaning of the term "national domain" in the 
 language defining the duties of the Director by taking the 
 conservative side and limiting the work of the new organ- 
 ization to the region west of the 102d meridian. This 
 region was divided into four geological divisions, and for 
 economy of time and money field headquarters were 
 established for these divisions. The Division of the 
 Rocky Mountains was placed under Mr. Emmons as 
 geologist in charge, the Division of the Colorado under 
 Captain Dutton, the Division of the Great Basin under 
 Mr. Gilbert, and the Di-vision of the Pacific under Arnold 
 Hague. The Division of the Colorado was intended as 
 merely temporary for the purpose of bringing to comple- 
 tion the scientific work of the Powell Survey. Similarly 
 Dr. Hayden was given the opportunity to prepare a sys- 
 tematic digest of his scientific results. This organ- 
 ization of the work and the selection of geolo- 
 gists in charge showed the relation of the new and the 
 old, and a glance at the personnel of the new Survey 
 indicates the extent to which the geologic investigation 
 of the Western country was to continue without interrup- 
 tion. Of the twenty-four geologists and topographers 
 listed in the first administrative report, four had been 
 connected with the Powell Survey, two with the Hayden, 
 three with the Wlieeler, and five with the King Survey. 
 
 In planning the initial work of the United States 
 
ik<u^6o^ U. 
 
GOVERNMENT GEOLOGICAL SURVEYS 209 
 
 Geological Survey, the Director speaks of the "most 
 important geological subjects" and "mining industries," 
 of "instructive geological structure" and "great bullion 
 yield" in the same sentences, so that the intent was plain 
 to make the geologic investigations both theoretical and 
 practical. 
 
 It was expected that the field of operations of this 
 Federal Survey would be at once extended by Congress 
 over the whole United States, but the measure making 
 this extension, which would simply carry out the intent 
 of the framers of the legislation creating the new bureau, 
 passed the House alone, and it was only by subsequent 
 modification of the wording of appropriation items that 
 the United States Geological Survey became national in 
 scope as well as in name. The critical question of the 
 effective coordination of State and Federal geologic sur- 
 veys was met by Director King, who corrected an errone- 
 ous impression "industriously circulated" by stating 
 his policy to be to urge the inauguration and continuance 
 of State surveys.'' This was the initial step in the 
 cooperation between State and Federal surveys which 
 became effective on a large scale in subsequent years. 
 
 Though the Geological Survey has extended its opera- 
 tions over the whole United States, its largest activities 
 have always been directed toward the exploration and 
 development of the newer territory in the public-land 
 States. All four of its directors had their field training 
 in the West : the name of Major Powell, who succeeded 
 King in 1880, is inseparably connected with scientific 
 exploration ; Charles D. Walcott, who was Director from 
 1894 to 1907, the period of the Survey's greatest expan- 
 sion, made the largest contribution to the Paleozoic stra- 
 tigraphy and paleontology of the West ; and the present 
 Director spent seven field seasons in the Northern Cas- 
 cades and one in a mining district in Utah. The scope of 
 the activities both East and West as developed during 
 the 39 years since the establishment of the new bureau 
 can be best described, perhaps, in terms of its present 
 functions as expressed in the organization of to-day. 
 
 The growth of the Survey is measured in the increase 
 of annual appropriation from $106,000 in 1879-80 to the 
 amount available for the current year— $1,925,520, not 
 
210 A CENTURY OF SCIENCE 
 
 including half a million dollars from War Department 
 appropriations being spent in the topographic work of 
 the Survey. The corresponding increase in personnel 
 has been from 39, listed in the first report, to 911 holding 
 regular appointments at the present time, divided among 
 the different branches as follows : A scientific force of 
 173 in the Geologic Branch, 169 in the Water Resources 
 Branch, 71 in the Topographic Branch, and 15 in the 
 Land Classification Board, with a clerical force of 168 
 divided among the same branches, and the remainder 
 the technical and clerical employees of the publication 
 and administrative branches. These personnel statistics 
 are not expressive of normal conditions, since a large 
 number of the topographic engineers are commissioned 
 officers and thus are not included on the civilian roll, 
 while, on the other hand, the classification of the stock- 
 raising homestead lands makes the technical force of the 
 Water Resources Branch unusually large this year. 
 
 The primary aim of the Geological Survey is geo- 
 logic, whether directed by authority of law toward 
 the "examination of the geological structure, mineral 
 resources, and products of the national domain," toward 
 the preparation of the authorized "reports upon gen- 
 eral and economic geology and paleontology," of the 
 "geologic map of the United States," or of the "report 
 on the mineral resources of the United States," or 
 toward the "continuation of the investigation of the 
 mineral resources of Alaska" or "chemical and physi- 
 cal researches relating to the geology of the United 
 States." The spirit and the purpose of the Sur- 
 vey's work in all these fields are not believed to have 
 materially changed from those of the founders of the 
 science in America. From time to time too much empha- 
 sis may have appeared to be laid upon applied geology as 
 contrasted with pure science, yet the report of the 
 National Academy to Congress in terms placed the stress 
 upon economic resources and referred to paleontology as 
 "necessarily connected" with general and economic 
 geology. The practical purpose of geologic research 
 under Government auspices must be recognized by the 
 administrator, whether he be the paleontologist like Wal- 
 
GOVERNMENT GEOLOGICAL SURVEYS 211 
 
 cott, the philosopher like Powell, or the mining geologist / 
 like King. That the task of steering the true course is 
 no new problem can be seen from the statement of Owen^" 
 written 70 years ago, and these words describe conditions 
 of Government geological work even to-day : 
 
 Scientific researches, wliicli to some may seem purely specu- 
 lative and curious, are essential as preliminaries to these 
 practical results. Further than such necessity dictates, they 
 have not been pushed, except as subordinate and incidental, 
 and chiefly at such periods as, under the ordinary requirements 
 of public service, might be regarded as leisure moments ; so that 
 the contributions to science thus incidentally afforded, and which 
 a liberal policy forbade to neglect, may be considered, in a 
 measure, a voluntary offering, tendered at little or no additional 
 expense to the department. 
 
 The increased attention given to mineral resources has ' 
 been a matter of gradual growth. Mr. King early 
 organized a Division of Mining Geology with Messrs. 
 Pumpelly, Emmons, and Becker as geologists in charge, 
 to whom were assigned the collection of mineral statis- 
 tics for the Tenth Census. These Survey geologists and 
 Director King himself held appointments as special 
 agents of the Census Bureau, and on the staff selected for 
 this work appear the names of T. B. Brooks, Edward 
 Orton, T. C. Chamberlin, Eugene A. Smith, George 
 Little, J. R. Proctor, R. D. Irving, N. S. Shaler, 
 John Hays Hammond, Bailey Willis, and G. H. Eldridge, 
 indicating the extent to which the supervision of these 
 inquiries was placed in the hands of economic geologists. 
 This procedure was reverted to by Director Walcott and 
 in the last ten years has become a well-established policy, 
 the statistics of annual production of all the important 
 mineral products being under the charge of geologists, as 
 best qualified to comprehend the resources of the coun- 
 try. Another of these special assistants in 1880 was 
 Albert Williams, Jr., who became the first chief of the 
 Division of Mineral Resources, in 1882. The study of i 
 ore deposits, which may be said to have begun with the j 
 King Survey, was inspired by King's own appreciation ; 
 of the broad geologic relations of the distribution of 
 mineral wealth and by the detailed studies of individual 
 
212 A CENTURY OF SCIENCE 
 
 mining districts by his associates, "based upon facts 
 accurately determined in the light of modern geology." 
 
 Geological surveys have been prosecuted in Alaska 
 since 1895, and in the last few years the annual appro- 
 priation for the work has been the same as that made for 
 the expenses of the whole Survey in the tirst year of its 
 history. The Division of Alaskan Mineral Resources is in 
 fact a geological survey in itself, except that it shares in 
 the administrative machinery of the larger organization 
 and has the advantage of the cooperation of the scientific 
 specialists of the Survey as they may be needed to sup- 
 plement its own force. All the investigations in this dis- 
 tant part of the country represent the Geological Survey 
 at its best, for here the organization's long experience in 
 the Western States can be applied to most effective and 
 helpful work on the frontier, where the geologist and 
 topographer in their exploration do not always follow 
 the prospector but often precede him. Undoubtedly no 
 greater factor has contributed to the development of 
 Alaskan resources than this pioneer work of the Federal 
 Survey, yet the work has also contributed notable addi- 
 tions to the sciences of geology and geography. 
 
 The first duty laid upon the Director of the Geological 
 Survey in the law of 1879 was "the classification of the 
 public lands," and this phrase undoubtedly expressed the 
 idea of the committee of the National Academy. The 
 same legislation, however, contained provision for the 
 further consideration by a commission of the classifica- 
 tion and valuation of the public lands, as also recom- 
 mended by the National Academy. Thus the decision of 
 Director King that the classification intended by Con- 
 gress was scientific and was intended for general informa- 
 tion and not to aid the Land Office in the disposition of 
 land by sale or otherwise was really based upon the 
 deliberate opinion of the Public Lands Commission,- of 
 which he was a member, that classification would seri- 
 ously impede rapid settlement of the unoccupied lands. 
 Nearly forty years later those who are intrusted with the 
 land-classification work of the Geological Survey recog- 
 nize this familiar argument, which undoubtedly had much 
 more force in that earlier stage of the utilization of the 
 
GOVERNMENT GEOLOGICAL SURVEYS 213 
 
 Nation's resources of land.^i The conception of land 
 classification as a business policy on the part of the Gov- 
 ernment as a landed proprietor belongs rather to this 
 day of more intensive development. At present current 
 public-land legislation calls for highest use, and hence 
 official investigation of natural values and possibilities 
 must precede disposition. Tliis type of mineral and 
 hydrographic classification of public lands has been in 
 progress in increasing amount since 1906, so that now 
 the Geological Survey is the kind of scientific adviser to 
 the Secretary of the Interior and Commissioner of the 
 General Land Office that may have been contemplated by 
 the National Academy of Sciences in 1878. It is plain, 
 however, to everyone at all conversant with Western con- 
 ditions that the recent land-classification surveys in 
 Wyoming, for instance — detailed geologic surveys which 
 form the basis for tlie valuation of public coal lands in 
 40-acre units — would have possessed no utility in 1871, 
 when the coal-land law was passed but when the demand 
 for railroad fuel had just begun. 
 
 The land-classification idea is of course the basis of 
 the National forest and irrigation movements. The laws 
 of 1888 and 1896, which marlv the beginning of active 
 endorsement by Congress of these conservation move- 
 ments, placed upon the Survey the duties of examining 
 reservoir sites and forest reserves respectively. The 
 earlier of these laws began the investigation of the water 
 resources of the country, which is still an important phase 
 of the Survey's activity, and led to the creation of an inde- 
 pendent organization — the Reclamation Service. It is 
 easy to trace the beginnings of Federal reclamation of 
 arid lands in the pioneer work of Powell, whose report 
 in 1878 on the arid region of the United States was the 
 first adequate statement of the problem of largest use of 
 these lands in terms broader than those of individual- 
 istic endeavor. For years, however, Powell's appeal for 
 Congressional consideration of this National task was 
 like the "voice of one crying in the wilderness." 
 
 In a somewhat similar way the forestry surveys under 
 the Geological Survey helped in the organization of a 
 separate bureau — now the Forest Service. The other 
 
2U A CENTURY OF SCIENCE 
 
 important Federal bureau tracing direct relationship to 
 the Survey is the Bureau of Mines, established in 1910, 
 which continued the investigations in mining technology 
 specifically provided for by Congress for six years under 
 the Geological Survey but in some degree begun m the 
 early days of the Survey under Directors King and \ 
 Powell. _ . ) 
 
 Another equally important organization of a public 
 nature, though not a Federal bureau, traces its begin- 
 nings to the Geological Survey : the Geophysical Labora- 
 tory of the Carnegie Institution, which now exercises so 
 potent an influence over geologic investigation, had its 
 origin in the official work of the Geological Survey's 
 Division of Chemical and Physical Research, and its per- 
 sonnel was at first largely recruited from the Survey. 
 The highly original experimental work of this laboratoiy 
 has extended far beyond the scope of the Survey's work — 
 at least far beyond the scope possible with the Federal 
 funds available — yet most of the results of these inves- 
 tigations may eventually come under even a strict 
 construction of the language used in the Survey's appro- 
 priation "for chemical and physical researches relating 
 to the geology of the United States." 
 
 The topographic work of the present Survey continues 
 with constant refinement of standards and economy of 
 methods the work of the earlier organizations. The 
 primary purpose of these topographic surveys is to pro- 
 vide the bases for geologic maps, yet these topographic 
 maps, which cover 40 per cent of the area of the United 
 States, are used in every type of civil engineering as well 
 as by the public generally. The annual distribution by 
 sale of half a million of these maps is an index of their 
 value to the people. 
 
 The hot discussion that was waged for years on the 
 question of military versus scientific administration of 
 topographic surveys is in striking contrast with the 
 present concentration of all the topographic mapping 
 under the Geological Surve}' in those areas where it may 
 best serve the needs of the Army. In 1916 Congress 
 specifically recognized the possibility of greater coop- 
 eration of this kind, both in the appropriation made to 
 
GOVERNMENT GEOLOGICAL SURVEYS 215 
 
 tlie Geological Survey and in a special appropriation 
 made to the War Department. For a number of years 
 indeed special military information had been contributed 
 to the Army by the Survey topographers, but since 
 March 26, 1917, every Geological Survey topographer 
 has worked exclusively on the program of military sur- 
 veys laid down by the General Staff of the Army, and the 
 places of some of the 44 Survey topographers now in 
 France as engineer officers are filled by 34 other reserve 
 engineer officers detailed by order of the Secretary of 
 War to the Director of the Geological Survey to assist 
 in this military mapping and to receive instruction fitting 
 them in turn for topographic service in France. 
 
 The contribution of this civilian service to the military 
 operations in the present emergency forms a fitting con- 
 clusion to this review of a century of Government sur- 
 veys. At present 215 members of the Geological Survey 
 are in uniform, 107 as engineer officers, two of whom are 
 on the staff of the American Commanding General in 
 France. In the war work carried on in the United 
 States the Survey's contribution is by no means limited 
 to military mapping : the geologists are also mobilized for 
 meeting war needs, assisting in developing new sources 
 of the essential war minerals, in speeding up production 
 of mineral products, in collecting information for the 
 purchasing officers both of our own and of the Allied gov- 
 ernments, in cooperating with the constructing quarter- 
 masters in the location of gravel and sand for structural 
 use and in both general and special examinations of 
 underground water supply and of drainage possibilities 
 at cantonment sites, and in supplying the Navy Depart- 
 ment with similar technical data. A special contribution 
 has been the application to aerial survej^s of photogram- 
 metric methods developed in the Alaskan topographic 
 work and the perfection of a camera specially adapted to 
 airplane use. The utilization of the Survey's map 
 engraving and printing plant for confidential and urgent 
 work for both the Army and Navy has necessitated post- 
 ponement of current work for the Geological Survey 
 itself. Throughout the organization the records, the 
 methods, and the personnel which represent the product 
 
216 A CENTUEY OF SCIENCE 
 
 of many years of scientific activity are all being utilized ; 
 thus is the experience of the past translated into special 
 service in the present crisis. 
 
 Notes. 
 
 ^ Hesa, E. H., Foundations of National Prosperity, p. 100. 
 
 = Eeport Nat'l Museum, 1904, pp. 189-733. 
 
 " Featherstonhaugh, J. D., Am. Geol., 3, 220, 1889. 
 
 'Whitney, Mineral Wealth of the United States, pp. 248-250. 
 
 Tester and Whitney, 31st Cong., 1st session. House Doe. 69, pp. 13-14, 
 1850. 
 
 " First Annual Eept. XJ. S. Geol. Survey, p. 4. 
 
 'Wheeler, Report 3d Internat'l Geog. Cong., p. 492, 1885. 
 
 * The views of the writer on "natural monopolies" in the Government 
 service are set forth in an address delivered at the centennial celebration 
 of the TJ. S. Coast and Geodetic Survey, April 5, 1916. (See Science, vol. 
 43, pp. 659-665, May 12, 1916.) 
 
 " For correspondence on this subject, see Minnesota Geol. Survey, Eighth 
 Ann. Eept., 1880, p. 173. 
 
 " Owen, D. D., 30th Cong., 1st sess.. Senate Doc. No. 57, p. 7, 1848. 
 
 " This essential difference between present-day requirements and the 
 needs of earlier generations has been discussed by W. C. Mendenhall, the 
 geologist in charge of the Land Classification IJoard of the Geological 
 Survey: Proceedings 2d Pan-American Sci. Cong., 1915-16, 3, 761. 
 
VI 
 
 ON THE DEVELOPMENT OF VERTEBRATE 
 PALEONTOLOGY 
 
 By KICHARD SWANN LUOj 
 
 Introducti on. 
 
 UNLIKE its sister science of Invertebrate Paleon- 
 tology, which has been approached so largely from 
 the viewpoint of stratigraphic geology, that of the 
 vertebrates is essentially a biologic science, having its 
 inception in the masterly work of Cuvier, who is also to 
 be regarded as the founder of comparative anatomy. 
 For long decades, vertebrate paleontology was simply a 
 branch of comparative anatomy or morphology in that it 
 dealt almost exclusively with the form and other pecul- 
 iarities of fossil bones and teeth, often in a more or less 
 fragmentary condition, very little or no attention being 
 paid to any other system of the creature's anatomy. 
 Distribution both in space and in time was recorded, but 
 the value of vertebrates in stratigraphy was still to be 
 appreciated and has hardly yet come into its own. It is 
 readily seen, therefore, that the two departments of 
 paleontology did not enlist the same workers or even the 
 same tj'pe of investigators, for while the two sciences have 
 much in common and should have more, the vertebratist 
 must, above all else, be a morphologist, with a keen 
 appreciation of form, and a mind capable of retaining 
 endless structural details and of visualizing as a whole 
 what may be known only in part. The initial work of the 
 brilliant Cuvier set so high a standard of preparedness 
 and mental equipment that as a consequence, the number 
 of those engaged in vertebrate research has never been 
 large as compared with the workers in some other 
 branches of science, but the results achieved by the few 
 
218 A CENTURY OF SCIENCE 
 
 who have consecrated their research to the fossil verte- 
 brates has been in the main of a high order. 
 
 At first, as has been emphasized, this work was largely 
 morphological, dealing both with the individual skeletal 
 elements and later with the bony framework as a whole. 
 Then came the endeavor to clothe the bones with sinews 
 and wdth flesh — to imagine, in other words, the life- 
 appearance of the ages-departed form — with such of its 
 habits as could be deduced from structure of body, tooth, 
 and limb. Next came the working out of systematic 
 series of vertebrates and their marshalling into species, 
 genera, and larger groups, and much time was thus spent, 
 especially when rapid discovery brought a continual 
 stream of new forms before the systematist, and hence 
 some appreciation of the countless hosts of bygone crea- 
 tures which peopled the world in the geologic past. This 
 systematic work, however, was based upon the most 
 painstaking morphologic comparisons and so the science 
 was still within the scope of comparative anatomy. 
 
 In connection with taxonomic research came increas- 
 ingly tangible evidence in favor of the law of evolution ; 
 investigators turned to the working out of phyletic series 
 showing the actual record of the successive evolutionary 
 changes that the various races had undergone. Coupled 
 with this evolutionarj^ evidence came an increased atten- 
 tion to the sequential occurrence in successive geologic 
 strata, and the stratigraphic distribution of vertebrates 
 became known with greater and greater detail. Then 
 followed the assemblage of faunas, which brought the 
 study of the fossil forms within the realm of historical 
 geology, rather than being the mere phylogeny of a single 
 race, and the value of vertebrate fossils as horizon 
 markers became more and more appreciated by the stra- 
 tigrapher. They serve to supplement the knowledge 
 gained from the invertebrates, and in this connection are 
 especially valuable in that they often give data concern- 
 ing continental formations about which invertebrate 
 paleontology is largely silent. 
 
 Itise of Vertebrate Paleontology in Europe. 
 
 To those who had been nurtured in the belief in a rela- 
 tively recent creation covering in its entirety a period of 
 
VEETEBRATE PALEONTOLOGY 219 
 
 but six days, and occurring but four millenniums before 
 the time of Christ, the appearance of the remains of 
 creatures in the rocks, the like of which no man ever saw 
 alive, must have given scope to the wildest imaginings 
 concerning their origin and significance; for many 
 believed that not only had no new forms been added to 
 the world's fauna since the creation, except possibly by 
 hybridizing, but that none had become extinct save a very 
 few through the agency of human interference. The 
 supposition was, therefore, that such creatures as were 
 thus discovered were still extant in some more remote 
 fastnesses of the world. Thus, our second president, 
 Thomas Jefferson, who wrote one of the first papers on 
 American fossil vertebrates, published in 1798, discussed 
 therein the remains of a huge ground-sloth which has 
 since borne the name Megalonyx jeffersoni. Jefferson, 
 however, described the great claws as pertaining to a 
 huge leonine animal which he firmly believed was yet 
 living among the mountains of Virginia. 
 
 Cuvier (1769-1832) has been spoken of as the founder 
 of our science. His opportunity lay in the profusion of 
 bones buried in the gypsum deposits of Montmartre 
 within the environs of the city of Paris. Cuvier 's 
 studies of these remains, done in the light of his very 
 broad anatomical knowledge, enabled him to prepare the 
 first reconstructions of fossil vertebrates ever attempted 
 and to bring before the eyes of his contemporaries a 
 world peopled with forms which were utterly extinct. 
 That these creatures were no longer li\dng, none was a 
 better judge than Cuvier, for his prominence was such 
 that material was sent him from all parts of the world, to 
 which must be added that which he saw in his visits to 
 the various museums of Europe. He felt it safe, there- 
 fore, to aflirm the unlikelihood of any further discovery 
 of unknown forms among the great manamals of the pres- 
 ent fauna of our globe, and few indeed have been the 
 additions since his day. To Cuvier is due not alone the 
 masterly contribution to the sister sciences of compara- 
 tive anatomy and vertebrate paleontology — the Osse- 
 ments Fossiles (1812) — but he also announced the 
 presence in continental strata of a series of faunas which 
 showed a gradual organic improvement from the earliest 
 
220 A CENTURY OF SCIENCE 
 
 such assemblage to the most modern, an idea of the most 
 fundamental importance and one with which he is rarely 
 credited. He believed in the sudden and complete 
 extinction of faunas, and the facts then known were in 
 accord with this idea, as no common genera nor transi- 
 tional forms connected the creatures of the Paris gypsum 
 with the mastodons, elephants, and hippopotami which 
 the later strata disclosed. It is not remarkable, there- 
 fore, that Cuvier advanced his theory of catastrophism to 
 account for these extinctions. He should not, however, 
 according to Deperet, be credited with the idea of suc- 
 cessive re-creations, such as that held by D'Orbigny and 
 others, but of repopulation by immigration from some 
 area which the catastrophe, be it flood or other destruc- 
 tive agency, failed to reach. 
 
 Cuvier was followed in Europe by a number of illus- 
 trious men, none of whom, however, with the exception of 
 Sir Eichard Owen, possessed his lareadth of knowledge 
 of comparative anatomy upon which to base their 
 researches among the prehistoric. The more notable of 
 them may be enumerated before going on to a discussion 
 of the American contributions to the science. 
 
 They were, first, Louis Agassiz, a pupil of Cuvier and 
 later a resident of America, whose researches on the fos- 
 sil fishes of Europe are a monumental work, the result of 
 ten years of investigation in all of the larger museums of 
 that continent, and which appeared in 1833-43, while he 
 was yet a young man. The fishes were practically the 
 only fossil vertebrates to come within the scope of his 
 investigations, for his later time was consumed in the 
 study of glaciers and of recent marine zoology. Another 
 student of these most primitive vertebrates who left 
 an enduring monument was Johannes Miiller. Huxley, 
 Traquair, and Jaekel also did masterly work upon this 
 group, while Smith Woodv/ard of the British Museum is 
 considered the highest living authority upon fossil fishes. 
 
 Of the Amphibia, the most famous foreign students 
 were Brong-niart, Jaeger, Burmeister, Von Meyer, and 
 Owen, although Ov^^en's claim to eminence lies rather in 
 the investigations of fossil reptiles which he began in 
 1839 and continued over a period of fifty years of 
 remarkable achievement. Not only did he describe the 
 
VERTEBRATE PALEONTOLOGY 221 
 
 dinosaurs of Great Britain in a series of splendidly illus- 
 trated monographs, but extended his researches to the 
 curious reptilian forms from the Karroo formation of 
 South Africa. It was to him, moreover, that the estab- 
 lishment of the true position of the famous Archaopteryx 
 as the earliest known bird and not a reptUe is due. Von 
 Meyer also enriched the literature of fossil reptiles, 
 discussing exhaustively those occurring in Germany, 
 while Huxley's classic work on the crocodiles as well as 
 on dinosaurs, and the labors of Buckland, Fraas, Koken, 
 Von Huene, Gaudry, Hulke, Seeley, and Lydekker have 
 added immensely to our knowledge of the group. 
 
 Of the birds, which at best are rare as fossils, our 
 knowledge, especially of the huge flightless moas, is due 
 largely again to Owen, and his realization of the syste- 
 matic position of Archceopteryx has already been men- 
 tioned. 
 
 The mammals were, perhaps, the most prolific source 
 of paleontological research during the nineteenth cen- 
 tury, for, as Zittel has said, Cuvier's famous investiga- 
 tions on the fossil bones, mentioned above, not only 
 contain the principles of comparative osteology, but also 
 show in a manner which has never been surpassed how 
 fossil vertebrates ought to be studied, and what are the 
 broad inductions which may be drawn from a series of 
 methodical observations. Such was Cuvier's influence 
 that until Darwin began to interest himself in mammalian 
 paleontology the study of these forms was conducted 
 entirely along the lines indicated by the French savant. 
 This was seen in a large work. Osteology of Recent and 
 Fossil Mammalia, bj^ De Blainville, which, although not 
 up to the standard set by the master, is nevertheless a 
 notable contribution, as was also the Osteology prepared 
 by Pander and D 'Alton. A summary of the knowledge of 
 the fossil Mammalia up to the year 1847 is contained in 
 Giebel's Fauna der Vorwelt, and Lydekker has done for 
 the mammals in the British Museum what Smith Wood- 
 ward did for the fishes, producing vastly more than the 
 mere catalogue which the title implies. 
 
 The first work wherein the fossil mammals were 
 treated genealogically was Gaudry 's Enchainements du 
 Monde Animal, written in 1878. Other work on the 
 
 14 
 
222 A CENTURY OF SCIENCE 
 
 fossil Mammalia was done by Kaup, who described those 
 from the Mainz basin and from Epplesheim near Worms 
 whence came one of the most famous of prehistoric 
 horses, the Hipparinn; this horse, together with the 
 remarkable proboscidean Dinotherhim, was described by 
 Von Meyer. One of the most remarkable discoveries, 
 ranking in importance, perhaps, next to Montmartre, was 
 that of the Pliocene fauna of Pikermi near Athens, 
 Greece, first made known through the publications of A. 
 Wagner of Munich and later, and much more extensively, 
 through that of Gaudry (1862-1867). H. von Meyer was 
 Germany's best authority on fossil Mammalia. After 
 his death the work was carried on by Quenstedt, Oscar 
 Fraas, Schlosser, Koken, and Pohlig, among others. 
 
 In France, rich deposits of fossil mammals were dis- 
 covered in the Department of Puy-de-D6me, the Rhone 
 basin, Sansan, Quercy, and near Rheims. These were 
 described by a number of writers, notably Croizet and 
 Jobert, Pomel, Lartet, Filhol, and Lemoine. 
 
 Riitimeyer of Bale was one of the most famous Euro- 
 pean writers on mammalian paleontology, and his 
 researches were both comprehensive and clothed in such 
 form as to give them a high place in paleontological lit- 
 erature. He studied comparatively the teeth of ungu- 
 lates, discussed the genealogy of mammals, and the 
 relationships of those of the Old and New Worlds. He 
 was an exponent of the law of evolution as set forth by 
 Darwin, and his "genealogical trees of the Mammalia 
 show a complete knowledge of all the data concerning the 
 different members in the succession, and are amongst the 
 finest results hitherto obtained by means of strict scien- 
 tific methods of investigation" (Zittel, History of Geol- 
 ogy and Paleontology, 1901). The mammals of the 
 Swiss Eocene have been studied in much detail by 
 Stehlin. 
 
 For Great Britain, the most notable contributors were 
 Buckland in his Reliquife Diluviaufp ; Falconer, co-author 
 Avith Cautley on the Tertiary mammals of India ; Charles 
 Murchison, who wrote on rhinoceroses and probosci- 
 deans ; and more recently Bush, Flower, Lydekker, Boyd 
 Dawkins, L. Adams, and C. W. Andrews. But by far the 
 most commanding figure of all was Sir Richard Owen, 
 
VERTEBRATE PALEONTOLOGY 223 
 
 who for half a century stood without a peer as the 
 greatest of authorities on fossil mammals. It was the 
 Natural History of the British Fossil Mammals and 
 Birds, published in 1846, that established Sir Richard's 
 reputation. 
 
 Russia has produced much mammalian material, 
 especially from the Tertiary of Odessa and Bessarabia, 
 and from the Quaternary of northern Russia and Siberia. 
 These have been described mainly by J. F. Brandt, A. 
 von Nordmann, but especially by Mme. M. Pavlow of 
 Moscow. 
 
 Forsyth-Ma.ior discovered in 1887 a fauna contem- 
 poraneous with that of Pikermi in the Island of Samos 
 in the Mediterranean. 
 
 One of the most remarkable recent discoveries of fossil 
 localities was that announced in 1901 by Mr. Hugh J. L. 
 Beadnell of the Geological Survey of Egypt and Doctor 
 C. W. Andrews of the British Museum of London, of 
 numerous land and sea mammals of Upper Eocene and 
 Lower Oligocene age in northern Egypt. The exposures 
 lay about 80 miles southwest of Cairo in the Payum dis- 
 trict and are the sediments of an ancient Tertiary lake, a 
 relic of which, Birket-el-Qurun, yet remains. These beds 
 contained ancient Hyracoidea, Sirenia, and Zeuglodontia, 
 but above all, ancestral Proboseidea which, together with 
 those known elsewhere, enabled Andrews to demonstrate 
 the origin and evolutionary features of this most remark- 
 able group of beasts. This discovery in the Fayum lends 
 color to the belief that Africa may have been the ancestral 
 home of at least five of the mammalian orders, those men- 
 tioned above, together with the Embrithopoda, a group 
 unknown elsewhere. This theory had been advanced 
 independently by TuUberg, Stehlin, and Osborn, before 
 the discovery in Egypt. 
 
 Another European worker of pre-eminence who wrote 
 more broadly than the faunal studies mentioned above 
 was W. Kowalewsky. He discussed especially the evo- 
 lutionary changes of feet and teeth in ungulates, a line of 
 research afterward developed in greater detail by the 
 Americans, Cope and Osborn. 
 
 South America has yielded series of rich faunas which 
 have been exploited by the great Argentinian, Florentine 
 
224 A CENTURY OF SCIENCE 
 
 Ame,£?hino, and by the Europeans, Owen, Gervais, Hux- 
 ley, Von Meyer, and more recently by Burmeister and 
 Lydekker. Later exploration and research by Hatcher 
 and Scott of North America will be discussed further on 
 in this paper. 
 
 Vertebi'ate Faleontologij in America, 
 
 Early Writers. — Having thus summarized paleontolog- 
 ical progress in the Old World, we can turn to a consid- 
 eration of the work done in the New, especially in the 
 United States, because while the Old AVorld investigation 
 has been invaluable, a science of vertebrate paleontology, 
 very complete both as to its zoological and geological 
 scope and in the extent and value of published results, 
 could be built exclusively upon the discoveries and 
 researches made by Americans. The science of verte- 
 brate paleontology may be said to have had its beginnings 
 in North America with the activities of Thomas Jeffer- 
 son, who, like Franklin, felt so strong an interest in 
 scientific pursuits that even the graver duties of the high- 
 est office in the gift of the American people could not 
 deter him from them. Wlien in 1797 Jefferson came to 
 be inaugurated as vice-president of the United States, he 
 brought with him to Philadelphia not only his manuscript 
 but the actual fossil bones upon which it was based. 
 Again in 1801 he was greatly interested in the Shawan- 
 gunk mastodon, despite heavy cares of state, and in 1808 
 made part of the executive mansion in Washington serve 
 as a paleontological laboratory, displajdng therein for 
 study the bones of proboscideans and their contempora- 
 ries which the Big Bone Lick of Kentucky had produced. 
 Jefferson's work would not, perhaps, have been epoch- 
 making were it not for its unique chronological position 
 in the annals of the science. 
 
 Jefferson was followed by another man — this time one 
 whose diverging lines of interest led him not into the 
 realm of political service, but of art, for Rembrandt 
 Peale possessed an enviable reputation among the early 
 painters of America. Peale published in 1802 an account 
 of the skeleton of the "mammoth," really the mastodon, 
 M. americanus, speaking of it as a nondescript carnivor- 
 
VERTEBRATE PALEONTOLOGY 225 
 
 ous animal of immense size found in America. It was 
 because of tlie form of the molar teeth that Peale said of 
 it: "If this animal was indeed carnivorous, which I 
 believe cannot be doubted, though we may as philoso- 
 phers regret it, as men we cannot but thank Heaven that 
 its whole generation is probably extinct. ' ' 
 
 With the work of these men as a beginning, it is not 
 strange that the more conspicuous Pleistocene fossils of 
 the East should have attracted the attention of many 
 subsequent writers in the first part of the nineteenth cen- 
 tury, nor that the early papers to appear in the Journal 
 should pertain to proboscideans or to the huge edentate 
 ground-sloths and the aberrant zeuglodons whose bones 
 frequently came to light. Therefore a number of men 
 such as Koch, both Sillimans, J. C. Warren, and others 
 made these forms their chief concern. 
 
 Fossil Footprints. — Among the early writers who con- 
 cerned themselves with these greater fossils was Edward 
 Hitchcock, sometime president of Amherst College, and 
 a geologist of high repute among his contemporaries. 
 Hitchcock is, however, better and more widely known as 
 the pioneer worker on a series of phenomena displayed 
 as in no other place in the region in which he made his 
 home. These are fossil footprints impressed upon the 
 Triassic rocks of the Connecticut valley. It was in the 
 Journal for the year 1836 (29, 307-340) that Hitchcock 
 first called attention to the footmarks, although they had 
 been known and discussed popularly for a number of 
 years previous. James Deane, of Greenfield, was per- 
 haps the first to appreciate the scientific interest of these 
 phenomena, but deeming his own qualifications insuffi- 
 cient properly to describe them, he brought them to the 
 attention of Hitchcock, and the interest of the latter 
 never waned until his death in 1864. Hitchcock wrote 
 paper after paper, publishing many of them in the Jour- 
 nal, again in his Final Report on the Geology of Massa- 
 chusetts (1841), and later in c^uarto works, one in the 
 Memoirs of the American Academy of Arts and Sciences 
 and the two others under the authority of the Common- 
 wealth, the Ichnology in 1858, and the Supplement in 
 1865, the last being a posthumous work edited by his son, 
 Charles H. Hitchcock. 
 
226 A CENTURY OF SCIENCE 
 
 Hitclicock's conception of the track-makers was more 
 or less imperfect because of the fact that for a long time 
 but a few fragmentary osseous remains were known, 
 either directly or indirectly associated with the tracks, 
 while on the other hand the bird-like character of many 
 of the latter and the discovery of huge flightless birds 
 elsewhere on the globe suggested a very close analogy if 
 not a direct relationship. Hence "bird tracks" they 
 were straightway called, a designation which it has been 
 difficult to remove, even though in 1843 Owen called atten- 
 tion to the need of caution in assuming the existence of 
 so highly organized birds at so early a period, especially 
 when large reptiles were known which might readily 
 form very similar tracks. The footprints are now 
 believed to be very largely of dinosaurian origin, and 
 dinosaurs whose feet corresponded in every detail with 
 the footprints have actually come to light within the same 
 geologic and geographic limitations. This of course 
 refers to the bipedal, functionally three-toed tracks. Of 
 the makers of certain of the obscurer of the quadrupedal 
 trails we are as much in the dark to-day as were the 
 first discoverers of a century ago, so far as demonstrable 
 proof is concerned. We assume, however, that they were 
 the tracks of amphibia and reptiles, beyond which we may 
 not go with certainty. 
 
 Agassiz, writing in 1865 (Geological Sketches), says: 
 
 "To sum up my opinion respecting these footmarks, I believe 
 that they were made by animals of a prophetic type, belonging 
 to the class of reptiles, and exhibiting many synthetic charac- 
 ters. The more closely we study past creations, the more 
 impressive and significant do the synthetic types, presenting 
 features of the higher classes under the guise of the lower ones, 
 become. They hold the promise of the future. As the opening 
 overture of an opera contains all the musical elements to be 
 therein developed, so this living prelude of the creative work 
 comprises all the organic elements to be successively developed 
 in the course of time." 
 
 Of those whose Avork was contemporaneous Avith that 
 of Hitchcock, but one, "W. C. Rediield, wrote on Triassic 
 phenomena, and he concerned himself mainly with the 
 fossil fishes of that time, his first paper on this subject 
 
VERTEBRATE PALEONTOLOGY 227 
 
 appearing in 1837 in the Journal (34, 201), and the last 
 twenty years later. 
 
 Paleozoic Vertebrates. — Later the vertebrates of the 
 Paleozoic began to attract attention, footprints from 
 Pennsj^lvania being described by Isaac Lea, beginning in 
 1849, a notice of his first paper appearing in the Journal 
 for that year (9, 124). Several papers followed on the 
 reptile Glepsysaurus. Alfred King also wrote on the 
 Carboniferous ichnites, his work slightly antedating that 
 of Lea, but being less authoritative. 
 
 But by far the most illuminating of the mid-century 
 writers on Paleozoic vertebrates was Sir William Daw- 
 son, a very large proportion of whose numerous papers 
 relate to the Coal Measures of Nova Scotia and their 
 contained plant and animal remains. In 1853 appeared 
 Dawson's first announcement, written in collaboration 
 with Sir Charles Lyell, of the finding of the bones of 
 vertebrates within the base of an upright fossil tree trunk 
 at South Joggins. These bones were identified by Owen 
 and Wyman as pertaining to a reptilian or amphibian to 
 which the name Dendrerpeton acadianum was given. 
 Following this were several papers published in the 
 Quarterly Journal of the Geological Society, London, 
 describing more vertebrates and associated terrestrial 
 molluscs. In 1863 Dawson summarized his discoveries 
 in the Journal (36, 430-432) under the title of "Air- 
 breathers of the Coal Period," a paper which was 
 expanded and published under the same title in the Cana- 
 dian Naturalist and Geologist for the same year. Daw- 
 son also printed in the same volume the first account of 
 reptilian(f) footprints from the coal. Thus from time 
 to time there emanated from his prolific pen the account 
 of further discoveries, both in bones and footprints, his 
 final synopsis of the air-breathing animals of the Paleo- 
 zoic of Canada appearing in 1895. The only other group 
 of vertebrates which claimed his attention were certain 
 whales, on which he occasionally wrote. 
 
 Fishes. — The fossil fishes from the Devonian of Ohio 
 found their first exponent in J. S. Newberry, appointed 
 chief geologist of the second geological survey of Ohio, 
 which was established in 1869. These fishes from the 
 Devonian shales belonged for the greater part to the 
 
228 A CENTURY OF SCIENCE 
 
 curious group of armored placoderms, the remains of 
 which consist very largely of armor plates with little or 
 no traces of internal skeleton. There was also found in 
 association a shark, Cladoselache, of such marvelous 
 preservation that from some of the Newberry specimens 
 now in the American Museum of Natural History, New 
 York, Bashford Dean has demonstrated the histology of 
 muscle and visceral organs, in addition to the very com- 
 plete skeletal remains. 
 
 Newberry's work on these forms, begun in 1868, has 
 been carried to further completion by Bashford Dean and 
 his pupil L. Hussakof, as well as by C. R. Eastman. 
 Newberry's other paleontological work was Avith the Car- 
 boniferous fishes of Ohio, the Carboniferous and Triassic 
 fishes of the region from Sante Fe to the Grand and 
 Green rivers, Colorado, and on the fishes and plants of 
 the Newark system of the Connecticut valley and New 
 Jersey. He also discussed certain mastodon and mam- 
 moth remains, and those of the peccary of Ohio, 
 Dicotyles. 
 
 Joseph Leidi/ (1823-1891). 
 
 We now come to a consideration of the work of Joseph 
 Leidy, one of the three great pioneers in American verte- 
 brate paleontology, for if we disregard the work of Hitch- 
 cock and others on the fossil footprints, few of the results 
 thus far obtained were based upon the fruits of organized 
 research. Leidy began his publication in 1847 and con- 
 tinued to issue papers ?ind books from time to time until 
 the year 1892, having published no fewer than 219 paleon- 
 tological titles, and 553 all told. His earlier paleontolog- 
 ical researches were exclusively on the Mammalia, which 
 were then coming in from the newly discovered fossil 
 localities of the West. The discovery of these forms, 
 one of the most notable events in the history of our 
 science, will bear re-telling. 
 
 The first announcement was made in 1847, when Hiram 
 A. Prout of St. Louis published in the Journal (3, 248- 
 250) the description of the maxillary bone of "Palceo- 
 therhim" {^Titanofherium proutii) from near White 
 River, Nebraska. This at once drew the attention of 
 geologists and paleontologists to the Bad Lands, or 
 
VERTEBRATE PALEONTOLOGY 229 
 
 Mauvaises Terres, which were to prove so highly produc- 
 tive of fossil forms. About the same time S. D. Culbert- 
 son of Chambersburg, Pennsylvania, submitted to the 
 Academy of Natural Sciences at Philadelphia some fos- 
 sils sent to him from Nebraslva by Alexander Culbertson. 
 These were afterward described by Leidy in the Pro- 
 ceedings of the Academy, together with the paleotheroid 
 jaw, in addition to which three other collections which 
 had been made were also placed at his disposal for study. 
 
 This aroused the interest of Doctor Spencer F. Baird 
 of the Smithsonian Institution, who sent T. A. Culbert- 
 son to the Bad Lands to make further collections. The 
 latter was successful in securing a valuable series of 
 mammalian and chelonian remains. These, together 
 with other specimens from the same locality, were sent 
 to Leidy, for, as Baird remarked, Leidy, although only 
 thirty years of age, was the only anatomist in the United 
 States qualified to determine their nature. The outcome 
 of Leidy 's study of this material was "The Ancient 
 Fauna of Nebraska," published in 1853, and constituting 
 the most brilliant work which up to that time American 
 paleontology had produced. Leidy 's determinations, 
 which are in the main correct, are the more remarkable 
 when it is realized that he had little recent osteolog- 
 ical material for comparative study. The forms thus 
 described by him were new to science, of a more gener- 
 alized character than those now living, and yet their 
 distinguished describer recognized, either at that time or 
 a little later, their true relationship to the modern tj^pes. 
 The extent of Leidy 's anatomical knowledge was almost 
 Cuvierian, and Cuvier-like he established the fact of the 
 presence of the rhinoceroses, then unheard of in the 
 American fauna, from a few small fragments of molar 
 teeth, an opinion shortly to be fully sustained through the 
 finding of complete molars and the entire skull of the 
 same individual animal. 
 
 Leidy next turned his attention to the huge edentates, 
 which he studied exhaustively, publishing his results in 
 the form of a memoir in 1855, two years after the appear- 
 ance of the "Ancient Fauna." 
 
 Extinct fishes of the Devonian of Illinois and Missouri 
 and the Devonian and Carboniferous of Pennsylvania 
 
230 A CENTURY OF SCIENCE 
 
 were made the subjects of his next researches, after 
 which he described the peccaries of Ohio, and later, in a 
 mucli larger and most important work, the Cretaceous 
 reptiles of the United States (1865). Most of the fossils 
 discussed in this last work are from the New Jersey Cre- 
 taceous marls and of them the most notable was the 
 herbivorous dinosaur Radrosaurus, the structure and 
 habits of which, together with its affinities with the Old 
 World iguanodons, Leidy described in detail. From 
 Leidy's descriptions and with his aid, Waterhouse Haw- 
 kins was enabled to restore a replica of the skeleton in a 
 remarkably efficient way. This restoration for a long 
 time graced the museum of the Philadelphia Academy of 
 Natural Sciences and there was a plaster replica of it in 
 the United States National Museum. These, together 
 with plaster replicas of Iguanodon from the Royal Col- 
 lege of Surgeons in London, gave to Americans their first 
 real conceptions of members of this most remarkable 
 group. The associated fossils from the New Jersey 
 marls were chiefly crocodiles and turtles. 
 
 From 1853 to 1866 F. V. Hayden was carrying on a 
 series of most energetic explorations in the West, 
 especially in Nebraska and Dakota as then delimited, 
 returning from each trip laden with fossils which Avere 
 given to Leidy for determination. The results appeared 
 in 1869 in Leidy's Extinct Mammalian Fauna of Dakota 
 and Nebraska, published as volume 7 of the Journal of 
 the Philadelphia Academy. In this large volume no fewer 
 than seventy genera and numerous species of forms, 
 many of them new to science, were described, repre- 
 senting many of the principal mammalian orders ; horses 
 were, however, especially conspicuous. This last group 
 led Leidy to the conclusion, afterward emphasized by 
 Huxley, that North America was the home of the horse in 
 geologic time, there being here a greater representation 
 of different species than in any recent fauna of the 
 world. Leidy's interest in the horses, for the forward- 
 ing of which he made a large collection of recent mate- 
 rial, extended over many ^^ears, as his first paper on the 
 subject bears the date of 1847, the last that of 1890. 
 
 _ Next came the discovery of Eocene material from the 
 vicinity of Fort Bridger, W3^oming, geologically older 
 
VERTEBRATE PALEONTOLOGY 231 
 
 than the Nebraska and Dakota formations. This 
 
 together with specimens from the Green Eiver and 
 Sweetwater Eiver deposits of "Wyoming and the Jolan 
 Day River (Oligocene) of Oregon, was also referred to 
 Leidy, and added yet more to the list of newly discov- 
 ered species with which he had already become familiar 
 in his earlier researches. The results of this study were 
 published by the Hayden Survey in 1873, under the title 
 "Contributions to the Extinct Vertebrate Fauna of the 
 Western Territories." This was the last of Leidy 's 
 major works, but he continued up to the time of his death 
 to report to the Academy concerning the various fossil 
 forms that were submitted to him for identification. Of 
 such reports the most important was one on the fossils 
 of the phosphate beds of South Carolina, published in 
 the Journal of the Academy in 1887. 
 
 As a paleontologist, Leidy ranks with Cope and 
 Marsh high among those who enriched the American lit- 
 erature of the subject, but it must be remembered that 
 this was but a single aspect of his many-sided scientific 
 career, for he made many contributions of high order to 
 botany, zoology, and general and comparative anatomy 
 as well, nor did his knowledge and usefulness as an 
 instructor of his fellow men keep within the limitations of 
 these subjects. 
 
 Othniel Charles 3Iarsh (1S31-1S90). 
 
 The sixth decade of the nineteenth century saw the 
 beginning of the labors of several paleontologists who, 
 like Leidy, were destined to raise the science of fossil 
 vertebrates in America to the level of attainment of the 
 Old World. They were, among others, Othniel Charles 
 Marsh and Edward Drinker Cope. Of these the names 
 of Marsh and Cope are linked together by the brilliance 
 of their attainments, their contemporaneity, and the 
 rivalry which the similarity of their pursuits unfortu- 
 nately engendered. Marsh produced his first paleon- 
 tological paper in 1862 (33, 278), Cope in 1864, but the 
 latter died first, so that his life of research was shorter. 
 
 To Professor Marsh should be given credit for the 
 first organized expedition designed exclusively for the 
 collection of vertebrate remains, the results of which con- 
 
232 A CENTURY OF SCIENCE 
 
 tain so much material that it has not yet entirely seen 
 the light of scientific exposition. Marsh's first trip to 
 the West was in 1868, the first formal expedition being 
 organized two years later. These expeditions, of which 
 there were four, were privately financed except for the 
 material and military escort furnished by the United 
 States Government, and consisted of a personnel drawn 
 entirely from the graduate or undergraduate body 
 of Yaie University. These parties explored Ivansas, 
 Nebraska, Wyoming, Utah, and Oregon, and returned 
 laden with material from the Cretaceous and Tertiary 
 formations of the West. Some of this is of necessity 
 somewhat fragmentary, but type after type was secured 
 which, with his exhaustive knowledge of comparative 
 anatomy, enabled Marsh to announce discovery after dis- 
 covery of species, genera, families, and even orders of 
 mammals, birds, and reptiles which were unknown to 
 science. The year 1873 saw the last of the student expe- 
 ditions, and thereafter until the close of his life the work 
 of collecting was done under Marsh 's supervision, but by 
 paid explorers, many of whom had been his scouts and 
 guides in the formal expeditions or had been especially 
 trained b}^ him in the East. In 1882, after fourteen years 
 of the experience thus gained, Marsh was appointed verte- 
 brate paleontologist to the United States Geological Sur- 
 vey, which relieved him in part of the personal expense 
 connected with the collecting, although up to within 
 a short time of his death his own fortune was very 
 largely spent in enlarging his collections. After his con- 
 nection with the Survey was established, ]\Iarsh had two 
 main purposes in view in making the collections: (1) to 
 determine the geological horizon of each locality where 
 a large series of vertebrate fossils was found, and (2) to 
 secure from these localities large collections of the more 
 important forms sufficiently extensive to reveal, if possi- 
 ble, the life histories of each. Llarsh believed that the 
 material thus secured would serve as key or diagnostic 
 fossils to all horizons of our western geology above the 
 Paleozoic, a belief in which he was in advanceof his time, 
 for few of his contemporaries appreciated the value of 
 vertebrates as horizon markers. The result of the ful- 
 filment of his second purpose saw the accumulation of 
 
u 
 
 /J 
 
 OyUCA 
 
VERTEBRATE PALEONTOLOGY 233 
 
 huge collections from all horizons above the Triassic and 
 some Paleozoic and Triassic as well. These contained 
 some very remarkable series, each of which Marsh hoped 
 to make the basis of an elaborate monograph to be pub- 
 lished under the auspices of the Survey. One can vis- 
 ualize the scope of his ambitions by the fact that no fewer 
 than twenty-seven projected quarto volumes, to contain 
 at least 850 lithographic plates, were listed by him in 
 1877. These covered, among other groups, the toothed 
 birds (Odontornithes), Dinocerata, horses, brontotheres, 
 pterodactyls, mosasaurs and plesiosaurs, monkeys, car- 
 nivores, perissodactyls and artiodactyls, crocodiles, 
 lizards, dinosaurs, various birds, proboscideans, eden- 
 tates and marsupials, brain evolution, and the Connecti- 
 cut Valley footprints. Much was done towards the prep- 
 aration of these memoirs, as evidenced by the long list 
 of preliminary papers, admirably illustrated by woodcuts 
 which were to form the text figures of the memoirs, 
 which appeared with great regularity in the pages of the 
 Journal for a period of thirty years. Of the actual 
 memoirs, however, but two had been published at the 
 time of Marsh's death in 1899 — the Odontornithes in 
 1880 and the Dinocerata in 1884. One must not overlook, 
 however, the epoch-making Dinosaurs of North America, 
 which was published by the Survey in 1896, although it 
 was not in the form nor had it the scope of the proposed 
 monographs. This was not due to lack of application, 
 for Professor Marsh was an indefatigable worker, but 
 rather to the fact that the program was of such magni- 
 tude as to necessitate a patriarchal life span for its con- 
 summation. As it is, Professor Marsh's fame rests first 
 upon his ability and intrepidity as a collector, ready him- 
 self to brave the very certain hardships and dangers 
 which beset the field paleontologist in the pioneer days, 
 and also by his judgment and command of men to secure 
 the very adequate services of others and so to direct 
 their endeavors that the results were of the highest value. 
 The material witness to Marsh's skill as a collector lies 
 in the collections of the Peabody Museum at Yale and in 
 the Marsh collection at the United States National 
 Museum, the latter secured through the funds of the 
 United States Geological Survey. Together they consti- 
 
234 A CENTURY OF SCIENCE 
 
 tute what is possibly the greatest collection of fossil 
 vertebrates in America, if not in the world ; individually, 
 they are second only to that of the American Museum in 
 New York City, the result of the combined labors of 
 Osborn and Cope and their very able corps of assistants. 
 
 As a scientist Marsh possessed in large measure that 
 wide knowledge of comparative anatomy so necessary to 
 the vertebrate paleontologist, and as a consequence was 
 not only able to recognize affinities and classify unerr- 
 ingly, but also to recognize the salient diagnostic fea- 
 tures of the form before him and in few words so to 
 describe them as to render the recognition of the species 
 by another worker relatively easy. The publication of 
 hundreds of these specific diagnoses in the Journal con- 
 stitutes a very large and valuable part of that periodi- 
 cal's contribution to the advancement of our science. 
 Marsh's method of indicating forms by so brief a state- 
 ment leaves much to be done, however, in the way of 
 further description of his types, which in many instances 
 were but partially prepared. 
 
 Yet another important service which Marsh rendered 
 to science was the restoration of the creatures as a whole, 
 made with the most painstaking care and precision 
 through assembling the drawings of the individual bones. 
 These restorations have become classic, embracing as they 
 did a score or more of forms, of beast, bird, and reptile. 
 Thej" also were published first in the Journal, although 
 they have subsequently been reproduced in text-books 
 and other works the world over. Part of Llarsh's popu- 
 lar reputation, at least, which was second to that of no 
 other American in his line, was due to his skill in 
 attaining publicity, for his papers, of whatever extent, 
 were carefully and methodically sent to correspondents 
 in the uttermost parts of the earth, and thus the ]\Iarsh 
 collection has reflected the fame of its maker. 
 
 Edward Drinhev Cope (1840-1S07). 
 
 The third great name in American vertebrate paleon- 
 tology, that of Edward Drinker Cope, stands out in shai'p 
 contrast with the other two, although in the range of his 
 interests he was probably more nearly comparable with 
 
VERTEBRATE PALEONTOLOGY 235 
 
 Leidy than with Marsh. The beginning of Cope's scien- 
 tific labors dates from 1859, the year made famous in the 
 annals of science by the appearance of Darwin's Origin 
 of Species. It is not surprising, therefore, that matters 
 evolutional should have interested him to the very end of 
 his career. Cope was not merely a paleontologist, but was 
 interested in recent forms, especially the three lower 
 classes of vertebrates, to such an extent that his work 
 therewith is highly authoritative and in some respects 
 epoch-making. Thirty-eight ytars of almost continual 
 toil were his, and the mere mass of his literary productions 
 is prodigious, especially when one realizes that, unlike 
 those of a writer of fiction, they were based on painstaking- 
 research and philosophical thought. The greater part of 
 Cope's life was spent in or near Philadelphia except for 
 his western explorations, and he is best known as pro- 
 fessor of geology and paleontology in the University of 
 Pennsylvania, although he served other institutions as 
 well. 
 
 Cope's early work was among the amphibia and rep- 
 tiles, his first paleontological paper, the description of 
 Amphibamus grandiceps, appearing in 1865. This year 
 he also began his studies of the mammals, especially the 
 Cetacea, both living and extinct, from the Atlantic sea- 
 board. The next year saw the beginning of his work on 
 the material from the Cretaceous marls of New Jersey, 
 describing therefrom one of the first carnivorous dino- 
 saurs, Lcelaps, to be discovered in America. In 1868 
 Cope began to describe the vertebrates from the Kansas 
 chalk and three j^ears later made his first exploration of 
 these beds. This led to his connection with the United 
 States Geological Survey of the Territories under Hay- 
 den, and to continued exploration of Wj^oming and Col- 
 orado in 1872 and 1873. The material thus gained, 
 consisting of fishes, mosasaurs, dinosaurs, and other 
 reptiles, was described in the Transactions of the 
 American Philosophical Society as well as in the Survey 
 Bulletins. In 1875 these results were summarized in a 
 large quarto volume entitled "Vertebrata of the Creta- 
 ceous formations of the West." Subsequent summers 
 were spent in further exploration of the Bridger, Washa- 
 kie, and Wasatch formations of Wyoming, the Puerco 
 
236 A CENTURY OF SCIENCE 
 
 and Torrejon of New Mexico, and the Judith River of 
 Montana. The material gathered in New Mexico proved 
 particularly valuable, and led to the publication in 1877 
 of another notable volume entitled "Report upon the 
 Extinct Vertebrata obtained in New Mexico by Parties 
 of the Expedition of 1874. ' ' 
 
 Material was now accumulating so fast as to necessi- 
 tate the concentration of Cope's own time on research, 
 so that, while he continued to make brief journeys to the 
 West, the real work of exploration was delegated to 
 Charles H. Sternberg and J. L. Wortman, both of whom 
 became subsequently very well known, the former as a 
 collector whose active service has not yet ceased, the 
 latter as an explorer and later an investigator of 
 extremely high promise. 
 
 As early as 1865, Cope began no fewer than five sep- 
 arate lines of research which he pursued concurrently 
 for the remainder of his career. On the fishes, he became 
 a high authority in the larger classification, owing to his 
 researches into their phylogeny, for which a knowledge 
 of extinct forms is imperative. On amphibia, he wrote 
 more voluminously than any other naturalist, discussing 
 not only the morphology but the paleontology and tax- 
 onomy as well. In this connection must be mentioned 
 not only Cope's exploration and collections in the Per- 
 mian of Ohio and Illinois, but especially the remains 
 from the Texas Permian, first received in 1877, upon 
 which some of his most brilliant results were based; 
 these of course included reptilian as Avell as amphibian 
 material. His third line of research, the Reptilia, is in 
 part included in the foregoing, but also embraced the 
 reptiles of the Bridger and other Tertiary deposits, those 
 of the Kansas Cretaceous, and the Cretaceous dinosaurs. 
 
 Up to 1868 Ijeidy alone was engaged in research in the 
 West, but that year saw the simultaneous entrance of 
 Marsh and Cope into this new field of research, and their 
 exploration and descriptions of similar regions and forms 
 soon led to a rivalry which in turn developed into a most 
 unfortunate series of controversies, mainly over the sub- 
 ject of priority. This resulted in a permanent rupture 
 of friendship and the division of American workers into 
 two opposing camps to the detriment of the progress of 
 
VERTEBRATE PALEONTOLOGY 237 
 
 our science. This breach has now been happily healed, 
 and for a number of years the degree of mutual good will 
 and aid on the part of our workers has been of the high- 
 est sort. 
 
 The extent of the western fossil area, and particularly 
 the explorations of three of Cope's aids, Wortman in the 
 Big Horn and Wasatch basins, Baldwin in the Puerco of 
 New Mexico, and Cummins in the Permian of Texas, gave 
 Mm so fruitful a field of endeavor that the occasion for 
 jealous rivalry was largely removed. The most manifest 
 result of Cope's western work was the publication in 
 1883 of his Vertebrata of the Tertiary Formations of the 
 West, which formed volume 3 of the quarto publications 
 of the Hayden Survey. This huge book contains more 
 than 1000 pages and 80 plates and has been facetiously 
 called "Copers Bible." 
 
 Cope's philosophical contributions, which covered the 
 domains of evolution, psychology, ethics, and meta- 
 physics, began in 1868 with his paper on The Origin of 
 Genera. In evolution he was a follower of Lamarck, and 
 as such, with Hyatt, Ryder, and Packard, was one of the 
 founders of the so-called Neo-Lamarckian School in 
 America. Cope's principal contribution, set forth in his 
 Factors of Organic Evolution, is the idea of kinetogenesis 
 or mechanical genesis, the principle that all structures 
 are the direct outcome of the stresses and strains to 
 which the organism is subjected. Weismann's forcible 
 attack on the transmission theory did not shake Cope's 
 faith in these doctrines, for he claimed that the paleon- 
 tological evidence for the inheritance of such characters 
 as are apparently the result of individual modification 
 was too strong to be refuted. Cope was more like 
 Lamarck than any other naturalist in his mental make-up 
 as well as his ideas. He was also, like Haeckel, given 
 to working out the phylogeny of whatever type lay before 
 him, and in many instances arrived marvellously near the 
 truth as we now see it. 
 
 Associated for a while with A. S. Packard, Cope soon 
 became chief editor and proprietor of the American Nat- 
 uralist, which was for many years his main means of pub- 
 lication and thus served our science in a way comparable 
 to the Journal. As Osborn says by way of summation: 
 
 15 
 
238 A CENTUEY OF SCIENCE 
 
 "Cope is not to be thought of merely as a specialist in Paleon- 
 tology. After Huxley he was the last representative of the old 
 broad-gauge school of anatomists and is only to be compared 
 with members of that school. His life-work bears marlis of great 
 genius, of solid and accurate observation, and at times of inac- 
 curacy due to bad logic or haste and overpressure of work. 
 . . . As a comparative anatomist he ranks both in the range 
 and effectiveness of his knowledge and his ideas with Cuvier and 
 Owen. . . . As a natural philosopher, wdiile far less logical 
 than Huxley, he was more creative and constructive, his meta- 
 physics ending in theism rather than agnosticism." 
 
 1S70-1SS0. 
 
 The seventh decade was productive of comparatively 
 few great names in the history of our science, but two, 
 J. A. Ryder and Samuel W. Williston, being notable con- 
 tributors. The former produced but few papers and 
 those between 1877 and 1892, yet they were of note and 
 such was their influence that he is named with Hyatt, 
 Packard, and Cope as one of the founders of the Neo- 
 Lamarckian School of evolutionists in America. Ryder 
 was a particular friend and a colleague of Cope, as they 
 were both concerned with the back-boned animals, while 
 the other two were invertebratists. Ryder wrote on 
 mechanical genesis of tooth forms and on scales of fishes, 
 also on the morphology and evolution of the tails of 
 fishes, cetaceans, and sirenians, and of the other fins of 
 aquatic types. He did, on the other hand, practically no 
 systematic or descriptive work. 
 
 Williston, on the contrary, has had a long and varied 
 career as an investigator and as an educator. Trained 
 at Yale, he prepared for medicine, and much of his teach- 
 ing has been of human anatomy, both at Yale and at the 
 University of Kansas where he served for a number of 
 years as dean of the Medical School. He is also a stu- 
 dent of flies, and as such not only the foremost but indeed 
 almost the only dipterologist in the United States. But 
 it is with his work as a vertebrate paleontologist that we 
 are chiefly concerned, and here again he stands among 
 the foremost. His initial work and training in this 
 department of science were with Marsh, for whom he 
 spent many months in field work, collecting largely in the 
 Niobrara Cretaceous of Kansas. He did, however, no 
 
VERTEBRATE PALEONTOLOGY 239 
 
 research while with Marsh, owing to the latter 's disin- 
 clination to foster such work on the part of his associates. 
 Williston began his publications in 1878 and has con- 
 tinued them until the present, working mainly with Cre- 
 taceous mosasaurs, plesiosaurs, and pterodactyls. Of 
 late, since his transference to the Universitj- of Chicago, 
 where as professor of paleontology and director of the 
 Walker Museum he has served since 1902, his interest has 
 lain mainly among the Paleozoic reptiles and amphibia. 
 Williston 's more notable works are American Permian 
 Vertebrates and Water Reptiles of the Past and Present, 
 wherein he sets forth his views of the phylogenesis and 
 taxonomy of the reptilian class. He is at present at 
 work on the evolution of the reptiles, a volume which is 
 eagerly awaited by his colleagues. It is in morphology 
 that Williston 's greatest strength lies and some of 
 his most effective work on the mosasaurs has appeared 
 in the Journal. 
 
 1880-1900. 
 
 The next decade, that of 1880-1890, saw a number of 
 notable additions to the workers in vertebrate paleontol- 
 ogy : Henry F. Osborn, W. B. Scott, R. W. Shufeldt, J. L. 
 Wortman, George Baur, F. A. Lucas, and F. W. True. 
 Shufeldt is our highest authority on the osteology of 
 birds, both recent and extinct, having recently described 
 all of the extinct forms contained in the Marsh collec- 
 tion ; True wrote of Cetacea ; Lucas of marine and Pleis- 
 tocene mammals and birds, and has also written popular 
 books on prehistoric life. Lucas's greatest service, how- 
 ever, lies in the museums, where he has manifested a 
 genius second to none in the installation of mute evi- 
 dences of living and past organisms. Wortman was for 
 a time associated with Cope, later with Osborn in the 
 American Museum, again at the Carnegie Museum at 
 Pittsburgh, and finally at Yale in research on the Bridger 
 Eocene portion of the Marsh collection. His work has 
 been chiefly the perfection of field methods in vertebrate 
 paleontology, and as a special investigator of Tertiary 
 Mammalia, treating the latter largely from the morpho- 
 logic and taxonomic standpoints. Wortman 's Yale 
 results on the carnivores and primates of the Eocene, 
 
240 A CENTURY OF SCIENCE 
 
 as yet unfinished, were published in the Journal in 
 1901-1904. 
 
 "William B. Scott is a graduate of Princeton, and has 
 spent thirty-four years in her service as Blair Professor 
 of Geology and Paleontology. His first publication, in 
 1S7S, issued in conjunction with Osborn and Speir, 
 described material collected by them in the Eocene for- 
 mations of the West, and since that time Scott's research 
 has been entirely with the mammals, on which he is one of 
 our highest authorities. His most notable works have 
 been a History of Land Mammals of the Western Hemi- 
 sphere, 1913, and the results of the Patagonian expedi- 
 tions by Hatcher, which are published in a quarto series 
 in conjunction with W. J. Sinclair, although they are the 
 authors of separate volumes, Scott's work being mainly 
 on the carnivores and edentates of the Santa Cruz forma- 
 tion. It is as a systematist in research and as an educa- 
 tor that Scott has attained his highest usefulness. 
 
 The man who, next to the three pioneers, has attained 
 the highest reputation in vertebrate paleontologic 
 research, is Henry Fairfield Osborn. Graduate of 
 Princeton in the same class that produced Scott, Osborn 
 served for a time as professor of comparative anatomy 
 in that institution, and in 1891 was called to New York to 
 organize the department of zoology in Columbia Uni- 
 versity and that of vertebrate paleontology in the Ameri- 
 can Museum of Natural History. He had, early in his 
 career, gone west in company with Professor Scott, and 
 had collected material from the Eocene formation of 
 Wyoming, upon which they based their first joint paper 
 in 1878, Osborn 's first independent production, a memoir 
 on two genera of Dinocerata, appearing in 1881. A num- 
 ber of papers followed, on the Mesozoic Mammalia, on 
 Cope's tritubercular theory, and on certain apparent evi- 
 dences for the transmission of acquired characters. It 
 was, however, with his acceptance of the New York 
 responsibilities, especially at the American Museum, 
 that Osborn 's most significant work began. Aided first 
 by Wortraan and Earle, later by W. D. Matthew and 
 others, he has built up the greatest and most complete 
 collection of fossil vertebrates extant; its value, how- 
 ever, was largely enhanced through the purchase of the 
 
VERTEBRATE PALEONTOLOGY 241 
 
 private collection of Professor Cope, which of course 
 included a large number of types. The American 
 Museum collection thus contains not only a vast series 
 of representative specimens from every class and order 
 of vertebrates, secured by purchase or expedition from 
 nearly all the great localities of the world, but an exhi- 
 bition series of skulls and partial and entire skeletons 
 and restorations which no other institution can hope to 
 equal. Based upon this wonderful material is a large 
 amount of research, tilling many volumes, published for 
 the greater part in the bulletin and memoirs of the 
 Museum. This research is not only the product of the 
 staff, including Walter Granger, Barnum Brown, W. D. 
 Matthew, and W. K. Gregory, but also of a number of 
 other American and some foreign paleontologists as well. 
 
 Professor Osborn's own work has been voluminous, his 
 bibliography from 1877 to 1916 containing no fewer than 
 441 titles, ranging over the fields of paleontology, — which 
 of course includes the greater number — geology, correla- 
 tion and paleogeography, evolutionary principles exem- 
 plified in the jMammalia, man, neurology and embry- 
 ology, biographies, and the theory of education. 
 
 In paleontology, Osborn's researches have been largely 
 Avith the Reptilia and Mammalia, partly morphological, 
 but also taxonomic and evolutional. Faunistic studies 
 have also been made of the mammals. Of his published 
 volumes the most important are, first, the Age of Mam- 
 mals (1910), in which he treats not of evolutionary series 
 of phylogenies, but of faunas and their origin, migra- 
 tions, and extinctions, and of the correlation of Old and 
 New World Tertiary deposits and their contents. Men 
 of the Old Stone Age (1916) is an exhaustive treatise and 
 is the first full and authoritative American presentation 
 of what has been discovered up to the present time 
 throughout the world in regard to human prehistory. In 
 his latest volume. The Origin and Evolution of Life 
 (1917), Osborn presents a new energy conception of evo- 
 lution and heredity as against the prevailing matter and 
 form conceptions. In this volume there is summed up 
 the whole story of the origin and evolution of life on 
 earth up to the appearance of man. This last book is 
 novel in its conceptions, but it is too early as yet to judge 
 
242 A CENTURY OF SCIENCE 
 
 of the acceptance of Osborn's theses by his fellow work- 
 ers in science. 
 
 Since the death of Professor Marsh, Osborn has served 
 as vertebrate paleontologist to the United States Geolog- 
 ical Survey, and has in charge the carrying through to 
 completion of the many monographs proposed by his dis- 
 tinguished predecessor. One of these, that on the horned 
 dinosaurs, has been completed by Hatcher and Lull 
 (1907), another on the stegosaurian dinosaurs has been 
 carried forward by C. W. Gilmore of the United States 
 National Museum, while under Osborn's own hand are 
 the memoirs on the titanotheres (aided by W. K. Greg- 
 ory), the horses, and the sauropod dinosaurs. Of these, 
 the first, when it shall have been completed, promises to 
 be the most monumental and exhaustive study of a group 
 of fossil organisms ever undertaken. 
 
 As a leader in science, a teacher and administrator, 
 Professor Osborn's rank is high among the leading verte- 
 bratists. He is remarkably successful in his choice of 
 assistants and in stimulating them in their productive- 
 ness so that their combined results form a very consider- 
 able share of the later literature in America. 
 
 The ninth decade ushered in the work of a valuable 
 group of students, of whom John Bell Hatcher should be 
 mentioned in particular, as his work is done. Graduate 
 of Yale in 1884, he spent a number of years assisting 
 his teacher, Professor Marsh, mainly in the field, collect- 
 ing during that time, either for Yale or for the United 
 States Geological Survey, an enormous amount of very 
 fine material, especially from the West, although he also 
 collected in the older Tertiary and Potomac beds near 
 Washington. In the West he secured no fewer than 
 105 titanothere skulls, explored the Tertiary, Judith 
 River, and Lance formations, collected and in fact vir- 
 tually discovered the remains of the Cretaceous mammals 
 and of the horned dinosaurs which he was later privileged 
 to describe. He then (1893) went to Princeton, which he 
 served for seven years, his principal work being explora- 
 tions in Patfigonia for the E. and M. ]\Iuseum, one direct 
 result of which was the publication of a large quarto on 
 the narrative of the expedition and the geography and 
 ethnography of the region. Going to the Carnegie 
 
VERTEBRATE PALEONTOLOGY 243 
 
 Museum in Pittsburgh in 1900, Hatcher carried forward 
 the work of exploration and collecting begun for that 
 institution by Wortman, and as a partial result prepared 
 many papers, the principal ones being memoirs on the 
 dinosaurs liaplocanthosaurus and Diplodocus. In 1903, 
 with T. W. Stanton of the United States Geological Sur- 
 vey, Hatcher explored the Judith River beds and together 
 they settled the vexatious problem of their age, the 
 published results appearing in 1905, after Hatcher's 
 death. His last piece of research, begun in 1902 and 
 continued until his death in 1904, was an elaborate mono- 
 graph on the Ceratopsia, one of the many projected by 
 Marsh. Of this memoir Hatcher had completed some 
 150 printed quarto pages, giving a rare insight into the 
 anatomy of these strange forms. The final chapters, 
 however, which were based very largely upon Hatcher's 
 own opinions, had to be prepared by another hand. 
 
 Despite his early death, therefore. Hatcher rendered 
 a very signal service to American paleontology — in 
 exploration, stratigraphy, morpholo.gy, and systematic 
 revision — and his activity in planning new fields of 
 research, such, for instance, as the exploration of the 
 Antarctic continent, gave promise of further high attain- 
 ment, when his hand was arrested by death. 
 
 Summari/. 
 
 It is not surprising that American vertebrate paleontol- 
 ogy has arisen to so high a plane, when one considers the 
 material at its disposal. Having a vast and virgin field 
 for exploration, a sufficient number of collectors, some of 
 whom have devoted much of their lives to the work, and 
 a refinement of technique that permitted the preservation 
 of the fragmental and ill conserved as well as the finer 
 specimens, the results could hardly have been otherwise. 
 Thus it has been possible to secure material almost 
 unique throughout the world for extent, for complete- 
 ness, and for variet}^ To this must be added a certain 
 American daring in the matter of the restoration of miss- 
 ing portions, both of the individual bones and of the 
 skeleton as a whole, such as European conservatism will 
 not as a rule permit. This work has for the most part 
 been done after the most painstaking comparison and 
 
244 A CENTURY OF SCIENCE 
 
 research and is highly justified in the accuracy of the 
 results, which render the fabric of the skeleton much 
 more intelligible, both to the scientist and to the layman. 
 Material once secured and prepared is then mounted, 
 and here again American ingenuity has accomplished 
 some remarkable results. Some of the specimens thus 
 mounted are so small and delicate as to require holding 
 devices comparable to those for the display of jewels; 
 yet others — huge dinosaurs the bones of which are enor- 
 mously hea\'y, but so brittle that they will not bear even 
 the weight of a process unsupported — require a care- 
 fully designed and skilfully worked out series of supports 
 of steel or iron which must be perfectly secure and at the 
 same time as inconspicuous as possible. And of late the 
 lifelike pose of the individual skeleton has been aug- 
 mented by the preparation of groups of several animals 
 which collectively exhibit sex, size, or other individual 
 variations and the full mechanics of the skeleton under 
 the varying poses assumed by the creature during life. 
 
 The work of further restoration has been rendered pos- 
 sible through comparative anatomical study, enabling us 
 to essay restorations in entirety by means of models and 
 drawings, clothing the bones with sinews and with flesh 
 and the flesh with skin and hair, if such the creature 
 bore ; while the laws of f aunal coloration have permitted 
 the coloring of the restoration in a way which if not the 
 actual hue of life is a very reasonable possibility. 
 
 Thus the American paleontologists have blazed a trail 
 which has been followed to good effect by certain of their 
 Old World colleagues. 
 
 With such means and methods and such material avail- 
 able, it is again not surprising that American paleontology 
 has furnished more and more of the evidences of evolu- 
 tion, and disclosed to the eyes of scientists animal rela- 
 tionships which were undreamed of by the systematist 
 whose research dealt only with the existing. It has also 
 explained some vexatious problems of animal distribution 
 and of extinction, and has connected up cause and effect 
 in the great evolutionary movements which are recorded. 
 
 The results of systematic research have added hosts of 
 new genera aud species and of families, but of orders 
 there are relatively few. Nevertheless a number, 
 
VERTEBRATE PALEONTOLOGY 245 
 
 especially among reptiles and mammals, have come to 
 light as the fruits of American discovery. But aside 
 from the dry cataloguing of such groups, the American 
 systematists have worked out some very remarkable phy- 
 logenies and have thus clarified our vision of animal 
 relationships in a way which the recent zoologist could 
 never have done. In this connection, the Permian ver- 
 tebrates, which have been collected and studied with 
 amazing success, principally by Williston and Case, 
 should be mentioned, although the work is yet incom- 
 plete. Some of these forms are amphibian, others rep- 
 tilian, yet others of such character as to link the two 
 classes as transitional forms. Of the Mesozoic reptiles, 
 a very remarkable assemblage has come to light, in a 
 degree of perfection unknown elsewhere. These are dino- 
 saurs, of which several phyla are now known ; carnivores 
 both great and small, some of the latter being actually 
 toothless ; Sauropoda, whose perfection and dimensions 
 are incomparable except for those found in East Africa; 
 and predentates, armored, unarmored, and horned, the 
 last exclusively American. The unarmored trachodonts 
 are now known in their entirety, for not only has our 
 "West produced articulated skeletons but mummified car- 
 casses whose skin and other portions of their soft 
 anatomy are represented, and which are thus far without 
 a parallel elsewhere in the world. Other reptilian 
 groups are well known, notably the Triassic ichthyosaurs, 
 and the mosasaurs and plesiosaurs of the Kansas chalk. 
 The last formation has also produced toothed birds, 
 Hesperornis and Ichthyornis, which again are absolutely 
 unique. 
 
 But it is in the mammalian class that the phylogenies 
 become so highly complete and of such great importance 
 as evolutionary evidences, for nowhere else than in our 
 own West have such series been found as the Dinocerata 
 and creodonts among archaic forms, the primitive 
 primates from the Eocene, the carnivores such as the 
 dogs and cats and mustellids, but especially the hoofed 
 orders such as the horses. Of these hoofed orders, the 
 classic American series of horses is complete, that of 
 the camels probably no less so, while much is known of 
 the deer and oreodonts, the last showing several parallel 
 
246 A CENTURY OF SCIENCE 
 
 phyla, and of the proboscideans, which while having their 
 pristine home in the Old World nevertheless soon sought 
 the new where their remains are found from the Miocene 
 until their final and apparently very recent extinction. 
 These creatures show increase of bulk, perfection of feet 
 and teeth, development of various weapons, horns and 
 antlers, which may be studied in their relationship with 
 the other organs to make the evolving whole, or their 
 evolution may be traced as individual structures which 
 have their rise, culmination, and sometimes their senile 
 atrophy in a way comparable to that of the representa- 
 tives of the order as a whole. Thus, for example, 
 Osborn has traced the evolution of the molar teeth, and 
 Cope of the feet, while Marsh has shown that brain devel- 
 opment runs a similar course and that its degree of per- 
 fection within a group is a potent factor for survival. 
 As a student of evolution, the paleontologist sees 
 tilings in a very different light from the zoologist. The 
 latter is concerned largely with matters of detail — with 
 the inheritance of color or of the minor and more super- 
 ficial characteristics of animals — and the period of 
 observation of such phenomena is of necessity brief 
 because of the mortality of the observer. Whereas the 
 paleontologist has a perspective which the other lacks, 
 since for him time means little in the terms of his own 
 life, and he can look into the past and see the great and 
 fundamental changes which evolution has wrought, the 
 rise of phyla, of classes, of orders, and he alone can see 
 the orderliness of the process and sense the majesty of 
 the laws which govern it. 
 
 Influence of the American Journal of Science, 
 
 The influence of the American Journal of Science as a 
 medium for the dissemination of the results of vertebrate 
 research has been in evidence throughout this discussion, 
 but it were well, perhaps, to emphasize that service more 
 fully. The Journal was, as we have seen, the chief outlet 
 for Professor Marsh's research, for there were published 
 in it during his lifetime no fewer than 175 papers descrip- 
 tive of the forms which he studied, as well as a great part 
 of the material in the published monographs. As ]\Iarsh 
 
VERTEBRATE PALEONTOLOGY 247 
 
 left very few manuscript notes, the importance of these 
 frequent publications in thus setting- forth much that he 
 thought and learned concerning the material is very 
 great indeed. The combined titles of all other authors in 
 the Journal in this line of research for the century of its 
 life fall far short of the number produced by Marsh 
 alone, as they include 136 all told, but the range of sub- 
 jects is highly representative of tlie entire field of verte- 
 brate research. It should be borne in mind, moreover, 
 that Leidy, Cope, and Osborn each had another medium 
 of publication, which of course is true of other workers 
 in the great museums such as the American, National, 
 and Carnegie, all of which issue bulletins and quarto 
 publications for the purpose of disseminating the work 
 of their staff. Many of the earlier announcements of the 
 discovery of vertebrate relics appeared in the Journal, as 
 did practically all the literature of the science of fossil 
 footprints (ichnology), except of course the larger 
 quartos of Hitchcock and Deane. Of the footprint 
 papers by Hitchcock, Deane, and others, there were no 
 fewer than thirty-two, with a number of additional com- 
 munications on attendant phenomena bones and plants. 
 Up to 1847, except for a few foreign announcements, 
 the Journal published almost exclusively on eastern Amer- 
 ican paleontology, the only exception being a notice of 
 bones from Oregon by Perkins in 1842. In 1847 came the 
 announcement of a western "PalEeothere" by Prout, 
 which marked the beginning of the researches of Leidy 
 and others in the Bad Lands of the great Nebraska 
 plains. The Journal thenceforth published paper after 
 paper on forms from all over North America, and on all 
 aspects of our science : discovery, systematic descrip- 
 tion, faunal relationships, evolutionary evidences — thus 
 showing that breadth and catholicity which has made it 
 so great a power in the advancement of science. 
 
VII 
 
 THE RISE OF PETROLOGY AS A SCIENCE 
 
 By LOUIS V. PIRSSON 
 
 THIS chapter is intended to present a brief sketch of 
 the progress of tlie science of petrology from its 
 early beginnings down to the present time. The 
 field to be covered is so large that this can be done only in 
 broadest outline, and it has therefore been restricted chiefly 
 to what has been accomplished in America. Although the 
 period covered by the life of the Journal extends back- 
 ward for a century it is, however, practically only 
 within the last fifty years that the rocks of the earth's 
 crust have been made the subject of such systematic 
 investigation by minute and delicately accurate methods 
 of research as to give rise to a distinct branch of geologic 
 science. It is not intended of course to affirm by this 
 statement that the broader features of the rocks, espe- 
 cially those which may be observed in the field and which 
 concern their relations as geologic masses, had not been 
 made the object of inquiry before this time, since this is 
 the very foundation of geology itself. Moreover, a cer- 
 tain amount of investigation of rocks, as to the minerals 
 of which they were composed, the significance of their 
 textures, and their chemical composition, had been car- 
 ried out, concomitant with the growth from early times 
 of geology and mineralogy. Thus, in 1S15, Cordier bv a 
 process of washing separated the components of a basalt 
 and ))y chemical tests determined the constituent min- 
 erals. At the time the Journal was founded, and for 
 many years following, the genesis of rocks, especially of 
 igneous rocks, was a subject of inquiry and of prolonged 
 discussion. The aid of the rapidly growing science of 
 chemistry was invoked by the geologists ancf analyses of 
 rocks were made m the attempt to throw light on 'impor- 
 
RISE OF PETROLOGY AS A SCIENCE 249 
 
 tant questions. It is remarkable, also, how keen were 
 the observations that the geologists of those days made 
 upon the rocks, as to their component minerals and 
 structures, aided only by the pocket lens. Many ideas 
 were put forward, the essentials of which have persisted 
 to the present day and have become interwoven into the 
 science, whereas others gave rise to contentions which 
 have not yet been settled to the satisfaction of all. At 
 times in these earlier days the microscope was called into 
 use to help in solving questions regarding the finer 
 grained rocks, but this employment, as Zirkel has shown, 
 was merely incidental, and no definite technique or 
 purpose for the instrument was established. 
 
 On the other hand, the fact that up to the middle of the 
 last century a large store of information relating to the 
 occurrence of rocks, and to the mineral composition of 
 those of coarser grain, and somewhat in respect to their 
 structure, had been accumulated, caused attempts in one 
 way or another to find means of coordinating these data 
 and to produce classifications, such as those of Von Cotta 
 and Cordier. The history of these attempts at classifi- 
 cation, before the revelations made by the use of the 
 microscope had become general, has been admirably 
 re^dewed by Whitman Cross^ and need not be further 
 enlarged upon here. 
 
 That a considerable amount of work was done along 
 chemical lines also is testified to by the publication of 
 Roth's Tabellen in 1861, in which all published analyses of 
 rocks up to that date were collected. What was accom- 
 plished during this period was done chiefly on the con- 
 tinent of Europe, and little attention had been paid to the 
 subject of rocks either in America or in Great Britain — 
 even so late as 1870 Geikie remarks, as referred to by 
 Cross,^ that there was no good English treatise on 
 petrography, or the classification and description of 
 rocks. In this country still less had been accomplished, 
 interest being almost wholly confined to the vigorous and 
 growing sciences of geology and mineralogy. This was 
 natural, for mineralogy is the chief buttress on which the 
 structure of petrology rests and must naturallj^ develop 
 first, especially in a relatively new and unexplored 
 region, whose mineral resources first attract attention. 
 
250 A CENTURY OF SCIENCE 
 
 The geologists in carrying out their studies also observed 
 the rocks as they saw them in the tield and made inci- 
 dental reference to them, but investigations of the rocks 
 themselves was very little attempted. An inspection of 
 the tirst two series of the Journal shows relatively little 
 of importance in petrology published in this country; 
 a few analyses of rocks, occasional mention of mineral 
 composition, of weathering properties, and notices of 
 methods of classification proposed by French and Ger- 
 man geologists nearly exhaust the list. 
 
 Introduction of the Microscope. 
 
 The beginnings of a particular branch of science are 
 generally obscure and rooted so imperceptibly in the 
 foundations on which it rests that it is difficult to point 
 to any particular place in its development and say that 
 this is the start. There are exceptions of course, like the 
 remarkable work of Willard Gibbs in physical chemistry, 
 and it may chance that the happy inspiration of a single 
 worker may give such direction to methods of investiga- 
 tion as to open the gates into a whole new realm of 
 research, and to thus create a separate scientific field, as 
 happened in Radiochemistry. 
 
 This is what occurred in petrology when Sorby in 
 England, in 1858,^ pointed out the value of the micro- 
 scope as an instrument of research in geologic investiga- 
 tions, and demonstrated that its employment in the study 
 of thin sections of rocks would yield information of the 
 highest value. Others beside Sorby had made use of the 
 microscope, as pointed out by Zirkel,* but, as he indi- 
 cates, no one before him had recognized its value. Dur- 
 ing the next ten years or so, however, its recognition w^as 
 very slow and the papers published by Sorby himself 
 were mainly concerned in settling very special matters. 
 
 As Williams"* has suggested, the greatest service of 
 Sorby was, perhaps, his instructing Zirkel in his ideas 
 and methods, for the latter threw himself whole-heart- 
 edly into the study of rocks by the aid of the microscope 
 and his discoveries stimulated other workers in this field 
 in Germany, his native country, until the dawning science 
 of petrology began to assume form. A further step for- 
 
RISE OF PETROLOGY AS A SCIENCE 251 
 
 ward was taken in 1873 in the appearance of the text- 
 books of ZirkeP and Rosenbusch' which collated the 
 knowledge which had been gained and furnished the 
 investigator more precise methods of work. It is diffi- 
 cult for the student of to-day to realize how much had 
 been learned in the interval and, for that matter, how 
 much has been gained since 1873, without an inspection 
 of these now obsolete texts. In 1863, Zirkel, who was 
 then at the beginning of his work, said in his first paper 
 presented to the Vienna Academy of Sciences^ that if he 
 confined himself chiefly to the structure of the rocks 
 investigated and of their component minerals, and stated 
 little as to what these minerals were, the reason for that 
 was because "although the microscope serves splendidly 
 for the investigation of the former relations, it promises 
 very little help for the latter. Labradorite, oligoclase 
 and orthoclase, augite and hornblende, minerals whose 
 recognition offers the most important problems in 
 petrography, in most cases cannot be distinguished from 
 one another under the microscope." How little could 
 Zirkel have foreseen, at this time, less than forty years 
 later, that not only could labradorite be accurately 
 determined in a rock-section, but that in a few minutes by 
 the making of two or three measurements on a properly 
 selected section, its chemical composition and the crys- 
 tallographic orientation of the section itself could be 
 determined ! 
 
 Tlie TJiin Section, 
 
 Before going further we may pause here a moment to 
 consider the origin and development of the thin section, 
 without which no progress could have been made in this 
 field of research. Wben we reflect upon the matter, it 
 seems a marvelous thing indeed that the densest, blackest 
 rock can be made to yield a section of the 1/1000 of an 
 inch in thickness, so thin and transparent that fine print- 
 ing can be easily read through it, and transmitting light 
 so clearly that the most high-powered objectives of the 
 microscope can be used to discern and study the minutest 
 structures it presents with the same capacity that they 
 can be employed upon sections of organic material pre- 
 pared by the microtome. This is no small achievement. 
 
252 A CENTURY OF SCIENCE 
 
 The first thin sections appear to have been prepared in 
 1828 by William Nicol of Edinburgh, to whom we owe the 
 prism which carries his name. He undertook the making 
 of sections from fossil wood for the purpose of studying 
 its structure. The method he developed was in principle 
 the same as that employed to-day, where machinery is 
 not used ; that is, he ground a flat smooth surface upon 
 one side of a chip of his petrified wood, then cemented 
 this to a bit of glass plate with Canada balsam, and 
 ground down the other side until the section was suffi- 
 ciently thin. This method was used by others for the 
 study of fossil woods, coal, etc., but it was not applied to 
 rocks until 1850, when Sorby used it for investigating a 
 calcareous grit. Oschatz, in Germany, also about this 
 time independently discovered the same method. A fur- 
 ther advance was made in melting the cement, floating off 
 the slice, and transferring it to a suitable object-glass 
 with cover, a process still employed by many ; though 
 most operators now cement the first prepared surface of 
 the rock chip directly to the object-glass, and mount the 
 section without transferring it. 
 
 Next came the use of machinery to save labor in grind- 
 ing, and another step was made in the introduction of the 
 saw, a circular disk of sheet iron wdiose edge was fur- 
 nished with embedded diamond dust. This makes it 
 possible to cut relatively thin slices with comparative 
 rapidity, but the final grinding which requires experience 
 and skill must still be done by hand. Carborundum has 
 also largely replaced emery. The skill and technique of 
 preparers has reached a point where sections of rocks of 
 the desired thinness (0-001 inch), and four or five inches 
 square have been exhibited. 
 
 The Era of Petrography. 
 
 In these earlier days of the science, as noted above, 
 great difficulty was at first experienced in the recognition 
 of the minerals as they wore encountered in the study of 
 rocks under the microscope. At that time the chemical 
 composition and outward crystal form of minerals were 
 relatively much better known than their physical and, 
 especially, their optical properties and constants. Some 
 
RISE OF PETROLOGY AS A SCIENCE 253 
 
 beginnings in this had been made by Brewster, Nicol, and 
 other physicists, and the mineralogists had commenced 
 to study minerals from this viewpoint. Especially 
 Des Cloiseaux had devoted himself to determining the 
 optical properties of many minerals, and the writer, 
 when a student in the laboratory of Rosenbusch in 1890, 
 well recalls the tribute that he paid to the work of 
 Des Cloiseaux for the aid which it had afforded him in his 
 earlier researches in petrographj^ 
 
 The twenty years following the publication of the 
 texts of Rosenbusch and Zirkel may be characterized as 
 the era of microscopical petrog■raphJ^ A distinction is 
 drawn here between the latter word and petrology, a 
 distinction often overlooked, for petrography means lit- 
 erally the description of rocks, whereas petrology denotes 
 the science of rocks. As time passed the broader and 
 more fundamental features of rocks, especiallj' of igneous 
 and metamorphic rocks, in addition to their mineral 
 constitution, were more studied and gained greater recog- 
 nition, petrograpli}' gradually became a department of 
 the larger field of petrology — the science of to-day. 
 
 The use of the microscope, as soon as the method 
 became more generally understood, opened up so vast a 
 field for investigation that at first the study and descrip- 
 tion of the rocks seemed of prime importance. This was 
 natural, for hitherto the finer grained rocks had for the 
 most part defied any adequate elucidation and here was a 
 key which enabled one to read the cipher. A flood of lit- 
 erature upon the composition, structure, and other char- 
 acters of rocks from all parts of the world began to 
 appear in ever increasing volume. The demands of the 
 petrographers for a greater and more accurate knowledge 
 of the physical and optical constants of minerals stimu- 
 lated this side of mineralogy, and increasing attention 
 was given to investigations in this direction. No definite 
 line between the two closely related sciences could be 
 drawn, and a large part of the work published under the 
 heading of petrography could perhaps be as well, or 
 better, described under the title of micro-mineralogy. 
 To some, in truth, the rocks presented themselves simply 
 as aggregates of minerals, occurring in fine grains. 
 
 The work of the German petrographers attracted 
 
 16 
 
254 A CENTURY OF SCIENCE 
 
 attention and drew students from all parts of the world 
 to their laboratories, especially to those of Zirkel and 
 Rosenbusch. The great opportunities, facilities, and 
 freedom for work which the German universities had 
 long offered to foreign students of science naturally 
 encouraged this. In France a brilliant school of petrolo- 
 gists, under the able leadership of Michel-Levy and 
 Fouque, had arisen whose work has been continued by 
 Barrois, Lacroi:x and others, but the rigid structure of 
 the French universities at that period did not permit 
 of the offering of great inducements for the attendance 
 of foreign students. The work of the French petrog- 
 raphers will be noticed in another connection. 
 
 In Great Britain, the home of Sorby, the new science 
 progressed at first slow^ly, until it was taken up by All- 
 port, Bonney, Judd, Rutley, and others. In 1885 the 
 evidence of the advance that had been made and of the 
 firm basis on which the new science was now placed 
 appeared in Teall's great work, "British Petrography," 
 which marked an epoch in that country in petrographic 
 publication. This work was of importance also in 
 another direction than that of descriptive petrography, 
 in that it contains valuable suggestions for the applica- 
 tion of the principles of modern physical chemistry in 
 solving the problems of the origin of igneous rocks. In 
 it, as in the publications of Lagorio, we see the passage of 
 the petrographic into the petrologic phase of the science. 
 
 The earliest publication in America of the results of 
 microscopic investigation of rocks that the writer has 
 been able to find is by A. A. Julien and C. E. Wright, 
 chiefly on greenstones and chloritic schists from the 
 iron-bearing regions of upper Michigan.'' Naturally, it 
 was of a brief and elementary character. In 1874 E. S. 
 Dana read a paper before the American Association for 
 the Advancement of Science on the result of his studies 
 on the "Trap-rocks of the Connecticut valley," an 
 abstract of which was published in this Journal.^* 
 Meanwhile Clarence King, in charge of the 40th Parallel 
 survey, feeling the need of a systematic study of the 
 crystalline rocks which had been encountered, and finding 
 no one in this country prepared to undertake it, had 
 induced Zirkel to give his attention to this task. The 
 
RISE OF PETROLOGY AS A SCIENCE 255 
 
 result of this labor appeared in 1876 in a fine volume" 
 which attracted great attention. In the same year 
 appeared also petrographical papers by J. H. Caswell,'" 
 
 E. S. Danais and G. W. Hawes.'^ The latter devoted 
 himself almost entirely to this field of research and may 
 thus, perhaps, be termed the earliest of the petrog- 
 raphers in this country. His work, "The Mineralogy 
 and Lithology of New Hampshire," issued in 1878 as one 
 of the reports of the State Survey under Prof. C. H. 
 Hitchcock, was the first considerable memoir by an 
 American. This was followed by various papers, one on 
 the "Albany Granite and its contact phenomena, "'° 
 being of especial interest as one of the earliest studies of 
 a contact zone, and in the fullness of methods employed 
 in attacking the problem forecasting the change to 
 the petrology era. 
 
 During the ten years following, or from 1880 to 1890, 
 the new science of petrography flourished and grew 
 exceedingly. Many young geologists abroad devoted 
 themselves to this field of research and the store of 
 accumulated knowledge concerning rocks from all parts 
 of the world, and their relations grew apace. The work 
 of Teall has been noticed and among others might be 
 mentioned the name of Brogger, whose first contribu- 
 tion'*' in this field gave evidence that his publications 
 would become classics in the science. 
 
 In America there appeared in this period a number of 
 eager workers, trained in part in the laboratories of 
 Eosenbusch and Zirkel, whose researches were destined 
 to place the science on the secure footing in this country 
 which it occupies to-day. Among the earlier of these may 
 be mentioned Whitman Cross, R. D. Irving, J. P. Iddings, 
 Q. H. Williams, J. F. Kemp, J. S. Diller, B. K. Emerson, 
 M. E. Wadsworth, G. P. Merrill, N. H. Winchell, and 
 
 F. D. Adams in Canada. Others were added yearly to 
 this group. As a result of their work a constantly grow- 
 ing volume of information about the rocks of America 
 became available, and one has only to examine the files 
 of the Journal and other periodicals and the listed pub- 
 lications of the National and State Surveys to appreciate 
 this. 
 
 In the Journal, for example, we may refer to papers'^ 
 
256 A CENTURY OF SCIENCE 
 
 by Emerson on the Deerfield dike and its minerals, and 
 on the occurrence of nephelite syenite at Beemersville, 
 N. J. ; to various interesting articles by Cross on lavas 
 from Colorado and the pneumatolytic and other min- 
 erals associated with them; to important papers by 
 Iddings on the rocks of the volcanoes of the Northwest, 
 and those of the Great Basin, to primary quartz in 
 basalt, and the origin of lithophysa?; to the results of 
 researches by G. H. Williams on the rocks of the Cort- 
 landt series, and on peridotite near Syracuse, N. Y. ; to 
 papers by Diller on the peridotites of Kentucky, and 
 recent volcanic eruptions in California; to articles by 
 R. D. Irving on the copper-bearing and other rocks of the 
 Lake Superior region, and to Kemp on dikes and other 
 eruptives in southern New York and northern New 
 Jersey. Other publications would greatly extend this 
 list. 
 
 T/ie Petrologic Era. 
 
 As the chief facts regarding rocks, especially igneous 
 rocks, as to their mineral and chemical composition, their 
 structure and texture and the limits within which these 
 are enclosed, became better known; and the relations, 
 which these bear to the associations of rocks and their 
 modes of occurrence, began to be perceived, the science 
 assumed a broader aspect. The perception that rocks 
 were no longer to be regarded merely as interesting 
 asseml)lages of minerals, but as entities whose charac- 
 ters and associations had a meaning, increased. More 
 and better rock analyses stimulated interest on the 
 chemical side and this and the genesis of their minerals 
 led to a consideration of the magmas and their func- 
 tions in rock-making. The fact that the different kinds 
 of rocks were not scattered indiscriminately, but that 
 different regions exhibited certain groupings with com- 
 mon characters, was noticed. These features led to 
 attempts to classify igneous rocks on different lines from 
 those hitherto employed, and to account for their origin 
 on broad principles. In other words, the descriptive 
 science of petrography merged into the broader one of 
 petrology. No exact time can be set which marks this 
 passage, since the evolution was gradual. Yet for this 
 
RISE OF PETROLOGY AS A SCIENCE 257 
 
 country, in reviewing the literature, for which the suc- 
 cessive issues of tlie "Bibliography of North American 
 Geology" published by the U. S. Geological Survey has 
 been of the greatest value ; the writer has been struck by 
 the fact that in the first volume containing the index of 
 papers down to and including 1891, the articles on sub- 
 jects of this nature are listed under the heading of 
 petrography, whereas in the second volume (1892-1900) 
 they are grouped under pefrolopy and the former head- 
 ing is omitted. A justification for this is found in 
 examining the list of publications and noting their char- 
 acter. With some reason, therefore, the beginning of 
 this period may be placed as in the early years of this 
 decade. Furthermore, it was at this time that the great 
 Avork of ZirkeP® began to appear, which sums up so com- 
 pletely the results of the petrographicera. Rosenbusch^'' 
 was formulating more definitely his views on the division 
 of rocks into magmatic groups, as displayed by their 
 associations in the field, and using this in classification ; 
 an idea which, appearing first in the second edition of his 
 "Physiographie der massigen Gesteine," finds fuller 
 development in the third and last editions of this work. 
 In this country Iddings-° published an important paper, 
 in which the family relationships of igneous rocks and 
 the derivation of diverse groups from a common magma 
 by differentiation are clearly brought out. The funda- 
 mental problems underlying the genesis of igneous rocks 
 had now been clearly recognized, and with this recogni- 
 tion the science passed into the petrologic phase. 
 Brogger-^ also had ascribed to the alkalic rocks of South 
 Norway a common parentage and had pointed out their 
 regional peculiarities. 
 
 From this time forward an attempt may be noted to find 
 an analog}" between rocks and the forms of organic life 
 and to apply those principles of evolution and descent, 
 which have proved so fruitful in the advancement of the 
 biological sciences, to the genesis and classification of 
 igneous rocks. This, perhaps, has on the whole been 
 more apparent than real, in the constant borrowing of 
 terms from those sciences to express certain features and 
 relationships observed, or imagined, to obtain among 
 rocks. Nevertheless, the perception of certain relations 
 
258 A CENTURY OF SCIENCE 
 
 wliicli "we owe so largely to Rosenbuscli and to Brogger^^ 
 has proved of undoubted value in furnishing a stimulus 
 for the investigation of new regions, and in affording 
 indications of what the petrologist should anticipate in 
 his work. 
 
 Thus, the labors of the men previously mentioned, with 
 those of Ba^dey, Bascom, Gushing, Daly, Lane, Lawson, 
 Lindgren, Pirsson, J. F. Williams, Washington, and 
 others, have thrown a flood of light upon the igneous 
 rocks of this continent, and has made it possible to draw 
 many broad generalizations concerning their origin and 
 distribution. Thus, the differentiated laccoliths of Mon- 
 tana"^ have been of service in affording clear examples of 
 the process of local differentiation. Many papers pub- 
 lished in the Journal during the last twenty years show 
 this evolution and growth of petrological ideas. The 
 contributions from American sources during this later 
 period, and of which those in the Journal form a consid- 
 eralile fraction, have indeed been of great weight in 
 shajung the development and future of the science. 
 
 By referring to the tiles of the Journal, it will be seen 
 that they cover a continually widening range of subjects 
 concerning rocks, and articles of theoretical interest are 
 more and more in evidence, along with those of a purely 
 descriptive character.-'* Thus we find discussions by 
 Becker on the physical constants of rocks, on fractional 
 crystallizntion, nnd on differentiation; by Cross on 
 classification; by Adams on the physical properties of 
 rocks ; by Daly on the methods of igneous intrusion ; by 
 AVright on schistosity ; by Fenner on the crystallization 
 of basaltic magma ; by Bowen on differentiation by 
 crystallization ; b}^ the writer on complementary rocks 
 and on the origin of phenocr^'sts ; by Smyth on the origin 
 of alkalic rocks ; by Murgoci on the genesis of riebcckite 
 rocks ; and by Barrell on contact-metamorphism. These 
 may serve as examples, selected almost at random, from 
 the files of the Journal, and we find with them articles 
 descriptive of the petrology of many particular regions, 
 which often contain also matter of general interest and 
 importance, such as papers by Lindgren on the grano- 
 diorite and related rocks of the Sierra Nevada; by 
 Ransome on latite ; by Cross on the Leucite Hills ; by 
 
RISE OF PETROLOGY AS A SCIENCE 259 
 
 Hague on the lavas of the Yellowstone Park ; by Pogue 
 on ancient volcanic rocks from North Carolina ; b> War- 
 ren on peridotites from Cumberland, R. I. ; on sandstone 
 from Texas by Goldman ; and on the petrology of vari- 
 ous localities in central New Hampshire by Washington 
 and the writer. Such a list could of course be much 
 extended and other papers of importance be cited, but 
 enough has been said to indicate how important a reposi- 
 tory of the results of petrologic research the Journal has 
 been and continues to be. 
 
 In thus looking backward over the list of active 
 workers we are involuntarily led to pause and reflect 
 how great a loss American petrology has sustained in 
 the premature death of some of its most brilliant and 
 promising exponents ; it is only necessary to recall the 
 names of R. D. Irving, G. H. Williams, G. W. Hawses, 
 J. F. Williams and Carville Lewis, to appreciate this. 
 
 The store of material gathered during these years has 
 led to the publication of extensive memoirs, in which the 
 science is treated not from the older descriptive side, but 
 from the theoretical standpoint and of classification.-^ 
 In these w^orks strong divergencies of views and opinions 
 are observed, which is a healthy sign in a developing 
 science. 
 
 It should be also noted that along with this evolution 
 on the theoretical side there has been a constant improve- 
 ment in the technique of investigating rocks. It is only 
 necessary to compare the older handbooks of Zirkel and 
 Rosenbuseh wnth the many modern treatises on petro- 
 graphic methods to be assured of this."« It is due on the 
 one hand to the vast amount of careful work wdiich has 
 been done in accurately determining the physical con- 
 stants of rock-minerals'* and in arranging these for their 
 determination microscopically, as in the remarkable 
 studies on the feldspars by Michel-Levy, and on the other 
 in researches on the apparatus employed, and in conse- 
 
 * We may mention here, for example, tTie work in mineralogy of Pen- 
 field, noticed in the aecompanying chapter on mineralogy. In addition to 
 the accurate determination of the composition and constants of many 
 minerals, some of which have importance from the petrographic standpoint, 
 we owe to him more than anyone the recognition of fluorine and hydroxyl 
 in a variety of species, and thereby the perception of their pneumatolytic 
 origin. His papers have been published almost entirely in the Journal. 
 
200 A CENTURY OF SCIENCE 
 
 quent improvements in tliem and in ways of using them, 
 as exemplitied in the delicately accurate methods intro- 
 duced by Wright.-" The development of the microscope 
 itself as an instrument of research in this field and in 
 mineralogy deserves a further word in this connection. 
 The first step toward making the ordinary microscope of 
 special use in this way was taken by Henry Fox Talbot 
 of England, when he introduced in 1834 the employment 
 of the recently invented nicol prisms for testing objects 
 in polarized light. The modern instrument may be said 
 to date from the design offered by Rosenbusch in 1876. 
 Since that time there have been constant improvements, 
 almost year by 3'ear, until the instrument has become one 
 of great precision and convenience, remarkably well 
 adapted for the work it is called upon to perform, with 
 special designs for various kinds of use, and an almost 
 endless number of accessory appliances for research in 
 different branches of mineralogy and crystallography, as 
 well as in petrography proper.-* This also calls to mind 
 the fact that for the convenience of those v/ho are not able 
 to use the microscope special manuals of petrology have 
 lieen prepared in which rocks are treated from the 
 megascopic standpoint.-'' 
 
 Metamorpfiic Rocks. 
 
 In this connection the metamorphic rocks should not 
 be forgotten. They afford indeed the most difficult 
 problems with which the geologist has to deal ; every 
 branch of geological science may in turn be called upon to 
 furnish its quota for help in solving them. Under the 
 attack of careful, accurate and persistent work in the 
 field, under the microscope and in the chemical labora- 
 tory, with the aid of the garnered knowledge in petrol- 
 ogy, stratigraphy, physiography, and other fields of 
 geologic science, their mystery has in large part given 
 Avny. The inaugural work of Lehmann, Lessen, Barrois, 
 Bonney, Teall, and other European geologists, was par- 
 alleled in America by that of R. D. Irving, owing to whose 
 efforts the Lake Superior region became the chief place 
 of study of the metamorphic rocks in this country. 
 TrA-ing soon obtained the assistance of G. H. AVilliams, 
 who had been engaged in the study of such rocks, and the 
 
RISE OP PETROLOGY AS A SCIENCE 201 
 
 latter published a memoir on the greenstone schist areas 
 of Menominee and Marquette in Michigan'^" which will 
 always remain one of the classics in the literature of 
 metamorphic rocks. Irving 's own contributions to 
 petrology, though valuable, were cut short by his 
 untimely death, but the study of this region under the 
 direction of his associate and successor, C. R. Van Hise, 
 with his co-laborers, has yielded a mass of information 
 of fundamental importance in our understanding of met- 
 amorphism and the crystalline schists. Its fruitage 
 appears in the memoir by Van Hise'' which is the author- 
 itative work of reference on metamorphism, and in 
 various publications by him and his assistants, Bayley, 
 Clements, Loith, and others. The work of the Canadian 
 geologists, and of Kemp, Cushing, Smyth and Miller in 
 the Adirondack region, should also be mentioned in con- 
 nection with this field of petrology. 
 
 Chemical Analyses of Itocks, 
 
 It has been previously pointed out that, as the science 
 of petrology grew, chemical investigations of rocks in 
 bulk were undertaken. The object of such analyses was 
 to obtain on the one hand a better control over the 
 mineral composition and on the other to gain an idea of 
 the nature of the magmas from which igneous rocks had 
 formed. The earliest analysis of an American rock of 
 which I can find record is of a "wacke" by J. W. Webster 
 given in the first volume of the Journal, page 296, 1818. 
 
 During the next 40 years a few occasional analyses 
 were undertaken by American chemists, by C. T. Jackson, 
 T. Sterry Hunt, and others. In ]8fil, Justus Roth pub- 
 lished the first edition of his Tabellen, in which he 
 included all analyses which had been made to that date 
 and which he considered were worthy of preservation. 
 Although, naturally, from the status of analytical chem- 
 istry up to that time, most of these would now be con- 
 sidered rather crude, the publication of the work was of 
 great service and marked an epoch in geochemistry. In 
 these tables Roth lists four analyses of American igneous 
 rocks, two from the Lake Superior region by Jackson 
 and J. D. ■\■^^litney and two by European chemists, one of 
 w^hom was Bunsen. The material of the last two was a 
 
262 A CENTURY OF SCIENCE 
 
 "dolerite" and the same locality is given for each — ■ 
 "Sierra Nevada between 38° and 41°" which wasprob- 
 ablj^ considered quite precise for western America in 
 those days. 
 
 From these feeble beginnings the forward progress of 
 petrology on the chemical side in this country has been 
 a steady one until its development has reached the point 
 which will be indicated in what follows. 
 
 The collection of material by the various State surveys 
 and by those initiated by the National Government led to 
 an increasing number of rocks being analyzed during the 
 petrographic period. These became also increasingly 
 good in quality, like those published by G. W. Hawes in 
 his papers. When, however, chemists were appointed to 
 definite positions on the staffs of the Government surveys 
 and especialljr when, after the organization of the U. S. 
 Geological Survey in 1879, a general central laboratory 
 was founded in 1883 with F. W. Clarke in charge, 
 then a new era in the chemical investigation of rocks may 
 be said to have started. In this connection should be 
 mentioned the work of AV. F. Hillebrand, who set a stand- 
 ard of accuracy and detail in rock analysis which had not 
 hitherto been attempted. As a consequence of his accu- 
 rate and thorough methods and results the mass of 
 analyses performed by him and his fellow chemists in 
 this laboratory affords us the greatest single contribu- 
 tion to chemical petrology which has been made. Up to 
 January, 1914, the report of Clarke''- lists some 8000 
 analyses of various kinds made in this laboratory for 
 geologic purposes. Nearly everywhere also a great 
 improvement in the qualitj^ of rock-analyses is to be 
 noted, and in the manuals of Hillebrand'^" and Washing- 
 ton'^ the rock analyst has now at his command the 
 methods of a greatly perfected technique which should 
 insure him the best results. 
 
 Roth's Tabellen have been previouslj^ mentioned; sev- 
 eral supplements were published, but after his death a 
 long interval elapsed before this convenient and useful 
 work was again taken up by Washington^'^ and Osann.^'' 
 A now edition of Washington's Tables has recently been 
 published, listing some 8600 analyses of igneous rocks 
 made up to the close of 1913.=*^ 
 
EISE OF PETROLOGY AS A SCIENCE 263 
 
 On the theoretical side also, where petrology passes 
 into geology, the investigator of to-day will find a mass 
 of most useful and accurate data well discussed in the 
 modern representative of Bischof's Chemical Geology — ■ 
 Clarke's Data of Geochemistry.^® The advance on the 
 chemical side, therefore, has been quite commensurate 
 with that in the microscope as an instrument, and in the 
 results obtained by it. 
 
 FTit/sico-Chemical Work. 
 
 The study of geological results by experimental 
 methods, which should gain information concerning the 
 processes by which those results are caused, and the con- 
 ditions under which they operate, has been from the 
 earliest days of the developing science recognized as 
 most important, and the record of the literature shows 
 considerable was done in this direction. Experimental 
 work in modern petrology may, however, be considered 
 to date from 1882 when Fouque and Michel-Levy"" pub- 
 lished the results of their extensive researches on the 
 sjTithesis of minerals and rocks by pyrogenous methods. 
 The brilliant experiments of the French petrologists at 
 once attracted attention, and since that time a consid- 
 erable volume of valuable work has been done in this 
 field by a number of men, among whom may be men- 
 tioned Morozewicz,*'' Doelter,*' Tamman,*- and Meunier.^-^ 
 As this work continued the results of the rapid advances 
 made in physical chemistry began to be applied in this 
 field with increasing value. To J. H. L. Vogt we owe a 
 valuable series of papers,** in which the formation of 
 minerals and rocks from magmas is treated from this 
 standpoint. Most important of all for the future of 
 petrology has been the founding in Washington of the 
 splendid' research institution, the Carnegie Geophysical 
 Laboratory, under the leadership of Dr. A. L. Day with 
 its corps of trained physicists, chemists and petrologists, 
 devoted to the solving of the problems which the progress 
 of geological science raises. The publications of this 
 institution (many of them published in the Journal) are 
 too numerous to bo mentioned here; many of them 
 treat successfully of matters of the greatest importance 
 in petrology. This is an earnest of what we may hope in 
 
204 A CENTURY OF SCIENCE 
 
 the future. The accumulation of the exact physical and 
 chemical data, which is its aim, will serve as a necessary 
 check to hj^pothetical speculation and bring petrology, 
 and especially petrogenesis, in line with the other more 
 exact sciences by furnishing quantitative foundations for 
 its structure of theory to rest upon. 
 
 While the achievements of this great organization seem 
 to minimize the work of the individual investigator in 
 this field, he may take heart by observing the important 
 results on the strength of rocks under various condi- 
 tions which have been obtained by Adams in recent years, 
 data of wide application in theoretical geology. In this 
 field also a special text has appeared in which the prin- 
 ciples and acquired data are given."*' 
 
 Summary. 
 
 In this brief retrospect, giving only the barest ontlines 
 and omitting from necessity much of importance, we have 
 seen petrology grow from occasional crude experiments 
 into a fully organized science in the last half century. It 
 has to-day a well-perfected technique, a large volume 
 of literature, texts treating of general principles, of 
 methods of work, descriptive handbooks on the morph- 
 ological side, and has attained general recognition as a 
 field, which, though not large, is worthy of the concen- 
 tration of intellectual endeavor. Like other healthy 
 growing organisms it has given rise to offshoots, and the 
 sciences of metallography and of the micro-study of 
 ore deposits, which are rapidly assuming form, have 
 branched from it. 
 
 AVhat of the future? The old days of mostly descrip- 
 tive work, and of theorizing purely from observed results, 
 have passed. The science has entered upon the stage 
 where work and theory must be continually brought into 
 agreement with chemical, physical and mathematical 
 laws and data, and in the application of these new prob- 
 lems present themselves. As we climb, in fact, new hor- 
 izons open to our view indicating fresh regions for 
 exploration, for acquiring human knowledge and for 
 our satisfaction. 
 
RISE OF PETROLOGY AS A SCIENCE 205 
 
 Bibliography, 
 
 ^ W. Cross, Jour. Geology, 10, 451, 1902. 
 
 = Ihid., p. 45. 
 
 » Sorby, Quart. Jour. Geol. Soe., 14, 453, 1858. 
 
 ' Zirkel, Einfuhrung des Mikroskops in das mineralogisch-geologische 
 Studium, 1881. 
 
 " Williams, G. H., Modern Petrography, 1886. 
 
 " Zirkel, Mikroskopische Beschaft'enheit der Mineralien und Gesteine. 
 
 ' Eosenbusch, Mikroskopische Physiographie der petrographisch wichtigen 
 Mineralien. 
 
 " Zirkel, Mikroskopische Gesteinstudien, Sitzung vom 12 Miirz, 186.3. 
 
 "Julien and Wright, Geol. Surv. of Michigan, 2, 1873. Appendices A 
 and C. 
 
 '"Dana, E. S., the Journal, 8, 390-392, 1874. 
 
 "^Zirkel, Geological Exploration of the 40th Parallel; vol. VI, Micro- 
 scopical Petrography. 
 
 ^- Caswell, Microscopical Petrography of the Black Hills. U. S. Geog. 
 and Geol. Surv. Eocky Mts. Eep. on Black Hills of Dakota, 469-527. The 
 separate copies issued bear the imprint 1876; the complete report 1880. 
 
 " Dana, E. S., Igneous Eocks in the Judith Mts. Eep, of Eeconnaissance 
 Carroll, Mont., to Tellowstone Park in 1875. Col. Wm. Ludlovp, War 
 Dept., Washington, 105-106. 
 
 " Hawes, G. W., Eocks of the Chlorite Formation, etc., the Journal, 11, 
 122-126, 1876. Greenstones of New Hampshire, etc., ibid., 12, 129-137, 
 1876. 
 
 '=Hawes, G. W., the Journal, 21, 21-32, 1881. 
 
 " Brogger, Die sUurischen Etagen 2 und 3, Kristiania, 1882. 
 
 '' The references for the papers alluded to, all of them in the Journal, 
 are as follows : 
 
 Emerson, 24, 195-202, 270-278, 349-359, 1SS2; 
 
 23 302-308 1882 
 
 Cross, 21, 94-96, 1884; 31, 432-438, 1886; 39, 359-370, 1890; 41, 466- 
 475,1891; 23,452-458,1882. 
 
 Iddings, 26, 222-235, 1883; 
 
 , 27, 453-463, 1884; 
 
 , 36, 208-221, 1888; 
 
 , 33, 30-45, 1887. 
 
 Williams, 31, 26-41, 1886; 33, 135-144, 191-199, 1887; 35, 433-448, 
 1888; 36, 254-259, 1888. 
 
 , 34, 137-145, 1887. 
 
 Diner, 32, 121-125, 1886; 37, 219-220, 1889; 
 
 , 33, 45-50, 1887. 
 
 Irving (26, 27-32, 321-322, 27, 130-134, 1883; 29, 358-359, 1885). 
 
 Kemp (35, 331-332, 1888; 36, 247-253, 1888; 38, 130-134, 1889). 
 
 "Zirkel, Lehrbuch der Petrographie, 2d ed., 1893. 
 
 "'Hunter and Eosenbusch, Ueber Monchiquit, etc., Min. petr. Mitth., 11, 
 445, 1S90. Eosenbusch, Ueber Structur und Class, der Eruptivgcsteine, 
 ibid., 12, 351, 1891. 
 
 '"'Iddings, Origin of Igneous Eocks, Bull. Phil, Soc. Washington, 12, 
 89-213, 1-892. 
 
 " Brogger, Mineralien der Syenit-pegmatit-gange, etc., Zs. Kryst,, 16, 
 1890, 
 
 '- , Basic Eruptive Eocks of Gran, Quart. .Jour. Geol. Soc, 50, 
 
 15, 1894; Grorudit-Tinguait-Serie, Vidensk. Skrift. 1 Math, nat. Kl,, No. 
 4, 1894. 
 
206 A CENTURY OF SCIENCE 
 
 -'■ Weed and Pirsson, e. <j. Shonkin Sag, the Journal, 12, 1-17, 1901. 
 
 =* The references for the articles mentioned (all in the Journal) are aa 
 follows : 
 
 Becker, 46, 1893; 4, 257, 1897; 3, 21-40, 1897. 
 
 Gross, 39, 6.j7-(jljl, 1915. 
 
 Adams, 22, 95-123, 190G; 29, 465-487, 1910. 
 
 Daly, 22, 195-216, 1906; 26, 17-50, 1908. 
 
 Wright, 22, 224-230, 1906. 
 
 Fenner, 29, 217-234, 1910. 
 
 Bowen, 39, 175-191; 40, 161-185, 1915. 
 
 Pirsson, 50, 116-121, 1895; 7, 271-280, 1899. 
 
 Smyth, 36, 33-46, 1913. 
 
 Murgoci, 20, 133-145, 1905. 
 
 Barren, 13, 279-296, 1902. 
 
 Lindgren, 3, 301-314, 1897; 9, 269-282, 1900. 
 
 Ransome, 5, 355-375, 1898. 
 
 Cross, 4, 115-141, 1897. 
 
 Hague, 1, 445-457, 1896. 
 
 Pogue, 28, 218-238, 1909. 
 
 Warren, 25, 12-36, 1908. 
 
 Goldman, 39, 261-288, 1915. 
 
 Washington and Pirsson, Belknap Mts., 20, 344-353, 1905; 22, 439-457, 
 493-515, 1906. 
 
 , Red Hill, 23, 257-276, 433-447, 1907. 
 
 , Tripyramid Mt, 31, 405-431, 1911. 
 
 -■■ Quantitative Classification of Igneous Rocks, Cross, Iddings, Pirsson 
 and Washington, Chicago, 1903. 
 
 Petrogenesis, C. Doelter, Braunschweig, 1906. 
 
 Igneous Eocks, vols. 1 and 2, J. P. Iddings, New York, 1909 and 1913. 
 
 Problem of Yolcanism, Iddings, New Haven, 1914, 
 
 Natural History of Igneous Rocks, Alfred Harker, London, 1909. 
 
 Igneous Eocks and their Origin, R. A. Daly, New York, 1914. 
 
 =° Among these may be mentioned: 
 
 Rosenbusch u. Wiilfing, Physiog. der petrog. wicht. Min., Stuttgart, 1905. 
 
 Iddings, J. P., Rock-Minerals, "1st ed.. New York, 1906. 
 
 Johannsen, A., Manual of Petrographic Methods, New York, 1914. 
 
 Winehell, N. H. and A. N., Elements of Optical Mineralogy, New York, 
 1909. 
 
 "Wright, Methods of Petrographic-Microscopic Research, Carnegie Inst., 
 Washington, 1911, and various papers; many in the Journal. 
 
 ™ Conf . Wright 's work quoted above and the various manuals previously 
 mentioned. 
 
 "Kemp, Hand-book of Eocks, .3d ed.. New York, 1904. Pirsson, Rocks 
 and Rock-Minerals, New York, 1910. 
 
 "Williams, G. H., XJ. S. Geol. Surv., Bull. 62, Washington, 1890. 
 
 °^Van Hise, Treatise on Metamorphism, U. S. Geol. Surv., Monograph 17. 
 
 ="P. W. Clarke, IT. S. Geol. Surv., Bull. 591, 1915. 
 
 '^ Hillebrand, Analysis of Silicate and Carbonate Rocks, U. S. Geol. Surv., 
 Bull. 422, 1910. 
 
 "Washington, Chemical Analysis of Rocks, pp. 200, New York, 1910. 
 
 '^Id., Chemical Analyses of Igneous Eocks (1884-1900), U. S. Geol. Surv., 
 Prof. Paper, No. 14, 1903. 
 
 ^"Osann, Beitr. zu chem. Petrogr., II Toil. Anal. d. Eruptivgest., 1884- 
 1900, Stuttgart, 1905. 
 
 ■" Washington, ibid., 2d ed., XJ. S. Geol. Surv., Prof. Paper 99, pp. 1216, 
 1917. 
 
EISE OF PETROLOGY AS A SCIENCE 2G7 
 
 »« Clarke, U. S. Geol. Surv., Bull. 616, 1916. 
 
 " Fouque and Michel-Levy, Synthase des Mineraux et des Eoehes, Paris, 
 1882. 
 
 *' Morozewiez, Exper. Untersuch. u. Bildung dcr Min. im Magma, Min. 
 petr. Mitt., 18, 1S9S. 
 
 ■" Doelter, Synthetisehe Studien, N. Jahrb. Min. 1S97, 1, 1-26. AUg. 
 chem. Miiieralogie, etc. 
 
 *^ Tamman, Krystallisieren und Schmelzen, 190.3. 
 
 ■"St. Meunier, Les Methodes de Synthese en Mineralogie, Paris, 1891. 
 
 ■" Vogt, Mineralbildung in Smelzmassen, Christiania, 1892 ; Silikatsehmelz- 
 losungen, 1 and 2, 1903, 1904, and various other papers, esp. in Min. petr. 
 Mitt., vols. 24 and 25, 1906. 
 
 " H. E. Boeke, Grundlageu der physikaliach-chemisehen Petrographie, 
 Berlin, 1915. 
 
VIII 
 
 THE GROWTH OF MINERALOGY FROM 
 1818 TO 1918 
 
 By W1L,LIA3I E. FORD 
 
 ^'i /|~INERALOGY to-day would certainly be generally 
 V/i considered one of the minor members of the 
 AJ 1 group of the Geological Sciences. We commonly 
 look upon it in the light of an useful handmaiden, whose 
 chief function is to serve the other branches, and we are 
 inclined to forget that, in reality, mineralogy was the iirst 
 to be recognized and, with considerable truth, might be 
 claimed as the mother of all the others. Minerals, 
 because of their frequent beauty of color and form, and 
 their uses as gems and as ornamental stones, were the 
 first inorganic objects to excite wonder and comment and 
 we find many of them named and described in very early 
 writings. Theophrastus (368-284 B. C), a famous pupil 
 of Aristotle, wrote a treatise "On Stones" in which he 
 collected a large amount of information about minerals 
 and fossils. The elder Pliny (23-79 A. D.), more than 
 three centuries later, in his Natural History, described 
 and named many of the commoner minerals. At this time 
 it was natural that no clear distinction should be drawn 
 between minerals and rocks, or even between minerals 
 and fossils. As long as all study of the materials of the 
 earth's cnist was concerned with their superficial char- 
 acters, it was logical to include everything under the 
 single head. There were some writers' in the early cen- 
 turies of the Christian era, however, who believed that 
 fossils had been derived from living animals but the 
 majority considered them to be only strange and unusual 
 torms of minerals. During many succeeding centuries 
 httle was added to the general store of geological knowd- 
 edge and it Avas not until the beginning' of the sixteenth 
 
GROWTH OF MINERALOGY 269 
 
 century, that any further notable progress was made. 
 Agricola (1494-1555) was a physician, who, for a time, 
 lived in the mining district of Joachimstal. He studied 
 and described the minerals that he collected there. He 
 was the first to give careful and critical descriptions of 
 minerals, of their crystals and general phj^sical proper- 
 ties. Unfortunately, he also did not realize the funda- 
 mental distinction between fossils and minerals, and 
 probably because of his influence this error persisted, 
 even until the middle of the eighteenth century. But, 
 naturally, as the number of scientific students increased, 
 the number of those who rejected this conclusion grew, 
 until at last, the true character of fossils was established. 
 The keen interest in minerals and fossils which was 
 aroused by this controversy, together with the rapid 
 extension of mining operations, drew the attention of 
 scientific men to other features of the earth's surface 
 and led to a more extended investigation of its characters 
 and thus to the development of geology proper. It is 
 interesting to note also that mineralogy was the first of 
 the Geological Sciences to be officially recognized and 
 taught by the universities. 
 
 Although, as has been shown, the beginnings of min- 
 eralogy lie in the remote past, the science, as we know it 
 to-day, can be said to have had practically its whole 
 growth during the last one hundred years. Of the more 
 than one thousand mineral species that may now be con- 
 sidered as definitely established hardly more than two 
 hundred were known in the year 1800 and these were only 
 partially described or understood. It is true that Haiiy, 
 the "father of crystallography," had before this date dis- 
 covered and formulated the laws of crystal symmetry, 
 and had sho-wm that rational relations existed between 
 the intercepts upon the axes of the different faces of a 
 crystal. It was not until 1809, however, that WoUaston 
 described the first form of a reflecting goniometer, and 
 thus made possible the beginning of exact investigation 
 of crystals. The distinctions between the different crys- 
 tal groups were developed by Bernhardi, Weiss and Mohs 
 between the years 1807 and 1820, while the Naumann 
 system of crystal symbols was not proposed until 1826. 
 The fact that doubly refracting minerals also polarize 
 
 17 
 
270 A CENTURY OF SCIENCE 
 
 light was discovered by Malus in 1808, and in 1813 
 Brewster first recognized the optical differences between 
 uniaxial and biaxial minerals. The modern science of 
 chemistry was also just beginning to develop at this 
 period, enabling mineralogists to make analyses more 
 and more accurately and thus by chemical means to 
 establish the true character of minerals, and to properly 
 classify them. 
 
 Franz von Kobell, on page 372 of his "Geschichte der 
 Mineralogie," somewhat poetically describes the condi- 
 dition of the science at this period as follows : "With the 
 end of the eighteenth and the commencement of the nine- 
 teenth centuries exact investigations in mineralogy first 
 began. The mineralogist was no longer content with 
 approximate descriptions of minerals, but strove rather 
 to separate the essential facts from those that were acci- 
 dental, to discover definite laAvs, and to learn the rela- 
 tions between the physical and chemical characters of a 
 mineral. The use of mathematics gave a new aspect to 
 crystallography, and the development of the optical 
 relationships opened a magnificent field of wonderful 
 phenomena which can be described as a garden gay with 
 flowers of light, charming in themselves and interesting 
 in their relations to the forces which guide and govern the 
 regular structure of matter." 
 
 In the Medical Repository (vol. 2, p. 114, New York, 
 1799), there occurs the following notice : " Since the pub- 
 lication of the last number of the Repository an Associa- 
 tion has been formed in the city of New York 'for the 
 investigation of the Mineral and Fossil bodies which com- 
 pose the fabric of the Globe ; and, more especially, for 
 the Natural and Chemical History of the Minerals and 
 Fossils of the United States,' by the name and style 
 of The American Mineralogical Society." With this 
 announcement is given an advertisement in which the 
 society "earnestly solicits the citizens of the United 
 States to communicate to them, on all mineralogical sub- 
 jects, but especially on the following: 1, concerning 
 stones suitable for gun flints ; 2, concerning native brim- 
 stone or sulphur ; 3, concerning salt-petre ; 4, concerning 
 mines and ores of lead." Further the society asks "that 
 
t> 
 
 GROWTH OF MINERALOGY 2T1 
 
 specimens of all kinds be sent to it for examination and 
 determination. ' ' 
 
 This marks apparently the beginning of the serious 
 study of the science of mineralogy in the United States. 
 From this time on, articles on mineralogical topics 
 appeared with increasing frequencj^ in the Medical 
 Repository. Most of these were brief and were largely 
 concerned with the description of the general characters 
 and modes of occurrence of various minerals. Nothing 
 of much moment from the scientific point of view 
 appeared until many years later, but the growing inter- 
 est in things mineralogical was clearly manifest. An 
 important stimulus to this increasing knowledge and dis- 
 cussion was furnished by Col. George Gibbs who, about 
 the year 1808, brought to this country a large and notable 
 mineral collection. In the Medical Repository (vol. 11, 
 p. 213, 1808), is found a notice of this collection, a portion 
 of which is reproduced below: 
 
 "Gibbs' grand Collection of Minerals. 
 
 One of the most zealous cultivators of mineralogy in the 
 United States is Col. G. Gibbs of Rhode Island and his taste and 
 his fortune have concurred in making him the proprietor of tlie 
 most extensive and valuable assortment of minerals that prob- 
 ably exists in America. 
 
 This rich collection consists of the cabinets possessed by the 
 late Mons. Gigot D'Orcy of Paris and the Count Gregoire de 
 Eozamonsky, a Russian nobleman, long resident in Switzerland. 
 To which tlie present proprietor has added a number, either 
 gathered by himself on the spot, or purchased in different parts 
 of Europe . . . The whole consists of about twenty thousand 
 specimens. A small part of this collection was opened to 
 amateurs at Rhode Island, the last summer, and the next, if 
 circumstances permit, tlie remainder will be exposed." 
 
 In 1802 Benjamin Silliman was appointed professor of 
 chemistry and mineralogy in Yale College. After the 
 Gibbs Collection was brought to America he spent much 
 time with the owner in studying it and, as a result. Col. 
 Gibbs offered to place the collection on exhibition in New 
 Haven if suitable quarters would be furnished by the col- 
 lege. This was quickly accomplished and in 1810,, 1811 
 and 1812 the collection was transferred to New Haven 
 
272 A CENTURY OF SCIENCE 
 
 and arranged for exhibition by Col. Gibbs. Later, in 
 1825, it was purchased by Yale and served as the nucleus 
 about which the present Museum collection of the Univer- 
 sity has been formed. There is no doubt but that the 
 presence at this early date of this large and unusual min- 
 eral collection had a great influence upon the develop- 
 ment of mineralogical science at Yale, and in the country 
 at large. 
 
 In the year 1810 Dr. Archibald Bruce started the 
 "American Mineralogical Journal," the title page of 
 which reads in part as follows : ' ' The American Mineral- 
 ogical Journal, being a Collection of Facts and Observa- 
 tions tending to elucidate the Mineralogy and Geology of 
 the United States of America, together with other Infor- 
 mation relating to Mineralogy, Geology and Chemistry, 
 derived from Scientific Sources." Unfortunately the 
 health of Dr. Bruce failed, and the journal lasted only 
 through its first volume. It had, however, "been most 
 favorably received," as Silliman remarks, and it was felt 
 that another journal of a similar type should be insti- 
 tuted. Such a suggestion was made by Col. Gibbs to 
 Professor Silliman in 1817 and this led directly to the 
 founding of the American Journal of Science in 1818 
 under tire latter 's editorship. Although the field of the 
 Journal at the very beginning was made broad and inclu- 
 sive it has alwa3's published many articles on mineralog- 
 ical subjects. Three of its editors-in-chief have been 
 eminent mineralogists, and without question it has been 
 the most important single force in the development of 
 this science in the country. ]\Iore than 800 well-estab- 
 lished mineral species have been described since the year 
 1800, of which approximately 150 have been from Amer- 
 ican sources. More than two-thirds of the articles 
 describing these new American minerals have first 
 appeared in the pages of the Journal. While the 
 description of new species is not always the most import- 
 ant part of mineralogical investigation, still these fig- 
 ures serve to show the large part that the Journal has 
 played in the growth of American mineralogy. 
 
 It is convenient to review the progress in Mineralogy 
 according to the divisions formed by'the different series, 
 consisting of fifty volumes each, in which the Journal has 
 
GROWTH OF MINERALOGY 273 
 
 been published. These divisions curiously enough will 
 be found to correspond closely to four quite definite 
 phases through which mineralogical investigation in 
 America has passed. The first series covered the years 
 from 1817 to 1845. In looking through these volumes 
 one finds a large number of mineralogical articles, the 
 work of many contributors. The great majority of these 
 papers are purely descriptive in character, frequently 
 giving only general accounts of the mineral occurrences 
 of particular regions. However, a number of articles 
 dealing with more detailed physical and chemical descrip- 
 tions of rare or new species also belong in this period. 
 Among the mineralogists engaged at this time in the 
 description of individual species, none was more inde- 
 fatigable than Charles U. 'Shepard. He was graduated 
 from Amherst College in 1824, at the age of twenty. In 
 1827 he became assistant to Professor Silliman in New 
 Haven, continuing in this position for four years. Later 
 he was a lecturer in natural history at Yale, and was at 
 various times connected with Amherst College and the 
 South Carolina Medical College at Charleston. His 
 articles on mineralogy were very numerous. He assigned 
 a large number of new names to minerals, although with 
 the exception of some half dozen cases, these have later 
 been shown to be varieties of minerals already known and 
 described, rather than new species. In spite, however, of 
 his frequent hasty and inaccurate decision as to the char- 
 acter of a mineral, his influence on the progress of 
 mineralogy was marked. His great enthusiasm and 
 ceaseless industry throughout a long life could not help 
 but make a definite contribution to the science. His 
 "Treatise on Mineralogy" will be spoken of in a later 
 paragraph. He died in May, 1886, having published his 
 last paper in the Journal in the previous September. 
 
 The first book on mineralogy published in America was 
 that by Parker Cleaveland, professor of mathematics, nat- 
 ural philosophy, chemistry and mineralogy in Bowdoin 
 College. The first edition was printed in 1816 and an 
 exliaustive notice is given in the first volume of the Jour- 
 nal (1, 35, 308, 1818) ; a second edition followed in 1822. 
 In his preface Cleaveland gives an interesting discussion 
 concerning the two opposing European methods of classi- 
 
274 A CENTURY OF SCIENCE 
 
 fying minerals. The German school, led by "Werner, 
 classified minerals according to their external characters 
 while the French school, following Haiiy, put the empha- 
 sis on the ' ' true composition. ' ' Cleaveland remarks that 
 "the German school seems to be most distinguished by a 
 technical and minutely descriptive language; and the 
 French, by the use of accurate and scientific principles in 
 the classification or arrangement of minerals." He, 
 himself, tried to combine in a measure the two methods, 
 basing the fundamental divisions upon the chemical com- 
 position and using the accurate description of the physi- 
 cal properties to distinguish similar species and varieties 
 from each other. 
 
 Cleaveland 's mineralogy was followed nearly twenty 
 years later by the Treatise on Mineralogy by Charles 
 IT. Shepard already mentioned. The first part of this 
 book was published in 1832. This contained chiefly an 
 account of the natural history classification of minerals 
 according to the general plan adopted by Mohs, the 
 Austrian mineralogist. The second part of the book, 
 which appeared in 1835, gave the description of indi- 
 vidual species, the arrangement here being an alpha- 
 betical one throughout. Subsequent editions appeared 
 in 1844, 1852 and 1857. 
 
 James Dwight Dana was graduated from Yale College 
 in 1833 at the age of twenty. Four years later (1837) he 
 published "The System of Mineralogy," a volume of 580 
 pages. The appearance of this book was an event of 
 surpassing importance in the development of the science. 
 The book, of course, depended largely upon the previous 
 works of Haiiy, Mohs, Naumann and other European 
 mineralogists, but was in no sense merely a compilation 
 from them. Dana, particularly in his discussion of 
 mathematical crystallography, showed much original 
 thought. He also proved his originality by proposing 
 and using an elaborate system of classification patterned 
 after those already in use in the sciences of botany and 
 zoology. He later became convinced of the undesira- 
 bility of this method of classification and abandoned it 
 entirely in the fourth edition of the System, published in 
 1854, substituting for it the chemical classification which, 
 in its essential features, is in general use to-day. The 
 
GROWTH OF MINERALOGY 275 
 
 System of Mineralogy started in tliis way in 1837, has 
 continued by means of successive editions to be tlie stand- 
 ard reference book in the subject. The various editions 
 appeared as follows: I, 1837; II, 1844: III, 1850; 
 IV, 1854; V, 1868; VI, 1892 (by Edward S. Dana). 
 
 J. D. Dana also contributed numerous mineralogical 
 articles to the first series of volumes of the Journal. 
 It is interesting to note that they are chiefly concerned 
 with the more theoretical aspects of the subject, in fact 
 they constitute practically the only articles of such a 
 character that appeared during this period. Among the 
 subjects treated were crj^stallographic symbols, forma- 
 tion of twin crystals, pseudomorphism, origin of minerals 
 in metamorphosed limestones, origin of serpentine, 
 classification of minerals, etc. 
 
 The volumes of the Second Series of the Journal cov- 
 ered the years from 1846 through 1870. This period was 
 characterized by great activity in the study of the chem- 
 ical composition of minerals. A number of skilled 
 chemists, notably J. Lawrence Smith, George J. Brush 
 and Frederick A. Genth, began about 1850 a long series 
 of chemical investigations of American minerals. Very 
 few articles during this time paid much attention to the 
 physical properties of the minerals under discussion, 
 practically no description of optical characters was 
 attempted, and onlj^ occasionally were the crystals of a 
 mineral mentioned. J. D. Dana was almost the only 
 writer who constantly endeavored to discover the funda- 
 mental characters and relationships in minerals. He 
 published many articles in these years which were con- 
 cerned chiefly with the classification and grouping of 
 minerals, with similarities in the crystal forms of dif- 
 ferent species, with relations between chemical compo- 
 sition and crystal form, chemical formulas, mineral 
 nomenclature, etc. The following titles give an idea of 
 the character of the more important series of articles by 
 him which belong to this category : On the isomorphism 
 and atomic volume of some minerals (9, 220, 1850) ; vari- 
 ous notes and articles on homoeomorphism of minerals 
 (17, 85, 86, 210, 430; 18, 35, 131, 1854) ; on a connection 
 between crystalline form and chemical constitution, with 
 some inferences therefrom (44, 89, 252, 398, 1867). 
 
276 A CENTURY OF SCIENCE 
 
 A great many new mineral names were proposed 
 between 1850 and 1870, a large number of which have con- 
 tinued to be well-recognized species. But there was 
 also a tendency, which has not wholly disappeared even 
 now, to base a mineral determination upon insufficient 
 evidence, and to propose a new species with but little 
 justification for it. In this connection a quotation from 
 the introduction by J. D. Dana to the 3rd Supplement to 
 the System of Mineralogy (4th edition) published in the 
 Journal (22, page 246, 1856), will be of interest. He 
 says: 
 
 "It is a matter of regret, that mineral species are so often 
 brought out, especially in this country, without sufficient inves- 
 tigation and full description. It is not meeting the just 
 demands of the science of mineralogy to say that a mineral has 
 probably certain constituents, or to state the composition in a 
 general way without a complete and detailed analysis, especially 
 when there are no crystallographic characters to afford the 
 species a good foundation. We have a right to demand that 
 those who name species, should use all the means the science of 
 the age admits of, to prove that the species is one that nature 
 will own, for only such belong to science, and if enough of the 
 material has not been found for a good description there is not 
 enough to authorize the nitroduction of a new name in the 
 science. The publication of factitious species, m whatever 
 department of science, is progress not towards truth, but into 
 regions of error ; and often much and long labor is required 
 before the science recovers from these backward steps. ' ' 
 
 J. Lawrence Smith was born in 1818 and died in 1883. 
 He was a graduate of the University of Virginia and of 
 the Medical College of Charleston and later spent three 
 years studying in Paris. Shortly after the completion 
 of his studies he went to Turl5:ey as an advisor to the 
 government of that country in connection with the grow- 
 ing of cotton there. During this time he investigated the 
 emery mines of Asia Minor, and wrote a memoir upon 
 them which was later published by the French Academy. 
 He served as professor of chemistry in the University of 
 Virginia and later held the same chair in the University 
 of Illinois. He published a long series of papers on the 
 chemical composition of minerals and meteorites, as well 
 as on pure chemical subjects. Among the more notable 
 
GEOWTH OF MINERALOGY 277 
 
 of his contributions are the "Memoir on Emery" (1850), 
 a series of papers on the "Reexamination of American 
 Minerals" (1853) written with the collaboration of 
 George J. Brush, and his "Memoir on Meteorites" 
 (1855). 
 
 George J. Brush entered on his scientific career at the 
 moment when science and scientitic methods of research 
 were just beginning to be appreciated in this country, 
 and he soon became one of the leading pioneers in the 
 movement. While his half century of active service was 
 largely occupied by administrative duties in connection 
 with the Sheffield Scientific School, his interest in min- 
 eralogy never flagged. His papers on mineralogical sub- 
 jects number about thirty, all of which were published in 
 the Journal. These began in 1849, even before his 
 graduation from college, and continued until his last 
 paper (in collaboration with S. L. Penfield) appeared in 
 1883. Three of the early papers were written with 
 J. Lawrence Smith as noted above. These papers first set 
 in this country the standard for thorough and accurate 
 scientific mineral investigation. Later in life he was 
 active in the development of the remarkable mineral 
 locality at Branchville, Conn., and, with the collaboration 
 of E. "S. Dana, published in the Journal (1878-90) five 
 important articles on its minerals. This locality, with the 
 exception of the zinc deposits at Franklin Furnace, N. J., 
 was the most remarkable yet discovered in this country. 
 Nearly forty different mineral species were found there, 
 of which nine (mostly phosphates) were new to science. 
 There has certainly been no other series of descriptive 
 papers on a mineralogical locality of equal importance 
 published in this country. 
 
 In addition to publishing original papers. Brush did 
 considerable editorial work in connection with the fourth 
 (1854) and fifth (1868) editions of the System of Miner- 
 alogy and the Appendices to them. JHis Manual of 
 Determinative Mineralogy, with a series of determinative 
 tables adapted from similar ones by von Kobell, was first 
 published in 1874. It was revised in 1878 and later 
 rewritten by S. L. Penfield. This book did much to make 
 possible the rapid and accurate determination of mineral 
 species. Throughout his life. Brush was an enthusiastic 
 
278 A CENTURY OF SCIENCE 
 
 collector of minerals, building up the notable collection 
 that now bears his name. Perhaps, however, his most 
 important contribution to the development of mineralogy 
 in America lay rather in his influence upon his many 
 students. With his enthusiasm for accurate and pains- 
 taking investigation he was an inspiration to all who 
 came in contact with him and his own field and science 
 in general owes much to that influence. 
 
 Among the early mineralogists in this country, who 
 were concerned in the chemical analyses of minerals, 
 none accomplished more or better work than Frederick 
 A. Genth. He was born in Germany in 1820 and lived 
 in that country until 1848, when he came to the United 
 States and settled in Philadelphia. He had studied in 
 various German universities and worked under some of 
 the most famous chemists of that time. His papers in 
 mineralogy number more than seventy-five, in the great 
 majority of which chemical analyses are given. He pub- 
 lished fifty-four successive articles, the greater part of 
 which appeared in the Journal, which were entitled Con- 
 tributions to Mineralogy. In these he gave descriptions 
 of more than two hundred different minerals, most of 
 which were accompanied by analyses. He described 
 more than a dozen new and well-established mineral spe- 
 cies. He was especially interested in the rarer elements 
 and many of his analyses were of minerals containing 
 them. Especially interesting was his work with the tel- 
 lurides, the species coloradoite, melonite and calaverite 
 being first described by him. A long and important 
 investigation was recorded on Corundum, "Its Altera- 
 tions and Associate Minerals," published in the Pro- 
 ceedings of the American Philosophical Society in 1873 
 (13, 361). Dr. Genth died in 1893. 
 
 The period from 1860 until 1875 was not very produc- 
 tive in mineralogical investigations. The first ten vol- 
 umes of the Third Series of the Journal, covering the 
 years 1871-1876, contained mineralogical articles by only 
 some fifteen different authors. But from that time on, 
 the amount of work done and the number of investigators 
 grew rapidly. With this increase in activity came also 
 a decided change in the character of the work. The 
 period between 1871 and 1895 can be characterized as one 
 
GROWTH OF MINERALOGY 279 
 
 in which all the various aspects of mineral investigation 
 received more nearly equal prominence. While the 
 chemical composition of minerals still held rightly its 
 prominent place, the investigation of the crystallographic 
 and optical characters and the relationships existing 
 between all three were of much more frequent occurrence. 
 Edward S. Dana commenced his scientific work by pub- 
 lishing in 1872 an article on the crystals of datolite which 
 was probably the first American article concerned wholly 
 with the description of the crystallography of a mineral. 
 Samuel L. Penfield began his important investigations in 
 1877 and the first articles by Frank W. Clarke appeared 
 during this period. The first edition of the Text Book 
 of Mineralogy by Edward S. Dana with its important 
 chapters on Crystallography and Optical Mineralogy 
 was published in 1877 and his revision of the System of 
 Mineralogy (sixth edition) appeared in 1892. 
 
 Unquestionably the foremost fig-ure in American min- 
 eralogy during this period was that of Samuel L. Pen- 
 field. He embodied in an unusual degree the characters 
 making for success in this science, for few investigators 
 in mineralogy have shown, as he did, equal facility in all 
 branches of descriptive mineralogy. He was a skilled 
 chemist and possessed in a high degree that ingenuity in 
 manipulation so necessary to a great analyst. He was 
 also an accurate and resourceful crystallographer and 
 optical mineralogist. His contributions to the science of 
 mineralogy can be partially judged by the following 
 brief summary of his work. He published over eighty 
 mineralogical papers, practically all of which were 
 printed in the Journal. These included the descriptions 
 of fourteen new mineral species, the establishment of the 
 chemical composition of more than twenty others, and 
 the crystallization of about a dozen more. By a series 
 of brilliant investigations he established the isomorphism 
 between fluorine and the hydroxyl radical. He first 
 enunciated the theory that the crystalline form of a min- 
 eral was due to the mass effect of the acid present rather 
 than that of the bases. He contributed also a number of 
 articles on the stereographic projection and its use in 
 crystallographic investigations, devising a series of pro- 
 tractors and scales to make possible the rapid and accu- 
 
280 A CENTURY OF SCIENCE 
 
 rate use of this projection in solving problems in 
 crystallography. 
 
 Penfield was born in 1856, was graduated from the 
 Sheffield Scientific School in 1877 and immediately 
 became an assistant in the chemical laboratory of that 
 institution. At this time he, together with his colleague 
 Horace L. Wells, made the analyses of the minerals from 
 the newly discovered Branchville locality. He spent the 
 years 1880 and 1881 in studying chemistry in Germany, 
 returning to Yale as an instructor in mineralogy in the 
 fall of 1881. Except for another semester in Europe at 
 Heidelberg he continued as instructor and professor of 
 mineralogy in the Sheffield Scientific School until his 
 early death in 1906. 
 
 It is difficult to choose for mention the names of other 
 investigators in Mineralogy during this period. Toward 
 its end a groat many writers contributed to the pages of 
 the Journal, more than fiftj^ different names being 
 counted for the volumes 41 to 50 of the Third Series. 
 ]\Iany of these are still living and still active in scientific 
 research. Mention should be made of Frank W. Clarke, 
 who contributed many important articles concerning 
 the chemical constitution of the silicates. His work on 
 the mica and zeolite groups is especially noteworthy. 
 The work of W. H. Hillebrand, particularly in regard to 
 his analytical investigations of the minerals containing 
 the rarer elements, was of great importance. The name 
 of W. E. Hidden should be remembered, because, with 
 his keen and discriminating eye and active search for new 
 mineral localities, he was able to make many additions to 
 the science. 
 
 In glancing over the indices to the Journal the close 
 interrelation of mineralogy to the other sciences is strik- 
 ingly shown by the fact that so many scientists whose 
 particular fields are along other lines have published 
 occasional mineralogical papers. Frequently a young 
 man has commenced with mineralogical investigations 
 and then later been drawn definitely into one of these 
 allied subjects. Men, who have won their reputation in 
 chemistry, physics, and all the various divisions of geol- 
 ogy, even that of palfeontology, have all contributed arti- 
 cles distinctly mineralogical in character. For this 
 
GROWTH OF MINERALOGY 281 
 
 reason the number of American writers who have pub- 
 lished what may be called casual papers on mineralogy 
 is very great in comparison to the number of those who 
 continue such publications over a series of years. 
 
 That the subject of meteorites is one which has been 
 constantly studied by American mineralogists and petrog- 
 raphers is shown by the long list of papers concerning it 
 that have been published in the Journal ; it should, there- 
 fore, be considered briefly here. Many of these papers 
 are short and of a general descriptive nature but others 
 which give more fully the chemical, mineralogical and 
 physical details are numerous. Among the earlier 
 writers on this subject Benjamin Silliman, Jr., and C. U. 
 Shepard should be mentioned. The latter was the first 
 to recognize a new mineral in the Bishopville meteorite 
 which he called chladnite. The same substance was 
 afterwards found in a terrestial occurrence and was more 
 accurately described by Kenngott under the name of 
 enstatite. J. Lawrence Smith later showed that these 
 two substances were identical. Smith did a large 
 amount of important chemical work on meteorites. He 
 was the first to note the presence of ferrous chloride in 
 meteoric iron, the mineral being afterwards named law- 
 rencite in his honor. The iron-chronium sulphide, 
 daubreelite, was also first described by him. Other 
 names that should be mentioned in this connection are 
 those of A. W. Wright who studied the gaseous con- 
 stituents of meteorites, G. F. Kunz, W. E. Hidden, A. E. 
 Foote and H. A. Ward, all of whom published numerous 
 descriptions of these bodies. Among the more recent 
 workers in this field the names of G. P. Llerrill and 0. C. 
 Farrington deserve especial mention. 
 
 The publication of the Fourth Series of the Journal 
 began in 1896. Although the years since then have seen 
 a great amount of very important work accomplished, the 
 history of the period is fresh in the minds of all and as 
 the majority of the active workers are still living and 
 productive it seems hardly necessary to go into great 
 detail concerning it. Twenty years ago it seemed to 
 some mineralogists that the science could almost be con- 
 sidered complete. All the commoner minerals had cer- 
 tainly been discovered and exhaustively studied. Little 
 
to 
 
 282 A CENTURY OF SCIENCE 
 
 apparently was left that could be added to our knowledge 
 of them. New occurrences would still be recorded, new 
 crystal habits would be observed, and an occasional new 
 and small crystal face might be listed, but few facts of 
 great importance seemed undiscovered. This view was 
 not wholly justified because new facts of interest and 
 importance have continuously been brought forward, and 
 the finding of new minerals does not appear to diminish 
 in amount with the years. The work of the investigators 
 on the United States Geological Survey along these lines 
 is especially noteworthj^ 
 
 This last of our periods, however, is chiefly signalized 
 by a practically new development along the lines that 
 might be characterized as experimental mineralogy. 
 New ways have been discovered in which to study min- 
 erals. The important but hitherto baffling problems of 
 their genesis, together with their relations to their 
 surroundings, and to associated minerals, have been 
 attacked by novel methods. 
 
 In this pioneer work that of the Geophysical Labora- 
 tory of the Carnegie Institution of Washington has been 
 of the greatest importance. This laboratory was estab- 
 lished in 1905 and, under the directorship of Arthur L. 
 Day, a notable corps of investigators has been assembled 
 and remarkable work already accomplished. While the 
 field of investigation of the laboratory is broader than 
 that of mineralogy, including much that belongs to 
 petrography, vulcanology, etc., still the greater part of 
 the work done can be properly classed as mineralogical in 
 character and should be considered here. Because of its 
 great value, howe^^er, it was felt that an authoritative, 
 although nec/^ssarily, under existing conditions, a brief, 
 account of it should be given. A concise summary of the 
 objects, methods and results of the investigations of the 
 laboratory has been kindly prepared by a member of its 
 staff, Dr. R. B. Sosman, and is given later. 
 
 During the last few years another line of investigation 
 has been opened by the discovery of the effect of crystal- 
 line structure upon X-rays. Through the refraction or 
 reflection of the X-ray by means of the ordered arrange- 
 ment of the particles forming the crystalline network, we 
 are apparently going to be able to discover much con- 
 
GROWTH OF MINERALOGY 283 
 
 cerning the internal structure of crystals. And, partly 
 through these discoveries, is likely to come in turn the 
 solution of the hitherto insolvable mystery of the consti- 
 tution of matter. Without doubt the multitudinous facts 
 of mineralogy assembled during the past century by the 
 painstaking investigation of a large number of scientists 
 are destined to play a large part in the solution of this 
 problem. Further, it does not seem too bold a prophecy 
 to suggest, that the time will come when it will be possi- 
 ble to assemble all these iinorganized facts that we know 
 about minerals into a harmonious whole and that we shall 
 be then able to formulate the underlying and fundamental 
 principles upon which they all depend. These are the 
 great problems for the future of mineralogical inves- 
 tigation. 
 
IX 
 
 THE WORK OF THE GEOPHYSICAL, LABOR- 
 ATORY OF THE CARNEGIE INSTITUTION 
 OF WASHINGTON 
 
 By R. B. SOSMAN 
 
 THERE are three methods of approach to the great 
 problem of rock formation. The tirst undertakes to 
 reproduce by suitable laboratory experiments some 
 of the observed changes in natural rocks. The second 
 seeks to apply the principles of physical chemistry to a 
 great body of carefully gathered statistics. The third 
 method of attack is like the first in being a laboratory 
 method, and like the second in seeking to apply existing 
 knowledge to the association of minerals as found in 
 rocks, but in its procedure differs widely from both. It 
 consists of bringing together pure materials under 
 measurable conditions, and thus in establishing by 
 strictly quantitative methods the relations in which min- 
 erals can exist together under the conditions of tempera- 
 ture and pressure that have the power to affect such 
 relations. 
 
 It is to this third method of investigation of the prob- 
 lems of the rocks that the Geophysical Laboratory has 
 lieen devoted since its establishment in 1905. It has 
 proved entirely practicable to make quantitative studies 
 of the relations among the principal earth-forming 
 oxides (silica, alumina, magnesia, lime, soda, potash, and 
 the oxides of iron) over a very wide range of tempera- 
 tures. The resources of physics have proved adequate 
 to establish temperature with a high degree of precision 
 and to measure the quantity of energy involved in the 
 various reactions. The chemist has been able to obtain 
 materials in a high degree of purity, and to follow out in 
 detail the chemical relationships that exist among the 
 
GEOPHYSICAL LABORATORY 285 
 
 earth-forming oxides. The petrographic laboratory has 
 been available for the comparison of synthetic laboratory 
 products with the corresponding natural minerals. 
 
 It has also proved entirely practicable to extend the 
 same methods of research to some of the principal ore 
 minerals such as the sulphides of copper. Other infor- 
 mation which is certain to be of ultimate economic value 
 has also come out of the thorough study of the silicates, 
 which are basic materials for the vast variety of indus- 
 tries which are classed under the name of ceramic indus- 
 tries. The best example of this is the facility with which 
 the experience and the personnel of the laboratory has 
 been adapted to the very important problem of manufac- 
 turing an adequate supply of optical glass for the needs 
 of the United States in the present war. 
 
 It has further been possible to show within the last two 
 years that rock formation in which volatile ingredients 
 play a necessary and determining part can be completely 
 studied in the laboratory with as much precision as 
 though all the components were solids or liquids. 
 
 Along with the laboratory work on the formation of 
 minerals and rocks has gone an increasing amount of field 
 work on the activities of accessible volcanoes, such as 
 Kilauea and Vesuvius, where the fusion and recrystal- 
 lization of rocks on a large scale can be observed and 
 studied. 
 
 There was once a time when the confidence of the lab- 
 oratory in the capacity of physics and chemistry to solve 
 geological problems was not shared by all geologists. 
 There were some who were inclined to view with consid- 
 erable apprehension the vast ramifications and com- 
 plications of natural rock formation as a problem 
 impossible of adequate solution in the laboratory. It is, 
 therefore, a matter of satisfaction to all those who have 
 participated in these efforts to see the evidences of this 
 apprehension disappearing gradually as the work has 
 progressed. A careful appraisement of the situation 
 to-day, after ten years of activity, reveals the fact that 
 the tangible grounds for anxiety about the accessihilUy 
 of the problems which were confronted at first are now 
 for the most part dissipated. 
 
 It will not be possible to review in detail the lines of 
 
 18 
 
286 A CENTURY OF SCIENCE 
 
 work sketched above. An outline of the synthetic work 
 on systems of the mineral oxides and a paragraph on the 
 volcano researches will perhaps suffice to indicate the 
 general plan and purpose of the laboratory's work. It 
 should be added that the results of many of the researches 
 of the laboratory, detailed below, have been published in 
 the pages of the Journal (see 21, 89, 1906, and later 
 volumes). 
 
 Mineral Researches. — The mineral studies include : 
 
 I. One-component systems: silica, with its numerous 
 polymorphic forms and their relations to temperature 
 and the conditions of rock formation; alumina; mag- 
 nesia ; and lime. 
 
 II. Tivo-component systems: silica-alumina, includ- 
 ing sillimanite and related minerals ; silica-magnesia, 
 including the tetramorphic metasilicate MgSiOg ; silica- 
 lime, including woUastonite ; the alkali silicates, par- 
 ticularly with reference to their equilibria with carbon 
 dioxide and with water ; ferric oxide-lime ; alumina-lime ; 
 alumina-magnesia, including spinel ; and hematite-mag- 
 netite, a solid-solution series of an unusual type. 
 
 III. Three-component systems: silica-alumina-mag- 
 nesia, completed but not yet published; silica-alumina- 
 lime, comjolete, including the compounds that enter into 
 the composition of portland cement; silica-magnesia- 
 lime, completed but not yet published, including, however, 
 published work on the diopside-forsterite-silica system, 
 and on the CaSiOg-MgSiOg series ; and alumina-mag- 
 nesia-lime. 
 
 IV. Four components: SiOo-AlaOg-MgO-CaO : the in- 
 complete system anorthite-f orsterite-silica ; SiOo-ALOg- 
 CaO-Na^O: the series of lime-soda feldspars (albite- 
 anorthite), and the series nephelite (carnegieite)-anor- 
 thite; SiOo-ALOg-NaoO-KoO : the sodium-potassium 
 nephelites. 
 
 V. Five components: SiOj-ALOg-MgO-CaO-NaoO: 
 the ternary S3^stem diopside-anorthite-albite (haplo-basal- 
 tic and haplo-dioritic magmas). 
 
 Fairly complete studies have also been made of the 
 mineral sulphides of iron, copper, zinc, cadmium, and 
 mercury, and the conditions controlling the secondary 
 enrichment of copper sulphide ores are now being inves- 
 
GEOPHYSICAL LABORATORY 287 
 
 tigated. In connection with the sulphide investigations, 
 the hj'drated oxides of iron have been studied cliemically 
 and microscopically and the results will soon be ready for 
 publication. 
 
 Throughout the work the mere accumulation of bodies 
 of facts has been held to be secondary in importance to 
 the development of new methods of attack and the eval- 
 uation of new general principles, and the specific prob- 
 lems studied have been selected from this point of view. 
 
 Volcano Researches. — A branch of the laboratory's 
 work that is of general as well as petrological interest 
 is the study of active volcanoes. Observations and col- 
 lections have been made at Kilauea, Vesuvius, Etna, 
 Stromboli, Vulcano, and (through the courtesy of the 
 directors of the National Geographic Society) Katmai in 
 Alaska. The great importance of gases in volcanicity is 
 emphasized by all the studies. The active gases include 
 hydrogen and water vapor, carbon monoxide and carbon 
 dioxide, and sulphur and its oxides, as well as a variety 
 of other compounds of lesser importance. The crater of 
 Kilauea proves to be an active natural gas-furnace, in 
 which reactions are continuously occurring among the 
 gases, often resulting in making the lava basin hotter at 
 the surface than it is at some depth. These reactions 
 are being studied in the laboratory on mixtures of the 
 pure constituent gases in known proportions, in order to 
 lay the foundation for accurate interpretation and pre- 
 diction concerning the gases as actually collected from 
 the volcanoes themselves. 
 
THE PROGRESS OF CHEMISTRY DURING THE 
 PAST ONE HUNDRED YEARS 
 
 By HORACE L. ^^ELLS and HARRY W. FOOTE 
 
 Introduction, 
 
 AS we look back to the time of tlie founding of tlie 
 /\ Journal in 1818, we see that the science of chem- 
 i% istry had recently made and was then making great 
 advances. That the scientific men of those days were 
 much impressed with what was being accomplished is well 
 shown by the following statement made in an early num- 
 ber of the Journal (3, 330, 1821) by its founder in 
 reviewing Gorham's Elements of Chemical Science. He 
 says : "The present period is distinguished by wonderful 
 mental activity; it might indeed be denominated as the 
 intellectual age of the world. At no former period has 
 the mind of man been directed at one time to so many and 
 so useful researches." 
 
 A very remarkable revolution in chemical ideas had 
 recently taken place. Soon after the discovery of oxy- 
 gen by Priestley in 1774, and the subsequent discovery 
 by Cavendish that water was formed by the combustion 
 of hydrogen and oxygen, Lavoisier had explained com- 
 bustion in general as oxidation, thus overthrowing the 
 curious old phlogiston theory which had prevailed as the 
 basis of chemical philosophy for nearly a century. 
 
 The era of modern chemistry had thus begun, and the 
 additional views that matter was indestructible and that 
 chemical compounds were of constant composition had 
 been generally accepted at the beginning of the nine- 
 teenth century. 
 
 Dalton had announced his atomic theory in 1802, hav- 
 ing based it largely upon the law of multiple proportions 
 
ONE HUNDRED YEARS OF CHEMISTRY 289 
 
 which he had previously discovered, and he had begun 
 to express the formulas for compounds in terms of 
 atomic symbols. 
 
 In 1808 Gay-Lussac had discovered his law of gas com- 
 bination in simple proportions,^ a law of supreme import- 
 ance in connection with the atomic theory, but neither he 
 nor Dalton had seen this theoretical connection. Avo- 
 gadro had understood it, however, and in 1811 had 
 reached the momentous conclusion that all gases and 
 vapors have equal numbers of molecules in equal volumes 
 at the same temperature and pressure. 
 
 Daw in 1807 had isolated the alkali-metals, sodium 
 and potassium, by means of electrolysis, thus practically 
 dispelling the view that certain earthy substances might 
 be elementary ; and about four years later he had demon- 
 strated that chlorine was an element, not an oxide as had 
 been supposed previously, thus overthrowing Lavoisier's 
 view that oxygen was the characteristic constituent of all 
 acids. 
 
 At the time that our period of history begins, the 
 atomic theory had been accepted generally, but in a some- 
 what indefinite form, since little attention had been paid 
 to Avogadro 's principle, and since Dalton had used only 
 the principle of greatest simplicity in writing the formu- 
 las of compounds, considering water as HO and ammonia 
 NH, for example. At this time, however, Berzelius for 
 ten or fifteen years had been devoting tremendous energy 
 to the task of determining the atomic weights of nearly 
 all of the elements then known by analyzing their 
 compounds. He had confirmed the law of multiple pro- 
 portions, accepted the atomic theory, and utilized Avo- 
 gadro 's principle, and it is an interesting coincidence 
 that his first table of atomic weights was published in the 
 year 1818. 
 
 An interesting account of the views on chemistry held 
 at about that time was published in the Journal by Deni- 
 son Olmsted (11, 349, 1826; 12, 1, 1827), who had 
 recently become professor of natural philosophy in Yale 
 College. 
 
 The most illustrious European chemists of that time 
 were Berzelius of Sweden, Davy of England, and Gay- 
 Lussac of France, and the curious circumstance may be 
 
290 A CENTUEY OF SCIENCE 
 
 mentioned that all three of them and also Benjamin Silli- 
 man, the founder of the Journal, were born withm a 
 period of eight months in 1778-1779. 
 
 In this country Robert Hare of Philadelphia and Ben- 
 jamin Silliman were undoubtedly the most prominent 
 chemists of those days. Hare is best known for his 
 invention of the compound blowpipe, but his contribu- 
 tions to the Journal were very numerous, beginning 
 almost with the first volume and continuing for over 
 thirty years. Among the first of these contributions was 
 a most vigorous but well-merited attack upon a Doctor 
 Clark of Cambridge, England, who had copied his inven- 
 tion mthout giving him proper credit. He begins (2, 
 281, 1820) by saying: "Dr. Clark has published a book 
 on the gas blowpipe m which he professes a sincere desire 
 to render everyone his due. That it would be difficult for 
 the conduct of any author to be more discordant with 
 these professions, I pledge myself to prove in the fol- 
 lowing pages. " 
 
 Hare also invented a galvanic battery which he called 
 a "deflagrator," consisting of a large number of single 
 cells in series. With this, using carbon electrodes, he 
 was able to obtain a higher temperature than with his 
 oxy-hydrogen blowpipe. He was the first to apply gal- 
 vanic ignition to blasting (21, 139, 1832), and he first 
 carried out electrolyses with the use of mercury as the 
 cathode (37, 267, 1839). In this way he prepared 
 metallic calcium and other metals from solutions of their 
 chlorides, while the principle employed by him has in 
 recent times been used as the basis of a very important 
 process for manufacturing caustic potash and soda. 
 
 Silliman, who had become an intimate friend of Hare 
 during two periods of chemical study under "Woodhouse 
 in Philadelphia in 1802-1804, and who soon afterwards 
 spent fourteen months as a student abroad, chiefly in 
 England and Scotland, took a broad interest in science 
 and gave much attention to geology as well as to chem- 
 istry. In spite of this divided interest and his work as 
 a teacher, popular scientific lecturer, and editor, he found 
 time for a surprising amount of original chemical work. 
 For instance, using Hare's deflagrator, he showed that 
 carbon was volatilized in the electric arc (5, 108, 1822) ; 
 
ONE HUNDRED YEARS OF CHEMISTRY 291 
 
 he was the first in this country to prepare hydrofluoric 
 acid (6, 354, 1823), and he first detected bromine in one of 
 our natural brines (18, 142, 1830). 
 
 Atomic Weights. 
 
 As soon as the atomic theory was accepted, the relative 
 weights of the atoms became a matter of vital importance 
 in connection with formulas and chemical calculations. 
 In advancing his theory, Dalton had made some very 
 rough atomic weight determinations, and it has been men- 
 tioned already that Berzelius, at the time that our histor- 
 ical period begins, was engaged in the prodigious task of 
 accurately determining these constants for nearly all the 
 known elements. It is recorded that he analyzed quan- 
 titatively no less than two thousand compounds in 
 connection with this work during his career. His table 
 of 1818 has proved to be remarkably accurate for that 
 pioneer period, and it indicates his remarkable skill as an 
 analyst. 
 
 It is to be observed that Berzelius in this early table 
 made use of Avogadro's principle in connection with 
 elements forming gaseous compounds, and thus obtained 
 correct formulas and atomic weights in such cases, but 
 that in many instances his atomic weights and those now 
 accepted bear the relation of simple multiples to one 
 another, because he had then no means of deciding upon 
 the formulas of many compounds except the rule of 
 assumed simplicity. For example, the two oxides of 
 iron now considered to be FeO and FcjOg he regarded as 
 FeOa and FeOo, knowing as he did that the ratio of 
 oxygen in them was 2 to 3, and believing that a single 
 atom of iron in each was the simplest view of the case, 
 so that as the consequence of these formulas the atomic 
 weight of iron was then considered to be practically 
 twice as great in its relation to oxygen as at present. 
 
 These old atomic weights of Berzelius, used with the 
 corresponding formulas, were just as serviceable for cal- 
 culating compositions and analytical factors as though 
 the correct multiples had been selected. As time went 
 on, the true multiples were gradually found from consid- 
 erations of atomic heats, isomorphism, vapor densities, 
 
292 A CENTURY OF SCIENCE 
 
 the periodic law, and so on, and suitable changes were 
 made in the chemical formulas. 
 
 Berzelius used 100 parts of oxygen as the basis of his 
 atomic weights, a practice which was generally followed 
 for several decades. Dalton, however, had originally 
 used hydrogen as unity as the basis, and this plan finally 
 came into use everywhere, as it seemed to be more log- 
 ical and convenient, because hydrogen has the smallest 
 atomic weight, and also because the atomic weights of a 
 number of common elements appeared to be exact multi- 
 ples of that of hydrogen, thus giving simpler numbers for 
 use in calculations. 
 
 Within a few years a slight change has been made by 
 the adoption of oxygen as exactly 16 as the basis, which 
 gives hydrogen the value of 1-008. 
 
 As early as 1815, Prout, an English physician, had 
 advanced the view that hydrogen is the primordial sub- 
 stance of all the elements, and consequently that the 
 atomic weights are all exact multiples of that of hydro- 
 gen. This hypothesis has been one of the incentives to 
 investigations upon atomic weights, for it has been found 
 that these constants in the cases of a considerable num- 
 ber of the elements are very close to whole numbers 
 when based upon hj^drogen as unity, or even still closer 
 when based upon oxygen as 16. 
 
 With our present knowledge Front's hj'pothesis may 
 be regarded as disproved for nearly all the elements 
 whose atomic weights have been accurately determined, 
 but the close or even exact agreement with it in a few 
 cases is still worthy of consideration. There is an inter- 
 esting letter from Berzelius to B. Silliman, Jr., in the 
 Journal (48, 369, 1845) in which Berzelius considers the 
 theory entirely disproved. 
 
 For a long time entire reliance was placed upon the 
 atomic weights obtained by Berzelius, but it came to be 
 observed that the calculation of carbon from carbon diox- 
 ide appeared to give high results in certain eases, so that 
 doubt arose as to the accuracy of Berzelius 's work. Con- 
 sequently in 1840 Dumas, assisted by his pupil Stas, made 
 a new determination of the atomic weight of carbon, and 
 found that the number obtained by Berzelius, 12-12, was 
 slightly too large. Subsequently Dumas determined 
 
ONE HUNDEED YEARS OF CHEMISTRY 293 
 
 more than twenty other atomic weights, but this great 
 amount of work did not bring about any considerable 
 improvement, for it appears that Dumas did not greatly 
 excel Berzelius in accuracy, and that the latter had made 
 one of his most noticeable errors in connection with 
 carbon. 
 
 Soon after assisting Dumas in the work upon carbon, 
 Stas began his very extensive and accurate, independent 
 determinations, leading to the publication of a book in 
 1867 describing his work. Stas made many improve- 
 ments in methods by the use of great care in purifying 
 the substances employed, and especially by using large 
 quantities of material in his determinations, thus dimin- 
 ishing the proportional errors in weighing. His results, 
 which dealt with most of the common elements, were 
 accepted with much confidence by chemists everywhere. 
 
 Stas reached the conclusion that there could be no real 
 foundation for Prout's hypothesis, since so many of his 
 atomic weights varied from whole numbers, and this 
 opinion has been generally accepted. 
 
 The first accurate atomic weight determination pub- 
 lished in the Journal was that by Mallett on lithium (22, 
 349, 1856; 28, 349, 1859), showing a result almost identi- 
 cal with that accepted at the present time. Johnson and 
 Allen's determination (35, 94, 1863) on the rare element 
 CEesium was carried out with extraordinary accuracy. 
 Lee, working with Wolcott Gibbs, made good determina- 
 tions on nickel and cobalt (2, 44, 1871). The work of 
 Cooke on antimony (15, 41, 107, 1878) was excellent. 
 
 Concerning the more recent work published elsewhere 
 than in the Journal, attention should be called particu- 
 larly to the investigations that have been carried on for 
 the past twenty-five years by Richards and his associates 
 at Harvard University. Richards has shown masterly 
 ability in the selection of methods and in avoiding errors. 
 His results have displayed such marvelous agreements 
 among repeated determinations by the same and by dif- 
 ferent processes as to inspire the greatest confidence. 
 His work has been very extensive, and it is a great credit 
 to our country that this atomic weight work, so superior 
 to all that has been previously done, is being carried 
 out here. 
 
294 A CENTURY OF SCIENCE 
 
 It may be mentioned that for a number of years the 
 decision in regard to the atomic weights to be accepted 
 has been in the hands of an International Committee of 
 which our fellow countrjmian F. W. Clarke has been 
 chairman. In connection with this position and pre- 
 viously, Clarke has done valuable service in re-calculat- 
 ing and summarizing atomic weight determinations. 
 
 Analytical Ctiemistry, 
 
 Analysis is of such fundamental importance in nearly 
 every other branch of chemical investigation that its 
 development has been of the utmost importance in con- 
 nection with the advancement of the science. It attained, 
 therefore, a comparatively early development, and one 
 hundred years ago it was in a flourishing condition, par- 
 ticularly as far as inorganic qualitative and gravimetric 
 analysis were concerned. There is no doubt that Ber- 
 zelius, whose atomic weight determinations have already 
 been mentioned, surpassed all other analysts of that time 
 in the amount, variety, and accuracy of his gravimetric 
 work. He lived through three decades of our period, 
 until 1848. 
 
 During the past century there has been constant prog- 
 ress in inorganic analysis, due to improved methods, 
 better apparatus and accumulated experience. An 
 excellent work on this subject was published by H. Rose, 
 a pupil of Berzelius, and the methods of the latter, with 
 many improvements and additions by the author and 
 others, were thus made accessible. Fresenius, who was 
 born in 1818, did much service in establishing a labora- 
 tory in which the teaching of analytical chemistry was 
 made a specialty, in writing text-books on the subject 
 and in establishing in 1862 the "Zeitschrift fllr analy- 
 tische Chemie," which has continued up to the present 
 time. 
 
 Besides Berzelius, who was the first to show that min- 
 erals were definite chemical compounds, there have been 
 many prominent mineral analj^sts in Europe, among 
 whom Rammelsberg and Bunsen may be mentioned, but 
 there came a time towards the end of the nineteenth cen- 
 tury when the attention of chemists, particularlj^ in Ger- 
 many, was so much absorbed by organic chemistry that 
 
ONE HUNDEED YEARS OF CHEMISTEY 295 
 
 mineral analysis came near becoming a lost art there. 
 It was during that period that an English mineralogist, 
 visiting New Haven and praising the mineral analyses 
 that were being carried out at Yale, expressed regret that 
 there appeared to be no one in England, or in Germany 
 either, who could analyze minerals. 
 
 The best analytical worli done in this country in the 
 early part of our period was chiefly in connection with 
 mineral analysis, and a large share of it was published in 
 the Journal. Henry Seybert, of Philadelphia, in par- 
 ticular, showed remarkable skill in this direction, and 
 published numerous analyses of silicates and other min- 
 erals, beginning in 1822. It was he who first detected 
 boric acid in tourmaline (6, 155, 1822), and beryllium in 
 chrysoberyl (8, 105,1824). His methods for silicate 
 analyses were very similar to those used at the present 
 time. 
 
 J. Lawrence Smith in 1853 described his method for 
 determining alkalies in minerals (16, 53), a method which 
 in its final form (1, 269, 1871) is the best ever devised for 
 the purpose. He also described (15, 94, 1853) a very 
 useful method, still largely used in analytical work, for 
 destroying ammonium salts by means of aqua regia. 
 Carey Lea (42, 109, 1866) described the well-known test 
 for iodides by means of potassium dichromate. F. W. 
 Clarke (49, 48, 1870) showed that antimony and arsenic 
 could be quantitatively separated from tin by the pre- 
 cipitation of the sulphides in the presence of oxalic acid. 
 In 1864 Wolcott Gibbs (37, 346) began an important 
 series of analytical notes from the Lawrence Scientific 
 School, and he worked out later many difficult analytical 
 problems, particularly in connection with his extensive 
 researches upon the complex inorganic acids. 
 
 From 1850 on, Brush and his students made many 
 important investigations upon minerals, and from 1877 
 Penfield (13, 425), beginning with an analysis of a new 
 mineral from Branchville, Connecticut, described by 
 Brush and E. S. Dana, displayed remarkable skill and 
 industry in this kind of work. Both of the writers of 
 this article were fortunate in being associated with Pen- 
 field m some of his researches upon minerals and one of 
 us began as he did with the Branchville work It is 
 
296 A CENTURY OF SCIENCE 
 
 probably fair to say that Penfield did the most accurate 
 work in mineral analysis that has ever been accom- 
 plished, and that he was similarly successful in crystal- 
 lography and other physical branches of mineralogy. 
 
 The American analytical investigations that have been 
 mentioned were all published in the Journal, with the 
 exception of a part of Gibbs's work. Many other Amer- 
 ican workers at mineral analysis might be alluded to 
 here, but only the excellent work of a number of chemists 
 in the United States Geological Survey will be mentioned. 
 Among these Hillebrand deserves particular praise for 
 the extent of his investigations and for his careful 
 researches in improving the methods of rock analysis. 
 
 To our own Professor Gooch especial praise must be 
 accorded for the very large number of analytical methods 
 that have been devised, or critically studied, by him and 
 his students, and for the excellent quality of this work. 
 The publications in the Jouimal from his laboratory 
 began in 1890 (39, 188), and the extraordinary extent of 
 this work is shown by the fact that the three hundredth 
 paper from the Kent Laboratory appeared in May, 1918. 
 These very numerous and important investigations have 
 been of great scientific and practical value, and they have 
 formed a striking feature of the Journal for nearly 30 
 years. In 1912 Gooch published his "Methods in Chem- 
 ical Analysis," a book of over 500 pages, in which the 
 work in the Kent Chemical Laboratory up to that time 
 was concisely presented. Among the many workers who 
 have assisted in these investigations, P. E. Browning, W. 
 A. Drushel, F. S. Havens, D. A. Kreider, C. A. Peters, I. 
 K. Phelps and R. G. Van Name are particularly promi- 
 nent. Besides many other useful pieces of apparatus, 
 the perforated filtering crucible was devised by Gooch, 
 and this has brought his name into everyday use in all 
 chemical laboratories. 
 
 A'olumetric analysis was originated by Gay-Lussac, 
 who described a method for chlorimetry in 1824, for 
 alkalimetry in 1828, and for the determination of silver 
 and chlorides in 1832. Margueritte devised titrations 
 with potassium permanganate m 1846, while Bunsen, not 
 far from the same time, introduced the use of iodine and 
 sulphur dioxide solutions for the purpose of determmmg 
 
ONE HUNDRED YEARS OF CHEMISTRY 297 
 
 many oxidations and reductions. We owe to Mohr some 
 improvements in apparatus and a German text-book on 
 the subject, while Sutton wrote an excellent English work 
 on volumetric analysis, of which many editions have 
 appeared. 
 
 Wliile volumetric analysis began to be used less than 
 one hundred years ago, its applications have been grad- 
 ually extended to a very great degree, and it is not only 
 exceedingly important in investigations in pure chemis- 
 try, but its use is especially extensive in technical labora- 
 tories where large numbers of rapid analyses are 
 required. 
 
 Not a few volumetric methods have been devised or 
 improved in the United States, but mention will be made 
 here only of- Cooke's important method for the deter- 
 mination of ferrous iron in insoluble silicates, published 
 in the Journal (44, 347, 1867) ; to Penfield's method for 
 the determination of fluorine in 1878 ; and to the more 
 recent general method of titration with an iodate in 
 strong hydrochloric acid solutions, due to L. W. 
 Andrews, a number of applications of which have been 
 worked out in the Sheffield Laboratory. 
 
 A considerable amount of work with gases had been 
 done by Priestley, Scheele, Cavendish, Lavoisier, Dalton, 
 Gay-Lussac, and others before our hundred-year period 
 began. Cavendish, about 1780, had analyzed atmos- 
 pheric air with remarkable accuracy, and had even sep- 
 arated the argon from it and wondered what it was, and 
 later Gay-Lussae had shown great skill in the study of 
 gas reactions. During our period gas analysis has been 
 further developed by many chemists. Bunsen, in par- 
 ticular, brought the art to a high degree of perfection in 
 the course of a long period beginning about 1838, the last 
 edition of his "Methods of Gas Analysis" having been 
 published in 1877. 
 
 Important devices for the simplification of gas-analy- 
 sis in order that it might be used more conveniently for 
 technical purposes have been introduced by Orsat in 
 France and by Winkler, Hempel and Bunte in Germany. 
 
 It appears that our countryman Morley has surpassed 
 all others in accurate work with gases in connection 
 with his determinations of the combining weights and 
 
298 A CENTURY OF SCIENCE 
 
 volumes of liydrogen and oxygen about the year 1891. 
 Some of his publications have appeared in the Journal 
 (30, 140, 1885 ; 41, 220, 1891 ; and others ) . 
 
 Electrolytic analysis, involving the deposition of 
 metals, or sometimes of oxides, usually upon a platinum 
 electrode, was brought into use in 1865 by Wolcott Gibbs 
 through an article published in the Journal (39, 58, 1865). 
 He there described the electrolytic precipitation of cop- 
 per and of nickel by the methods still in use. The appli- 
 cation of the process has been extended to a number of 
 other metals, and it has been largely employed, particu- 
 larly in technical analyses. Important investigations 
 and excellent books on this subject have been the contri- 
 butions of Edgar F. Smith of the University of Pennsyl- 
 vania, and the useful improvement, the rotating cathode, 
 was devised by Gooch and described in the Journal (15, 
 320, 1903). 
 
 General Inorganic ChemistTy. 
 
 The Chemical Symbols. — It is to Berzelius that we owe 
 our symbols for the atoms, derived usually from their 
 Latin names, such as C for carbon, Na for sodium, CI for 
 chlorine, Fe for iron, Ag for silver, and Au for gold. 
 We owe to him also the use of small figures to show the 
 number of atoms in a formula, as in NoOg. This was a 
 marked improvement over the hieroglyphic symbols pro- 
 posed by Dalton, which were set down as many times as 
 the atoms were supposed to occur in formulas, forming 
 groups of curious appearance, but in some respects not 
 unlike some of our modern developed formulas. The 
 advantages of Berzelius 's symbols were their simplicity, 
 legibility, and the fact that they could be printed without 
 the need of special type. It is true that at a later period 
 Berzelius used certain symbols with horizontal lines 
 crossing them to represent double atoms, and that these 
 made some difficulty in printing. It should be mentioned 
 also that Berzelius at one time made an effort to simplify 
 formulas by placing dots over other sjrmbols to represent 
 oxygen, and commas to represent sulphur atoms. Exam- 
 ples of these are : 
 
 . ... ^ ,, 
 
 CaS, calcium sulphate ; Fe, iron disulphide 
 
ONE HUNDEED YEARS OF CHEMISTRY 299 
 
 This form of notation was quite extensively employed 
 for a time, especially by mineralogists, but it was entirely 
 abandoned later. 
 
 It is interesting to notice that Dalton, who lived until 
 1844, to reach the age of 78, differed from other chemists 
 in refusing to accept the letter-symbols of Berzelius. 
 In a letter written to Graham in 1837 he said: " Ber- 
 zelius 's symbols are horrifying. A young student in 
 chemistry might as soon learn Hebrew as to make him- 
 self acquainted with them. They appear like a chaos of 
 atoms . . . and to equally perplex the adepts of science, 
 to discourage the learner, as well as to cloud the beauty 
 and simplicity of the atomic theory." 
 
 This forcibly expressed opinion was apparently tinged 
 with self-esteem, but there is no doubt that Dalton was 
 sincere in believing that the atoms were best represented 
 by his circular symbols, because, as is well known, he 
 thought that all the atoms were spherical in form, and it 
 is evident that circles give the proper picture of spherical 
 objects. At the present time some insight as to the 
 structure of atoms is being gained, and it appears possi- 
 ble that the time may come when pictures of their 
 external appearance that are not wholly imaginary may 
 be made. 
 
 Changes in Formulas. — Even before the year 1826, 
 Berzelius displayed great skill in arriving at many for- 
 mulas that agree with our present ones, for example, HgO 
 for water, ZnClg for zinc chloride, NoOr; for nitric acid 
 (anhydride), CaO for calcium oxide, CO and CO2 for the 
 oxides of carbon, and many others. But at the same 
 period other authorities, especially Ga^^-Lussac in France 
 and Gmelin in Germany, on account of a lack of appreci- 
 ation for Avogadro's principle and for other reasons, 
 such as the use of symbols to represent combining 
 weights rather than atoms, were using different formulas 
 for some of these compounds, such as HO, ZnCl and NOg, 
 so that their formulas for many of the compounds of 
 hydrogen, chlorine, nitrogen and several other elements 
 differed from those of Berzelius. The employment of 
 different formulas involved the use of different atomic 
 or combining weights. For example, with the formula 
 H2O for water the composition by weight requires the 
 
300 A CENTURY OF SCIENCE 
 
 ratio 1 to 16 for the weights of the hydrogen and oxy- 
 gen atoms, while with HO the ratio is 1 to 8. 
 
 Berzelius attempted to bring about greater uniformity 
 in formulas and atomic weights by making changes in his 
 table of atomic weights published in 1826. He prac- 
 tically doubled the relative atomic weights of hydrogen, 
 chlorine, nitrogen, and of the other elements that gave 
 twice as many atoms in his formulas as in those of others, 
 and at the same time he wrote the symbols of these 
 elements with a bar across them to indicate that they 
 represented double atoms. For example, he wrote : 
 
 HO Zn€l NO. 
 
 instead of 
 
 H,0, ZnCl. N,0. 
 
 This appears to have been an unfortunate concession 
 to the views of others on the part of Berzelius, for the 
 barred symbols were not generally adopted, partly on 
 account of difficulties in printing, and the great achieve- 
 ment in theory made by him was lost sight of for a long 
 period of time. , 
 
 Tlie Law of Atomic Heats. — In 1819, Dulong and Petit 
 of France, from experiments upon the specific heats of a 
 number of solid elementary substances, came to the con- 
 clusion that the atoms of simple substances have equal 
 capacities for heat, or in other words, that the specific 
 heats of elements multiplied by their atomic weights give 
 a constant called the atomic heat. For instance, the 
 specific heats of sulphur, iron, and gold have been given 
 as 0-2026, 0-110, and 0-0324, while their atomic weights 
 are about 32, 56, and 197, respectively; hence the atomic 
 heats obtained by multiplication are 6-483, 6-116, and 
 6-383. 
 
 Further investigations showed that the atomic heats 
 display a considerable variation. Those of carbon, 
 boron, beryllium, and silicon are very low at ordinary 
 temperatures, although they increase and approach the 
 usual values at higher temperatures. More recent work 
 has shown, however, that the specific heats of other ele- 
 ments vary greatly with the temperature, almost disap- 
 pearing at the temperature of liquid hydrogen, and hence 
 possibly disappearing entirely at the absolute zero, where 
 
ONE HUNDRED YEARS OF CHEMISTRY 301 
 
 the electrical resistance of the metals appears to vanish 
 likewise. 
 
 It has been found that most of the solid elements near 
 ordinary temperatures give atomic heats that are 
 approximately 64. Berzelius applied the law in fixing 
 a number of atomic weights, and its importance for this 
 purpose is still recognized. 
 
 It may be mentioned here that two well-known Yale 
 men, W. G. Mixter and E. S. Dana, while students in 
 Bunsen's laboratory at Heidelberg in 1873, made deter- 
 minations of the specific heats of boron, silicon, and zir- 
 conium. This was the first determination of this con- 
 stant for zirconium, and it was consequently important 
 in establishing the atomic weight of that element. 
 
 Isomorphism and Polymorphism. — Mitscherlich ob- 
 served in 1818 that certain phosphates and arsenates 
 have the same crystalline form, and afterwards he 
 reached the conclusion that identity in form indicates 
 similarity in composition in connection with the number 
 of atoms and their arrangement. This law of isomorph- 
 ism was of much assistance in the establishment of cor- 
 rect formulas and consequently of atomic weights. For 
 instance, since the carbonates of barium, strontium, and 
 lead crystallize in the same form, the oxides of these 
 metals must have analogous formulas. From such con- 
 siderations Berzelius was able to make several improve- 
 ments in his atomic weight table of 1826. 
 
 Mitscherlich was the first to observe two forms of 
 sulphur crystals, and from this and other cases of 
 dimorphism or of poljTnorphism it became evident that 
 analogous compounds were not necessarily always iso- 
 morphous, a circumstance which has restricted the 
 application of the law to some extent. 
 
 Besides its application in fixing analogous formulas, 
 the law of isomorphism has come to be of much practical 
 use in the understanding and simplification of the formu- 
 las for minerals, for these natural crystals very often 
 contain several isomorphous compounds in varying pro- 
 portions, and an understanding of this "isomorphous 
 replacement," as it is called, makes it possible to deduce 
 simple general formulas for them. 
 
 19 
 
302 A CENTURY OF SCIENCE 
 
 In some cases isomorphism takes place to a greater or 
 less extent between substances which are not chemically 
 similar, and this brings about a variation in composition 
 which at times has caused confusion. For instance, the 
 mineral pyrrhotite has a composition which usually 
 varies between Fe-S,, and FcuSio, and both these formu- 
 las have been assigned to it. It was recently shown by 
 Allen, Crenshaw and Johnston in the Journal (33, 169, 
 1912) that this is a case where the compound FeS is 
 capable of taking up various amounts of sulphur 
 isomorphously. 
 
 The idea of solid solution was advanced by van't Hoff 
 to explain the crystallization of mixtures, including cases 
 of evident isomorphism. This view has been widely 
 accepted, and it has been particularly useful in cases 
 where isomorphism is not evident. Solid solution 
 between metals has been found to be exceedingly com- 
 mon, many alloys being of this character. A case of 
 this kind was observed by Cooke and described in the 
 Journal (20, 222, 1855). He prepared two well-crystal- 
 lized compounds of zinc and antimony to which he gave 
 the formulas Zn^Sb and Zn^Sb, but he observed that 
 excellent crystals of each could be obtained which varied 
 largely in composition from these formulas. As the two 
 compounds were dissimilar in their formulas and crys- 
 talline forms, Cooke assumed that isomorphism was 
 impossible and concluded "that it is due to an actual 
 perturbation of the law of definite proportions, produced 
 by the influence of mass." We should now regard this 
 as a case of solid solution. 
 
 A Lack of Confidence in Avogadro's Principle. — One 
 reason why chemists were so slow in arriving at the 
 correct atomic weights and formulas was a partial loss 
 of confidence in Avog-adro's principle. About 1826 the 
 young French chemist Dumas devised an excellent 
 method for the determination of vapor densities at high 
 temperatures, and his results and those of others showed 
 some discrepancies in the expected densities. For 
 example, the_ vapor density of sulphur was found to be 
 about three times too great, that of phosphorus twice too 
 great, that of mercury vapor and that of ammonium 
 
ONE HUNDRED YEARS OF CHEMISTRY 303 
 
 chloride only about half large enough to correspond to 
 the values expected from analogy and other considera- 
 tions. Thus, one volume of oxygen with two volumes of 
 hydrogen make two volumes of steam, but only one-third 
 of a volume of sulphur vapor was found to unite with 
 two volumes of hydrogen to make two volumes of hj^dro- 
 gen sulphide. Berzelius saw clearly that the results 
 pointed to the existence of such molecules as S,,, P4, and 
 Hgi, but it was not generally realized in those days that 
 Avogadro 's rule is fundamentally reliable, and Berzelius 
 himself appears to have lost confidence in it on account 
 of these complications, for he did not apply Avogadro 's 
 principle to decisions about atomic weights except in the 
 cases of substances gaseous at ordinary temperatures. 
 
 Elect ro-chemical Theories. — The observation was 
 made by Nicholson and Carlisle in 1800 that water 
 was decomposed into its constituent gases by the 
 electric current. Then in 1803 Berzelius and Hisinger 
 found that salts were decomposed into their bases and 
 acids by the same agency, and in 1807 Davy isolated 
 potassium, sodium, and other metals afterwards, by a 
 similar decomposition. Since those early times a vast 
 amount of attention has been paid to the relation of 
 electricity to chemical changes, a relation that is evi- 
 dently of great importance from the fact that while 
 electric currents decompose chemical compounds, these 
 currents, on the other hand, are produced by chemical 
 reactions. 
 
 Berzelius was particularly prominent in this direc- 
 tion, and in 1819 he published an elaborate electro-chem- 
 ical theory. He believed that atoms were electrically 
 polarized, and that this was the cause of their combina- 
 tion with one another. He extended this idea to groups 
 of atoms, particularly to oxides, and regarded these 
 groups as positive or negative, according to the excess of 
 positive or negative electricity derived from their con- 
 stituent atoms and remaining free. He thus arrivedat 
 his dualistic theory of chemical compounds, which 
 attained great prominence and prevailed for a long time 
 in chemical theory. According to this idea, each com- 
 pound was supposed to be made up of a positive and a 
 
304 A CENTURY OF SCIENCE 
 
 negative atom or group of atoms. For example, the for- 
 mulas for potassium nitrate, calcium carbonate, and 
 sulphuric acid corresponded to K0O.N0O5, CaO.COo and 
 H0O.SO3 where we now write KNOg, CaCOg and H2SO4, 
 and the theory was extended to embrace organic com- 
 pounds also. 
 
 The eminent English chemist and physicist Faraday 
 announced the important law of electro-chemical equiva- 
 lents in 1834. This law shows that the quantities of 
 elements set free by the passage of a given quantity of 
 electricity through their solutions correspond to the 
 chemical equivalents of those elements. Faraday made a 
 table of the equivalents of a number of elements, regard- 
 ing them important in connection with atomic weights, 
 but at that time no sharp distinction was usually made 
 between equivalents and atomic weights, and it was not 
 fully realized that one atom of a given element may be 
 the electrical equivalent of several atoms of another. 
 
 Faraday's law, which is still regarded as fundamen- 
 tally exact, has been of much practical use in the 
 measurement of electric currents and in calculations con- 
 nected with electro-chemical processes. In discussing 
 his experiments, Faraday made use of several new terms, 
 such as "electrolyte" for a substance which conducts 
 electricity when in solution, and is thus "electrolyzed," 
 "electrode," "anode," and "cathode," terms that have 
 come into general use, and finally "ions" for the parti- 
 cles that were supposed to "wander" towards the elec- 
 trodes to be set free there. 
 
 This term "ion" remained in comparative obscurity 
 for more than half a century, when it was brought into 
 great prominence among chemists by Arrhenius in con- 
 nection with the ionic theory. 
 
 Canniszaro's Ideas. — Up to about 1869 chaos reigned 
 among the formulas used by different chemists. Various 
 compound radicals and numerous type-formulas were 
 employed, dualistic and unitary formulas of several 
 kinds were in use, but the worst feature of the situation 
 was the fact that more than one system of atomic weights 
 was in vogue, so that water might be written 
 
 no, HO, or B.f) 
 
ONE HUNDRED YEARS OF CHEMISTRY 305 
 
 and similar discrepancies might appear in nearly all 
 formulas containing elements of different valencies. In 
 1858, however, an article by the Italian chemist Canniz- 
 zaro appeared in which the outlines of a course in chem- 
 ical philosophy were presented. This acquired wide 
 circulation in the form of a pamphlet at a chemical con- 
 vention somewhat later, and it dealt so clearly and ably 
 with Avogadro's principle, Dulong and Petit 's law, and 
 other points in connection with formulas that it led to a 
 rapid and almost universal reform among those who 
 were using unsatisfactory formulas. 
 
 At about this time also the dualistic formulas of Ber- 
 zelius were generally abandoned, and hydrogen came to 
 be regarded as the characteristic element of all acids. 
 For instance, CaO.SO^, called "sulphate of lime," came 
 to be written CaS04 and was called "calcium sulphate," 
 and while it had been shown as early as 1815 by Da^'y 
 that "iodic acid," IjOg, showed no acid reaction until it 
 was combined with water, the accumulation of similar 
 facts led to the formulation of sulphuric acid as HoSOj^ 
 instead of SO, or HoO.SO^, and that of other "oxygen 
 acids" in a similar way. As a necessary consequence of 
 this view of acids, the bases came to be regarded as com- 
 pounds of the "hydroxyl" group, OH. Therefore the 
 formula for caustic soda came to be written NaOH 
 instead of Na^O.HoO, and so on. 
 
 The Periodic System of the Elements. — The perio- 
 dicity of the elements in connection with their atomic 
 weights was roughly grasped by Newlands in England, 
 who announced his "law of octaves" in 1868. This was 
 at the time when the atomic weights were being modified 
 find their numerical relations properly shown. The sub- 
 ject was worked out more fully by L. Meyer in Germany 
 a little later, but it was most clearly and elaborately pre- 
 sented by the Russian chemist Mendeleeff in 1869. 
 
 In order that this subject may be explained to some 
 extent Mendeleeff 's table is given here, with the addition 
 of the recently discovered elements and some other mod- 
 ifications. 
 
«M 
 
 MM 
 
 O 
 
 M 
 
 «M 
 
 m'm 
 
 z", CO 
 
 OS 
 
 MM 
 
 «M 
 
 
 
 g» 
 
 
 IxM 
 
 M 
 
 M 
 
 MMft< 
 
 
 San 
 3 S a 
 
 B 
 
 la 
 
 5.° 
 C —I 
 
 S 
 
 'Ceo 
 
 
 as 
 
 3 oo 
 
 03 CO 
 
 do 
 H2 
 
 O 1-1 
 
 PI CO 
 
 -co 
 
 §2 3 
 
 
 
 a 
 
 as 
 
 §8 
 
 
 
 -So, 
 
 
 
 
 
 
 
 1-; 
 
 m 
 
 
 s2 
 o 
 
 o ^ 
 
 ■O CD 
 
 Hi 
 
 
 IT ^ 
 
 *^i 
 
 -- 
 
 
 
 
 
 a 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 p 
 
 
 
 hj 
 
 ^- 
 
 a' 
 
 s? 
 
 = 9 
 
 
 
 
 
 
 
 w 
 
 iH 
 
 
 
 a 
 
 a 
 
 
 Ho 
 
 
 
 
 
 0) 
 
 
 CO 
 
 
 
 a' 
 
 
 
 
 
 
 
 
 ^(D 
 
 
 
 1 
 
 H 
 
 H 
 
 
 D 
 
 a" 
 
 ES 
 
 ^ lo 
 
 
 
 
 
 
 
 
 0) 
 
 H 
 
 14 
 
 
 H 
 
 
 
 a 
 
 fl 
 
 D 
 
 
 C )f^ 
 
 -MO 
 
 o^ 
 
 t-^ 
 
 ^ 
 
 >, 
 
 
 fl 
 
 Ci^ 
 
 
 i-g 
 
 
 ■^2 
 cdIZ. 
 
 "tl lO 
 
 O 
 
 H 
 
 
 
 H 
 
 a 
 
 
 
 
 Cl fU 
 
 JH^ 
 
 
 O'-' 
 
 d 
 
 -d 
 
 
 aj 
 
 k5 
 
 c 
 
 m 
 
 
 
 
 
 
 
 
 
 
 
 
 A 
 
 
 
 
 
 
 <& 
 
 
 W 
 
 
 a> 
 
 
 
 
 
 
 M 
 
 
 • 
 
 
ONE HUNDRED YEARS OF CHEMISTRY 307 
 
 In this table the elements arranged in the order of 
 their atomic weights fall into eight groups where the 
 known oxides progress regularly, with the exception of 
 two or three elements, from R^O in Group I to RoO^ in 
 G-roup VII, while in Group VIII two oxides (of ruthen- 
 ium and osmium) are kno^vn which carry the progression 
 to RO,. 
 
 ^ It was pointed out by Mendeleetf that, with the excep- 
 tion of series 1 and 2 at the top of the table, the alternate 
 members of the groups show particularly close relation- 
 ships. These subordinate groups, marked A and B, in 
 most cases show remarkable analogies and gradations in 
 their .properties, for example, in the alkali-metals from 
 lithium to csesium, and in the halogens from fluorine to 
 iodine. The two divisions of a group do not usually 
 show very close relations to each other, except in their 
 valency, and they even display, in several instances, 
 opposite gradations in chemical activity in the order of 
 their atomic weights. For instance, caesium stands at 
 the electro-positive end, while gold stands at the electro- 
 negative end of its subordinate group. The difference 
 between the two divisions is very great in Groups VI and 
 VII, but it is extreme in Group VIII, where heavy metals 
 are on one side and inactive gases on the other. Many 
 authorities separate these gases into a "Group 0" by 
 themselves at the left-hand side of the table, but this does 
 not change their relative positions, and the plan may be 
 objected to on the ground that many vacant places are 
 thus left in the groups YIU and 0. 
 
 The periodic law has been useful in rectifying certain 
 atomic weights. At the outset Mendeleetf was obliged to 
 change beryllium from 14-5 (assuming BeoOo) to 9 
 (assuming BeO), and later the atomic weights of indium 
 and uranium were changed to make them fit the system. 
 All of these changes have been confirmed by physical 
 means. 
 
 Mendeleeff found a number of vacant places in his 
 table, and was thus able to render further service to 
 chemical science by predicting the properties of undis- 
 covered elements, and his predictions were very closely 
 confirmed by the later discovery of scandium, gallium, 
 and germanium. The table indicates that there are still 
 
308 A CENTUEY OF SCIENCE 
 
 two undiscovered elements below manganese and prob- 
 ably two more among the rare-earth metals. The inter- 
 esting observation has just recently been made by Soddy 
 that the products of radioactive disintegration appear to 
 pass in a symmetrical way through positions in the 
 periodic system, giving off a helium molecule at alternate 
 transformations until the place of lead is reached. It 
 appears, therefore, that the iive vacant places in the table 
 above bismuth are probably occupied by these evanes- 
 cent elements, and it is to be noticed that all of the 
 elements that have been placed in this region of high 
 atomic weights are radioactive. 
 
 There are some inconsistencies in the periodic system. 
 The increments in the atomic weights are irregular, and 
 there are three cases, argon and potassium, cobalt and 
 nickel, and tellurium and iodine, wdiere a higher atomic 
 weight is placed before a lower one in order to bring 
 these elements into their undoubtedly proper places. 
 There is a peculiarity also in the hea^-y-nietal division of 
 Group VIII, where three similar elements occur in each 
 of three places, and where the usual periodicity appears 
 to be suspended, or nearly so, in comparison with most 
 of the other elements. However, there seems to be a 
 still more remarkable case of this kind in Group III, 
 where fourteen metals of the rare-earths have been 
 placed. They are astonishingly similar in their chemical 
 properties, hence it seems necessary to assume that 
 periodicity is suspended here throughout the wide range 
 of atomic weights from 139 to 174, where no elements 
 save these have been found. 
 
 Several other interesting features of the table may be 
 pointed out. The chlorides and hydrides, as indicated 
 by the "typical compounds," show a regular progres- 
 sion in both directions towards Group IV. (Where the 
 type-formulas do not apply, as far as is known, to more 
 than one or two elements, they have been placed in 
 parentheses in the table given here.) It is a striking 
 fact that the acid-forming elements occur together in a 
 definite part of the table, and that the gases and other 
 non-metallicelements, except the inactive gases of Group 
 VIII, occur in the same region. 
 
ONE HUNDRED YEARS OF CHEMISTRY 309 
 
 Atomic Numbers. — As the result of a spectroscopic 
 study of the wave-lengths or frequencies of the X-rays 
 produced when cathode rays strike upon anti-cathodes 
 composed of different elements, Moseley in 1914 discov- 
 ered that whole numbers in a simple series can be 
 attributed to the atoms. These atomic numbers are: 1 
 for hydrogen, 2 for helium, 3 for lithium, 4 for beryllium, 
 and so on, in the order in which the elements occur in 
 Mendeleeff 's periodic table, and in the cases of argon and 
 potassium, cobalt and nickel, and tellurium and iodine, 
 they follow the correct chemical order, while the atomic 
 weights do not. They appear to indicate, therefore, an 
 even more fundamental relation between the atoms than 
 that shown by the atomic weights. 
 
 These numbers are now available for every element 
 up to lead, and they are particularly interesting in indi- 
 cating, on account of missing numbers, the existence of 
 two undiscovered elements in the manganese group, and 
 two more among the rare-earth metals, in confirmation 
 of the vacant places below lead in Mendeleeff 's table. 
 
 Tlie Isolation of Elements. — In the year 1818 about 
 53 elements Avere recognized, and since that time about 
 30 more have been discovered, but the elements already 
 known comprised the more common ones, and nearly all 
 of those which have been commercially important. A 
 few of them, including beryllium, aluminium, silicon, 
 magnesium, and fluorine, were then kno^vn only in their 
 compounds, as they had not yet been isolated in the free 
 condition. 
 
 Berzelius in 1823 prepared silicon, a non-metallic 
 element resembling carbon in many respects. This 
 element has recently been prepared on a rather large 
 scale in electric furnaces at Niagara Falls, and has been 
 used for certain purposes in the form of castings. 
 
 "Wohler created much sensation in 1827 by isolating 
 aluminium and finding it to be a very light, strong and 
 malleable metal, stable in the air, and of a silver-white 
 color. For a long time this metal was a comparative 
 rarity, being prepared by the reduction of aluminium 
 chloride with metallic sodium; but about 25 years_ ago 
 Hall, an American, devised a method of preparing it by 
 
310 A CENTURY OF SCIENCE 
 
 electrolyzing aluminium oxide dissolved in fused cryo- 
 lite. This process reduced the cost of aluminium to such 
 an extent that it has now come into common use. 
 
 Wohler and Bussy prepared beryllium in 1828, and 
 Liebig and Bussy did the same service for magnesium in 
 1830. The latter metal has come to be of much practical 
 importance, both as a very powerful reducing agent in 
 chemical operations, and as an ingredient of flash-light 
 powders and of mixtures used for fireworks. It is also 
 used in making certain light alloys. 
 
 After almost innumerable attempts to isolate fluorine, 
 during a period of nearly a century, this was finally 
 accomplished in 1886 by Moissan in France by the elec- 
 trolysis of anhydrous hydrogen fluoride. The free 
 fluorine proved to be a gas of extraordinary chemical 
 activity, decomposing water at once with the formation 
 of hydrogen fluoride and ozonized oxygen. This fact 
 explains the failure of many previous attempts to pre- 
 pare it in the presence of water. 
 
 Early Discoveries of New Elements. — The remarkable 
 activity of chemical research at the beginning of our 
 period is illustrated by the fact that three new elements 
 were discovered in 1817. In that j^ear Berzelius had dis- 
 covered selenium, Arfvedson, working in Berzelius 's 
 laboratory had discovered the important alkali-metal 
 lithium, and Stromeyer had discovered cadmium. 
 
 In 1826 Ballard in France discovered bromine in the 
 mother-liquor from the crystallization of common salt 
 from sea-water. Bromine proved to be an unusually 
 interesting element, being the only non-metallic one that 
 is liquid at ordinary temperatures, and being strikingly 
 intermediate in its properties between chlorine and 
 iodine. It has been obtained in large quantities from 
 brines, and is produced extensively in the United States. 
 The elementary substance and its compounds have found 
 important applications in chemical operations, while the 
 bromides have been found valuable in medicine and 
 silver bromide is very extensively used in photography. 
 
 In 1828 Berzelius discovered thorium. The oxide of 
 this metal has recently been employed extensively as the 
 principal constituent of incandescent gas-mantles, and 
 the element has acquired particular importance from the 
 
ONE HUNDRED YEARS OF CHEMISTRY 311 
 
 fact that, like uranium, it is radio-active, decomposing 
 spontaneously into other elements. 
 
 Vanadium had been encountered as early as 1801 by 
 Del Rio, who named it " erythronium, " but a little later 
 it was thought to be identical with chromium and was lost 
 sight of for a while. In 1830, however, it was re-discov- 
 ered by, and received its present name from Sefstrom in 
 Sweden. Berzelius immediately made an extensive 
 study of vanadium compounds, but he gave them incor- 
 rect formulas and derived an incorrect atomic weight for 
 the element, because he mistook a lower oxide for the 
 element itself. Roscoe in England in 1867 isolated 
 vanadium for the first time, found the right atomic 
 weight, and gave correct formulas to its compounds. 
 Vanadium is particularly interesting from the fact that 
 it displays several valencies in its compounds, many of 
 which are highly colored. It has found important use as 
 an ingredient in verj^ small proportions in certain 
 "special steels" to which it imparts a high degree of 
 resistance to rupture by repeated shocks. 
 
 Columbium was discovered early in the nineteenth 
 century in the mineral columbite from Connecticut by 
 Hatchett, an Englishman, who did not, however, obtain 
 the pure oxide. It was afterwards obtained by Rose who 
 named it niobium. Both names for the element are in 
 use, but the former has priority. Attention was called 
 to this fact by an article in the Journal by Connell, an 
 Englishman (18, 392, 1854). 
 
 The Platinum Group of Metals. — In 1854 a new mem- 
 ber of the platinum group of metals, ruthenium, was dis- 
 covered by Clans. Platinum had been discovered about 
 the middle of the eighteenth century, while its other rarer 
 associates, iridium, osmium, palladium, and rhodium, had 
 been recognized in the very early years of the nineteenth 
 century. It was during the latter period that platinum 
 ware began to be employed to a considerable extent in 
 chemical operations, and this use was greatly extended 
 as time went on. The discovery was made by Phillips 
 in 1831 that finely divided platinum by contact would 
 bring about the combination of sulphur dioxide with 
 atmospheric oxygen, and this application during the past 
 20 years has become enormously important in the sul- 
 
312 A CENTUEY OF SCIENCE 
 
 phuric acid industry, while other important applications 
 of platinum as a "catalytic agent" have also been made. 
 Wolcott Gribbs and Carey Lea have contributed perhaps 
 more than any other recent chemists to a knowledge of 
 the platinum metals. Carey Lea (38, 81, 248, 1864) 
 dealt chiefly with the separation of the metals from each 
 other, while Gibbs's work (31, 63, 1861; 34, 341, 1862) 
 included investigations of many of the compounds. 
 
 It may be mentioned that while platinum and its asso- 
 ciates were formerly known only in the uncombined con- 
 dition in nature, the arsenide sperrylite, PtAsj, was 
 described by the late S. L. Penfield, and the senior writer 
 of this chapter, in articles published in the Journal (37, 
 67, 71, 1889). 
 
 Applications of the Spectroscope. — The discovery in 
 certain mineral waters of the rare alkali-metals rubidium 
 and cfesium by Bunsen and Kirchoff in 1861 was in conse- 
 quence of the application of spectroscopy by these same 
 scientists a short time previously to the identification of 
 elements imparting colors to the flame. Since that time 
 the employment of the spectroscope for chemical pur- 
 poses has been much extended, as it has been used in the 
 examination of light from electric sparks and arcs, as 
 well as from Geissler tube discharges and from colored 
 solutions. 
 
 The metals rubidium and caesium are interesting in 
 being closely analogous to potassium and in standing at 
 the extreme electro-positive end of the series of known 
 metals. It should be noticed here that Johnson and 
 Allen of our Sheffield Laboratory, having obtained a 
 good supply of rubidium and caesium material from the 
 lepidolite of Hebron, Maine, made some important 
 researches upon these elements, accounts of which were 
 published in the Journal (34, 367, 1862; 35, 94, 1863). 
 They established the atomic weight of cfesium, thus cor- 
 recting Bunsen 's determination which was unsatisfac- 
 tory on account of the small quantity and impurity of his 
 material. PoUucite, a mineral rich in csesium, which had 
 been found in very small amount on the Island of Elba, 
 has more recently been obtained in large quantities — hun- 
 dreds of pounds— at Paris, Maine, and its vicinity. 
 This American pollucite was first analyzed and identi- 
 
ONE HUNDRED YEAES OF CHEMISTRY 313 
 
 fied by the senior writer of this article (41, 213, 1891), 
 and later (43, 17, 1892 et seq.) the results of many inves- 
 tigations on cfEsium and rubidium compounds, in which 
 the junior writer played an important part, carried out 
 in Sheffield Laboratory, were published in the Journal. 
 
 The application of the spectroscope led to the discov- 
 ery of thallium in 1861 by Crookes of England, and to 
 that of indium in 1863 by Reich and Richter in Germany. 
 Both of these metals are extremely rare, but they are of 
 considerable theoretical interest. Thallium is particu- 
 larly remarkable in showing resemblances in its different 
 compounds to several groups of metals. 
 
 The spectroscope was employed again in connection 
 with the discovery of gallium in 1875 by Boisbaudran. 
 It is in the same periodic group as thallium and indium, 
 and it has a remarkably low melting point, just above 
 ordinary room-temperature. It has been among the 
 rarest of the rare elements, but within two or three years 
 a source of it has been found in the United States in cer- 
 tain residues from the refining of commercial zinc. The 
 recent issues of the Journal (41, 351, 1916 ; 42, 389, 1916) 
 show that Browning and Uhler of Yale have availed 
 themselves of this new material in order to make import- 
 ant chemical and physical researches upon this metal. 
 
 Germanium. — The discovery of germanium in the min- 
 eral argyrodite in 1886 by Winkler revealed a curious 
 metal which gives a white sulphide that may be easily 
 mistaken for sulphur and which is volatilized completely 
 when its hydrochloric acid solution is evaporated, so that 
 it is evasive in analytical operations. This element had 
 been predicted with much accuracy by Mendeleeff, and 
 it is rather closely related to tin. 
 
 A few years after the discovery of germanium. Pen- 
 field published in the Journal (46, 107, 1893; 47, 451, 
 1894) some analyses of argyrodite, correcting the for- 
 mula given by "Winkler to the mineral ; also he described 
 canfieldite, an analogous mineral from Bolivia, in which 
 a large part of the germanium was replaced by tin. 
 
 The Rare Earths. — Before the year 1818 two rare 
 earths, the oxides of yttrium and cerium, were known 
 in an impure condition. Since that time about fourteen 
 others have been discovered as associates of the first 
 
3U A CENTURY OF SCIENCE 
 
 two. The rare earths are peculiar from the fact that 
 many of them are always found mixed together in the 
 minerals containing them, and also from the circum- 
 stance that most of them are remarkably similar in their 
 chemical reactions and consequently exceedingly difficult 
 to separate from each other. In many cases multitudes 
 of fractional precipitations or crystallizations are needed 
 to obtain pure salts of a number of these metals. The 
 solutions of the salts of several of these elements give 
 characteristic absorption bands when examined spectro- 
 scopically by the use of transmitted light. 
 
 No important practical application has been found for 
 any of these earthy oxides, excejDt that about one per cent 
 of cerium oxide is mixed with thorium oxide in incandes- 
 cent gas-mantles in order to obtain greatly increased 
 luminosity. 
 
 Tlie Inactive Gases. — As long ago as 1785, Cavendish, 
 that remarkable Englishman who first weighed the woiid 
 and first discovered the composition of water, actually 
 obtained a little argon in a pure condition by sparking 
 atmospheric nitrogen with oxygen converting it into 
 nitric acid (another discovery of his) and absorbing the 
 excess of oxygen. The volume of this residual gas as 
 estimated by him corresponds very closely to the volume 
 of argon in the atmosphere, as now known. 
 
 It was more than a century later, in 1894, that Rayleigh 
 and Ramsay discovered argon in the air. Lord Rayleigh 
 had found that atmospheric nitrogen was about one-half 
 per cent heavier than chemical nitrogen, a fact which led 
 to the investigation. It was only necessary to repeat 
 Cavendish's experiment on a large scale, or to absorb 
 oxygen with hot copper and nitrogen with hot mag- 
 nesium, in order to obtain argon. The gas attracted 
 much attention, both on account of having but a single 
 atom in its molecule, and particularly because it failed to 
 enter into chemical combination of any kind. This gas 
 has been used of late for filling the bulbs of incandescent 
 electric lamps in cases w-here a gas-pressure without 
 chemical action is desired. 
 
 In 1890 and 1891, Hillebrand published in the Journal 
 40, 384, 1890: 42, 390, 1891) a series of analyses of the 
 mineral uraninite and reported in some samples of the 
 
ONE HUNDRED YEAES OF CHEMISTRY 315 
 
 mineral as mucli as 2-5 per cent of an inactive gas. 
 HiUebrand examined tlie gas spectroscopically but, just 
 missing an important discoverjr, lie detected only the 
 spectrum lines of nitrogen. Ramsay, in searching for 
 argon in some sort of natural combination, and doubt- 
 less remembering Hillebrand's work, heated some 
 cleveite, a variety of uraninite, and obtained, not argon, 
 but a new gas. This gave a j^ellow spectrum-line cor- 
 responding to a line previously observed in the light of 
 the sun's corona and attributed to an element in the sun 
 called helium. Helium, therefore, in 1895 had been found 
 on the earth. This gas is a constant constituent of 
 uranium minerals, as it is produced by the breaking down 
 of radioactiA'e elements. It has been found in very small 
 quantity in the atmosphere, and is the most difficult of all 
 known gases to liquefy, as its boiling point, as shown by 
 Onnes in 1908, is only 4^ above the absolute zero. It has 
 not yet been solidified. 
 
 In 1898 Ramsay and Travers, by the use of ingenious 
 methods of fractional distillation and absorption by char- 
 coal, obtained three other much rarer inactive gases 
 from the atmosphere which they called neon, krypton and 
 xenon. 
 
 The inactive gases are all colorless, and as they form 
 no chemical compounds they are characterized by their 
 densities, which give their atomic weights, by their boil- 
 ing points, and by their characteristic Geissler-tube spec- 
 tra. 
 
 The gaseous radium emanation, or niton, belongs also 
 to the inactive group, and it was also collected and 
 studied by Ramsay who was compelled to work with only 
 0-0001 cc.of it, as "the volume obtained by heating radium 
 salts is very small. It is an evanescent element, disap- 
 pearing within a few days on account of radioactive dis- 
 integration. Meanwhile it glows brilliantly when lique- 
 fied and cooled to the temperature of liquid air. It has 
 an atomic weight of 222, four units below that of radium, 
 and the difference is considered as due to the loss by 
 radium of an atom of helium in passing into the 
 emanation. 
 
 The Radioactive Elements. — The discovery of radium 
 in 1898 by Madame Curie, and the study of that and other 
 
316 A CENTURY OF SCIENCE 
 
 radioactive elements has produced a profound effect 
 upon chemical theory. It was found that the two ele- 
 ments of the highest atomic weights, uranium and 
 thorium, are alwaj's spontaneously decomposing into 
 other elements at a fixed rate of speed which can be con- 
 trolled by no artificial means, and that the elements 
 resulting from these decompositions likewise undergo 
 spontaneous changes into still other elements at greatly 
 varying rates of speed, forming in each case a remark- 
 able series of temporary elements. These transforma- 
 tions are accompanied by the emission at enormous 
 velocities of three kinds of rays, one variety of which has 
 been shown to consist of helium atoms. The greater 
 number of the elements formed in these transformations 
 have not as yet been obtained in a pure condition, and 
 they are known only in connection with their radio- 
 activity, volatility, etc. ; but radium and niton, two of 
 these products, have been obtained in a pure condition, 
 so that their atomic weights and their places in the 
 periodic system have been fixed. 
 
 We owe much of our knowledge of the radioactive 
 transformations to the researches of Rutherford and of 
 Soddy, and of their co-workers, but one of the important 
 products of the transformation of uranium, an element 
 which he called ionium, was characterized by Boltwood of 
 Yale (25, 365, 1908). 
 
 Radium and niton, apart from their radioactive prop- 
 erties, resemble barium and the inert gases of the atmos- 
 phere, respectively. The rates at which their progeni- 
 tors produce them, and the rates at which they themselves 
 decompose, bring about a state of equilibrium after a 
 time. Therefore a given amount of uranium, which 
 decomposes exceedingly slowly, can yield even after 
 thousands of years only a very small proportional 
 quantity of undecomposed radium, one-half of which 
 disappears in about 2500 years, because the amount 
 decomposed must eventually be equal to the amount pro- 
 duced. The first conclusive evidence that radium is a 
 product of the decomposition of uranium was given by 
 Boltwood in the Journal (18, 97, 1904). He found that 
 all uranium minerals contain radium; and the amount 
 of radium present is always proportional to the amount 
 
ONE HUNDRED YEARS OF CHEMISTRY 317 
 
 of iiraiiium, which shows the genetic relation between 
 the two. 
 
 In the ease of niton, which is produced by radium, and 
 is called also the radium emanation, the rate of decay is 
 rapid, so that if the gas is expelled from radium by heat- 
 ing, equilibrium is reached after a few days, with the 
 accumulation of the largest possible amount of niton. 
 
 The conclusion has been reached by Rutherford and 
 others that the final product besides helium, in the radio- 
 active transformations, is lead, or at least an element 
 or elements resembling lead to such a degree that no 
 separation of them by chemical means is possible. 
 Atomic weight determinations by Richards and others 
 have shown that specimens of lead found in radioactive 
 minerals give distinctly different atomic weights from 
 that of ordinary lead. This fact has led to the view that 
 possibly the atoms of the elements are not all of the same 
 weight, but vary within certain limits — a view that is 
 contrary to previous conclusions derived from the uni- 
 formity in atomic weights obtained with material from 
 many different sources. 
 
 The results of the investigations upon radioactivity 
 have led to modified views in regard to the stability of 
 the elements in general. There has been little or no 
 proof obtained that any artificial transmutation of the 
 elements is possible, but the spontaneous transformation 
 of the radioactive elements brings forward the possibility 
 that other elements are changing imperceptibly, and that 
 a state of evolution exists among them. AH of the radio- 
 active changes that we know proceed from higher to 
 lower atomic weights, and we are entirely ignorant of the 
 process b}^ which uranium and thorium must have been 
 produced originally. 
 
 Since radioactive changes have been found to be 
 accompanied by the release of vast amounts of energy. 
 compared with which the energy of chemical reactions is 
 trivial, a new aspect in regard to the structure of atoms 
 has arisen, — they must be complex in structure, the seats 
 of enormous energy. 
 
 The determination of the amount of radium in the 
 earth's crust has indicated that the heat produced by it is 
 amply sufficient to supply the loss of heat due to radia- 
 
 20 
 
318 A CENTUEY OF SCIENCE 
 
 tion, and this source of heat is regarded by many as the 
 cause of volcanic action. The sun's radiant heat also 
 has been supposed to be supplied by radioactive action, 
 so that the older views regarding the limitation of the 
 age of the earth and the solar system on account of loss of 
 heat have been considerably modified by our knowledge 
 of radioactivity. 
 
 Fhysical Chemistry. 
 
 The application of physical methods as aids to chem- 
 ical science began in early times, and some of these, such 
 as the determinations of gas and vapor densities, specific 
 heats, and crystalline forms have been mentioned already 
 in this article. Within recent times physical chemistry 
 has greatly developed and a few of its important achieve- 
 ments will now be described. 
 
 Molecular Weight Determinations. — Gas and vapor 
 densities in connection with Avogadro's principle, 
 formed the only basis for molecular weight determina- 
 tions until comparatively recent times. The early 
 methods of Gay-Lussac and Dumas for vapor density 
 were supplemented in 1868 by the method of Hofmann, 
 whereby vapors were measured under diminished pres- 
 sure over mercury. In 1878 Victor Meyer introduced a 
 simpler method depending upon the displacement of air 
 or other gas by the vapor in a heated tube. As refrac- 
 tory tubes, such as those of porcelain or even iridium, 
 could be used in this method, molecular weights at 
 estremely high temperatures were determined witli inter- 
 esting results. For instance, it was found that iodine 
 vapor, which shows the molecule lo at lower tempera- 
 tures, gradually becomes monatomic with rise in tem- 
 perature, that sulphur vapor dissociates from Sg to 83 
 under _ similar conditions, and that most of the metals^ 
 including silver, have monatomic vapors. 
 
 In 1883 and later it was pointed out by Raoult that the 
 molecular weights of substances could be found from the 
 freezing points of their solutions, but this method was 
 complicated from the fact that salts, strong acids and 
 strong bases behaved quite differently from other sub- 
 stances in this respect, and allowances had to be made for 
 the types of substances used. The complication was 
 
ONE HUNDRED YEARS OF CHEMISTRY S19 
 
 afterwards explained by the ionization theory of Arr- 
 henius. Better apparatus for this method was soon 
 devised by Beckmann, who introduced also a method 
 depending upon the boiling points of solutions, and these 
 two methods are still the standard ones for determining 
 molecular weights in solution. They are very exten- 
 sively employed by organic chemists. 
 
 It has been found that the majority of substances when 
 dissolved have the same molecular weight as in the 
 gaseous condition, provided that they can be volatilized 
 at comparable temperatures. For instance, sulphur in 
 solution has the formula Sg, iodine is lo and the metals 
 are monatomic. 
 
 Van't Hoff's Law and Arrhenius's Theory of Ions. — 
 Modern views on solutions date largely from 1886, when 
 van't Hoff called attention to the relations existing 
 between the osmotic pressure exerted by dissolved sub- 
 stances and gas pressure. 
 
 Pfeffer, a botanist, was the first to measure osmotic 
 pressure (1877). Basing his conclusions chiefly upon 
 Pfeffer 's determinations, van't Hoff formulated a new 
 and highly important law, which may be stated as fol- 
 lows : The osmotic pressure exerted by a substance in 
 solution is equal to the gas pressure that the substance 
 would exert if it were a gas at the same temperature and 
 the same volume. Further investigations have fully 
 established the fact that molecules in dilute solution obey 
 the simple laws of gases. 
 
 It was pointed out by van't Hoff that salts, strong 
 acids and strong bases showed marked exceptions to his 
 law in exerting much greater osmotic pressures than 
 those calculated for them. 
 
 The next year in 1887, Arrhenius explained this abnor- 
 mal beha^vior of salts, strong acids and strong bases by 
 assuming that they dissociate spontaneously into ions 
 when they dissolve, and that these more numerous par- 
 ticles act like molecules in producing osmotic pressure. 
 He showed that these exceptional substances all conduct 
 electricity in solution, while those conforming with van't 
 Hoff's law do not, and according to his theory the ions 
 become positively or negatively charged when they are 
 formed, and these charged ions conduct the current. 
 
320 A CENTURY OF SCIENCE 
 
 For example a molecule of sodium chloride was supposed 
 to give the two ions Na+ and CI", thus exerting twice as 
 much osmotic pressure as a single molecule. 
 
 Determinations of osmotic pressure or related values, 
 such as depression of the freezing point and of electric 
 conductivity, indicated that ionization could not be 
 regarded as complete in any case except in exceedingly 
 dilute solutions, and that the extent of ionization varied 
 with different substances. The fact that osmotic pres- 
 sures and electric conductivities gave closely agreeing 
 results in regard to the extent of ionization in various 
 cases, is the strongest evidence in support of the theory. 
 
 It was difficult at first for many chemists to believe 
 that atoms, such as those of sodium and chlorine, and 
 groups such as NH^ and SO4 could exist independently 
 in solution, even though electrically charged. However, 
 the theory rapidly gained ground and is now accepted 
 by nearly every chemist as a satisfactory explanation of 
 many facts. 
 
 During recent years, many investigations relating to 
 osmotic pressure and ionization have been carried out in. 
 the United States, but only the work of Morse, A. A. 
 Noyes, and the late H. C. Jones can be merely alluded to 
 here. It should be mentioned that the eminent author 
 of the ionic hjrpothesis gave the Silliman Memorial course 
 of lectures at Yale in 1911 on Theories of Solution. 
 
 Colloidal Solutions. — Graham, an English chemist, in 
 1861 was the first to make a distinction between sub- 
 stances forming true solutions, which he called crystal- 
 loids, and those of a gummy nature resembling glue, 
 which in solution do not diffuse readily through parch- 
 ment membranes, as crystalloids do, and which he called 
 colloids. The separation of colloids by means of parch- 
 ment was called dialysis, and this process has come into 
 extensive use in preparing pure colloidal solutions. 
 Slow diffusion is now regarded as characteristic of col- 
 loids rather than their gummy condition. 
 
 Colloidal solutions occupy an intermediate position 
 between true solutions and suspensions, resembling one 
 or the other according to the kind of colloid and the fine- 
 ness of division. By preparing filters with pores of 
 varying degrees of fineness, Bechold has been able to 
 
ONE HUNDRED YEAES OF CHEMISTEY 321 
 
 separate colloids from each other in accordance with the 
 size of their particles. It has also been possible to pre- 
 pare different solutions of a colloid varying gradually 
 from one in which the particles were undoubtedly in sus- 
 pension to one which had many of the properties of a 
 true solution. 
 
 Beginning in 1889, Carey Lea described in the Journal 
 37, 476, 1889 et seq.) a variety of methods for preparing 
 colloidal solutions of the metals, consisting in general of 
 treating solutions of metallic salts with mild reducing 
 agents. His work on colloidal silver was particularly 
 extensive and interesting. Solutions of this kind have 
 recently yielded some extremely interesting results by 
 means of the ultra-microscope, an apparatus devised by 
 Zsigmondy and Siedentopf. A very intense beam of 
 light is passed through the solution and observed at right 
 angles with a powerful microscope. Under these condi- 
 tions, particles much too small to be seen by other means, 
 reveal their presence by reflected light. It has been pos- 
 sible in a very dilute solution of known strength to count 
 the particles and thus to calculate their size. The small- 
 est colloidal particles measured in this way were of gold 
 and were sho'WTi to have approximately ten times the 
 diameter, or 1000 times the volume, attributed to ordi- 
 nary molecules. It is of interest that the particles 
 appear in rapid motion corresponding to the well-known 
 Brownian movement. 
 
 The chemistry of colloids has now assumed such 
 importance that it may be considered as a separate 
 branch of the science. It has its own technical journal 
 and deals largely with the chemistry of organic products. 
 All living matter is built up of colloids, and hfemoglobin, 
 starch, proteins, rubber and milk are examples oi col- 
 loidal substances or solutions. Among inorganic sub- 
 stances, many sulphides, silicic acid, and the amorphous 
 hydroxides, like ferric hydroxide, frequently act as 
 colloids. 
 
 Law of Mass-Action. — Berthollet about the beginning 
 of the last century was the first chemist to study the 
 effect of mass, or more correctly, the concentration of 
 substances on chemical action. His views summarized 
 by himself are as follows: "The chemical activity of a 
 
322 A CENTURY OF SCIENCE 
 
 substance depends upon the force of its affinity and upon 
 the mass which is present in a given volume." The 
 development of this idea, which is fundamentally correct, 
 was greatly hindered by the fact that BerthoUet drew the 
 incorrect conclusion that the composition of chemical 
 compounds depended upon the masses of the substances 
 combining to produce them, a conclusion in direct con- 
 tradiction to the law of definite proportions, and since 
 this view was soon disproved by Proust and others, 
 BerthoUet 's law in its other applications received no 
 immediate attention. Mitchell, however, pointed out 
 in the Journal (16, 234, 1829) the importance of 
 BerthoUet 's work, and Heinrich Rose in 1842 again 
 called attention to the effect of mass, mentioning as one 
 illustration the effect of water and carbonic acid in 
 decomposing the very stable natural silicates. Some- 
 what later several other chemists made important contri- 
 butions to the question of the influence of concentration 
 upon chemical action, but it w^as the Norwegians, Guld- 
 berg and Waage, who first formulated the law of mass 
 action in 1867. 
 
 This law has been of enormous importance in chemical 
 theory, since it explains a great many facts upon a 
 mathematical basis. It applies particularly to equilib- 
 rium in reversible reactions, where it states that the 
 product of the concentrations on the one side of a simple 
 reversible equation bears a constant relation to the 
 products of the concentrations on the other side, provided 
 that the temperature remains constant. In cases of this 
 kind where two gases or vapors react with two solids, 
 the latter if always in excess may be regarded as con- 
 stant in concentration, and the law takes on a s im pler 
 aspect in applying only to the concentrations of the 
 gaseous substances. For example, in the reversible 
 reaction 
 
 3Fe + 4n,^0:;i±Fe.O, + 4H^, 
 
 which takes place at rather high temperatures, a definite 
 mixture of steam and hydrogen at a definite temperature 
 wUl cause the reaction to proceed with equal rapidity in 
 both directions, thus maintaining a state of equilibrium, 
 provided that both iron and the oxide are present in 
 
ONE HUNDRED YEARS OF CHEMISTRY 323 
 
 excess. If, however, the relative concentrations of the 
 hydrogen and steam are changed, or even if the tempera- 
 ture is changed, the reaction will proceed faster in one 
 direction than in the other until equilibrium is again 
 attained. 
 
 The principle of mass-action also explains why it is 
 sometimes possible for a reversible reaction to become 
 complete in either direction. For instance, in connec- 
 tion with the reaction that has just been considered, if 
 steam is passed over heated iron and if hydrogen is 
 passed over the heated oxide, the gaseous product in each 
 case is gradually carried away, and the reaction contin- 
 ually proceeds faster in one direction than in. the other 
 until it is complete, according to the equations 
 
 3Fe 4- 4H,0 > SFeP^ + 4H, and 
 
 Fe.O. -t- 4H, > 3Fe -|- 4H,0. 
 
 Many other well-known and important facts, both 
 chemical and physical, depend upon this law. It explains 
 the circumstance that a vapor-pressure is not dependent 
 upon the amount of the liquid that is present; it also 
 explains the constant dissociation pressure of calcium 
 carbonate at a given temperature, irrespective of the 
 amounts of carbonate and oxide present; in connection 
 with the ionic theory, it furnishes the reason for the 
 variable solubility of salts due to the presence of elec- 
 trolytes containing ions in common; and it elucidates 
 Henry's law which states that the solubilities of gases are 
 proportional to their pressures. 
 
 Ostwald, more than any other chemist, has been instru- 
 mental in making general applications of this law, and he 
 made particularly extensive use of it in connection with 
 analytical chemistry in a book upon this subject which he 
 published. 
 
 The Phase Rule.— In 1876 Willard Gibbs of Yale pub- 
 lished a paper in the Proceedings of the Connecticut 
 Academy of Science on the "Equilibrium of Heteroge- 
 neous Substances," and two years later he published an 
 abstract of the article in the Journal (16, 441, 1878). He 
 had discovered a new law of nature of momentous 
 importance and wide application which is called the 
 
324 A CENTURY OF SCIENCE 
 
 "Phase-Rule" and is expressed by a very simple 
 formula. 
 
 The application of this great discovery to chemical 
 theory was delayed for ten years, partly, perhaps, 
 because it was not sufficiently brought to the attention of 
 chemists, but largely it appears because it was not at 
 first understood, since its presentation was entirely 
 mathematical. 
 
 It Avas Rooseboom, a Dutch chemist, who first applied 
 the phase-rule. It soon attracted profound attention, 
 and the name of Willard Gibbs attained world-wide fame 
 among chemists. When Nernst, who is perhaps the most 
 eminent physical chemist of the present time, was deliv- 
 ering the Silliman Memorial Lectures at Yale a few years 
 ago, he took occasion to place a wreath on the grave of 
 Willard Gibbs in recognition of his achievements. 
 
 To understand the rule, it is necessary to define the 
 three terms, introduced by Gibbs, phase, degrees of free- 
 dom and component. 
 
 By the first term, is meant the parts of any system of 
 substances which are mechanically separable. For 
 instance, water in contact with its vapor has two phases, 
 while a solution of salt and water is composed of but one. 
 The degrees of freedom are the number of physical con- 
 ditions, including pressure, temperature and concentra- 
 tion, which can be varied independently in a system 
 without destroying a phase. The exact definition of a 
 component is not so simple, but in general, the com- 
 ponents of a system are the integral parts of which it is 
 composed. Any system made up of the compound HoO, 
 for instance, whether as ice, water or vapor, contains but 
 (^one component,- while a( solution of salt and water con- 
 tains two. j Letting P, ¥. and C stand for the three terms, 
 the phase-rule is simply 
 
 F = C-f 2 — P 
 
 that is, the number of degrees of freedom in a system in 
 equilibrium equals the number of components, plus two, 
 minus the number of phases. The rule can be easily 
 understood by means of a simple illustration. In a sys- 
 tem composed of ice, water and water-vapor, there are 
 three phases and one component and therefore 
 
Jc , ^I'^t^^^-Cc-^^^^^^ 
 
ONE HUNDRED YEARS OF CHEMISTRY 325 
 F=l+2— 3=0 
 
 Such a system has no degrees of freedom. This means 
 that no physical condition, pressure or temperature can 
 be varied without destroying a phase, so that such a sys- 
 tem can only exist in equilibrium at one fixed tempera- 
 ture, with a fixed value for its vapor-pressure. 
 
 For instance, if the system is heated above the fixed 
 temperature, ice disappears and if the pressure is raised, 
 vapor is condensed. If this same system of water alone 
 contains but two phases, for instance, liquid and vapor, 
 F = 1 -f 2 — 2 = 1, or there is one degree of freedom. 
 In such a system, one physical condition such as tempera- 
 ture can be varied independently, but only one, without 
 destroying a phase. For instance, the temperature may 
 be raised or lowered, but for every value of temperature 
 there is a corresponding value for the vapor pressure. 
 One is a function of the other. If both values are varied 
 independently, one phase will disappear, either vapor 
 condensing entirely to Avater or the reverse. Finally if 
 the system consists of one phase only, as water vapor, 
 F ^ 2, or the system is divariant, which means that at 
 any given temperature it is possible for vapor to exist at 
 varying pressures. 
 
 The illustration which has been given relates to physi- 
 cal equilibrium, but the rule is applicable to cases involv- 
 ing chemical changes as well. In comparing the 
 phase-rule with the law of mass action, it will be noticed 
 that both have to do with equilibrium. The great advan- 
 tage of the former is that it is entirely independent of the 
 molecular condition of the substances in the different 
 phases. For instance, it makes no difference so far as 
 the application of the rule is concerned, whether a sub- 
 stance in solution is dissociated, undissociated or com- 
 bined with the solvent. In any case, the solution 
 constitutes one phase. On the other hand, the rule is 
 purely qualitative, giving information only as to whether 
 a given change in conditions is possible. The law of 
 mass action is a quantitative expression so that when the 
 value of the constant is once known, the change can be 
 calculated which takes place in the entire system if the 
 concentration of one substance is varied. Tlie law, how- 
 ever, requires a knowledge of the molecular condition of 
 
320 A CENTURY OF SCIENCE 
 
 the reacting substances, which may be uncertain or un- 
 known, and chiefly on this account it has, like the phase- 
 rule, often only a qualitative significance. 
 
 The phase rule has served as a most valuable means 
 of classifying systems in equilibrium and as a guide in 
 determining the possible conditions under Avhich such 
 systems can exist. As illustrations of its practical appli- 
 cation, van't Hoff used it as an underlying principle in 
 his investigations on the conditions under which salt 
 deposits have been formed in nature, and Rooseboom was 
 able by its means to explain the very complicated rela- 
 tions existing in the alloys of iron and carbon which form 
 the various grades of wrought iron, steel and cast iron. 
 
 Thermochemistry. — This branch of chemistry has to 
 do with heat evolved or absorbed in chemical reactions. 
 It is important chiefly because in many cases it furnishes 
 the only measure we have of the energj^ changes involved 
 in reactions. To a great extent, it dates from the dis- 
 covery by Hess in 1840 of a fundamental law which states 
 that the heat evolved in a reaction is the same whether it 
 takes place in one or in several stages. This law has 
 made it possible to calculate the heat values of a large 
 number of reactions which cannot be determined by 
 direct experiment. 
 
 Thermochemistry has been developed by a compara- 
 tively few men who have contributed a surprisingly 
 large number of results. Favre and Silbermann, begin- 
 ning shortly after 1850, improved the apparatus f or cal- 
 orimetric determinations, which is called the calorimeter, 
 and published many results. At about the same time 
 Julius Thomsen, and in 1873 Berthelot, began their 
 remarkable series of publications which continued until 
 recently. Thomsen 's investigations were published in 
 1882 in 4 volumes. It is probably safe to say that the 
 greater part of the data of thermochemistry was obtained 
 by these two investigators. The bomb calorimeter, an 
 apparatus for determining heat values by direct combus- 
 tion, was developed by Berthelot. The' recent work of 
 Mixter at Yale, published in the Journal, and of Rich- 
 ards at Harvard should be mentioned particularly. 
 Mixter 's work in this field began in 1901 (12, 347). 
 Usmg an improved bomb calorimeter, he has developed a 
 
ONE HUNDRED YEARS OF CHEMISTRY 327 
 
 method of determining the heats of formation of oxides 
 by combustion with sodium peroxide. By tliis same 
 method as well as by direct combustion in oxygen, he has 
 obtained results which appear to equal or excel in accu- 
 racy any which have ever been obtained in his field of 
 work. Richards 's work has consisted largely of improve- 
 ments in apparatus. He developed the so-called adia- 
 batic calorimeter which practically eliminates one of the 
 chief errors in thermal work caused by the heating or 
 cooling effect of the surroundings. This modification is 
 being generally adopted where extremely accurate work 
 is required. 
 
 Organic Chemistry. 
 
 One hundred years ago qualitative tests for a few 
 organic compounds were known, the elements usually 
 occurring in them were recognized, and some of them had 
 been analyzed quantitatively, but organic chemistry was 
 far less advanced than inorganic, and almost the whole of 
 its enormous development has taken place during our 
 period. 
 
 Berzelius made a great advance in the subject by estab- 
 lishing the fact, which had been doubted previously, that 
 the elements in organic compounds are combined in con- 
 stant, definite proportions. In 1823 Liebig brought to 
 light the exceedingly important fact of isomerism by 
 showing that silver fulminate had the same percen- 
 tage composition as silver cyanate, a compound_ of very 
 different properties. Isomeric compounds with identical 
 molecular weight as well as the same composition have 
 since been found in very many cases, and they have 
 played a most important part in determining the 
 arrangements of atoms in molecules. They have been 
 f oundto be very numerous in many cases. For instance, 
 three pentanes with the formula Cr,H,2 are known, all 
 that are possible according to theory, and in each case 
 the structure of the molecule has been established. On 
 theoretical grounds it has been calculated that 802 
 isomeric compounds with the formula CjoHog are possi- 
 ble, while with more complex formulas the numbers of 
 isomers may be very much greater. 
 
328 A CENTURY OF SCIENCE 
 
 A particularly interesting case of isomerism was 
 observed by Wohler in 1828, when he found that ammo- 
 nium cyanate changes spontaneously into urea 
 
 (NH.CNO > N,H,CO). 
 
 This was the first synthesis of an organic compound from 
 inorganic material, and it overthrew the prevailing view 
 that vital forces were essential in the formation of 
 organic substances. A great many natural organic com- 
 pounds have been made artificially since that time, and 
 some of them, such as artificial alizarin, indigo, oil of 
 wintergreen, and vanillin, have more or less fully 
 replaced the natural products. The preparation of a 
 vast number of compounds not known in nature, many of 
 which are of practical importance as medicines, dyes, 
 explosives, etc., has been another great achievement of 
 organic chemistry. 
 
 The development of our present formulas for organic 
 compounds, by means of which in many cases the rela- 
 tive positions of the atoms can be shown with the great- 
 est confidence, has been gradual. Formulas based on the 
 dualistic idea of Berzelius were used for some time, type 
 formulas, with the employment of compound radicals, 
 came later, the substitution of atoms or groups of atoms 
 for others in chemical reactions came to be recognized, 
 but one of the most important steps was the recognition 
 of the quadrivalence of carbon and the general applica- 
 tion of valency to atoms by Kekule about 1858. This led 
 directly to the use of modern structural formulas which 
 have been of the greatest value in the theoretical inter- 
 pretation of organic reactions. It was Kekule also who 
 proposed the hexagonal ring-formula for benzene, CgHg, 
 Avhich led to exceedingly important theoretical and prac- 
 tical developments. The details of the formulas for 
 many other rings and complex structures have been estab- 
 lished since that time, and there is no doubt that the 
 remarkable achievements in organic chemistry during the 
 past sixty years have been much facilitated by the use of 
 these formulas. 
 
 Many important researches in organic chemistry have 
 been carried out in the United States, and the activity in 
 this direction has greatly increased in recent vears. In 
 
ONE HUNDRED YEARS OF CHEMISTRY 329 
 
 this connection the large amount of work of this kind 
 accomplished in the Sheffield Laboratory, at present 
 under the guidance of Professor T. B. Johnson, should be 
 mentioned. 
 
 It has happened that comparatively few publications 
 on organic chemistry have appeared in the Journal, but 
 it may be stated that the preparation of chloroform and 
 its physiological effects were described by Guthrie (21, 
 64, 1832). Unknown to him, it had been prepared by 
 Souberain, a French chemist, the previous year, but the 
 former was the first to describe its physiological action. 
 Silliman gave a sample to Doctor Eli Ives of the Yale 
 Medical School, who used it to relieve a case of asthma. 
 This was the first use of chloroform in medical practice 
 (21, 405, 1832). Guthrie also described in the Journal 
 (21, 284, 1832) his new process for converting potato 
 starch into glucose, a method which is essentially the 
 same as that used to-day in converting cornstarch into 
 glucose. Lawrence Smith (43, 301, 1842 et seq.), Hors- 
 ford (3, 369, 1847 et seq.), Sterry Hunt (7, 399, 1849), 
 Carey Lea (26, 379, 1858 et seq.), Remsen (5, 179, 1873 et 
 seq.), and others have contributed articles on organic 
 chemistry. 
 
 Agricultural Chemistry. 
 
 Until near the middle of the nineteenth century, it was 
 believed that plants, like animals, used organic matter for 
 food, and depended chiefly upon the humus of the soil 
 for their growth. This view was held even long after it 
 was known that plant leaves absorb carbon dioxide and 
 give off oxygen, and after the ashes of plants had been 
 accurately analyzed. 
 
 This incorrect view was overthrown by the celebrated 
 German chemist, Liebig, Avho made many investigations 
 upon the subject, and, properly interpreting previous 
 knowledge, published a book in 1840 upon the applica- 
 tion of chemistry to agriculture and physiology in which 
 he maintained that the nutritive materials of all green 
 plants are inorganic substances, namely, carbon dioxide, 
 water, ammonia (nitrates), sulphates, phosphates, silica, 
 lime, magnesia, potash, iron, and sometimes common salt. 
 He drew the vastly important conclusion that the effective 
 
330 A CENTURY OF SCIENCE 
 
 fertilization of soils depends upon replenishing the 
 inorganic substances that have been exhausted by the 
 crops. 
 
 The fundamental principles set forth by Liebig have 
 been confirmed, and it has been found that the fertilizing 
 constituents most commonly lacking in soils are nitrogen 
 compounds, phosphates, and potassium salts, so that 
 these have formed the important constituents of artificial 
 fertilizers. Liebig himself found that humus is valuable 
 in soils, because it absorbs and retains the soluble salts. 
 
 The foundation established by Liebig in regard to arti- 
 ficial fertilizers has led to an enormous application of 
 these materials, much to the advantage of the world's 
 food-supply. 
 
 It was Liebig 's belief, in accordance with the prevail- 
 ing views, that decay and putrefaction as well as 
 alcoholic and other fermentations were spontaneous 
 processes, and when the eminent French chemist, Pas- 
 teur, in 1857, explained fermentation as directly caused 
 by yeast, an epoch-making discovery which led to the 
 explanation of decay and i^utrefaction by bacterial action 
 and to the germ-theory of disease, the explanation was 
 violently opposed by Liebig and other German chemists. 
 Pasteur's view prevailed, however, and since that time 
 it has been found that various kinds of bacteria are 
 responsible for the formation of ammonia from nitro- 
 genous organic matter and also for the change of ammo- 
 nia into the nitrates that are available as plant-food. 
 
 The long-debated question as to the availability of 
 atmospheric nitrogen for plant-food was settled in 1886 
 by the discovery of Hellriegel that bacteria contained in 
 nodules on the roots, especially of leguminous plants, are 
 capable of bringing nitrogen into combination and fur- 
 nishing it to the plants. 
 
 No more than an allusion can be made to agricultural 
 experiment stations where soils, fertilizers, "foods and 
 other products are examined, and where other problems 
 connected with agriculture are studied. 
 
 The late S. W. Johnson of Yale studied with Liebig 
 and siibsequently did much service for agricultural chem- 
 istry in this country, by his investigations, his teaching, 
 and his Avritings. His book, "How Crops Grow," pub- 
 
ONE HUNDRED YEAES OF CHEMISTRY 331 
 
 listed in 1868, gave an excellent account of the principles 
 of agricultural chemistry. He did much to bring about 
 the establishment of agricultural experiment stations in 
 this country, and for a long time he was the director of 
 the Connecticut Station. 
 
 In the Journal, as early as 1827, Amos Eaton (12, 370) 
 published a simple method for the mechanical analysis 
 of soils to determine their suitability for wheat-culture, 
 and Hilgard, between 1872 and 1874, described an elab- 
 orate study of soil-analysis. J. P. Norton, a Yale 
 professor, in 1847 (3, 322) published an investigation 
 on the analysis of the oat, which was awarded a prize of 
 fifty sovereigns by a Scotch agricultural society, while 
 Johnson, Atwater, and others have contributed articles 
 on the analysis of various farm products. 
 
 Industrial Acids and Alkalies. 
 
 One hundred years ago sulphuric acid was manufac- 
 tured on a comparatively very small scale in lead 
 chambers. In 1818, an English manufacturer of the 
 acid introduced the modern feature of using pyrites in 
 the place of brimstone, while the Gay-Lussac tower in 
 1827 and the Glover tower in 1859 began to be applied as 
 great improvements in the chamber process. Within 
 about twenty years the contact process, employing plat- 
 inized asbestos, has replaced the old chamber process to 
 a large extent. It has the advantage of producing the 
 concentrated acid, or the fuming acid, directly. 
 
 During our period the manufacture of sulphuric acid 
 has increased enormously. Very large quantities of it 
 have been used in connection with the Leblanc soda pro- 
 cess in its rapid development. It came to be employed 
 extensively for absorbing ammonia in the illuminating- 
 gas industry, which was in its infancy one hundred years 
 ago. New industries such as the manufacture of "super- 
 phosphates" as artificial fertilizers, the refining of petro- 
 leum, the manufacture of artificial dyestuffs and many 
 other modern chemical products have greatly increased 
 the demand for it, while its employment in the production 
 of nitric and other acids, and for many other purposes 
 not already mentioned, has been very great. 
 
 The manufacture of nitric acid has been greatly 
 
332 A CENTURY OF SCIENCE 
 
 extended during our period on account of its employment 
 for producing explosives, artificial dyestuffs, and for 
 many other purposes. Chile saltpeter became available 
 for making it about 1852. This acid has been manufac- 
 tured recently from atmospheric nitrogen and oxygen by 
 combining them by the aid of powerful electric dis- 
 charges. This process has been used chiefly in Norway 
 where water-power is abundant, as it requires a large 
 expenditure of energy. A still more recent method for 
 the production of nitric acid depends upon the oxidation 
 of ammonia by air with the aid of a contact substance, 
 such as platinized asbestos. 
 
 The production of ammonia, which was very small a 
 hundred years ago, has been vastly increased in connec- 
 tion Avith the development of the illuminating-gas indus- 
 try and the employment of by-product coke ovens. This 
 substance is very extensively used in refrigerating 
 machines and also in a great many chemical operations, 
 including the Solvay soda-process. Ammonium salts 
 are of great importance also as fertilizers in agriculture. 
 The conversion of atmospheric nitrogen into ammonia 
 on a commercial scale is a recent achievement. It has 
 been accomplished by heating calcium carbide, an elec- 
 tric-furnace product made from lime and coke, with nitro- 
 gen gas, thus producing calcium cyanamide, and then 
 treating this cyanamide with water under proper condi- 
 tions. Another method devised by Haber consists in 
 directly combining nitrogen and hydrogen gases under 
 high pressure with the aid of a contact substance. 
 
 Leblanc's method for obtaining sodium carbonate from 
 sodium chloride by tirst converting the latter into the 
 sulphate b}^ means of sulphuric acid and then heating the 
 sulphate with lime and coal in a furnace was invented 
 as early as 1791, but it was not rapidly developed and did 
 not gain a foothold in England until 1826 on account of a 
 high duty on salt up to that time. Afterwards the 
 process flourished greatly in connection with the sul- 
 phuric acid industry upon which it depended, and with 
 the bleaching-powder industry Avhieh utilized the hydro- 
 chloric acid incidentally produced by it, and, of course, 
 in connection with soap manufacture and many other 
 industries in which the soda itself was employed. 
 
ONE HUNDRED YEARS OF CHEMISTRY 333 
 
 About 1866 the Solvay process appeared as a rival to 
 the Leblanc process. This depends upon the precipita- 
 tion of sodium bicarbonate from salt solutions by means 
 of carbon dioxide and ammonia, with the subsequent 
 recovery of the ammonia. It has displaced the older 
 process to a large extent, and it is carried on extensively 
 in this country, for instance, at Syracuse, New York. 
 
 Other processes for soda depend upon the electrolysis 
 of sodium chloride solutions. In this case caustic soda 
 and chlorine are the direct products, and the chlorine 
 thus produced and liquified by pressure in steel cylinders, 
 has become an important commercial article. 
 
 In earlier times wood-ashes were the source of potash 
 and potassium salts. Wurtz in the Journal (10, 326, 
 1850) suggested the availability of New Jersey green- 
 sand as a source of potash and showed how this mineral 
 could be decomposed, but it does not appear that this 
 mineral has ever been utilized for the purpose. About 
 1861 the German potash-salt deposits began to be devel- 
 oped, and these have since become the chief source of 
 this material. At present many efforts are being made 
 to obtain potassium compounds from other sources, such 
 as brines, cement-kiln dust, and feldspar and other min- 
 erals but thus far the results have not satisfied the 
 demand. 
 
 Conclusion, 
 
 This account of chemical progress has given only a 
 limited view of small portions of the subject, because the 
 amount of available material is so vast in comparison 
 with the space allowed for its presentation. Since the 
 Joui'nal has published comparatively little organic chem- 
 istry, it was decided to make room for a better presenta- 
 tion of other things by giving only a brief discussion of 
 this exceedingly active and important branch of the 
 science. For similar reasons industrial and metallurgi- 
 cal chemistry, and other branches besides, in spite of 
 their great growth and importance, have been neglected, 
 except for some incidental references to them, and some 
 account of a few of the more important industrial 
 chemicals. 
 
 It appears that we have much reason to be proud of the 
 
 21 
 
334 A CENTURY OF SCIENCE 
 
 advances in chemistry that have been made during the 
 Journal's period, and of the part that the Journal has 
 taken in connection with them, and there seems to be no 
 doubt that this progress has not diminished during more 
 recent times. 
 
 The present tendency of chemical research is evidently 
 towards a still greater development of organic chemis- 
 try, and an increased application of physics and mathe- 
 matics to chemical theory and practice. 
 
 The very great improvements that have been made in 
 chemical education, both in the number of students and 
 the quality of instruction, during the period under dis- 
 cussion, and particularly in rather recent times, gives 
 promise for escellent future progress. 
 
 Note. 
 
 ^ It appears that the most accurate experimental demonstration ever made 
 of this law was that of E. W. Morley, published in the Journal (41, 220, 
 276, 1891). He showed that 2-0002 volumes of hydrogen combine with one 
 volume of oxygen. 
 
XI 
 
 A CENTURY'S PROGRESS IN PHYSICS 
 
 By LEIGH PAGE 
 
 D 
 
 YNAMICS. — At the beginning of the nineteenth 
 century mechanics was tlie only major branch of 
 pliysical science which had attained any consider- 
 able degree of development. Two centuries earlier, 
 Galileo's experiments on the rate of fall of iron balls 
 dropped from the top of the Leaning Tower of Pisa, had 
 marked the origin of dynamics. He had easily disproved 
 the prevalent idea that even under conditions where air 
 resistance is negligible heavy bodies would fall more 
 rapidly than light ones, and further experiments had led 
 him to conclude that the increase in velocity is propor- 
 tional to the time elapsed, and not to the distance 
 traversed, as he had at first supposed. Less than a 
 century later Newton had formulated the laAvs of motion 
 in the same words in which they are given to-day. These 
 laws of motion, coupled with his discovery of the law of 
 universal gravitation, had enabled him to correlate at 
 once the planetary notions which had proved so puzzling 
 to his predecessors. His success gave a tremendous 
 stimulus to the development and extension of the funda- 
 mental dynamical principles that he had brought to light, 
 which culminated in the work of the great French mathe- 
 maticians, Lagrange and Laplace, a little over a hundred 
 years ago. 
 
 Newton's laws of motion, it must be remembered, 
 apply only to a particle, or to those bodies which can be 
 treated as particles in the problem under consideration. 
 In his "Mecanique Analytique" Lagrange extended 
 these principles so as to make it possible to treat the 
 motion of a connected system by a method almost as sim- 
 ple as that contained in the second law of motion. 
 
336 A CENTURY OF SCIENCE 
 
 Instead of three scalar equations for each of the innumer- 
 ably large number of particles involved, he showed how 
 to reduce the ordinary djmamical equations to a number 
 equal to that of the degrees of freedom of the system. 
 This is made possible by a combination of d'Alembert's 
 principle, which eliminates the forces due to the connec- 
 tions between the particles, and the principle of virtual 
 work, which confines the number of equations to the num- 
 ber of possible independent displacements. The aim of 
 Lagrange was to make dynamics into a branch of 
 analysis, and his success may be inferred from the fact 
 that not a single diagram or geometrical figure is to be 
 found in his great work. 
 
 Celestial Mechanics. — Almost simultaneously with the 
 publication of the "Mecanique Analytique" appeared 
 Laplace's "Mecanique Celeste." Laplace's avowed 
 aim was to offer a complete solution of the great 
 dynamical problem involved in the solar system, taking 
 into account, in addition to the effect of the sun's gravi- 
 tational field, those perturbations in the motion of each 
 planet caused by the approach and recession of its 
 neighbors. So successful was his analysis of planetary 
 motions that his contemporaries believed that they were 
 not far from a complete explanation of the world on 
 mechanical principles. Laplace himself was undoubt- 
 edly convinced that nothing was needed beyond a 
 knowledge of the masses, positions, and initial velocities 
 of every material particle in the universe in order to 
 completely predetermine all subsequent motion. 
 
 The greatest triumph of these djmamical methods was 
 to come half a century later. The planet Uranus, dis- 
 covered in 1781 by the elder Herschel, was at that time 
 the farthest known planet from the sun. But the orbit 
 of Uranus was subject to some puzzling variations. 
 After sifting all the known causes of these disturbances, 
 Leverrier in Prance and Adams in England independ- 
 ently reached the conclusion that another planet still 
 more remote from the sun must be responsible, and com- 
 puted its orbit. Leverrier coimiiunicated to Galle of 
 Berlin the results of his calculations, and during the next 
 few days the German astronomer discovered Neptune 
 within one degree of its predicted position ! 
 
M 
 
 ( yhu^-y^^^^^^ 
 
A CENTURY'S PROGRESS IN PHYSICS 337 
 
 We shall mention but one other achievement of the 
 methods of celestial mechanics. Those visitors of the 
 skies, the comets, which become so prominent only to fade 
 away and vanish perhaps forever, had interested astron- 
 omers from the earliest times. Soon after the discovery 
 of the law of gravitation, Newton had worked out a 
 method by which the elements of a comet's orbit can be 
 computed from observations of its position. It was 
 found that the great majority of these bodies move in 
 nearly parabolic paths and only a few in ellipses. Of the 
 latter the most prominent is the brilliant comet first 
 observed by Halley in 1681. It has reappeared regu- 
 larly at intervals of seventy-six years ; the last appear- 
 ance in the spring of 1910 is no doubt well remembered 
 by the reader. Kant had considered comets to be 
 formed by condensing solar nebulas, whereas Laplace had 
 maintained that they originate in matter which is scat- 
 tered throughout stellar space and has no connection 
 with the solar system. A study of the distribution of 
 inclinations of comet orbits by H. A. Newton (16, 165, 
 1878) of New Haven substantiated Laplace's hypothesis, 
 and led to the conclusion that the periodic comets have 
 been captured by the attraction of those planets near to 
 which they have passed. Of these comets a number 
 have comparatively short periods, and are found to have 
 orbits which are in general only slightly inclined to those 
 of the planets, and are traversed in the same direction. 
 Moreover, the fact that the orbit of each of these comets 
 comes very close to that of Jupiter made it seem probable 
 that they have been attached to the solar system by the 
 attraction of this planet. Further confirmation of this 
 hypothesis was furnished by H. A. Newton's (42, 183 and 
 482, 1891) explanation of the small inclination of their 
 orbits and the scarcity of retrograde motions among 
 them. 
 
 In 1833 occurred one of the greatest meteoric showers 
 of history. Olmstead (26, 132, 1834) and Twining (26, 
 320, 1834) of New Haven noticed that these shooting 
 stars traverse parallel paths, and were the first to sug- 
 gest that they must be moving in swarms in a permanent 
 orbit. From an examination of all accessible records, 
 H. A. Newton (37, 377, 1864; 38, 53, 1864) was able to 
 
338 A CENTURY OF SCIENCE 
 
 show that meteoric showers are common in November, 
 and of particular intensity at intervals of 33 or 34 years. 
 He confidently predicted a great shower for Nov. 13th, 
 1866, which not only actually occurred but was followed 
 by another a year later, showing that the meteoric swarm 
 extended so far as to require two years to cross the 
 earth's orbit. H. A. Newton (36, 1, 1888) in America 
 and Adams in England took up the study of meteoric 
 orbits with great interest, and the former concluded that 
 these orbits are in every sense similar to those of the 
 periodic comets, implying that a swarm of meteors 
 originates in the disintegration of a comet. In fact 
 Schiaparelli actually identified the orbit of the Perseids, 
 or August meteors, with Tuttle's comet of 1862, and 
 shortly after the orbit of the Leonids, or November 
 meteors, was found to be the same as that of Tempel's 
 comet. 
 
 Electromar/netism. — During the eighteenth century 
 much interest had been manifested in the study of elec- 
 trostatics and magnetism. Du Fay, Cavendish, Michell 
 and Coulomb abroad and Franklin in America had sub- 
 jected to experimental investigation many of the phe- 
 nomena of one or both of these sciences, and in the early 
 years of the nineteenth century Poisson developed to a 
 remarkable extent the analytical consequences of the law 
 of force which experiment had revealed. Both Laplace 
 and he made much use of the function to which Green 
 gave the name "potential" in 1828, and which is such a 
 powerful aid in solving problems involving magnetism 
 or electricity at rest. 
 
 Meantime electric currents had been brought under the 
 hand of the experimenter by the discoveries of Galvani 
 and Volta. Large numbers of cells were connected in 
 series, and interest seemed to lie largely in producing 
 brilliant sparks or fusing metals by means of a heavy 
 current. Hare (3, 105, 1821) of the" University of Penn- 
 sjdvania constructed a battery consisting of two troughs 
 of forty cells each, so arranged that the coppers and 
 zincs can be lowered simultaneously into the acid and 
 large currents obtained before polarization has a chance 
 to interfere. This "deflagrator" was used to ignite 
 
A CENTURY'S PROGRESS IN PHYSICS 339 
 
 charcoal in the circuit, or melt fine "wires, and was for 
 some time the most powerful arrangement of its kind. 
 That "galvanism" is something quite different from 
 static electricity was the opinion of many investigators ; 
 Hare considered the heat developed to be the distinguish- 
 ing mark of the electric current. He says: "It is 
 admitted that the action of the galvanic fluid is upon or 
 between atoms ; while mechanical electricity when unco- 
 erced, acts only upon masses. This difference has not 
 been explained unless by my hypothesis, in which caloric, 
 of which the influence is only exerted between atoms, 
 is supposed to be a principal agent in galvanism. ' ' 
 
 Questioning minds were beginning to suspect that 
 there must be some connection between electricity and 
 magnetism. For lightning had been known to make 
 magnets of steel knives and forks, and Franklin had mag- 
 netized a sewing needle by the discharge from a Leyden 
 jar. Finally Oersted of Copenhagen undertook syste- 
 matic investigation of the effect of electricity on the mag- 
 netic needle. His researches were without result until 
 during the course of a series of lectures on "Electricity, 
 Galvanism, and Magnetism" delivered during the winter 
 of 1819-20 it occurred to him to investigate the action of 
 an electric current on a magnetic needle. At first he 
 placed the wire bearing the current at right angles to the 
 needle, with, of course, no result; then it occurred to 
 him to place it parallel. A deflection was observed, for 
 to his surprise the needle insisted on turning until per- 
 pendicular to the wire. 
 
 Oersted's discovery that an electric current exerts a 
 couple on a magnetic needle was followed a few months 
 later by Ampere's demonstration before the French 
 Academy that two currents flowing in the same direction 
 attract each other, while two in opposite directions repel. 
 The story goes that a critic attempted to belittle this dis- 
 covery by remarking that as it was known that two cur- 
 rents act on one and the same magnet, it was obvious 
 that they would act upon each other. Whereupon Arago 
 arose to defend his friend. Drawing two keys out of 
 his pocket he said, "Each of these keys attracts a mag- 
 net; do you believe that they therefore attract each 
 other?" 
 
340 A CENTURY OF SCIENCE 
 
 A few years later Ampere showed how to express 
 quantitatively the force between current elements, and 
 indeed developed to a considerable degree the equiva- 
 lence between a closed circuit carrying a current and a 
 magnetic shell. So convincing was his analysis and so 
 thorough his discussion of the subject, that Maxwell said 
 of this memoir half a century later, ' ' The whole, theory 
 and experiment, seems as if it had leaped, full grown and 
 full armed, from the brain of the 'Newton of electricity.' 
 It is perfect in form and unassailable in accuracy; and 
 it is summed up in a formula from which all the phe- 
 nomena may be deduced, and which must always remain 
 the cardinal formula of electrodjmamics. " 
 
 Shortly afterwards the dependence of a current on the 
 conductivity of the wire used and the grouping of cells 
 employed, was made clear by the work of Ohm. Many 
 of his results were obtained independently by Joseph 
 Henry (19, 400, 1831) of the Albany Academy, who 
 described in 1831 a powerful electromagnet in which a 
 great many coils of wire insulated with silk were wound 
 around an iron core and connected in parallel with a sin- 
 gle cell. He remarks in this paper that with long wires, 
 as in the telegraph, many cells arranged in series should 
 be used, whereas for several short wires connected in 
 parallel a single cell with large plates is more efficient. 
 
 Current Induction. — Impressed by the fact that elec- 
 tric charges have the power of inducing other charges 
 on neighboring conductors without coming into contact 
 mth them, Faraday was engaged in investigating the 
 possibility of an analogous phenomenon in the case of 
 electric currents. His idea at first seems to have been 
 that a current should induce another current in any 
 closed conducting circuit which happens to be in its 
 vicinity. Experiment readily showed the falsity of this 
 conception, but a brief deflection of the galvanometer in 
 the secondary circuit was noticed at the instant of mak- 
 ing and breaking the current in the primary. Further 
 experiments showed that thrusting a permanent steel 
 magnet into a coil connected to a galvanometer caused 
 the needle to deflect. In fact Faraday's report to the 
 Royal Society on November 24th, 1831, contains a com- 
 
A CENTUEY'S PEOGEESS IN PHYSICS 341 
 
 plete account of all experimental methods available for 
 inducing a current in a closed circuit. 
 
 "VVliile Faraday is entitled to credit for the discovery of 
 current induction by virtue of the priority of his publica- 
 tion, it must not pass unnoticed that Henry obtained 
 many of the same experimental results independently 
 and some even earlier. Henry was at this time instruc- 
 tor in mathematics at the Albany Academy, and seven 
 hours of teaching a day made it well-nigh impossible to 
 carry on original research except during the vacation 
 month of August. As early as the summer of 1830 he 
 had wound 30 feet of copper wire around the armature 
 of a horseshoe electromagnet and connected it to a gal- 
 vanometer. When the magnet was excited, a momen- 
 tary deflection was observed. "I was, however, much 
 surprised," he says, "to see the needle suddenly 
 deflected from a state of rest to about 20° to the east, or 
 in a contrary direction, when the battery was withdrawn 
 from the acid, and again deflected to the west when 
 it was re-immersed." In addition a deflection was 
 obtained by detaching the armature from the magnet, 
 or by bringing it again into contact. Had the results of 
 these experiments been published promptly, America 
 would have been entitled to credit for the most import- 
 ant discovery of the greatest of England's many great 
 experimenters. But Henry desired first to repeat his 
 experiments on a larger scale, and while new magnets 
 were being constructed, the news of Faraday's discovery 
 arrived. This occasioned hasty publication of the work 
 already done in an appendix to volume 22, 1832, of the 
 Journal. 
 
 At almost the same time Henry made another import- 
 ant discovery and this time he was anticipated by no 
 other investigator in making public his results. In the 
 paper already referred to he describes the phenomenon 
 known to-day as self-induction. "When a small battery 
 is moderately excited by diluted acid and its poles, which 
 must be terminated by cups of mercury, are connected by 
 a copper wire not more than a foot in length, no spark 
 is perceived when the connection is either formed or 
 broken; but if a wire thirty or forty feet long be used, 
 
342 A CENTURY OF SCIENCE 
 
 instead of the short wire, though no spark will be per- 
 ceptible when the connection is made, yet when it is 
 broken by drawing one end of the wire from its cup of 
 mercury a vivid spark is produced. . . . The _ effect 
 appears somewhat increased by coiling the wire mto a 
 helix; it seems to depend in some measure on the lengch 
 and thickness of the wire; I can account for these phe- 
 nomena only by supposing the long wire to become 
 charged with electricity which by its reaction on itself 
 projects a spark when the connection is broken." 
 
 Soon after, Henry went to Princeton and there con- 
 tinued his experiments in electromagnetism. No diffi- 
 culty was experienced in inducing currents of the third, 
 fourth and fifth orders by using the first secondary as 
 primary for yet another secondary circuit, and so on 
 (38, 209, 1840). The directions of these currents of 
 higher orders when the primary is made or broken 
 proved puzzling at first, but were satisfactorily explained 
 a year later (41, 117, 1841). In addition induced cur- 
 rents were obtained from a Leyden jar discharge. Fara- 
 day failed to find any screening effect of a conducting 
 cylinder placed around the primary and inside the 
 secondary. Henry examined the matter, and found that 
 the screening effect exists only when the induced current 
 is due to a make or break of the primary circuit, and not 
 when it is caused by motion of the primary. 
 
 Henry's work was mainly descriptive ; it remained for 
 Faraday to develop a theory to account for the phenomena 
 discovered and to prepare the way for quantitative for- 
 mulation of the laws of current induction. This he did in 
 his representation of a magnetic field by means of lines 
 of force ; a conception which he found afterwards to be 
 equally valuable when applied to electrostatic problems. 
 Every magnet and every current gives rise to these 
 closed curves ; in the case of a magnet they thread it 
 from south pole to north, while a straight wire bearing 
 a current is surrounded by concentric rings. The con- 
 nection between lines of force and the induction of cur- 
 rents is contained in the rule that a current is induced in 
 a closed circuit only when a change takes place in the 
 number of lines of force passing through it. Further- 
 more the dependence of the current strength on the 
 
A CENTURY'S PROGRESS IN PHYSICS 343 
 
 conductivity of the wire employed has led to recognition 
 of the fact that it is the electromotive force and not the 
 current itself which is conditioned by the change in mag- 
 netic flux. 
 
 Great interest was attached to the utilization of the 
 newly discovered forces of electromagnetism. In 1831 
 Henry (20, 340, 1831) described a reciprocating engine 
 depending on magnetic attraction and repulsion, and C. 
 G. Page (33, 118, 1838; 49, 131, 1845) devised many 
 others. The latter 's most important work, however, was 
 the invention of the Ruhmkorff coil. In 1836 (31, 137, 
 1837) he found the strongest shocks to be obtained from a 
 secondary coil of many windings forming a continuation 
 of a primary of half the number of turns. His perfec- 
 tion of the self-acting circuit breaker (35, 252, 1839) 
 widened the usefulness of the induction coil, and his sub- 
 stitution of a bundle of iron wires for a solid iron core 
 (34, 163, 1S3S) greatly increased its efficiency. 
 
 Conservation of Energy. — Perhaps the most important 
 advance of the nineteenth century has been the estab- 
 lishment of the principle of conservation of energy. 
 Despite the fact that the "principe de la conservation des 
 force vives" had been recognized by the French mathe- 
 maticians of the early part of the century, the application 
 of this principle even to purely mechanical problems was 
 contested by some scientists. Through the early num- 
 bers of the Journal runs a lively controversy as to 
 whether there is not a loss of power involved in impart- 
 ing momentum to the reciprocating parts of a steam 
 engine only to check the motion later on in the stroke. 
 Finally Isaac Doolittle (14, 60, 1828), of the Bennington 
 Iron Works, ends the discussion by the pertinent remark: 
 "If there be, as is contended by one of your correspond- 
 ents, a loss of more than one third of the power, in trans- 
 forming an alternating rectilinear movement into a 
 continuous circular one by means of a crank, I should 
 like to be informed what would be the effect if the propo- 
 sition were reversed, as in the case of the common 
 saw mill, and in many other instances in practical 
 mechanics." 
 
 A realization of the equivalence of heat and mechani- 
 cal work did not come until the middle of the century, in 
 
344 A CENTURY OF SCIENCE 
 
 spite of the conclusive experiments of the American 
 Count Rumford and the English Davy before the year 
 1800. So firmly enthroned was the caloric theory, 
 according- to which heat is an indestructible fluid, that 
 evidence against it was given scant consideration. In 
 fact the success of the analytical method introduced by 
 Fourier in 1822 for the solution of problems in conduc- 
 tion of heat only added to the difficulties of the adherents 
 of the kinetic theory. But recognition of heat as a form 
 of energy was on the way, and when it came it made its 
 appearance almost simultaneously in half a dozen differ- 
 ent places. Perhaps Robert Mayer of Heilbronn was 
 the first to state explicitly the new principle. His paper 
 "On the Forces of Inorganic Nature" was refused 
 publication in Poggendorff 's Annalen, but fared better at 
 the hands of another editor. During the next few years 
 Joule determined the mechanical equivalent of heat 
 experimentally by a number of different methods, some 
 of which had already been devised by Carnot. Of those 
 he used, the most familiar consists in churning up a 
 measured mass of water by means of paddles actuated by 
 falling weights and calculating the heat developed from 
 the rise in temperature. However, the work of the 
 young Manchester brewer received little attention from 
 the members of the British Association before whom it 
 was reported until Kelvin showed them its significance 
 and attracted their interest to it. Meanwhile Helmholtz 
 had completed a very thorough disquisition on the con- 
 servation of energy not only in dynamics and heat but in 
 other departments of physics as well. His paper on 
 "Die Erhaltung der Kraft" was frowned upon by the 
 members of the Physical Society of Berlin before whom 
 he read it, and received the same treatment as Mayer's 
 from the editor of Poggendorff' s Annalen. Helmholtz 's 
 "Kraft," like the "vis viva" of other writers, is the 
 quantity which Young had already christened energy. 
 Not many years elapsed, however, until the convictions of 
 Mayer, Joule, Kelvin and Helmholtz became the most 
 clearly recognized of all phvsical principles. As early 
 as 18.50 Jeremiah Day (10, 174, 1850), late president of 
 Yale College, admitted the improbability of constructing 
 
A CENTURY'S PROGRESS IN PHYSICS 345 
 
 a machine capable of perpetual motion, even though the 
 "imponderable agents" of electricity, galvanism and 
 magnetism be utilized. 
 
 Thermodynamics. — The importance of the principle of 
 conservation of energy lies in the fact that it unites under 
 one rule such diverse phenomena as gravitation, electro- 
 magnetism, heat and chemical action. Another principle 
 as universal in its scope, although depending upon the 
 coarseness of human observations for its validity rather 
 than upon the immutable laws of nature, was fore- 
 shadowed even before the first law of thermodynamics, 
 or principle of conservation of ener,gy, was clearly 
 recognized. This second law was the consequence of 
 efforts to improve the efficiency of heat engines. In 1824 
 Carnot introduced the conception of cyclic operations 
 into the theory of such engines. Assuming the impos- 
 sibility of perpetual motion, he showed that no engine can 
 have an efficiency greater than that of a reversible 
 engine. Finally Clausius expressed conciselj^' the princi- 
 ple toward which Carnot 's work had been leading, when 
 he asserted that "it is impossible for a self-acting 
 machine, unaided by any external agency, to convey heat 
 from one body to another at a higher temperature." 
 Kelvin's formulation of the same law states that "it is 
 impossible, by means of inanimate material agency, to 
 derive mechanical effect from any portion of matter by 
 cooling it below the temperature of the coldest of the 
 surrounding objects." 
 
 The consequences of the second law were rapidly 
 developed by Kelvin, Clausius, Rankine, Barnard (16, 
 218, 1853, et seq.) and others. Kelvin introduced the 
 thermod;^Tiamic scale of temperature, which he showed 
 to be independent of such properties of matter as con- 
 dition the size of the degree indicated by the mercury 
 thermometer. This scale, which is equivalent to that of 
 the ideal gas thermometer, was used subsequently by 
 Rowland in his exhaustive determination of the mechan- 
 ical equivalent of heat by an improved form of Joule's 
 method. He found different values for different ranges 
 in temperature, showing that the specific heat of water 
 is by no means constant. Since then electrical methods 
 
3i6 A CENTURY OF SCIENCE 
 
 of measuring this important quantity have been used to 
 confirm the results of purely mechanical determinations. 
 
 The definition of a new quantity, entropy, was found 
 necessary for a mathematical formulation of the second 
 law of thermodynamics. This quantity, which acts as a 
 measure of the unavailability of heat energy, was given 
 a new significance when Boltzmann showed its connec- 
 tion with the probability of the thermodynamic state of 
 the substance under consideration. If two bodies have 
 widely different temperatures, a large amount of the 
 heat energy of the system is available for conversion 
 into mechanical work. From the macroscopic point of 
 view this is expressed by saying that the entropy is small, 
 or if the motions of the individual molecules are taken 
 into account, the probability of the state is low. The 
 interpretation of entropy as the logarithm of the thermo- 
 dynamic probability has thrown much light on the 
 meaning of this rather abstruse quantity. Gibbs's 
 ''Elementary Principles in Statistical Mechanics" treats 
 in detail the fundamental assumptions involved in 
 this point of view, its limitations and its consequences. 
 In his "Equilibrium of Heterogeneous Substances "^ 
 he had already extended the principle of thermal equi- 
 librium to include substances which are no longer homo- 
 geneous. The value of the chemical potential he intro- 
 duced determines whether one phase is to gain at the 
 expense of another or lose to it. It is unfor'tunate that 
 the analytical rigor and austerity of his reasoning com- 
 bined with lack of mathematical training on the part of 
 the average chemist, delayed true appreciation of his 
 work and full utilization of the new field which he 
 opened up. 
 
 Liquefaction of Gases. — ^Meanwhile the problem 'of 
 liquefying gases was attracting much attention on the 
 part of experimental physicists. Faraday had succeeded 
 m makmg liquid a number of substances which had 
 hitherto been known only in the gaseous state. His 
 method consists in evolving the gas from chemicals 
 placed in one end of a bent tube, the other end of which 
 IS immersed in a freezing mixture. The high pressure 
 caused by the production of the gas combin'ed with the 
 low temperature is sufficient to bring about liquefaction 
 
A CENTURY'S PROGRESS IN PHYSICS 3i7 
 
 in many cases. Failure with other more permanent 
 gases was unexplained until the researches of Andrews 
 in 1863 showed that no amount of pressure will produce 
 liquefaction unless the temperature is below a certain 
 critical value. The method of reducing the temperature 
 in use to-day depends on a fact discovered by Kelvin and 
 Joule in connection with the free expansion of a gas. 
 These investigators allowed the gas to escape through a 
 porous plug from a chamber in which the pressure was 
 relatively high. With the single exception of hydrogen, 
 the effect of the sudden expansion is to cool the gas, and 
 even with it cooling is found to take place after the tem- 
 perature has been made sufficiently low. By this method 
 all known gases have been liquefied. Helium, with a 
 boiling point of — 269 "C, or only 4°C. above the absolute 
 zero, was the last to be made a liquid, finally yielding to 
 the efforts of Kammerlingh Onnes in 1907. This inves- 
 tigator- finds that at temperatures near the absolute zero 
 the electrical conductivity of certain substances undergoes 
 a profound modification. For example, a coil of lead 
 shows a superconductivity so great that a current once 
 started in it persists for days after the electromotive 
 force has ceased to act. 
 
 Electrodynamics. — Faraday's representation of elec- 
 tric and magnetic fields by lines of force had been of 
 great value in predicting the results of experiments in 
 electromagnetism. But a more mathematical formula- 
 tion of the laws governing these phenomena was needed 
 in order to make possible quantitative development of 
 the theory. This was supplied by Maxwell in his 
 epoch-making treatise on "Electricity and Mag- 
 netism." Starting with electrostatics and magnetism, 
 he gives a complete account of the mathematical 
 methods which had been devised for the solution 
 of problems in these branches of the subject, and 
 then turning to Ampere's work he shows how the 
 Lagrangian equations of motion lead to Faraday's law 
 if the single assumption is made that the magnetic 
 energy of the field is kinetic. In the treatment of open 
 circuits Maxwell's intuition led to a great advance, the 
 introduction of the displacement current. Consider a 
 charged condenser, the plates of which are suddenly con- 
 
348 A CENTURY OF SCIENCE 
 
 nected by a wire. A current will flow througli the wire 
 from the positively charged plate to the negative, but in 
 the gap between the two plates the conduction current 
 is missing. So convinced was Maxwell that currents 
 must always flow in closed circuits, that he postulated an 
 electrical displacement in the medium between the plates 
 of a charged condenser, which disappears when the con- 
 denser is short-circuited. Thus even in the so-called 
 open circuit the current flows along a closed path. 
 
 Maxwell's theory of the electromagnetic field is based 
 essentially on Faraday's representation by lines of force 
 of the strains and stresses of a universal medium. So it 
 is not surprising that he was led to a consideration of 
 the propagation of waves through this medium. The 
 introduction of the displacement current made the form 
 of the electrodynamic equations such as to yield a typical 
 wave equation for space free from electrical charges and 
 currents. Moreover, the disturbance was found to be 
 transverse, and its velocity turned out to be identical 
 with that of light. The conclusion was irresistible. 
 That light could consist of anything but electromagnetic 
 waves of extremely short length was inconceivable. In 
 fact so certain was Maxwell of this deduction from 
 theory that he felt it altogether unnecessary to resort to 
 the test of experiment. For the electromagnetic theory 
 explained so many of the details which had been revealed 
 by experiments in light, that no doubt of its validity 
 could be entertained. Even dispersion received ready 
 elucidation on the assumption that the dispersing 
 medium is made up of vibrators having a natural period 
 comparable with that of the light passing through it. 
 
 Maxwell's book was published in 1873. Fifteen years 
 later, Hertz,^ at the instigation of Helmholtz, succeeded 
 m detecting experimentally the electromagnetic waves 
 predicted by Maxwell's theory. His oscillator consisted 
 of two sheets of metal in the same plane, to each of which 
 was attached a short wire terminating in a knob. The 
 knobs were placed within a short distance of each other, 
 and connected to the terminals of an induction coil. By 
 reflection standing waves were formed, and the positions 
 ot nodes and loops determined by a detector composed of 
 a movable loop of wire containing an air gap. Thus the 
 
Gy^nu^) (a-^/iy^uz: 
 
 'xa^t 
 
A CENTURY'S PEOGRESS IN PHYSICS 349 
 
 wave length was measured. Hertz calculated the fre- 
 quency of his radiator from its dimensions, and then 
 computed the velocity of the disturbance. In spite of an 
 error in his calculations, later pointed out by Poincare, 
 he obtained very nearly the velocity of light for waves 
 traveling through air, but a velocity considerably smaller 
 for those propagated along wires. Subsequent work by 
 Lecher, Sarasin and de la Rive, and Trowbridge and 
 Duane (49, 297, 1895; 50, 104, 1895) cleared up this dis- 
 crepancy, and showed the velocity to be in both cases 
 identical with that of light. The last-named investiga- 
 tors increased the size of the oscillator until it was possi- 
 ble to measure the frequency by photographing the spark 
 in the secondary with a rotating mirror. The positions 
 of nodes and loops were obtained by means of a bolom- 
 eter after the secondary had been tuned to resonance 
 with the vibrator. The velocity thus found for electro- 
 magnetic waves along wires is within one-tenth of one 
 percent of the accepted value of the velocity of light. 
 Hertz's later experiments showed that waves in air suf- 
 fer refraction and diffraction, and he succeeded in 
 polarizing the radiation by passing it through a grating 
 constructed of parallel metallic wires. 
 
 In order to satisfy the law of action and reaction, it 
 is found necessary to attribute a quasi-momentum to 
 electromagnetic waves. When a train of such waves is 
 absorbed, their momentum is transferred to the absorb- 
 ing body, while if they are reflected an impulse twice as 
 great is imparted. This consequence of theory, foreseen 
 by Maxwell and developed in detail by Poynting, Abra- 
 ham and Larmor, has been verified by the experiments of 
 Lebedew, and Nichols and Hull.* The latter used a deli- 
 cate torsion balance from which was suspended a couple 
 of silvered glass vanes. In order to eliminate the effect 
 of impulses imparted by the molecules of the residual 
 gas, such as Crookes had observed in his radiometer, 
 readings were made at many different pressures and the 
 ballistic rather than the static deflection recorded. 
 After the pressure produced by light from a carbon arc , 
 had been measured, the intensity of the radiation was ®i j\i?'' 
 determined with a bolometer. Preliminary experiments . ,vp' ^ 
 indicated the existence of a pressure of the order ^ 
 
 33 
 
350 A CENTURY OF SCIENCE 
 
 expected, and later more careful measurements showed 
 good quantitative agreement with theory. This pressure 
 had already found an important application in Lebedew's 
 explanation of the solar repulsion of comet's tails. 
 These tails are made up of enormous swarms of very 
 minute particles, and as the comet swings around the 
 sun they suffer a repulsion due to the pressure of the 
 intense solar radiation which counteracts the sun's gravi- 
 tational attraction. Hence the tail, instead of following 
 after the comet in its orbit, points in a direction away 
 from the sun. 
 
 Some uncertainty existed as to whether a convection 
 current produces a magnetic field. A compass needle 
 is deflected by a current from a Daniell cell ; is the same 
 effect obtained when a conductor is charged electro- 
 statically and then whirled around the needle by means 
 of an insulating handle? The experimental difficulties 
 involved in settling this question are realized when the 
 enormous difference between the electrostatic and elec- 
 tromagnetic units of current is taken into consideration. 
 For a sphere one centimeter in radius, charged to a 
 potential of 20,000 volts, and revolving in a circle sixty 
 times a second, constitutes a current of little over a 
 millionth of an ampere. 
 
 This problem was undertaken by Rowland (15, 30, 
 1878) in Helmholtz's laboratory at Berlin in 1876. A 
 hard rubber disk coated on both sides with gold was 
 charged and rotated about a vertical axis at a rate of 
 sixty revolutions a second. On reversing the sign of the 
 electrification on the disk, the astatic needle hung above 
 its center showed a deflection of over five millimeters. 
 The current was calculated in electrostatic units from the 
 charge on the disk and its rate of motion, and in electro- 
 magnetic units from the magnetic deflection. The ratio 
 of these two quantities gave fair agreement with its theo- 
 retical value, the velocity of light. 
 
 Although the result of this experiment was confirmed 
 by Rowland and Hutchinson in 1889, Cremieu was con- 
 vinced by an investigation carried out at Paris in 1900 
 that the Rowland effect did not exist. Consequently 
 further repetition of the experiment was desirable. So 
 the following year Adams (12, 155, 1901) arranged two 
 
A CENTURY'S PROGRESS IN PHYSICS 351 
 
 rings of eight spheres each so that they could be rotated 
 about their common axis from fifty to sixty times a sec- 
 ond. One set of spheres was connected by brushes to the 
 positive pole of a battery of 20,000 volts, the other to the 
 negative pole. The deflection of a neai'by magnetometer 
 needle was observed when the electrification of the two 
 rings was reversed, and from the reading so obtained the 
 ratio of the electromagnetic to the electrostatic unit of 
 current computed. This quantity was found to differ 
 from the velocity of light by only a few percent. This 
 experiment and the even more exhaustive investigations 
 carried out by Pender, both independently and in collab- 
 oration with Cremieu, finally convinced the scientific 
 world that a convection current produces the same mag- 
 netic field as a conduction current of the same magnitude. 
 
 In discussing the ponderomotive force experienced in a 
 magnetic field by a conductor through which a current is 
 passing, Maxwell had said, "It must be carefully remem- 
 bered, that the mechanical force which urges a conductor 
 carrjang a current across the lines of magnetic force, 
 acts, not on the electric current, but on the conductor 
 which carries it." Hall (19, 200, 1880), one of Row- 
 land's students, questioned this statement, and deter- 
 mined to put it to the test of experiment. Efforts to find 
 an increase in the resistance of a wire placed at right 
 angles to the lines of magnetic force were unsuccessful. 
 So the current was passed through a moderately broad 
 strip of gold leaf and the effect of the magnetic field 
 on the equipotential lines investigated. The results 
 obtained confirmed Hall's belief that the force exerted by 
 the field acts on the current itself, and is transmitted 
 through it to the conductor. Further investigation (20, 
 161, 1880) revealed the same deflection of equipotential 
 lines in thin strips of other metals, although the effect 
 was found to be reversed in iron. 
 
 During the closing years of the nineteenth century 
 occurred three events of far reaching importance. The 
 electron was isolated, and its charge and mass measured 
 by J. J. Thomson in England ; X-rays were discovered 
 by Rontgen in Germany; and the first indications of 
 radioactivity were found by Becquerel in France. The 
 first two are certainly to be attributed largely to the 
 
352 A CENTUEY OF SCIENCE 
 
 great advances which had been .made in obtaining high 
 vacua, and the last two might not have occurred so soon 
 had it not been for the pliotographic plate. 
 
 The Electron. — The atomic theory of electricity dates 
 from the time of Faraday. His experiments oii electroly- 
 sis showed that each monovalent atom or radical, what- 
 ever its nature, carries the same charge, each bivalent ion 
 a charge twice as great. Only a lack of knowledge of the 
 number of atoms "in a gram of the dissociated salt pre- 
 vented him from calculating the value of the elementary 
 charge. As the discharge of electricity through gases at 
 low pressures became a subject for experimental inves- 
 tigation, another line of approach to the study of the 
 atom of electricity was opened up. As early as the sev- 
 enties Hittorf and Goldstein had observed that a shadow 
 is cast by a screen placed in front of the cathode of a 
 Crookes tube. Varley suggested that the cathode rays 
 producing the shadow consist of "attenuated particles of 
 matter, projected from the negative pole by electricity." 
 The discovery that these rays are deflected by a magnetic 
 field led English physicists to the conclusion that they 
 must be composed of charged particles, and the direction 
 of the deflection was such as to require the charge to be 
 negative. Hertz contested this view on the ground that 
 his experiments showed the rays to be unaffected by an 
 electrostatic field, and suggested that they consist of 
 etherial disturbances. Finally Perrin succeeded in pass- 
 ing the rays into a metal cylinder, which received from 
 them a negative charge, and Lenard showed how exces- 
 sively minute these negatively charged particles must be 
 by actually passing them through a thin sheet of alumi- 
 nium in the wall of a vacuum tube, and detecting their 
 presence in the air outside. Conclusive information as 
 to the nature of the electron, as it was named by John- 
 stone Stoney, was supplied by the classic experiments 
 of J. J. Thomson.^ First he showed that Hertz's failure 
 to find a deflection when a stream of electrons passes 
 between the plates of a charged condenser was due to the 
 screening effect of the gaseous ions produced by the dis- 
 charge. With a much more highly evacuated tube he 
 found no difficulty in obtaining a deflection in an electro- 
 static field. By using crossed electric and magnetic 
 
A CENTURY'S PROGRESS IN PHYSICS 353 
 
 fields the deflection produced by one was just balanced by 
 that caused by the other, and from the field strengths 
 employed both the velocity of the particles and the ratio 
 
 — of charge to mass was calculated. The former was 
 
 found to be about one-tenth the velocity of light, but the 
 most startling result of the experiment was that the same 
 
 value of — was obtained no matter what residual gas 
 
 was contained in the tube or of what metal the cathode 
 was made. 
 
 To calculate e and then m other methods are necessary. 
 C. T. R. Wilson has shown that in supersaturated air, 
 water drops form easih^ on charged molecules, and that 
 negative ions are more effective in causing condensation 
 than positive ones. By making use of the results of this 
 research Thomson has been able to measure the elemen- 
 tary charge. For suppose a stream of negative ions to 
 pass through supersaturated air. A little drop forms 
 on each charged particle, and the cloud of condensed 
 vapor settles to the bottom of the vessel. The charge 
 carried and the mass of water deposited can be meas- 
 ured directly. Stokes' law for the rate of fall of a 
 minute particle through a gaseous medium enables the 
 average size of the drops to be computed from the 
 observed rate of descent of the cloud. Hence the number 
 of drops formed and the charge carried by each follows 
 at once. H. A. Wilson improved the method by noting 
 the effect of an electric field upon the rate of fall of the 
 charged drops, and subsequent experiments undertaken 
 by Millikan*' have been of such a character as to enable 
 him to follow the motion of a single drop. Instead of 
 water, the latter uses oil drops less than one ten- 
 thousandth of a centimeter in diameter. A drop, after 
 one or more electrons have attached themselves to it, 
 is actually iveighed in terms of the charge on its surface 
 by applying an upward electric force just sufficient to 
 balance the force of gravity. Then its weight is inde- 
 pendently obtained from the density of the oil and the 
 radius of the drop as determined by "the rate of fall when 
 the electric field is absent. Comparison of these two 
 expressions gives 4-774(10)"i'' electrostatic units for the 
 
354 A CENTURY OF SCIENCE 
 
 elementary charge. Combining this result with the 
 value of -^ found by Thomson, the mass of the electron 
 comes out to be about one eighteen-hundredth that of an 
 atom of the lightest known element, hydrogen. 
 
 That the electron is a fundamental constituent ot ail 
 matter is attested by the fact that charge and mass are 
 the same regardless of the source or manner of produc- 
 tion. Wliether emitted by a heated metal, under the 
 action of ultra-violet light, from a radioactive_ substance, 
 by a body exposed to X-rays, as a result of friction, it is 
 the same negatively charged particle that constitutes the 
 cathode ray'of the discharge tube. Moreover, it makes 
 its effect felt indirectly in many other phenomena, and 
 from an investigation of some of these the ratio of 
 charge to mass "can be determined independently. Of 
 such perhaps the most interesting is the Zeeman effect. 
 
 Spectroscopy. — Early in the nineteenth century Fraun- 
 hofer had observed that the solar spectrum is crossed 
 by a large number of dark lines. Their presence was 
 unexplained until in 1859 Kirchhoff and Bunsen showed 
 "that a colored flame, the spectrum of which contains 
 bright sharp lines, so weakens rays of the color of these 
 lines when they pass through it, that dark lines appear 
 in place of bright lines as soon as there is placed behind 
 the flame a light of sufficient intensity, in which the lines 
 are otherwise absent." For intra-atomic oscillators 
 must have the natural frequency of the radiation which 
 they emit, and consequently resonance will take place 
 when they are exposed to rays of this frequency coming 
 from an outside source, and selective absorption ensue. 
 By comparing the bright lines in the spectra of metallic 
 vapors made luminous by a gas flame with the dark lines 
 in the sun's spectrum these investigators showed that 
 many of the common terrestrial elements exist in the 
 sun. The interest in spectroscopy grew rapidly. The 
 excellent diffraction gratings made by Rutherfurd were 
 succeeded by the superior concave gratings of Rowland. 
 In 1877 Draper (14, 89, 1877) announced the discovery of 
 the bright lines of oxygen in the solar spectrum, but his 
 interpretation of his photographs has not been corrob- 
 orated by the work of later investigators. Langley (11, 
 
A CENTURY'S PROGRESS IN PHYSICS 355 
 
 401, 1901), by the aid of his newly invented bolometer, 
 succeeded in detecting the emission of energy from the 
 sun in the infra-red in amounts far exceeding that con- 
 tained in the visible spectrum. In 1842 Doppler drew 
 attention to the fact that motion of the source should 
 cause a displacement of the spectral lines, the shift being 
 to the blue if the light is approaching and to the red if 
 it is receding, and a few years later Fizeau suggested the 
 application of Doppler 's principle to the measurement of 
 the velocity of a star moving in the line of sight. Thus 
 the spectroscope has been able to supply one of the 
 deficiencies of the telescope, and the two together are 
 sufficient to reveal all components of stellar motion. 
 When spectra formed by light from the sun's limb and 
 from its center are compared, the same effect reveals 
 the rotation of the sun about its axis. (C. S. Hastings, 5, 
 369, 1873; C. A. Young, 12, 321, 1876.) 
 
 Further Evidence of the Electron. — In 1845 Faraday 
 discovered a rotation of the plane of polarization when 
 light passes in the direction of the lines of force through 
 a piece of glass placed between the poles of an electro- 
 magnet. Examination of the spectrum from a glowing 
 vapor situated between the poles of a magnet, however, 
 failed to reveal any effect of the field. The latter prob- 
 lem was attacked anew by Zeeman^ in 1896, and with the 
 aid of the improved appliances of modern science he suc- 
 ceeded in detecting a broadening of the lines. Later 
 experiments with more powerful apparatus resolved 
 these broadening lines into several components. 
 
 Lorentz** showed at once how the electron theory fur- 
 nishes an explanation of the Zeeman effect. He found 
 that when the source is viewed at right angles to the lines 
 of magnetic force, a spectral line should be split into 
 three components. Of these he predicted that the mid- 
 dle, or undisplaced component, would be found to be 
 polarized at right angles to the direction of the field, and 
 the other components parallel to the field. When the 
 light proceeds from the source in a direction parallel to 
 the magnetic lines of force, two components only should 
 be formed, and these should be circularly polarized in 
 opposite senses. Moreover, from the separation of the 
 components can be calculated the ratio of charge to mass 
 
356 A CENTURY OF SCIENCE 
 
 of the electronic vibrator which is responsible for the 
 emission of radiant energy. Zeeman's experiments con- 
 firmed Lorentz's theory" in every detail, and yielded a 
 
 value of — ■ in substantial ae-reement with that obtained 
 
 for cathode rays. Subsequent research, however, has 
 shown that in many cases more components are found 
 than the elementary theory calls for. Hale has detected 
 the Zeeman effect in light from sun spots, proving that 
 these blemishes on the sun's face are vortices caused by 
 whirling swarms of electrified particles. Recently Stark 
 and Lo Surdo have found a similar splitting up of lines 
 in the spectrum formed by light from canal rays (rays of 
 positivel}' charged particles) passing through an intense 
 electric field. This phenomenon has as yet received no 
 adequate explanation. 
 
 On discovering that an electric current is capable of 
 producing a magnetic field, Ampere had suggested that 
 the magnetic properties of such substances as iron might 
 be explained on the assumption of molecular currents. 
 The electron theory considers these currents to be due to 
 the revolution, inside the atom, of negatively charged 
 particles about an attracting nucleus. It occurred to 
 Richardson that this motion should give the atom the 
 properties of a gyrostat. Hence if an iron bar be rotated 
 about its axis, the atoms should orient themselves so as to 
 make their axes more nearly parallel to the axis of rota- 
 tion. Thus its rotation should cause the bar to become 
 a magnet. Barnett" has tested this hj^Dothesis, and has 
 found the effect Richardson had predicted. From the 
 
 strength of the magnetization produced, the value of -^ 
 
 can be computed. Barnett finds a value somewhat 
 smaller than that for cathode rays, but of the right order 
 of magnitude and sign. Einstein and De Haas have 
 detected the inverse of this effect, i. e., the rotation of an 
 iron rod when it is suddenly magnetized. 
 
 '^-Rays.—hx 1895, on developing a plate which had 
 been lymg near a vacuum tube, Rontgen^o was surprised 
 to find distinct markings on it. As the plate had never 
 been exposed to light, it was necessary to suppose the 
 
A CENTURY'S PEOGRESS IN PHYSICS 357 
 
 effect to be due to some new and unknown type of radia- 
 tion._ Further investigation showed that this radiation 
 originates at the points where cathode rays impinge on 
 the glass walls of the tube. Besides being able to pass 
 with ease through all but the most dense material objects 
 X-rays were found to have the power of ionizing gases 
 through which they pass and ejecting electrons from metal 
 surfaces against which they strike. The points at which 
 these electrons are produced are in turn the sources of 
 secondary X-rays whose properties are characteristic of 
 the metal from which they come. 
 
 Rontgen's discovery excited intense interest among 
 laymen as well as in scientific circles. Of the many 
 X-ray photographs taken, those of Wright (1, 235, 1896) 
 of Yale were the first to be produced in this country. 
 His experiments were made immediately on receipt of 
 the news of Rontgen's research, and resulted in the pub- 
 lication of a number of photographs showing the trans- 
 lucency for these rays of paper, wood, and even 
 aluminium. 
 
 As X-rays are undeviated by electric or magnetic fields, 
 Schuster, and later Wiechert and Stokes, suggested that 
 they might be electromagnetic waves of the same nature 
 as light, but much shorter and less regular. The great 
 objection to this hypothesis was the failure either to 
 refract or diffract these rays. In fact Bragg contended 
 that they were not etherial disturbances at all, but con- 
 sisted of neutral particles moving with very high veloci- 
 ties. Finally Laue" demonstrated their undulatory 
 nature by showing that diffraction took place under 
 proper conditions. Just as the distance between adja- 
 cent lines of a grating must be comparable to the wave 
 length of light for a spectrum to be formed, a periodic 
 structure with a grating space of their very much shorter 
 wave length is necessary to diffract X-rays. Such a 
 structure is altogether too fine to be made by human 
 tools. Nature, however, has already prepared it for 
 man's use. The distance between the atoms of a crystal 
 is just right to make it an excellent X-ray grating, and 
 Lane had no difficulty in obtaining diffraction patterns 
 when Rontgen rays were passed through a block of zinc- 
 blende. The distance between adjacent atoms of this 
 
358 A CENTURY OF SCIENCE 
 
 cubic crystal can be computed at once from its density 
 and molecular weight, and then the wave length of the 
 radiation calculated from the deviation suffered. In this 
 way X-rays are found to have a length less than one 
 thousandth as great as visible light. Further study of 
 this phenomenon, particularly by the two Braggs, father 
 and son, has revealed many of the structural details of 
 more complicated crystals. 
 
 The most significant investigation in the field opened 
 up by Laue's discovery is that undertaken by Moseley'- 
 only a couple of years before he lost his life in the 
 trenches at Gallipoli. Using many different metals as 
 anticathodes in a vacuum tube, he measured the fre- 
 quencies of the characteristic rays emitted. He found 
 that if the elements are arranged in order of increasing 
 atomic weight, the square roots of the characteristic fre- 
 quencies form an arithmetical progression. If to each 
 element is assigned an integer, beginning with one for 
 hydrogen, two for helium, and so on, the square root of 
 the frequency of the characteristic radiation is found to 
 be proportional to this atomic number. Even though 
 Uhler has shown recently that over wide ranges Mose- 
 ley's law does not hold within the limits of experimental 
 error, there is undoubtedly much significance to be 
 attached to this simple relation. 
 
 Radioactivity. — The year following the discovery of 
 X-rays, Becquerel found that a photographic plate 
 is similarly affected by radiations from uranium 
 salts. Two years later the Curies separated from 
 pitchblende the very active elements polonium and 
 radium. Passage of the rays from these substances 
 through electric and magnetic fields revealed the 
 existence of three types. The alpha rays have 
 been shown by Rutherford and his co-workers to be 
 positively charged helium atoms ; the beta rays are very 
 rapidly moving electrons ; and the gamma ravs are elec- 
 tromagnetic pulses of the same nature as X-ravs but 
 somewhat shorter. In 1902 Rutherford and 'Soddy 
 advanced the theory of atomic disintegration, according 
 to which the emission of a ray is an indication of the 
 breaking down of the atom to a simpler form. Thus in 
 the radioactive substances there is going on before our 
 
A CENTURY'S PROGRESS IN PHYSICS 359 
 
 eyes a continual transformation of one element into 
 another, a change, by the way, which appears to be in no 
 slightest degree either hastened or delayed by changes in 
 temperature (H. L. Bronson, 20, 60, 1905) or external 
 electrical condition of the radioactive element. Uranium 
 is the progenitor of a long line of descendants, of which 
 radium was supposed for some time to be the first mem- 
 ber. Boltwood (25, 365, 1908) of Yale, however, showed 
 that the slow growth of radium in uranium solutions is 
 incompatible with this assumption, and soon isolated an 
 intermediate product which he named ionium. Radium 
 itself disintegrates into a gas known as radium emana- 
 tion, which in turn gives rise to a succession of other 
 products. Analyses by Boltwood (23, 77, 1907) of radio- 
 active minerals from the same locality show such a con- 
 stant ratio between the amounts of uranium and lead 
 present that it is natural to conclude that lead is the end 
 product of the series. This hj^oothesis is confirmed by 
 the fact that the oldest rocks show relatively the greatest 
 amounts of this element. 
 
 In addition to the Ionium-Radium series two others 
 have been discovered. Of these Boltwood 's (25,269,1908) 
 investigations seem to indicate that the one which starts 
 with actinium is a collateral branch of the radium series 
 and comes from the same parent uranium. The other 
 begins with thorium and comprises ten members. As 
 yet the end products of the actinium and thorium series 
 have not been identified, although there is some reason 
 for believing that an isotope of lead may be the final 
 member of the latter. 
 
 As the amount of a radioactive element which disin- 
 tegrates in a given time is proportional to the total mass 
 present, an infinite time would be required for the sub- 
 stance to be completely transformed. Hence the life of 
 such an element is measured by the half value period, or 
 time taken for half the initial mass to disintegrate. 
 This time varies widely for different radioactive sub- 
 stances, ranging from a small fraction of a second for 
 actinium A to five billion years for uranium. Bolt- 
 wood's (25, 493, 1908) original determination of the life 
 of radium from the rate of its growth in a solution con- 
 taining ionium gave 2000 years as its result, although 
 
3G0 A CENTURY OF SCIENCE 
 
 recent measurements by Miss Gleditsch (41, 112, 1916) 
 agree more closely with the value 1760 years obtained by 
 Eutherford and Geiger from the number of alpha parti- 
 cIgs GinittcQ.. 
 
 Under the action of X-rays or the radiations from 
 radioactive substances, gases acquire a conductivity 
 which has been attributed by Thomson and Ruthertord 
 to the formation of ions. Zeleny has found that ions of 
 opposite sign have somewhat different mobilities m an 
 electric field, and experiments of Wellisch (39, 583, 1915) 
 show that at low pressures some of the negative ions are 
 electrons. T. S. Taylor (26, 169, 1908 et seq.) and Duane 
 (26, 464, 1908) have investigated the ionization produced 
 by alpha particles, and Bumstead (32, 403, 1911 et seq.) 
 lias studied the emission of electrons from metals which 
 are bombarded by these rays. The investigations of 
 Franck and Hertz, and McLennan and Henderson, show 
 a significant relation between the ionizing potential 
 (energy which must be possessed by an electron in order 
 to produce an ion on colliding with an atom) and a quan- 
 tity, to be considered later in more detail which has been 
 introduced by Planck into the theory of radiation. 
 
 Methods of Science. — Scientific progress seems to fol- 
 low a more or less clearly defined path. Experimenta- 
 tion brings to light the hidden processes of nature, and 
 hypotheses are advanced to correlate the facts discov- 
 ered. As more and more phenomena are found to fit into 
 the same scheme, the hypotheses at first proposed tenta- 
 tively, although often only after extensive alterations, 
 become firmly established as theories. Finally there may 
 appear a fundamental clash between two theories, each of 
 which in its respective domain seems to represent the only 
 possible manner in which a large group of phenomena 
 can be correlated. The maze becomes more perplexing 
 at every step. At last a genius appears on the scene, 
 approaches the problem from a new and unsuspected 
 point of view, and the paradox vanishes. Such changes 
 in point of view are the milestones which mark the 
 progress of science. That science is stagnant whose 
 only function is to collect, classify and correlate vast 
 stores of experimental data. The sign of vitality is the 
 existence of clearly defined and fundamental problems 
 
A CENTURY'S PROGRESS IN PHYSICS 361 
 
 any possible solution of which seems irreconcilable with 
 the most basic truths of the science in question. The 
 greater the paradox grows, the more certain the advent 
 of a new point of view which will bring one step nearer 
 the comprehensive picture of nature which is the goal of 
 natural philosophy. 
 
 The Ether. — From the earliest times philosophers have 
 been attracted by the possibility of explaining physical 
 phenomena in terms of an all-pervading medium. So 
 strong had this tendency become by the middle of the 
 nineteenth century that the English school of physicists 
 were attributing rigidity, density and nearlj^ all the prop- 
 erties of material media to the ether. In fact most 
 physicists seemed to have forgotten that no experiment 
 had ever given direct evidence of the existence of such a 
 medium. Not until the first decade of the twentieth cen- 
 tury was it realized that the experimental evidence actu- 
 ally pointed in quite the opposite direction, and that a 
 new point of view was needed in dealing with those phe- 
 nomena of light and electromagnetism which had been 
 previously described in terms of a universal medium. 
 Some account of the development of the ether theory 
 and of the origin and growth of the point of view which 
 has its principal exemplification in the principle of rela- 
 tivity is essential for an understanding of present ten- 
 dencies in formulating a philosophic basis for scientific 
 thought. 
 
 In the time of Newton and for a century after there wag 
 much controversy between the adherents of two irrecon- 
 cilable theories of light. Hooke had suggested that 
 light is a wave motion traveling through a homogeneous 
 medium which fills all space, and Huygens had shown 
 that the law of refraction can be deduced at once from 
 this hypothesis if it is assumed that the velocity of light 
 in a transparent body is less than that in free ether. 
 However, Newton, impressed by the fact that a ray 
 obtained by double refraction in Iceland spar differs from 
 a ray of ordinary light just as a rod of rectangular cross 
 section differs from one of circular cross section, and 
 seeing no way of explaining this dissymmetry in terms 
 of a wave motion analogous to longitudinal sound waves, 
 adhered to the view that light consists of infinitesimal 
 
3<12 A CENTUEY OF SCIENCE 
 
 particles shot out from the luminous body with enormous 
 velocities. So great was liis reputation on account of his 
 discoveries in other fields that this theory of light held 
 sway among his contemporaries and successors until the 
 labors of Young and Fresnel at the beginning of the 
 nineteenth century definitely established the undulatory 
 theory. However, in spite of the fact that a corpuscular 
 theory of light made the assumption of an ether unneces- 
 sary in so far as the simpler of the observed phenomena 
 are concerned, even Newton postulated the existence of 
 such a medium, partly in order to explain the more com- 
 plicated results of experiments in light, and partly in 
 order to provide a vehicle for the propagation of gravi- 
 tational forces. 
 
 Now an ether, if it is to explain anything at all, must 
 have at least some of the simpler properties of material 
 media. The most fundamental of these, perhaps, is posi- 
 tion in space. As a first approximation in explaining 
 optical phenomena on the earth's surface, the earth 
 might be supposed to be at rest relative to the ether. 
 But the establishment of the Coperniean system made the 
 sun the center of the solar system and gave the earth an 
 orbital speed of eighteen miles a second. It may be 
 remarked parenthetically that the speed of a point on the 
 equator due to the earth's diurnal rotation is quite insig- 
 nificant compared to its orbital velocity. Hence as a 
 second approximation the sun might be considered at 
 rest relative to the ether and the earth as moving 
 through this unresisting medium. 
 
 The first indication of this motion lav in the discovery 
 of aberration by the British astronomer Bradley in 1728. 
 Bradley noticed that stars near the pole of tlie ecliptic 
 describe small circles during the course of a year while 
 those m the plane of the ecliptic vibrate back and forth 
 m straight lines, stars in intermediate positions describ- 
 ing ellipses. The surprising thing, however, was that 
 the time taken to complete one of these small orbits is in 
 a 1 cases exactly a year. Bradley concluded that the 
 phenomenon is m some way dependent on the earth's 
 motion around the sun, and he was not long in reaching 
 the correct explanation. For suppose the earth to be at 
 rest. Then m observing a star at the pole of the ecliptic 
 
A CENTURY'S PROGRESS IN PHYSICS 363 
 
 it would be necessary to keep the axis of the telescope 
 exactly at right angles to the plane of the earth's orbit. 
 However, as the earth is in motion, the telescope must be 
 pointed a little forward, just as in walking rapidly 
 through the rain an umbrella must be inclined forward so 
 as to intercept the raindrops which would otherwise fall 
 on the spot to be occupied at the end of the next step. 
 The angle through which the telescope has to be tilted is 
 known as the angle of aberration, and the tangent of this 
 angle may easily be shown to be equal to the ratio of the 
 velocity of the earth to the velocity of light. Knowing 
 the velocity of the earth, the velocity of light can then be 
 calculated. This method was one of the first of obtaining 
 the value of this important quantity. 
 
 More recently, terrestrial methods of great precision 
 have been devised for measuring the velocity of light. 
 The most accurate of these is that employed by the 
 French physicist Foucault in 1862. A ray of light is 
 reflected by a rotating mirror to a fixed mirror placed at 
 some distance, which in turn reflects the ray back to 
 the moving mirror. The latter, however, has turned 
 through a small angle during the time elapsed since the 
 first reflection, and consequently the direction of the ray 
 on returning to the source is not quite opposite to that in 
 which it had started out. This deviation in direction is 
 determined from the displacement of the image formed 
 by the returning light, and from it the velocity of light 
 is calculated. In order to make the deflection appreci- 
 able the distance between the two mirrors should be very 
 great. As originally arranged bj^ Foucault, it was 
 found impractical to make this distance greater than 
 twenty meters, and consequently the displacement of the 
 image was less than a millimeter. Such a small deflection 
 limited the accuracy of the experiment to one percent. 
 In 1879, however, ]\iichelson (18, 390, 1879), then a mas- 
 ter in the United States Navy, improved Foucault 's opti- 
 cal arrangements to such an extent that he was able to 
 use a distance of nearly seven hundred meters between 
 the two mirrors. With a rate of two hundred and fifty- 
 seven revolutions a second for the rotating mirror, the 
 displacement obtained was over thirteen centimeters. 
 This experiment gave 299,910 kilometers a second for 
 
364 A CENTURY OF SCIENCE 
 
 the velocity of light, with a probable error of one part in 
 ten thousand. Later investigations by Newcomb and 
 Michelson (31, 62, 1886) gave substantially the same 
 result. So great has been the accuracy of these terres- 
 trial determinations that recent practice has been to cal- 
 culate from them and the angle of aberration the earth's 
 orbital velocity, and hence the distance of the earth from 
 the sun. This indirect method of measuring the astro- 
 nomical unit has a probable error no greater than the best 
 parallax methods of the astronomer. (J. Lovering, 36, 
 161, 1863.) 
 
 Aberration is a first order effect, i. e., it depends upon 
 the first power of the ratio of the velocity of the earth to 
 the velocity of light, and at first sight it seemed to prove 
 conclusively that the earth must be in motion relative to 
 the luminiferous medium. Other questions had to be set- 
 tled, however, and one of these was whether or not light 
 coming from a star would be refracted differently when 
 passing through optical instruments from light which 
 had a terrestial origin. Arago subjected the matter to 
 experiment, and concluded that in every respect the light 
 from a star behaved as if the earth were at rest and the 
 star actually occupied the position which it appears to 
 occupy on account of aberration. Finally optical exper- 
 iments with terrestrial sources seemed to be in no way 
 affected by the motion of the earth through the ether. 
 
 In order to account for these facts Fresnel advanced 
 the following theory. To explain the refraction that 
 takes place when light enters a transparent body, it is 
 necessary to assume that light waves travel more slowly 
 through matter than in free ether. Now the velocity of 
 sound is known to vary inversely with the square root of 
 the density of the material medium through which it 
 passes. Hence it is natural to assume that ether is con- 
 densed inside material objects to such an extent that 
 this same relation connects its density with the velocity 
 of light traveling through it. But when a lens or prism 
 is set in motion, Fresnel supposed it to carry along only 
 the excess ether which it contains, ether of the normal 
 density remaining behind. This assumption suffices to 
 explain Arago 's results, and yet fits in with the phenom- 
 enon of aberration. It gives for light traveling in the 
 
A CENTURY'S PROGRESS IN PHYSICS 365 
 
 direction of motion through a moving material medium 
 of index of refraction n an absohite velocity greater than 
 that when the medium is at rest by an amount 
 
 I) '' 
 
 which is only a fraction of the velocity v which would 
 have to be added if convected matter carried along all 
 the ether which resides within it. This expression was 
 tested directly, first by Fizeau in 1851, and later by 
 Michelson and Morley"(31, 377, 1886) in this country. 
 The experiment consists in bifurcating a beam of light, 
 passing one half in one direction and the other in the 
 opposite direction through a stream of running water. 
 On reuniting the two rays the usual interference fringes 
 are produced. Reversing the direction of motion of the 
 water causes the fringes to shift, and from the amount of 
 this shift the velocity imparted to the light by the motion 
 of the stream is computed. The divergence between the 
 experimental value of this quantity and that calculated 
 from Presnel's coefficient of entrainment was found by 
 Michelson and Morley to be less than one percent, which 
 'was about their experimental error. Thus Fresnel's 
 expression for the velocity of light in a moving medium is 
 entirely confirmed by experiment. The derivation of it 
 accepted to-day, however, is very different from his orig- 
 inal deduction. 
 
 It has been noted that the phenomena of polarization 
 led Newton to reject the wave theory of light. The only 
 type of wave kno^vn to him was the longitudinal wave, 
 in which the vibrations of the particles of the medium are 
 in the same direction as that of propagation of the wave, 
 and it Avas impossible to suppose that such a wave could 
 have different properties in different directions at right 
 angles to the line in which it is advancing. But in 1817 
 Young suggested that this inconsistency between the 
 wave theory and the facts of polarization could be 
 removed by supposing the vibrations constituting light to 
 be executed at right angles to the direction of propaga- 
 tion. Thus in ordinary light the vibrations are to be 
 conceived as taking place haphazard in all directions in 
 the plane perpendicular to the ray, while in plane polar- 
 
 23 
 
366 A CENTURY OF SCIENCE 
 
 ized light these vibrations are confined to a single 
 direction. This supposition explained so many ot the 
 puzzling results of experiment, that it was accepted at 
 once and led to the complete vindication of the undula- 
 
 tory theory. , -r> • 
 
 Elastic Solid T/zeor^.— Shortly afterwards Foisson 
 succeeded in solving the differential equation which 
 determines the motion of a wave through an elastic 
 medium. His solution shows that such a medium is 
 capable of transmitting two tjTies of wave— one longi^ 
 tudinal, the other transverse. If k denotes the volume 
 elasticity, v the rigidity and p the density of the medium, 
 the velocities of the two waves are respectively 
 
 a/^JlJi and a/JL 
 
 ' P P 
 
 Now a solid has both compressibility and rigidity, 
 and transmits in general both types of wave. A 
 fluid, on the other hand, on account of its lack of 
 rigidity, cannot support a transverse vibration. Hence 
 it was natural that Green, in searching for a djmamical 
 explanation of the ether, should have proposed in a paper 
 read before the Cambridge Philosophical Society iu 
 1837 that the ether has the elastic properties of a solid. 
 One great difficulty presented itself ; disturbances 
 inside an elastic solid must give rise to compressional as 
 well as to transverse waves. But no such thing as a 
 compressional wave had been found in the experimental 
 study of light. Green attempted to overcome this diffi- 
 culty by attributing an intinite volume-elasticity to the 
 ether. The expression above shows that longitudinal 
 waves originating in such an incompressible medium 
 would be carried away with an infinite velocity, and it 
 may be shown that the energy associated with them 
 would be infinitesimal in amount. The next step was to 
 calculate the coefficients of transmission and reflection 
 for light passing from one material medium to another. 
 Here the elastic solid theory is not altogether successful. 
 If the ether is supposed to have different densities in the 
 two media, as in Fresnel's theory, but the same rigidity, 
 certain of these coefficients fail to give the values 
 
A CENTURY'S PEOGRESS IN PHYSICS 367 
 
 demanded by experiment, while if the densities are 
 assumed the same but the rigidities different, other of the 
 coefficients have discordant values. In connection with 
 the phenomena of double refraction even more serious 
 difficulties are encountered. 
 
 Electromagnetic Theory. — It was beginning to be felt 
 that an ether must explain more than the phenomena of 
 light, for Faraday's conception of electromagnetic 
 action as carried on through the agency of a medium 
 had added greatly to its functions. Finally Maxwell's 
 demonstration that electromagnetic waves are propa- 
 gated with the velocity of light made the theory 
 of light into a subdivision of electrod^mamics. Maxwell 
 himself did not apply electromagnetic theory to the 
 explanation of reflection and refraction. This defi- 
 ciency, however, was remedied by Lorentz in 1875. The 
 results obtained, as well as those for double refraction 
 (J. W. Gibbs, 23, 262, 1882 et seq.), and metallic reflec- 
 tion (L. P. Wheeler, 32, 85, 1911), provided a complete 
 vindication of the electromagnetic theory of light. This 
 is all the more significant when the extreme precision 
 obtainable in optical experiments is taken into account. 
 For instance, Hastings (35, 60, 1888) has tested Huy- 
 gens' construction for double refraction in Iceland spar 
 and found that "the difference between a measured index 
 of refraction ... at an angle of 30° with the crystalline 
 axis, and the index calculated from Huygens' law and 
 the measured principal indices of refraction" is a matter 
 of only 4-5 units in the sixth decimal place. Since Max- 
 well's time the gamut of electromagnetic waves has been 
 steadily extended. The shortest Hertzian waves merge 
 almost imperceptibly into the longest heat waves of the 
 infra-red, and from there the known spectrum runs con- 
 tinuously through the visible region to the short waves 
 of the extreme ultra-violet recently disclosed by Lyman. 
 Here there is a short gap until soft X-rays are reached, 
 and finally the domain of radiation comes to an end with 
 gamma rays a billionth of a centimeter in length. 
 
 Maxwell's ether was not a dynamical ether in the sense 
 of Green's elastic solid medium. In spite of the fact that 
 Maxwell was always active in devising mechanical ana- 
 
368 A CENTUEY OF SCIENCE 
 
 loo-ues to illustrate the phenomena of electromagnetism, 
 he was never enthusiastic over the speculations^ ot tne 
 advocates of a d^mamical ether. The electrodynamic equa- 
 tions provided an accurate representation of the electric 
 and mametic fields, and beyond that he felt it was need- 
 less to go. That Gibbs (23, 475, 1882) held the same 
 view is made evident by the closing paragraphs o± a 
 paper in which he shows that the electromagnetic theory 
 of light accounts in minutest detail for the intricate phe- 
 nomena accompanying the passage of light through cir- 
 cularly polarizing media. He says : 
 
 "The laws of the propagation of light in plane waves, which 
 have thus been derived from the single hypothesis that the dis- 
 turbance by which light is transmitted consists of solenoidal 
 electrical fluxes, ... are essentially those which are received 
 as embodying the results of experiment. In no particular, so 
 far as the writer is aware, do they conflict with the results of 
 experiment, or require the aid of auxiliary and forced hypotheses 
 to bring them into harmony therewith. 
 
 In this respect the electromagnetic theory of light stands in 
 marked contrast with that theory in which the properties of an 
 elastic solid are attributed to the ether, — a contrast which was 
 very distinct in Maxwell's derivation of Fresnel's laws from 
 electrical principles, but becomes more striking as we follow the 
 subject farther into its details, and take account of the want of 
 absolute homogeneity in the medium, so as to embrace the 
 phenomena of the dispersion of colors and circular and elliptical 
 polarization." 
 
 Further Dynamical Theories. — Kelvin, however, was 
 not satisfied with this type of ether. To him dynamics 
 was the foundation of all physical phenomena, and noth- 
 ing could be said to be explained until a mechanical model 
 was provided. So he returned to the elastic solid theory, 
 and developed the consequences of the assumption, 
 already made use of by Cauchy, that the ether has a nega- 
 tive volume elasticity of such a value as to make the 
 velocity of the compressional wave zero. In order to 
 prevent such an ether from collapsing it is necessary to 
 assume that it is rigidly attached at its boundaries and 
 that cavities cannot be formed at any point in its interior. 
 Now Gibbs (37, 129, 1889) has pointed out the remark- 
 
A CENTURY'S PROGRESS IN PHYSICS 369 
 
 able fact that the equations describing the motion of 
 Kelvin's quasi-labile ether are of exactly the same form 
 as the electromagnetic equations. Electric displacement 
 is represented by an actual displacement of the ether, 
 magnetic intensity by a rotation. Hence everything 
 which can be explained by the electrodynamic equations 
 finds an analogue in terms of Kelvin's ether. Still 
 another type of dynamic ether which fits the known facts 
 was proposed by McCullagh and perfected by Larmor. 
 In this ether a rotational elasticity is premised, such as 
 would exist if each particle of the medium consisted of 
 three rigidly connected gyrostats with mutually perpen- 
 dicular axes. In this ether electrical displacements cor- 
 respond to rotations, and magnetic strains to etherial dis- 
 placement. 
 
 A Neiv Point of View. — Wliile tlie dynamical school 
 was still dominant in England, another point of view 
 was developing on the continent. Kirchhoff denied 
 that it was the province of science to provide mechanical 
 explanations of the ether and electrodynamic phenomena 
 such as Kelvin conceived to be necessary in order to make 
 these phenomena intelligible. Kirchhoff's contention 
 was that the object of science is purely descriptive, — 
 phenomena must be observed, classified, and mutual con- 
 nections described by the fewest number of differential 
 equations possible. Mach expressed the same idea 
 somewhat more concisely when he asserted that the aim 
 of science is "economy of thought." For instance, in 
 the time of Newton, planetary motions could be described 
 quite satisfactorily by means of the three laws of Kepler. 
 The motion of falling bodies on the earth's surface had 
 been described with a fair degree of accuracy by Galileo. 
 The value of Newton's law of gravitation, however, lay in 
 the fact that this great generalization made it possible to 
 describe these and many other types of motion by a 
 single simple formula, instead of leaving each to be gov- 
 erned by a number of separate and apparently unrelated 
 laws. The importance of such a generalization is meas- 
 ured by the economy of thought which it introduces. 
 
 Electron Theory. — The electron theory was leading to 
 a reversal of Kelvin's idea that dynamical principles 
 
370 
 
 A CENTUEY OF SCIENCE 
 
 must underlie electrodynamics. Lorentz had shown that 
 a rigorous solution of the electrodynamic equations did 
 away entirely with Maxwell's displacement current, but 
 made the electromagnetic field at a point in space depend 
 not upon the distribution of charges and currents at the 
 same instant, but at a time earlier sufficient to allow the 
 effect to travel with the velocity of light from the charges 
 and currents producing the field to the point at which the 
 electric and magnetic intensities are to be found. The 
 l^osition of a charge or current element at this earlier time 
 he denoted its "effective position." The effective distri- 
 bution, then, is that actually seen by an observer stationed 
 
 Fie. 1. 
 
 Fig. 
 
 Fig. 3. 
 
 at the point under consideration at the instant for which 
 the mtensity of the electromagnetic field is to be deter- 
 mmed. This solution of the electrodynamic equations 
 led m turn to rigorous expressions for the electric and 
 magnetic mtensities produced by a very small charo-ed 
 particle, such as an electron. Fig. 1 shows the electro- 
 static field produced by a charged particle at rest. The 
 lines of force spread out radially and uniformly in all 
 directions. In fig. 2 the electron is supposed to have a 
 velocity V horizontally to the right of an amount smaller 
 than, though comparable with, the velocity of light c 
 It IS seen that the lines of electric force still diverge 
 racially from the charge, but are crowded in the equato- 
 rial plane and spread apart in the polar regions The 
 dissyinmetry grows as the velocity increases until if the 
 velocity of light should be reached the field would be 
 entirely concentrated in a plane at right angles to the 
 direction of motion. Now it may be sho\vn that fi- 2 is 
 
A CENTURY'S PROGRESS IN PHYSICS 371 
 
 obtainable from fig. 1 by reducing dimensions in the 
 direction of motion in the ratio of 
 
 a/i - 13" '■ 1> where /3 = ^. 
 
 For a uniformly convected electric field differs from an 
 electrostatic field only in that the dimensions in the direc- 
 tion of motion are contracted in this particular ratio. 
 Fig. 3 represents the electric field of a charged particle 
 which has a uniform acceleration to the right. Consider 
 Faraday's analogy between lines of force and stretched 
 elastic bands. The symmetry of the first two figures 
 shows that in neither of these cases would there be a 
 resultant force on the charged particle. But in the third 
 figure it is obvious that a force to the left is exerted on 
 the charge by its own field. Calculation shows this force 
 to be proportional in magnitude to the acceleration. Let 
 it be postulated that the resultant force on a charged 
 particle is always zero. Then if F is the applied force, 
 the force on the particle due to the reaction of its field 
 will be — m f, where / stands for the acceleration and m 
 is a positive constant, and we have the fundamental 
 equation of dynamics 
 
 J' — m / = 
 
 Hence, instead of admitting Kelvin's contention that all 
 physical phenomena must be given a mechanical explana- 
 tion, it would seem more logical to assert that electro- 
 dynamics actually underlies mechanics. 
 
 Calculation shows the electromagnetic mass m to vary 
 inversely with the radius of the charged particle. Now 
 Thomson's experiments made it possible to calculate the 
 mass of an electron. Hence its radius can be computed, 
 and is found to be about 2(10)"^* part of a centimeter, or 
 one fifty-thousandth part of the radius of the atom. 
 Since numbers so small convey little meaning, consider 
 the following illustration, due, in part, to Kelvin. 
 Imagine a single drop of water to be magnified until it is 
 as large as the earth. The individual atoms would then 
 have the size of baseballs. Now magnify one of these 
 atoms until it is comparable in size with St. Peter's 
 cathedral at Rome. The electrons within the atom would 
 appear as a few grains of sand scattered about the nave. 
 
372 A CENTUEY OF SCIENCE 
 
 This separation between the constituent electrons of the 
 atom, — so great in comparison witli their dimensions, — 
 explains how alpha particles can be shot by the billion 
 through thin-walled glass tubing without leaving any 
 holes behind or impairing in the slightest degree the high 
 vacuum within the tube. The much smaller high-speed 
 beta particles pass through an average of ten thousand 
 atoms without even coming near enough to one of the 
 component electrons to detach it and form an ion. 
 
 Michelson-Morley Experiment. — In 1881 Michelson 
 (22, 120, 1881) conceived an ingenious and bold method 
 of measuring the orbital motion of the earth through the 
 luminiferous ether. As the experiment was one involv- 
 ing considerable expense. Bell, the inventor of the tele- 
 phone receiver, was appealed to successfully for the 
 funds necessary to carry it through. Michelson 's 
 experimental plan was as follows : A beam of light 
 traveling in the direction of the earth's motion strikes 
 an unsilvered mirror m at an angle of 45°. Part of the 
 light passes through, the rest Ijeing reflected at right 
 angles to its original direction. Each ray is returned by 
 a mirror at a distance I from m. On meeting again, the 
 ray whose path has been at right angles to the direction 
 of the earth's motion passes on through the mirror, while 
 the other ray is reflected so as to bring the two in line 
 and form interference fringes. Now consider the effect 
 of the earth's motion on the paths of the two rays. In 
 fig. 4 the earth is supposed to be moving to the right. 
 The unsilvered mirror m bifurcates a beam of light com- 
 ing from a source a. By the time the ray reflected from 
 m has traveled to the mirror h and back, m will have 
 moved forward to m' ; a distance 2 pl, where the small 
 quantity p is the ratio of the earth's velocitv to the 
 velocity of light. Hence the length of the path traversed 
 by this ray is approximately 
 
 The other ray will reach the mirror c after the latter has 
 moved forward a distance 
 
A CENTUEY'S PROGRESS IN PHYSICS 373 
 
 1 -H' 
 
 and on returning find m at m'. Hence its path has a 
 length of roughly 21 {!-]- p"). The difference in path of 
 the two rays is p- 1 and consequently they should be a 
 little out of phase on meeting at d. By rotating the 
 apparatus clockwise through 90° the directions of the 
 two rays relative to the earth's motion are interchanged, 
 
 and the interference fringes would be expected to shift 
 an amount corresponding to a difference in path of 2 li'^ I. 
 This quantity is of course small, — IB^ is about one one- 
 hundred millionth, — but so sensitive are the methods of 
 interferometry that Michelson felt confident that he 
 would be able to detect the earth's motion through the 
 ether. The apparatus consisted of a table which could 
 be rotated about a vertical axis in much the same way 
 as a spectrometer table, and provided with arms a meter 
 long to carry the mirrors h and c. With this length of 
 arm the interference fringes from sodium light should 
 shift by an amount corresponding to four hundredths of 
 a wave length when the table is rotated through a right 
 angle. When the experiment was first performed the 
 apparatus was placed on a stone pier in the Physical Insti- 
 
37i A CENTURY OF SCIENCE 
 
 tute at Berlin. So sensitive was the instrument to outside 
 vibrations that even after midnight it was found impos- 
 sible to get consistent readings. Finally a satisfactory 
 foundation was constructed in the cellar of the Astro- 
 physical observatory at Potsdam. But what was the 
 astonishment of the experimenters to find that the 
 expected shift of the interference fringes did not exist! 
 
 The extreme delicacy of the experiment made it desir- 
 able to confirm the result by repeating it. This was 
 done by Michelson and Morley (34, 333, 1887) in 1887. 
 In place of a revolving table a massive slab of stone 
 floating on mercury was used to carry the apparatus. 
 This slab was kept in constant rotation, the observer 
 following it around. Moreover, the precision of the 
 experiment was greatly increased by reflecting each ray 
 back and forth across the slab a number of times between 
 leaving and returning to the mirror m. The accuracy 
 attained was such as to justify Michelson in declaring 
 that if the effect sought actually existed it could not be 
 so great as one-twentieth of its calculated value. In 
 1905 Morley and Miller^^ repeated the experiment for the 
 second tune and succeeded in increasing the sensitiveness 
 of the apparatus to a point such that a motion through 
 the ether of one-tenth of the earth's orbital velocity 
 could have been detected. 
 
 The displacement looked for in the Michelson-Morley 
 experiment is known as a second-order effect in that it 
 depends upon the square of the ratio of the velocity of the 
 earth to that of light. Michelson at first considered that 
 the negative result obtained confirmed a theory proposed 
 by Stokes in which it was assumed that the ether inside 
 and near its surface partakes of the motion of the earth, 
 while that at a distance is practically quiescent. But 
 there are many objections to Stokes' theorj^ one of which 
 was brought out by an experiment of Michelson's (3, 475, 
 1897) in which he attempted by an interference method 
 to detect a difference in the velocity of light at different 
 levels above the earth's surface. The negative result 
 obtained led him to conclude that if Stokes' theory were 
 true the earth's influence on the ether would have to 
 extend to a distance above its surface comparable with 
 its diameter. Meanwhile a more satisfactory explana- 
 
A CENTURY'S PROGRESS IN PHYSICS 375 
 
 tion was forthcoming. It has been pointed out that a 
 uniformly convected electric field is derivable from an 
 electrostatic field by contracting dimensions in the direc- 
 tion of motion in the ratio 
 
 a/i - 0' ■■ 1. 
 
 Fitzgerald and Lorentz showed independently that if 
 moving matter is distorted in this same way the result 
 obtained by Michelson would be just that to be expected. 
 For then the distance of the mirror c from m would be 
 
 instead of I, and the path of the ray moving parallel to 
 the earth's orbit 
 
 21 
 
 (■ + '"') 
 
 which is just that of the other ray. Of course when the 
 apparatus is rotated through 90°, the distance of this 
 mirror from in assumes its normal value again, and the 
 distance of the other mirror becomes shortened. As all 
 measurement consists in comparing the object to be 
 measured with a standard this contraction could never 
 be detected by experimental methods, for the measuring 
 rod would contract in exactly the same ratio as the body 
 to be measured. 
 
 In computing its electromagnetic mass Abraham had 
 assumed the electron to be a uniformly charged rigid 
 sphere which keeps its spherical form no matter how 
 great a velocity it may be given. He found that the mass 
 increases with the speed at very high velocities, becom- 
 ing infinite as the velocity of light is approached, and 
 that its value depends upon the direction of the applied 
 force. After the Fitzgerald-Lorentz contraction was 
 seen to be necessary in order to explain Michelson 's 
 result, Lorentz calculated the electromagnetic mass of a 
 charged sphere which is deformed into an oblate spheroid 
 when set in motion. For this type of electron too, the 
 mass approaches infinity for velocities as great as that of 
 light, and is different for different directions. If a 
 force is applied in the direction of motion the inertia to 
 
376 A CENTURY OF SCIENCE 
 
 be overcome is a little greater than when the force is 
 applied at right angles to this direction. Thus we 
 have to distinguish between longitudinal and transverse 
 masses. But the masses of Lorentz's electron are not 
 the same functions of its velocity as those of Abraham's. 
 Kaufmann and after him Bucherer tested experimentally 
 the relation between transverse mass and velocity by 
 observing the deflections produced by electric and mag- 
 netic fields in the joaths of high sjoeed beta particles. 
 The latter 's work was such an ample confirmation of 
 Lorentz's formula that it may be considered as proven 
 that a moving electron at least suffers contraction in the 
 direction of motion in the ratio 
 
 Vn^ : 1. 
 
 The electromagnetic theory of light had proved so 
 successful when applied to bodies at rest that Lorentz 
 was anxious to extend this theory to the optics of moving 
 media. His problem was to find a group of homogeneous 
 linear transformations that would leave the form of the 
 electrodynamic equations unchanged. The Michelson- 
 Morley experiment had shown that dimensions in the 
 direction of motion must be contracted in the moving 
 system, those at right angles remaining unaltered. But 
 Lorentz soon found that it was also necessary to use a 
 new unit of time in the moving system, and as this time 
 was found to depend upon the position of the point at 
 which it is to be determined, he called it the local time. 
 Lorentz's transformation is just that of the principle 
 of relativity, but he did not succeed in expressing the 
 electrodynamic equations in terms of the new coordinates 
 and time in exactly the same form as for a system at 
 rest, for the reason that he failed to endow these new 
 units with sufficient reality to .iustify him in using them 
 when it came to transforming the velocity term involved 
 in an electric current. 
 
 Principle of Relativity .—In 1905 appeared in the 
 Annalen der Physik" a paper destined to alter entirely 
 the pomt of view from which problems in light and elec- 
 tromagnetic theory are to be approached. The author 
 was Albert Einstein, of Berne, Switzerland, a young man 
 
A CENTURY'S PROGRESS IN PHYSICS 377 
 
 of twenty-six who had already made a number of notable 
 contributions to theoretical physics. 
 
 The principle of relativity proposed by Einstein was 
 by no means new to students of dynamics. Newton's 
 first two laws of motion express very clearly the fact that 
 in mechanics all motion is relative. Force is propor- 
 tional to acceleration, and the relation between the two 
 is the same whether the motion under consideration is 
 referred to fixed axes or to axes moving with a constant 
 velocity. But in connection with the phenomena of light 
 and electromagnetism the case seemed to be quite differ- 
 ent. There everything was referred to a fixed ether, and 
 even though Lorentz had found a set of transformations 
 which left the electrodjonanic equations practically 
 unchanged, he continued to think in terms of an ether. 
 So physicists were not a little startled when Einstein 
 postulated that no experiment, practical or ideal, could 
 ever distinguish between two systems in such a manner 
 as to warrant the assertion that one of them is at rest 
 and the other in motion. All motion is relative, and the 
 laws governing physical, chemical and biological phe- 
 nomena are the same in terms of the units of one system 
 as in terms of those of any other. 
 
 Einstein next considers some very fundamental ques- 
 tions. Wliat do we mean when we say that two events, 
 one at A and the other at a point B far from A, occur at 
 the same time? Obviously the expression has no signi- 
 ficance unless synchronous clocks are stationed at the 
 two points. But how is it to be determined whether or 
 not these two clocks are synchronous? If instantaneous 
 communication could be established between A and B 
 the matter would be simple enough. Since no infinite 
 velocity of transmission is available, however, let a light 
 wave be sent from A to B and returned to A immediately 
 upon its arrival. If the time indicated by the clock at 
 B when the signal is received is half way between that at 
 which it left A and the time at which it arrives on its 
 return, then the two clocks may be considered syn- 
 chronous. Now if it desired to measure the length of a 
 bar which is moving parallel to the scale with which the 
 measurement is to be made, it is necessary to note the 
 positions of the two ends of the bar at the same instant. 
 
378 A CENTURY OF SCIENCE 
 
 So even the measurement of the length of a moving body 
 depends upon the condition of synchronism at different 
 points in space. 
 
 The principle of relativity requires that the velocity 
 of light shall be the same in one system as in another 
 relative to which the first is in motion. Hence the 
 definition of synchronism makes it possible to obtain a 
 set of transformations connecting space and time meas- 
 urement on one system with those on another. This 
 group of transformations is exactly that which Lorentz 
 had found would transform the electrod5mamic equations 
 into themselves. But Einstein's point of view brought 
 out a remarkable reciprocity which Lorentz had missed. 
 If two parallel rods MN and OP are in motion relative to 
 each other in the direction of their lengths, not only does 
 OP appear shortened to an observer at rest with respect 
 to MN, but MN appears shoi'ter than normal in the 
 same ratio to an observer who is moving along with the 
 rod OP. 
 
 Einstein's theory makes the velocity of light the maxi- 
 mum speed with which a signal can be transmitted. This 
 leads to his celebrated addition theorem. Consider three 
 observers A, B and C. Let B be moving relative to A 
 with a velocity of nine-tenths the velocity of light, and 
 in the same direction with an equal velocity relative to B. 
 In terms of old-fashioned notions of time and space, the 
 velocity of C relative to A would be computed as one and 
 eight-tenths the velocity of light. But the relativity 
 theory gives it as ninety-nine hundredths the velocity of 
 light. For the velocity of light can never be surpassed 
 by that of any material object. This deduction from 
 theory is most strikingly confirmed by the fact that 
 although beta particles have been observed with velocities 
 as high as ninety-nine hundredths that of light, the 
 velocity of light is never quite equalled. It mav be 
 remarked in passing that the principle of relativity 
 requires that the masses of all material bodies shall vary 
 with the velocity in the same manner as Lorentz found 
 to be the case for the electromagnetic mass of the deform- 
 able electron. In this connection Bumstead (26, 498, 
 1908) has devised an elegant method of deducing the 
 ratio of longitudinal to transverse mass. 
 
A CENTURY'S PROGRESS IN PHYSICS 379 
 
 The close connection between electrodynamics and the 
 principle of relativity is obvious from the fact that both 
 lead to the same time and space transformations. Fur- 
 thermore L. Page (37, 169, 1914) has shown that the 
 electrodynamic equations can be derived exactly and in 
 their entirety from nothing more than the kinematics of 
 relativity and the assumption that everj^ element of 
 charge is a center of uniformly diverging lines of force. 
 Hence it may safely be asserted that no purely electro- 
 magnetic phenomenon can ever come into contradiction 
 with this principle. The simplicity thus introduced into 
 the solution of a certain class of problems is enormous. 
 As an example consider the question as to whether a mov- 
 ing star is retarded by the reaction of its own radiation. 
 This purely electrodynamical problem is of such com- 
 plexity that attempts to solve it have led to some contro- 
 versy among mathematical physicists. The principle of 
 relativity tells us without recourse to analysis that no 
 retardation can exist. 
 
 Throughout the nineteenth century the ether has 
 played a fundamental part in all important physical 
 theories of light and electromagnetism. But if it is not 
 possible for experiment to detect even the state of 
 motion of the ether, why postulate the existence of such a 
 medium? If it does not possess the most fundamental 
 characteristic of matter, how can it possess such derived 
 properties as density and elasticity, — properties which 
 any conceivable mechanical medium must have in order 
 to transmit transverse vibrations? The relativist does 
 not deny the existence of an ether. To him the question 
 has no more meaning than if he were asked to express an 
 opinion as to the reality of parallels of latitude on the 
 earth's surface. As a convenient medium of expression 
 in describing certain phenomena the ether has justified 
 much of the use which has been made of it. But to 
 attribute to it a degree of substantiality for which there 
 is no warrant in experiment, is to change it from an aid 
 into an obstacle to the progress of science. From the 
 relativist point of view the distinction is very sharp 
 between those motions of charged particles which are 
 experimentally observable, and such geometrical conven- 
 tions as electromagnetic fields, or analytical sjonbols as 
 
to 
 
 380 A CENTUEY OF SCIENCE 
 
 electric and magnetic intensities. Tliese modes of repre- 
 sentation have been and still are of the greatest use and 
 importance, but their value in scientific description must 
 not lead to lack of appreciation of their purely specula- 
 tive character. 
 
 Final]}' attention must be drawn to the fact that the 
 discoveries of inductive science, embodied in the great 
 generalization we have just been discussing, have led to 
 a more intimate knowledge of the nature of time and 
 space than twenty centuries of introspection on the part 
 of professional philosophers. Minskowski, whose prom- 
 ise of greater achievement was cut off by an untimely 
 death, has shown that four dimensional geometry makes 
 possible the representation with beautiful simplicity of 
 the time and space relationships of this theory. The 
 one time and three space dimensions merge in such a 
 manner as to form a single whole with not a vestige of 
 differentiation between these fundamental quantities. 
 Wilson and Lewis'^ have made this representation famil- 
 iar to American readers through their admirable trans- 
 lation of Minskowski's work into the notation of Gibbs's 
 vector analj'sis. 
 
 Aberration, the Doppler effect, anomalous dispersion, 
 — indeed all known phenomena, — are found to be in 
 accord with the principle of relativity. It must be 
 borne in mind, however, that this principle applies only 
 to systems moving relative to one another in straight 
 lines with constant velocities. That there is something- 
 absolute about rotation has been recognized since Fou- 
 cault performed his famous pendulum experiment in 1851. 
 This experiment (C. S. Lyman, 12, 251 and 398, 1851) 
 consisted in setting a pendulum composed of a heavy 
 brass ball suspended by a long wire into oscillation in 
 such a way as to avoid appreciable ellipticity in its 
 motion. Observation of the rate at which the ground 
 rotates relative to the plane of vibration of the pendulum 
 furnished a method of measuring the rotation of the 
 earth about its axis ivitliout reference to celestial bodies. 
 The gyroscopic compass in use to-day provides yet 
 another terrestrial method of detecting this rotation. 
 
 The Future of Physics. — At times during the history 
 of physics it has seemed as if the fundamental laws of 
 
A CENTURY'S PROGRESS IN PHYSICS 381 
 
 this science had been so completely formulated that 
 nothing remained to future generations beyond the 
 routine of deducing to the full the consequences of these 
 laws, and increasing the precision of the methods used 
 to measure the constants appearing in them. That 
 Laplace held this view has already been pointed out, and 
 Maxwell, in his introductory lecture at the opening of the 
 Cavendish laboratory in 1871, said, "This characteristic 
 of modern experiments — that they consist principally of 
 measurements — is so prominent, that the opinion seems 
 to have gotten abroad that in a few years all the great 
 physical constants will have been approximately esti- 
 mated, and that the only occupation which will then be 
 left to men of science will be to carry on these measure- 
 ments to another place of decimals." That he himself 
 did not entertain this view is made evident by a succeed- 
 ing paragraph. "But we have no right to think thus of 
 the unsearchable riches of creation, or of the untried fer- 
 tility of those fresh minds into which these riches will 
 continue to be poured. It may possibly be true that, in 
 some of those fields of discovery which lie open to such 
 rough observations as can be made without artificial 
 methods, the great explorers of former times have 
 ajopropriated most of what is valuable, and that the 
 gleanings which remain are sought after rather for their 
 abstruseness than for their intrinsic worth. But the his- 
 tory of science shows that even during that phase of her 
 progress in which she devotes herself to improving the 
 accuracy of the numerical measurement of quantities 
 with which she has long been familiar, she is preparing 
 the materials for the subjugation of new regions, which 
 would have remained unknown if she had been contented 
 with the rough methods of her early pioneers. ..." 
 
 That Maxwell's forecast of the prospects of his science 
 was no overestimate will be granted by those who have 
 followed the progress of physics during the last twenty 
 years. Yet the work accomplished in the past appears 
 small compared to that which is left to the future. Many 
 of the unsolved problems are matters of fitting together 
 puzzling details, but there is at least one whose solution 
 appears to demand a radical modification in our funda- 
 mental physical conceptions. This is the formulation of 
 
 24 
 
382 A CENTUEY OF SCIENCE 
 
 the laws which govern the motions of electrons and pos- 
 itively charged particles inside the atom. 
 
 Blacli Radiation. — The significance of the problem was 
 first brought to light through the study of black raclia- 
 tion. Bya black body is meant one whose distinguishing 
 characteristic is that it emits and absorbs radiation of all 
 frequencies, and black radiation is that which will exist in 
 thermal equilibrium with such a body. The interest of 
 this type of radiation lies in the fact, demonstrated by 
 Kirchhoff, that its nature depends only upon the temper- 
 ature of the black body with which it is in equilibrium, 
 and on none of this body's physical or chemical charac- 
 teristics. Thus we may speak of the "temperature" of 
 the radiation itself, meaning by this the temperature of 
 the material body with which it would be in equilibrium. 
 
 The problem of black radiation is to find the distribu- 
 tion of energy among the waves of different frequencies 
 at any given temperature. The first step toward a solu- 
 tion was made when Stefan showed experimentally, and 
 Boltzmann as a deduction from thermodynamics and 
 electrodynamics, that the total energy density summed 
 up over all wave lengths varies with the fourth power of 
 the absolute temperature. If the energy density is 
 plotted as ordinate against the wave length as abscissa, 
 the experimental curve for any one temperature rises 
 from the axis of abscissas at the origin, reaches a maxi- 
 mum, and falls to zero again as the wave length becomes 
 infinitely great. Now Wien's displacement law, the 
 second important step toward the determination of the 
 form of this curve, shows that as the temperature is 
 raised the wave length to which its highest point cor- 
 responds becomes shorter, — in fact this particular wave 
 length varies inversely with the absolute temperature. 
 This theoretical conclusion is entirely confirmed by 
 experiment. (J. W. Draper, 4, 388, 184*7.) 
 
 Farther than this general thermodjaiamical princi- 
 ples are unable to go. Statistical mechanics, however, 
 asserts that when a large number of like elements are in 
 thermal _ equilibrium, the average kinetic energy asso- 
 ciated with each degree of freedom is equal to a universal 
 constant multiplied by the absolute temperature. This 
 "principle of equi-partition of energy" has been applied 
 
A CENTURY'S PROGRESS IN PHYSICS 383 
 
 in various ways to obtain a radiation law. The most 
 straightforward method is based on the equilibrium 
 which must ensue between radiation field and material 
 oscillators when the latter emit, on the average, as much 
 energy as they absorb. From whatever aspect the prob- 
 lem is treated, however, the radiation law obtained from 
 the application of the equi-partition principle is the same. 
 And while this law agrees well with the experimental 
 curve for long wave lengths, it shows an energy density 
 that becomes indefinitely great for extremely short 
 waves, which is not only at variance with the facts, but 
 actually leads to an infinite value of this quantity when 
 integrated over the entire spectrum. 
 
 The Energy Quantum. — Now the principle of equi- 
 partition of energy rests securely on most general 
 dynamical principles. That these dynamical laws are 
 inexact to any such extent as the divergence between 
 theory and experiment would indicate, is inconceivable; 
 that they are insufficient when applied to motions of elec- 
 trons in such intense fields as occur within the atom 
 seems no longer open to doubt. In order to obtain a 
 radiation formula in accord with experiment Planck has 
 found it necessary to extend the atomic idea to energy, 
 which he conceives to exist in multiples of a fundamental 
 quantum Jw, v being the frequency and h Planck's con- 
 stant. That some such hypothesis of discontinuity is 
 essential in order to obtain any law that will even 
 approximately fit the experimental facts has been proved 
 by Poincare. But the precise spot at which the quantum 
 is introduced differs for every new derivation of Planck's 
 law. As deduced most recently by Planck himself, the 
 quantum shows itself in connection with the emission of 
 energy by the material oscillators with which the radi- 
 ation field is in equilibrium. These oscillators are sup- 
 posed to act quite normally in every respect except 
 emission ; here the radiation demanded by the electro- 
 dynamic equations is cast aside, and an oscillator is 
 supposed to emit at once all its energy after it has accu- 
 mulated an amount equal to some integral multiple of /tv.; 
 A form of the theory which does not contain this improb- 
 able contradiction of the firmly established facts of 
 electrodynamics introduces the quantum into the specifi-, 
 
3S4 A CENTURY OF SCIENCE 
 
 cation of the energy of vibration which is permitted to 
 eacli oscillator. Here both emission and absorption fol- 
 low the classical theory, but the motion of an emitting 
 and absorbing linear oscillator of frequency v is supposed 
 to be stable only for those amplitudes for which the energy 
 of its oscillations is an integral multiple of hv. In order 
 to maintain the energy at these particular values, the 
 oscillator may draw energy from, or deposit surplus 
 energy with, other degrees of freedom which partake 
 neither in emission nor absorption, but act merely as 
 storehouses. 
 
 Photoelectric Effect. — When investigating the produc- 
 tion of electromagnetic waves, Hertz had noticed that a 
 spark passed more readily between the terminals of his 
 oscillator when the negative electrode was illuminated by 
 light from another spark. Further investigation by 
 Hallwachs, Elster and Geitel, and others showed that this 
 effect was due to the emission of electrons by a metal 
 exposed to the influence of ultra-violet light. Lenard 
 discovered that the energy with which a negatively 
 charged particle is ejected is entirely independent of the 
 intensity of the light, and further investigation showed 
 it to depend only on the frequency. Einstein suggested 
 that the electrons appearing in this so-called photo-elec- 
 tric effect start from within the metal with an initial 
 energy hv. In passing through the surface a resistance 
 is encountered, however, so he concluded that the energy 
 with which the fastest moving electrons appear outside 
 the metal should be equal to hv less the work done in 
 overcoming this resistance. Recent experiments not 
 only confirm this relation, but provide a most satisfac- 
 tory method of determining the value of h. Millikan^® 
 finds it to be 6-57(10)""'' ergs sec, which gives the quan- 
 tum for yellow light a value sixty times as great as the 
 heat energy of a monatomic gas molecule at 0°C. That 
 this large amount of energy can he transferred from the 
 incident light to the ejected electron is quite out of the 
 question; it must come from within the atom. In this 
 way some indication is obtained of how vast intra-atomic 
 energies must be. 
 
 Structure of the J/^om.— The generally accepted model 
 of the atom is that due chiefly to Rutherford.i^ He con- 
 
A CENTURY'S PEOGRESS IN PHYSICS 385 
 
 siders it to be constituted of electrons revolving about a 
 positive nucleus either singly or grouped in concentric 
 rings, in much the same manner as the planets revolve 
 around the sun. Experiments on the scattering of alpha 
 rays, however, show that the nucleus, while it must have 
 a positive charge sufficient to neutralize the charges of 
 all the electrons moving around it, cannot have a volume 
 of an order of magnitude greater than that of the elec- 
 tron. The number of unit charges residing on it, except 
 in the case of hydrogen, which is supposed to consist of a 
 singly charged nucleus and only one electron, is found to 
 be approximately half the atomic weight. Thus helium, 
 with an atomic weight of about four, has a doubly 
 charged nucleus with two electrons revolving about it, 
 and lithium a triply charged nucleus and three electrons. 
 The number of unit charges on the nucleus is supposed to 
 correspond with the atomic number used by Moseley in 
 interpreting the results of his experiment on the X-ray 
 spectra of the elements. 
 
 Now the electron which is revolving around the posi- 
 tive nucleus of a hydrogen atom, must, according to elec- 
 trodjTiamic laws, radiate energy. This radiation will 
 act as a resistance to its motion, causing its orbit to 
 become smaller and its frequency to increase. Hence 
 luminous hj^drogen would be expected to give otf a con- 
 tinuous spectrum. The very fine lines actually found 
 seem inexplicable on the classical dynamical and electro- 
 dynamical theories. These lines, and those of many 
 other spectra, may even be grouped into series, and the 
 relations between them expressed in mathematical form. 
 Formulse have been proposed by Balmer, Rydberg, Ritz 
 and others, all of which contain a universal constant N 
 as well as certain parameters which must be varied by 
 unity in passing from one line of a series to the next. 
 
 In 1913 Bohr^'^' proposed anatomic theory which brings 
 to light a remarkable numerical relationship between 
 this quantity N and Planck's constant h. He postulated 
 that the electron in the hydrogen atom, for instance, can- 
 not revolve in a circle of any arbitrary radius, but is con- 
 fined to those orbits for which its kinetic energy is an 
 integral multiple of I h n, n being its orbital frequency. 
 Now at times this electron is supposed to jump from an 
 
386 A CENTURY OF SCIENCE 
 
 outer to an inner orbit, when the excess energy of the first 
 orbit over the second is radiated away. But the energy 
 emitted is also talven to be equal to hv, where v is the fre- 
 quency of the radiation. Hence v can be determined, and 
 the expression obtained for it is exactly that given long 
 before by Balmer as an empirical law. The most 
 remarkable thing about it, however, is that Bohr's result 
 contains a constant involving /;, and the electronic charge 
 and mass which has precisely the value of the universal 
 constant N of Balmer 's and Rydberg's formulae. In all, 
 the theory accounts for three series of hydrogen, and 
 yields satisfactory results for helium atoms which have 
 lost an electron, or lithium atoms which have a double 
 positive charge. But for atoms which retain more than 
 a single electron it seems no longer to hold. 
 
 The three mentioned are only the most clearly defined 
 of a growing group of phenomena in which the quantum 
 manifests itself. Its significance and the alteration in 
 our fundamental conceptions to which it seems to be 
 leading is for the future to make clear. That it presents 
 the most important and interesting problem as yet 
 unsolved few physicists would deny. 
 
 American Physicists. — In attempting to cover the 
 progress of physics during the last hundred years in the 
 space of a few pages, many important developments of 
 the subject have of necessity remained untouched, and 
 the treatment of many others has been entirely inade- 
 quate. Among those appearing in the Journal of which 
 no mention has been made are LeConte's (25, 62, 1858) 
 discovery of the sensitive flame and Rood's (46, 173, 
 1893) invention of the flicker photometer. However, 
 enough has been recounted to indicate the pre-eminent 
 position in the history of physics in America occupied by 
 four men: Joseph Henry, of the Albany Academy, 
 Princeton, and the Smithsonian Institution; Henry 
 Augustus Rowland, of Johns Hopkins University; 
 Josiah Willard Gibbs, of Yale; and Albert Abraham 
 Michelson, of the United States Naval Academy, Case 
 School of Applied Science, Clark University, and the 
 University of Chicago. Of these, the last named has the 
 distinction of being the only American physicist to have 
 received the Nobel prize, though there is little doubt that 
 
A CENTURY'S PROGRESS IN PHYSICS 387 
 
 the other three would have been similarly honored had 
 not their important work been published prior to the 
 institution of this award. All four occupy high places 
 in the ranks of the world's great men of science, and the 
 investigations carried out by them and their fellow 
 workers in America have given to their country a posi- 
 tion in the annals of physics which is by no means insig- 
 nificant. 
 
 The Journal's Fart in 3Ieteoroloffy. 
 
 The meteorological investigations published in the 
 early numbers of the Journal have played an important 
 role in establishing a correct theory of storms. Before 
 the origin of the United States Signal Service in 1871 no 
 systematic weather reports were issued by any govern- 
 mental agency in this country, and consequently the work 
 of collecting as well as interpreting meteorological data 
 rested entirely in the hands of interested individuals and 
 institutions. The earliest important studies of storms 
 to appear in the Journal were contributed by Redfield of 
 New York, whose first paper (20, 17, 1831) treated in 
 considerable detail a violent storm which passed over 
 Long Island, Connecticut and Massachusetts in 1821. 
 He concluded that "the direction of the wind at a partic- 
 ular place, forms no part of the essential character of a 
 storm, but is only incidental to that particular portion 
 ... of the track of the storm which may chance to 
 become the point of observation, . . . the direction of 
 the wind being, in all cases, compounded of both the rota- 
 tive and progressive velocities of the storm." A few 
 years later, analvses of twelve "gales and hurricanes of 
 the Western Atlantic" (31, 115, 1837) led to the statement 
 that the phenomena involved "are to be ascribed mainly 
 to the mechanical gravitation of the atmosphere, as con- 
 nected with the rotative and orbital movements of the 
 earth's surface." In this paper is emphasized the fact 
 that the wind may blow in diametrically opposite direc- 
 tions at points near the storm center. "Wliile one ves- 
 sel has been lying-to in a heavy gale of wind, another, not 
 more than thirty leagues distant, has at the very same 
 time been in another gale equally heavy, and lying-to 
 with the wind in quite an opposite direction." From an 
 
388 A CENTURY OF SCIENCE 
 
 accompanying sketch showing wind directions, the reader 
 would infer that, at this time, Redtield believed the 
 motion of the air to be very nearly in circles about the 
 storm center. The same idea is conveyed by a later 
 paper (42, 112, 1842). Espy (39, 120, 1840) of Philadel- 
 phia, however, claimed that observation showed rather 
 that the wind blew inwards toward a central point, if the 
 storm were round in shape, or toward a central line, if 
 it were oblong. This view Redfield (42, 112, 1842) con- 
 tested, and brought forth much evidence to prove its 
 falsity. A later statement (1, 1, 1846) of his own theory 
 is as "follows: "I have never been able to conceive, that 
 the wind in violent storms moves only in circles. On the 
 contrary, a vortical movement . . . appears to be an 
 essential element of their violent and long continued 
 action, of their increased energy towards the center or 
 axis, and of the accompanying rain. . . . The degree of 
 vorticular inclination in violent storms must be subject, 
 locally, to great variations ; but it is not probable that, 
 on an average of the different sides, it ever comes near to 
 forty-five degrees from the tangent of a circle, — and 
 that such average inclination ever exceeds two points of 
 the compass, may well be doubted." A qualitative 
 explanation of the effect of the earth's rotation on the 
 direction of the wind near the storm center had already 
 been given by Tracy (45, 65, 1843), and this was followed 
 some years later by Ferrel's (31, 27, 1861) very thorough 
 quantitative investigation of the dynamics of the 
 atmosphere. 
 
 A number of individuals kept systematic records of 
 meteorological observations, among whom was Loomis, 
 whose storm analyses did much to settle the merits of the 
 rival theories of Redfield and Espy. In studying the 
 storm of 1836 (40, 34, 1841) he had drawn on "the map 
 lines through those points in the track of the storm where 
 the barometer, at any given hour, is lowest. While this 
 method revealed the general direction in which the storm 
 was progressing, it failed to give much indication of its 
 size or shape. In discussing the two tornadoes of Feb- 
 ruary, 1842, one of which had already been described 
 in the Journal (43, 278_, 1842), he adopted a new and 
 more illuminating graphical method. Instead of connect- 
 
A CENTURY'S PEOGRESS IN PHYSICS 389 
 
 ing points of lowest pressure, he drew a curve through all 
 points where the barometer stood at its normal level, then 
 one through those points at which the pressure was 2/10 
 of an inch below normal, and so on. Temperature he 
 treated in much the same way, arid the strength and 
 direction of the wind were indicated by arrows. This 
 innovation gave to his storm analyses a significance 
 which had been entirely lacking in those of his predeces- 
 sors, and led to the familiar systems of isobars and iso- 
 therms in use on the daily charts issued by the Weather 
 Bureau at the present time. Loomis advocated careful 
 observations for one year at stations 50 miles apart all 
 over the United States, so that sufficient data might be 
 olDtained to settle once for all the law of storms. His 
 efforts, seconded by those of Henry, Bache, Pierce, Abbe, 
 and Lapham, led eventually to the establishment of the 
 Signal Service, and the publication of daily weather 
 maps according to the plan advocated thirty years 
 before. These maps afforded a basis for further 
 analyses of storms, which he published in numerous 
 "Contributions to Meteorology" (8, 1, 1874, et seq.) 
 between 1874 and his death in 1890. 
 
 In addition to his work on storms, Loomis made a care- 
 ful study of the earth's magnetism (34, 290, 1838 et seq.), 
 and of the aurora borealis (28, 385, 1859 et seq.). That 
 a connection existed between sunspots, aurora, and ter- 
 restrial magnetism was already recognized. Loomis (50, 
 153, 1870 et seq.), however, showed that the periodicity 
 of the aurora borealis, as well as of excessive disturb- 
 ances in the earth's magnetic field, corresponds very 
 closely with that of sunspots. 
 
 Notes, 
 
 ' J. W. Gibbs, Trans. Conn. Acad. Arts and Sci., 3, 108 and 343. Abstract 
 by the author, the Journal, 16, 441, 1878. 
 = H. K. Onnes, Nature, 93, 481, 1914. 
 ° H. Hertz, Wied. Ann., 34, 551, 1888 et seq. 
 ♦E. F. Nichols and G. F. Hull, Phys. Rev., 13, 307, 1901 et seq. 
 "J. J. Thomson, Phil. Mag., 44, 293, 1897. 
 °E. A. Millikan, Phys. Eev., 2, 109, 1913. 
 ' P. Zeeman, Phil. Mag., 43, 226, 1897. 
 « H. A. Lorentz, Phil. Mag., 43, 232, 1897. 
 • S. J. Barnett, Phys. Rev., 6, 239, 1915, and 10, 7, 1917. 
 " W. C. Kontgen, Wied. Ann., 64, 1, 1898 et seq. 
 
390 A CENTURY OF SCIENCE 
 
 " W. Priedrieh, P. Knipping, and M. Laue, Ann. d. Phyg., 41, 971, 1913. 
 " H. G. J. Moseley, Phil. Mag., 26, 1024, 1913, and 27, 703, 1914. 
 "E. W. Morley and D. C. Miller, Phil. Mag., 9, 680, 1905. 
 "17, 891, 1905. 
 
 ''E. B. Wilson and G. N. Lewis, Proe. Am. Acad, of Arts and Sci., 48, 
 389, 1912. ' 
 
 "E. A. Millikan, Phys. Hey., 7, 355, 1916. 
 "E. Rutherford, PhU. Mag., 21, 669, 1911. 
 " N. Bohr, Phil. Mag., 26, 1, 1913 et seq. 
 
XII 
 
 A CENTURY OF ZOOLOGY IN AMERICA 
 
 By WESLEY R. COE 
 
 THIS article is intended as a brief survey of the 
 development of zoology in America, and no attempt 
 is made to give a general history of the science. 
 There are numerous accounts in several languages of 
 zoological history in general, among them being W. A. 
 Locy's "Biology and its Makers." Brief outlines of the 
 history of zoology may be found in many zoological and 
 biological test-books. 
 
 For the history of American zoology the reader is 
 referred to Packard's report on "A Century's Progress 
 in American Zoology," published in the American Nat- 
 uralist, (10, 591, 1876), to Packard's "History of Zool- 
 ogy," published in volume 1 of the Standard Natural 
 History (pp. Ixii to Ixxii, 1885); to G. B. Goode's 
 "Beginnings of Natural History in America,"^ and 
 "Beginnings of American Science,"' and to H. S. Pratt's 
 Manual of the Common Invertebrate Animals (pp. 1-9), 
 1916. In Binney's "Terrestrial Air-breathing MoUusks 
 of the United States" (1851) is a chapter on the rise of 
 scientific zoology in the United States which well describes 
 the zoological conditions in the early part of the century, 
 while numerous monographs and papers give the history 
 of the investigations on the various groups of animals 
 or on special fields of study. 
 
 Brief biographical sketches of the most distinguished 
 of our older Naturalists — Wilson, Audubon, Agassiz, 
 Wyman, Gray, Dana, Baird, Marsh, Cope, Goode and 
 Brooks are given in "Leading American Men of Sci- 
 ence," edited by David Starr Jordan, 1910. More exten- 
 sive biographies have been published separately, and the 
 activities of a number of the more prominent American 
 
392 A CENTURY OF SCIENCE 
 
 zoologists have been recorded in the Biographical 
 Memoirs of the National Academy of Sciences. 
 
 The developmental history of zoology in America falls 
 naturally into four fairly well marked periods, namely : — 
 1, Period of descriptive natural history, previous to 
 1847, embracing the early studies on the classification 
 and habits of animals, characteristic of the zoological 
 work previous to the arrival of Louis Agassiz in Amer- 
 ica. 2, Period of morphology and embryology, 1847- 
 1870, during which the influence of Agassiz directed the 
 zoological studies toward problems concerning the rela- 
 tionships of animals as indicated by their structure and 
 developmental history. 3, Period of evolution, 1870- 
 1890, when the principle of natural selection received 
 general recognition and the zoological studies were 
 largely devoted to the applications of the theory to 
 all groups of animals. 4, Period of experimental biol- 
 ogy, since 1890, during which time have occurred the 
 remarkable advances in our knowledge of the nature of 
 organisms through the application of experimental 
 methods in the various branches of the modern science of 
 biology. 
 
 American Zoology in 1818. 
 
 At the beginning of the century which this volume 
 commemorates, the accumulated biological knowledge of 
 the world consisted mainly of what is to-day called 
 descriptive natural history. The zoological treatises of 
 the time were devoted to the names, distinguishing char- 
 acters and habits of the species of animals and plants 
 known to the naturalists of Europe either as native 
 species or as the results of explorations in other parts 
 of the Avorld. This required little more than a super- 
 ficial knowledge of their general anatomical structures. 
 
 The naturalists of those days had no conception of the 
 life within the cell which we now know to form the basis 
 of all the activities of animals and plants, nor had they 
 even the necessary means of studying such life. The 
 compound microscope, so necessary for the study of even 
 the largest of the cells of the body, was not adapted to 
 such use until 1835, although the instrument was invented 
 in the seventeenth century. With the perfection of the 
 microscope came a period of enthusiastic study of micro- 
 
A CENTURY OF ZOOLOGY IN AMERICA 393 
 
 scopic organisms and microscopic structures of liiglier 
 animals and plants. It was not until twenty years after 
 the founding of the Journal that the cell theory of struc- 
 ture and function in all organisms was established by the 
 discoveries of Schleiden and Schwann. 
 
 The beginning of the nineteenth century saw great 
 zoological activity in Europe, and particularly in France. 
 Buff on 's great work on the Natural History of Animals 
 had recently been completed, Cuvier had only one year 
 before published his classic work in comparative anat- 
 omy, "Le Regne Animal," and Lamarck's "Philosophie 
 Zoologique" had then aroused a new interest in classi- 
 fication and comparative anatomy from an evolutionary 
 standpoint. E. Geoffrey St.-Hilaire was at the same 
 time supporting an evolutionary theory based on embry- 
 onic influences resulting in sudden modifications of adult 
 structure. These epoch-making discoveries and theories 
 gained a considerable following in France, Germany and 
 England, but seem to have had little influence on the 
 zoological work of the following half century in America. 
 
 The science of zoology as understood to-day is com- 
 monly said to have been founded by Linnfeus b}^ the 
 publication of the modern system of classification in the 
 tenth edition of his "Systema Naturos" in 1758. The 
 influence of Linnsus aroused an interest in biological 
 studies throughout Europe and stimulated new investi- 
 gations in all groups of organisms. Such studies as 
 related to animals naturally followed first the classifica- 
 
 (tion and relationship of species, that is, systematic 
 zoology, and then led gradually into the development of 
 the different branches of the subject, as morphology, 
 comparative anatomy, physiology, and embryology, 
 which eventually were recognized as almost independent 
 sciences. 
 
 Of these sciences systematic zoology, which has come 
 to mean the classification, structure, relationship, distri- 
 bution and habits, or natural history, is the pioneer in any 
 region. Thus we find in our new country at the time of 
 the founding of the Journal in 1818, only sixty years 
 after the publication of Linnaeus' great work, the begin- 
 ning of American zoology taking the form of the collec- 
 tion and description of our native animals. 
 
394 A CENTURY OF SCIENCE 
 
 It is true that many of our more conspicuous and easily 
 collected animals were described long before the opening 
 of the nineteenth century, but this is to be credited mainly 
 to the work of European naturalists who had made expedi- 
 tions to this country for the purpose of studying and 
 collecting. These collections were then taken to Europe 
 and the results published there. We thus find in the 12th 
 edition of Linn;p.us descriptions of over 500 American 
 species, about half of which were birds. As an illustra- 
 tion of the extent to which some of these works covered 
 the field even in those early days may be mentioned a 
 monograph in two quarto volumes with many beautifully 
 colored plates on the ' ' Natural History of the rarer Lepi- 
 dopterous Insects of Georgia." This was published in 
 London in 1797 by J. E. Smith from the notes and draw- 
 ings of John Abbot, one of the keenest naturalists of 
 any period. 
 
 During the early years of the nineteenth century, how- 
 ever, economic conditions in our country became such as to 
 give opportunity for scientific thought. Educated men 
 then formed themselves into societies for the discussion of 
 scientific matters. This naturally led to the establish- 
 ment of publications whereby the papers presented to the 
 societies could be published and made available to the 
 advancement of science generally. The most influential 
 of these was the Journal of the Philadelphia Academy of 
 Natural Science, which was established in 1817, and was 
 devoted largely to zoological papers. The Annals of the 
 New York Lyceum of Natural History date from 1823, 
 and the Journal of the Boston Society of Natural History 
 from 1834. The Transactions of the American Philo- 
 sophical Society in Philadelphia and the Memoirs of the 
 American Academy of Arts and Sciences in Boston also 
 published many zoological articles. 
 
 In these publications and in the Journal, which was 
 founded in 1818, appear the descriptions of newly dis- 
 covered animal species, with observations on their habits. 
 
 The number of investigators in this field in the first 
 quarter of the nineteenth century was but few, and most 
 of these were compelled to take for the work such time 
 as they could spare from their various occupations. 
 
 Gradually the workers became more numerous until 
 
A CENTURY OF ZOOLOGY IN AMERICA 395 
 
 about the middle of the century zoology was taught in all 
 the larger colleges. The science thereby developed into 
 a profession. 
 
 For some years the studies remained largely of a sys- 
 tematic nature, and embraced all groups of animals, but 
 long before the close of the century the attention of the 
 majority of the ever increasing group of zoologists was 
 directed into more promising channels for research and 
 there came the development of the sciences of compara- 
 tive anatomy, physiology, embryology, experimental 
 zoology, cytology, genetics, and the like, while the sys- 
 tematists became specialists in the various animal groups. 
 
 But the work in systematic zoology remains incomplete 
 and many native species are still undescribed or imper- 
 fectly classified. It is perhaps fortunate that a few 
 faithful systematists remain at their tasks and tend to 
 keep the experimentalists from the disaster which might 
 otherwise result from the confusion of the species under 
 investigation. 
 
 Period of Descriptive Nattiral History. — Previous to 1847 • 
 
 Of the few American naturalists whose writings were 
 published toward the end of the eighteenth century and 
 at the beginning of the nineteenth the names of William 
 Bartram (1739-1823), Benjamin Barton (1766-1815), 
 Samuel Mitchill (1764-1831), William Peck (1763-1822), 
 and Thomas Jefferson (1743-1826), require special men- 
 tion. Bartram 's entertaining volume describing his 
 travels through the Carolinas, Georgia and Florida, pub- 
 lished in 1793, contains a most interesting account of the 
 birds and other animals which he found. 
 
 Barton wrote many charming essays on the natural 
 history of animals, but was more particularly interested 
 in botany. Mitchill 's most important works include a 
 history of the fishes of New York (1814), and additions to 
 an edition of Bewick's General History of Quadrupeds. 
 The latter, published in 1804, contains descriptions and 
 figures of some American species and is the first Ameri- 
 ca work on mammals. 
 
 /^eck has the distinction of writing the first paper on 
 /systematic zoology published in America. This was^a 
 I description of new species of fishes and was printed in 
 
396 A CENTUEY OF SCIENCE 
 
 1794. He is also well known for his work on insects 
 and fungi. 
 
 Jefferson in 1781 published an interesting book 
 describing the natural history of Virginia, and during 
 his presidency was of inestimable service to zoology 
 through his support of scientific expeditions to the west- 
 ern portions of the country. 
 
 Previous to Agassiz's introduction of laboratory meth- 
 ods of study in comparative anatomy and embryology in 
 1847, American naturalists generally confined their atten- 
 tion to the study of the classification and habits of the 
 multitude of undescribed animals and plants of the 
 region. 
 
 "•^^uch studies were naturally begun on the larger and 
 more generally interesting animals such as the birds and 
 mammals, and although many of these were fairly well 
 described as to species before the opening of the nineteenth 
 century, little was known of their habits. The natural 
 history of our eastern birds first became well known 
 through the accurate illustrations and exquisitely written 
 descriptions of Alexander Wilson (in 1808-1813). Bona- 
 parte's continuation of Wilson's work was published in 
 four folio volumes beginning in 1826. 
 
 In 1828 appeared the first of Audubon's magnificent 
 folio illustrations of our birds. These w^ere published in 
 England, with later editions of smaller plates in America. 
 Nuttall 's Manual of the Ornithology of the United States 
 appeared in 1832-1834. 
 
 The second work on American mammals appeared in 
 the second American edition of Guthrie's GeographJ^ 
 published in 1815. The author is supposed to have been 
 George Ord, although his name does not appear. In 1825 
 Harlan published his "Fauna Americana: Descriptions 
 of the Mammiferous Animals inhabiting North Amer- 
 ica." This was largely a compilation from European 
 writers, particularly from Demarest's Mammalogie, and 
 had little value. 
 
 In 1826 Amos Eaton published a small "Zoological 
 Text-book comprising Cuvier's four grand divisions 
 of Animals: also Shaw's improved Linnean genera, 
 arranged according to the classes and orders of Cuvier 
 and Latreille. Short descriptions of some of the most 
 
A CENTURY OF ZOOLOGY IN AMERICA 397 
 
 common species are given for students' exercises. Pre- 
 pared for Rensselaer school and the popular class-room." 
 "Four hundred and sixty-one genera are described in 
 this text-book. They embrace every known species of 
 the Animal Kingdom." This is a compilation from 
 European sources with a few American species of various 
 groups included. On the other hand, Godman's Natural 
 History, in three volumes (1S26-1828), was an illustrated 
 and creditable work. Such was also the case with Sir 
 John Richardson's Fauna Boreali Americana of which 
 the volume on quadrupeds was published in England in 
 1829. The other volumes on birds, fishes and insects 
 appeared between 1827 and 1836. Audubon and Bach- 
 man's beautifully illustrated "Quadrupeds of North 
 America" was issued between 1841 and 1850. 
 
 About 1840 several of the states inaugurated natural 
 history surveys and published catalogues of the local 
 faunas. The reports on the animals of Massachusetts 
 and New York are the most complete zoological mono- 
 graphs published in America up to that time. This is 
 particularly true of DeKay's Natural History of New 
 York published between 1842 and 1844 in beautifully 
 illustrated quarto volumes. 
 
 The leader in the sj'stematic studies in the early part 
 of the century was Thomas Say, who published descrip- 
 tions of a large number of new species of animals, par- 
 ticularly reptiles, mollusks, Crustacea and insects. Say's 
 conchology, printed in 1816 in Nicholson's Cyclopedia, 
 is the first American work of its kind. This was 
 reprinted in 1819 under the title "Land and Fresh-water 
 Shells of the United States." In 1824-1828 appeared 
 the three volumes of Say's American Entomology. 
 
 The prominent position held by Say in the zoological 
 work of this period is illustrated by the following para- 
 graph from Eaton's Zoological Text-book (1826,p. 133)_: 
 "At present but a small proportion of American Ani- 
 mals, excepting those of large size, have been sought out 
 . . . And though Mr. Say is doing much; without assist- 
 ance, his life must be protracted to a very advanced 
 period to'^aSordTTnTcTtime to complete the work. _ But if 
 every student will contribute his mite, by sending Mr. 
 Say duplicates of all undescribed species, we shall prob- 
 
 25 
 
39S A CENTURY OF SCIENCE 
 
 ably be in possession of a system, very nearly complete, 
 in a few years." How different is the attitude of the 
 zoologist of to-day who sees the goal much further away 
 after a century's progress through the industry of hun- 
 dreds of investigators. 
 
 During the period of Say's most active work he is 
 reported to have "slept in "the hall of the Philadelphia 
 Academy of Natural Sciences, where he made his bed 
 beneath the skeleton of a horse and fed himself on bread 
 and milk. ' ' 
 
 Next to Say, the most active zoologist of the early part 
 of the century was Charles Alexander Lesueur, who 
 described and beautifully illustrated many new species of 
 fishes, reptiles, and marine invertebrates. A memoir by 
 George Ord, published in this Journal (8, 189, 1849), 
 gives a full list of Lesueur 's papers. 
 
 One of the most prolific writers of the period was Con- 
 stantine Rafinesque, a man of great brilliancy but one 
 whose imagination so often dominated his observations 
 that many of his descriptions of plants and animals are 
 wholly unreliable. 
 
 United States Exploring Expedition. — In 1838 a fortu- 
 nate circumstance occurred which eventually brought 
 American systematic zoology into the front ranks of the 
 science. This opportunity was offered by the United 
 States Exploring Expedition under the command of 
 Admiral Wilkes. With James D. Dana as naturalist, the 
 expedition visited Madeira, Cape Verde Islands, eastern 
 and western coasts of South America, Polynesia, Samoa, 
 Australia, New Zealand, Fiji, Hawaiian Islands, west 
 /coast of United States, Philippines, Singapore, Cape of 
 , Good Hope, etc. 
 
 Of the extensive collections made on this four-years' 
 cruise, Dana had devoted particular attention to the 
 study of the corals and allied animals (Zooph^'-fes) and to 
 the Crustacea. In 1846 the report on the Zooplwtes was 
 published in elegant folio form with colored plates. 
 Six years later the first volume of the report on Crus- 
 tacea appeared, with a second volume after two 
 I additional years (1854). These reports describe and 
 Vbeautifully illustrate hundreds of new species, and 
 include the first comprehensive studies of the animals 
 
A CENTURY OF ZOOLOGY IN AMERICA 399 
 
 forming well-known corals. They remain as the most 
 conspicuous monuments in American invertebrate zool- 
 ogy. Unfortunately the very limited edition makes them 
 accessible in only a few large libraries. The other, 
 equally magnificent, volumes include: MoUusca and 
 Shells, by A. A. Gould, 1856 ; Herpetology, by Charles 
 Girard, 1858; Mammalogy and Ornithology, by John 
 Cassin, 1858. 
 
 Principal investigators. — Of the many writers on ani- 
 mals at this period of descriptive natural history, the fol- 
 lowing were prominent in their special fields of study: 
 
 Ayres, Lesueur, Mitchill, Storer, Linsley, Wyman, 
 DeKay, Smith, Kirtland, Rafinesque and Haldeman 
 described the fishes. 
 
 Green, Barton, Harlan, Le Conte, Say, and especially 
 Holbrook, studied the reptiles and amphibia. Holbrook's 
 great monograph of the reptiles (North American Her- 
 petology) was published between 1834 and 1845. 
 
 Wilson, Audubon, Nuttall, Cooper, DeKay, Brewer, 
 Ord, Baird, Gould, Bachman, Linsley and Fox were 
 among the numerous writers on birds. 
 
 Godman, Ord, Richardson, Audubon, Bachman, De- 
 Kay, Linsley and Harlan published accounts of mam- 
 mals. 
 
 On the invertebrates an important general work enti- 
 tled "Invertebrata of Massachusetts; MoUusca, Crus- 
 tacea, Annelida and Radiata" was published by A. A. 
 Gould in 1841, which contains all the New England 
 species of these groups kno^vn to that date. 
 
 Lea, Totten, Adams, Barnes, Gould, Binney, Conrad, 
 Hildreth, Haldeman, were the principal writers on mol- 
 lusks. The Crustacea were studied by Say, Gould, Halde- 
 man, Dana; the insects by Say, Melsheimer, Peck, 
 Harris, Kirby, Herrick; the spiders by Hentz; the worms 
 by Lee ; the coelenterates and echinoderms by Say, Man- 
 tell and others. 
 
 ■' The history of entomology in the United States pre- 
 vious to 1846 is given by John G. Morris in the Journal 
 il 17, 1846). In this article F. V. Melsheimer is stated 
 to be the father of American Entomology, while Say was 
 the most prolific writer. Say's entomological papers, 
 edited by J. L. Le Conte, were completely reprinted with 
 
400 A CENTURY OF SCIENCE 
 
 their colored illustrations in 1859. Tlie first economic 
 treatise is that by Harris on Insects Injurious to Vege- 
 tation-, printed in 1841. This has had many editions. 
 
 Zoology in the American .Tournal of Science, 
 
 1818-184G. 
 
 The establishment of the Journal gave a further impe- 
 tus to the scientific activities of Americans in furnishing 
 a convenient means for publishing the results of their 
 work. In the first volume of the Journal, for example, 
 are two zoological articles hj Say and a dozen short 
 articles on various topics by Rafinesque, the latter being 
 curious combinations of facts and fancy. Most of the 
 zoological papers appearing in its first series of 50 vol- 
 umes are characteristic of an undeveloped science in an 
 undeveloped countr3^ They deal, naturally, with obser- 
 vational studies on the structure and classification of 
 species discovered in a virgin field, with notes on habits 
 and life histories. 
 
 Many of the papers are purely systematic and include 
 the first descriptions of numerous species of our mol- 
 lusks, Crustacea, insects, vertebrates and other groups. 
 Of these, the writings of C. B. Adams, Barnes, A. A. 
 Gould and Totten on mollusks, of J. D. Dana on corals 
 and Crustacea, of Harris on insects, of Harlan on reptiles, 
 and of Jeffries Wyman and D. Humphreys Storer on 
 fishes are representative and important. 
 
 The progress of zoology in America during the first 
 twenty-eight years of the Journal's existence, that is, up 
 to the year 1846, is thus summarized by Professor SiUi- 
 man in the preface to vol. 50 (page ix), 1847 : 
 
 "Our zoolony has been more fully investigated than our 
 mineralogy and botany; but neither department is in danger 
 of being exhausted. The interesting travels of Lewis and Clark 
 have recently brought to our knowledge several plants and 
 animals before unknown. Foreign naturalists are frequently 
 visiting our territory ; and, for the most part, convey to Europe 
 the fruits of their researches, while but a small part of our 
 own is examined and described by Americans: certainly this 
 is little to our credit and still less to our advantage. Honorable 
 exceptions to the truth of this remark are furnished by the 
 
A CENTURY OF ZOOLOGY IN AMERICA 401 
 
 exertions of some gentlemen in our principal cities, and in 
 various other parts of the Union." 
 
 During these 28 years the Journal had been of great 
 service to zoology not only in the publication of the 
 results of investigations but also in the review of import- 
 ant zoological publications in Europe as well as in 
 America. There were also the reports of meetings of 
 scientific societies. In fact all matters of zoological 
 interest were brought to the attention of the Journal's 
 readers. 
 
 The Influence of Louis Agassis, 
 
 At the time of the founding of the Journal and for 
 nearly thirty years thereafter descriptive natural his- 
 tory constituted practically the entire work of American 
 zoologists. In this respect American science was far 
 behind that in Europe and particularly in France. It 
 was not until the fortunate circumstances which brought 
 the Swiss naturalist, Louis Agassiz, to our country in 
 1846 that the modern conceptions of biological science 
 were established in America. 
 
 Agassiz was then 39 years of age and had already 
 absorbed the spirit of generalization in comparative 
 anatomy which dominated the work of the great leaders 
 in Europe, and particularly in Paris. The influence of 
 Leuckart, Tiedemann, Braun, Cuvier and Von Humboldt 
 directed Agassiz 's great ability to similar investigations, 
 and he was rapidly coming into prominence in the study 
 of modern and fossil fishes when the opportunity to con- 
 tinue his research in America was presented. On arriv- 
 ing on our shores the young zoologist was so inspired 
 with the opportunities for his studies in the new country 
 that he decided to remain. 
 
 Bringing with him the broad conceptions of his dis- 
 tinguished European masters, he naturally founded a 
 eimilar school of zoology in America. It is from this 
 beginning that the present science of zoology with its 
 many branches has developed. 
 
 It must be remembered in this connection that the great 
 service which Agassiz rendered to American zoology con- 
 sisted mainly in making available to students in America 
 the ideals and methods of European zoologists. This he. 
 
402 A CENTURY OF SCIENCE 
 
 was eminently fitted to do both because of his European 
 training and because of his natural ability as an inspir- 
 ing leader. 
 
 The times in America, moreover, were fully ripe for 
 the advent of European culture. There were already in 
 existence natural history societies in many of our cities 
 and college communities. These societies not only held 
 meetings for the discussion of biological topics, but 
 established museums open to the public, and to which the 
 public was invited to contribute both funds and speci- 
 mens. This led to a wide popular interest in natural his- 
 tory. It was therefore comparatively easy for such a 
 man as Agassiz to develop this favorable public attitude 
 into genuine enthusiasm. 
 
 The American Journal of Science announces the 
 expected visit of Agassiz as a most promising event for 
 American Zoology (1, 451, 1846) : "His devotion, ability, 
 and zeal — his high and deserved reputation and . . . his 
 amiable and conciliating character, will, without doubt, 
 secure for him the cordial cooperation of our naturalists 
 . . . nor do we entertain a doubt that we shall be liberally 
 repaid by his able review and exploration of our 
 country. ' ' We of to-day can realize how abundantly this 
 prophecy was fulfilled. 
 
 In the succeeding volume (2, 440, 1846) occurs the 
 record of Agassiz 's arrival. "We learn with pleasure 
 that he will spend several years among us, in order 
 thoroughly to understand our natural history." 
 
 Immediately on reaching Boston, Agassiz began the 
 publication of articles on our fauna, and the following 
 year he was appointed to a professorship at Harvard. 
 The Journal says (4, 449, 1847) : "Every scientific man in 
 America will be rejoiced to hear so unexpected a piece of 
 good news." The next year the Journal (5, 139, 1848) 
 records Agassiz 's lecture courses at New York and 
 Charleston, his popularity with all classes of the people 
 and the gift of a silver case containing $250 in half eagles 
 from the students of the College of Physicians and 
 Surgeons. 
 
 The service of Agassiz to American zoology, therefore, 
 consisted not only in the publication of the results of his 
 researches and his philosophical considerations there- 
 
A CENTUBY OF ZOOLOGY IN AMERICA 403 
 
 from, but also, and perhaps in even greater degree, in the 
 popularization of science. In the latter direction were 
 his inspiring lectures before popular audiences and the 
 early publication of a zoological text-book. This book, 
 published in 1848, was entitled "Principles of Zoology, 
 touching the Structure, Development, Distribution and 
 Natural arrangement of the races of Animals, living and 
 extinct, with numerous illustrations." It was written 
 with the cooperation of Augustus A. Gould. The review 
 of this book in the Jovirnal (6, 151, 1848) indicates clearly 
 the broad modern principles underlying the new era 
 Avhich was beginning for American zoology. 
 
 "A work emanating from so high a source as the Principles 
 of Zoology, hardly requires commendation to give it currency. 
 The public have become acquainted with the eminent abilities 
 of Prof. Agassiz through his lectures, and are aware of his 
 vast learning, wide reach of mind, and popular mode of illus- 
 trating scientific subjects . . . The volume is prepared for 
 the student in zoological science; it is simple and elementary 
 in style, full in its illustrations, comprehensive in its range, yet 
 well considered and brought into the narrow compass requisite 
 for the purpose intended." 
 
 The titles of its chapters will show how little it differs 
 in general subject matter from the most recent text-book 
 in biology. Chapter I, The Sphere and fundamental 
 principles of Zoology; II, General Properties of Organ- 
 ized Bodies ; III, Organs and Functions of Animal Life ; 
 IV, Of Intelligence and Instinct; V, Of Motion (appa- 
 ratus and modes) ; Yl, Of Nutrition; VII, Of the Blood 
 and Circulation ; VIII, Of Respiration ; IX, Of the Secre- 
 tions; S, Embryology (Egg and its Development); 
 XI, Peculiar Modes' "of Reproduction; XII, Meta- 
 morphoses of Animals ; XIII, Geographical Distribution 
 of Animals ; XIV, Geological Succession of Animals, or 
 their Distribution in Time. 
 
 A moment's consideration of the fact that all these 
 topics are excellently treated will show how great had 
 been the progress of zoology in the first half of the nine- 
 teenth century. The sixty years that have elapsed since 
 the publication of this book have served principally to 
 develop these separate lines of biology into special fields 
 of science without reorganization of the essential princi- 
 
404 A CENTURY OF SCIENCE 
 
 pies here recognized. This remained for many years 
 the standard zoological and physiological text-book, and 
 was republished in several editions here and in England. 
 Another popular book is entitled "Methods of Study in 
 Natural History" (1864). 
 
 More than 400 books and papers were written by 
 Agassiz, over a third of which were published before 
 he came to America. They cover both zoological and 
 geological topics, including systematic papers on living 
 and fossil groups of animals, but most important of all 
 are his philosophical essays on the general principles- of 
 biology. 
 
 One of Agassiz 's greatest services to zoology was the 
 publication of his "Bibliographia Zoologise et Greologiae" 
 by the Ray Society, beginning with 1848. The jjublica- 
 tion of the Lowell lectures in Comparative Embryology 
 in 1849 gave wide audience to the general principles now 
 recognized in the biogenetic law of ancestral remin- 
 iscence. As stated in the Journal (8, 157, 1849), the 
 "object of the Lectures is to demonstrate that a natural 
 method of classifying the animal kingdom may be 
 attained by a comparison of the changes which are passed 
 through by different animals in the course of their devel- 
 opment from the egg to the perfect state; the change 
 they undergo being considered as a scale to appreciate 
 the relative position of the species." These "principles 
 of classification" are fully elucidated in a separate pam- 
 phlet, and are discussed at length in the Journal (11, 
 122, 1851). 
 
 One of the most interesting of Agassiz 's numerous 
 philosophical essays, originally contributed to the Jour- 
 nal (9, 369, 1850), discusses the "Natural Relations 
 between Animals and the elements in which they live." 
 Another philosophical paper contributed to the "journal 
 discusses the "Primitive diversity and number of Ani- 
 mals in Geological times" (17, 309, 1854). Of his sys- 
 tematic papers, those on the fishes of the Tennessee river, 
 describing many new species, were published in the Jour- 
 nal (17, 297, 353, 1854). 
 
 Agassiz 's beautifully illustrated "Contributions to the 
 Natural History of the United States" cover many sub- 
 jects in morphology and embryology, which are treated 
 
A CENTURY OF ZOOLOGY IN AMERICA 405 
 
 with such thoroughness and breadth of view as to give 
 them a place among the zoological classics. The Essay 
 on Classification, the North American Testudinata, the 
 Embryology of the turtle, and the Acalephs are the 
 special topics. These are sununarized and discussed at 
 length in the Journal (25, 126, 202, 321, 342, 1858 ; 30, 
 142,1860; 31,295,1861). 
 
 The volume on the "Journey in Brazil" (1868) in joint 
 authorship with Mrs. Agassiz is a fascinating narrative 
 of exploration. 
 
 The conceptions which Agassiz held as to the most 
 essential aim of zoological study are well illustrated 
 in his autobiographical sketch, where he writes :' 
 
 "I did not then know how much more important it is to the 
 naturalist to understand the structure of a few animals, than 
 to command the whole field of scientific nomenclature. Since I 
 have become a teacher, and have watched the progress of stu- 
 dents, I have seen that they all begin in the same way; but 
 how many have grown old in the pursuit, without ever rising 
 to any higher conception of the study of nature, spending their 
 life ia the determination of species, and in extending scientific 
 terminology!" 
 
 It is not surprising, then, that under such influence the 
 older systematic studies should be replaced in large 
 measure by those of a morphological and embryological 
 nature. 
 
 The personal influence of Agassiz is still felt in the 
 lives of even the younger zoologists of the present day. 
 For the investigators of the present generation are for 
 the most part indebted to one or another of Agassiz 's 
 pupils for their guidance in zoological studies. These 
 pupils include his son Alexander Agassiz, Allen, Brooks, 
 Clarke, Fewkes, Goode, Hyatt, Jordan, Lyman, Morse, 
 Packard, Scudder, Verrill, Wilder, and others— leaders 
 in zoological work during the last third of the nineteenth 
 century. Through such men as these the inspiration of 
 Agassiz has been handed on in turn to their pupils and 
 from them to the younger generation of zoologists. 
 
 The essential difference between the work of Agassiz 
 and that of the American zoologists who preceded him 
 was in his power of broad generalizations. To him the 
 
406 A CENTURY OF SCIENCE 
 
 organism meant a living witness of some great natural 
 law, in the interpretation of which zoology was engaged. 
 The organism in its structure, in its development, in its 
 habits furnished links in the chain of evidence which, 
 when completed, would reveal the meaning of nature. Of 
 all Agassiz's pupils, probably William K. Brooks most 
 fittingly perpetuated his m.aster's ideals. 
 
 Period of Morphology and Embryolofjij, 1847-1870. 
 
 The new aspect of zoology which came as a result of 
 the influence of Agassiz characterized the zoological work 
 of the fifties and sixties, that is, until the significance 
 of the natural selection theory of Darwin and Wallace 
 became generally appreciated. 
 
 The work in these years and well into the seventies was 
 largely influenced by the morphological, embryological 
 and systematic studies of Louis Agassiz and his school. 
 The structure, development, and homologies of animals 
 as indicating their relationship and position in the 
 scheme of classification was prominent in the work of 
 this period. The adaptations of animals to their envi- 
 ronment and the application of the biogenetic law to the 
 various groups of animals were also favorite subjects 
 of study. 
 
 The most successful investigators in this period on the 
 different groups of animals include: — Louis Agassiz on 
 the natural history and embryology of coelenterates and 
 turtles ; A. Agassiz, embryology of echinoderms and 
 worms; H. J. Clark, embryology of turtles and syste- 
 matic papers on sponges and coelenterates; E. Desor, 
 echinoderms and embryology of worms; C. Girard, 
 embryology, worms, and rep'tiles ; J. Leidy, protozoa, 
 coelenterates, worms, anatomy of moUusks ; W. 0. Ayres 
 and T. Lyman, natural history of echinoderms ; McCrady, 
 development of acalephs ; W. Stimpson, marine inverte- 
 brates ; A. E. Verrill, coelenterates, echinoderms, worms ; 
 A. Hyatt, evolutionary theories, bryozoa and mollusks; 
 Pourtales, deep sea fauna ; C. B. Adams, A. and W. G. 
 Binney, Brooks, Carpenter, Conrad, Ball, Jay, Lea, 
 S. Smith, Tryon, mollusks; E. S. Morse, brachiopods, 
 mollusks ; J. D. Dana, coelenterates and Crustacea ; Kirt- 
 
A CENTURY OF ZOOLOGY IN AMERICA 407 
 
 land, Loew, Edwards, Hagen, Melsheimer, Packard, 
 Riley, Scudder, Walsh, insects; Gill, Holbrook, Storer, 
 fishes; Cope, evolutionary theories, fishes and amphibia; 
 Baird, reptiles and birds ; J. A. Allen, amphibia, reptiles 
 and birds; Brewer, Cassin, Coues, Lawrence, birds; 
 Andubon, Bachman, Baird, Cope, Wilder, mammals. 
 
 The progress of ornithology in the United States pre- 
 vious to 1876 is well described in a paper by J. A. Allen in 
 the American Naturalist (10, 536, 1876). A sketch of the 
 early history of conchology is given by A. AV. Tryon in 
 the Journar(33, 13, 1862)': 
 
 Jeffries Wjonan was the most prominent comparative 
 anatomist of this period. His work includes classic 
 papers on the anatomy and embryology of fishes, 
 amphibia, and reptiles. 
 
 Zoology in the American Journal of Science, 
 184:6-1870. 
 
 The fifty volumes of the second series of the Journal, 
 including the years 1846 to 1870, cover approximately 
 this period of morphology and embryology. During this 
 period the Journal occupied a very important place in 
 zoological circles, for J. D. Dana was for most of this 
 period the editor-in-chief, while Louis Agassiz and Asa 
 Gray were connected with it as associate editors. More- 
 over, in 1864 one of the most promising of Agassiz 's 
 pupils, Addison E. Verrill, was called to Yale as pro- 
 fessor of zoology and was made an associate editor 
 in 1869. 
 
 In the Journal, therefore, may be found, in its original 
 articles, together with its reports of meetings and 
 addresses and its reviews of literature, a fairly complete 
 account of the zoological activity of the period. The 
 most important zoological researches, both in Europe 
 and America, were reviewed in the bibliographic notices. 
 
 The most important series of zoological articles are by 
 Dana himself. As his work on the zoophytes and Crus- 
 tacea of the U. S. Exploring Expedition continued, he 
 published from time to time general summaries of his 
 conclusions regarding the relationships of the various 
 groups. Included among these papers are philosophical 
 essays on general biological principles which must have 
 
408 A CENTURY OF SCIENCE 
 
 had much influence on the biological studies of the time, 
 and which form a basis for many of our present concepts. 
 The importance of these papers warrants the list being 
 given in full. The titles are here in many cases abbre- 
 viated and the subjects consolidated. 
 
 General views on Classification, 1, 286, 1846. 
 
 Zoophytes, 2, 64, 187, 1846 ; 3, 1, 160, 337, 1847. 
 
 Genus Astraea, 9, 295, 1850. 
 
 Conspectus crustaceorum, 8, 276, 424, 1849 ; 9, 129, 1850 ; 11, 
 268, 1851. 
 
 Genera of Gammaracea, 8, 135, 1849 ; of Cyclopacea, 1, 225, 
 1846. 
 
 Markings of Carapax of Crabs, 11, 95, 1851. 
 
 Classification of Crustacea, 11, 223, 425; 12, 121, 238, 1851; 
 13, 119 ; 14, 297, 1852 ; 22, 14, 1856. 
 
 Geographical distribution of Crustacea, 18, 314, 1854; 19, 6; 
 20, 168, 349, 1855. 
 
 Alternation of Generations in Plants and Radiata, 10, 341, 
 1850. 
 
 Parthenogenesis, 24, 399, 1857. 
 
 On Species, 24, 305, 1857. 
 
 Classification of Mammals, 35, 65, 1863 ; 37, 157, 1864. 
 
 Cephalization, 22, 14, 1856 ; 36, 1, 321, 440, 1863 ; 37, 10, 157, 
 184, 1864; 41, 163, 1866; 12, 245, 1876. 
 
 Homologies of insectean and crustacean types, 36, 233, 1863 ; 
 47 325 1894. 
 
 Origin of life, 41, 389, 1866. 
 
 Relations of death to life in nature, 34, 316, 1862. 
 
 Of the above, the articles on cephalization as a funda- 
 mental principle in the development of the system of 
 animal life have attracted much attention. The evidence 
 from comparative anatomy, paleontology, and embry- 
 ology alike supports the view that advance in the 
 ontogenetic as well as in the phylogenetic stages is cor- 
 related with the unequal growth of the cephalic region as 
 compared with the rest of the body. Dana shows that 
 this principle holds good for all groups of animals. His 
 homologies of the limbs of arthropods and vertebrates, 
 however, do not accord with more modern views. 
 
 Other papers on the same and allied topics were pub- 
 «Hshed by Dana in other periodicals. His most conspicu- 
 otj« zoological works, however, are his reports on the 
 Zoojrhytes and Crustacea of the United States Explor- 
 
A CENTURY OF ZOOLOGY IN AMERICA 409 
 
 ing Expedition, 1837-1842. The former consists of 741 
 quarto pages and 61 folio plates, describing over 200 new 
 species, while the Crustacea report, in two volumes, has 
 1620 pages and 96 folio plates, with descriptions of about 
 500 new species. Each of these remains to-day as the 
 most important contribution to the classification of the 
 respective groups. The relationships of the species, 
 genera and families were recognized with such remark- 
 able judgment that Dana's admirable system of classifi- 
 cation has remained the basis for all subsequent work. 
 
 Dana's critical reviews (25, 202, 321, 1858) of Agassiz's 
 "Contribution to the Natural History of the United 
 States" are among the most interesting of his philosoph- 
 ical discussions concerning the relationships of animals 
 as revealed by their structure, their embryology, and 
 their geological history. 
 
 The remaining zoological articles in this series cover 
 nearly the whole range of systematic zoology. Espe- 
 cially important are the articles by Verrill on coelenter- 
 ates, echinoderms, worms and other invertebrates. 
 
 In the years following the publication of Darwin's 
 Origin of Species in 1859 occur many articles on the 
 theory of natural selection. Some of the writers attack 
 the theory, whUe others give it more or less enthusiastic 
 support. 
 
 Experimental methods in solving biological problems 
 were little used at this time, although a few articles of 
 this nature appear in the Journal. Of these, a paper by 
 W. C. Minor (35, 35, 1863) on natural and artificial 
 fission in some annelids has considerable interest to-day. 
 
 Exploring Expeditions. 
 
 Of the important zoological expeditions the following 
 may be selected as showing their influence on American 
 Zoology : 
 
 The North Pacific Expedition, with William Stimpson 
 as zoologist, returned in 1856 with much new information 
 concerning the marine life of the coasts of Alaska and 
 Japan and manv new species of invertebrates. 
 
 In 1867-1869 the United States Coast Survey extended 
 its explorations to include the deep-sea marine life off 
 
410 A CENTURY OF SCIENCE 
 
 the sontlieastern coasts and Gulf of Mexico under the 
 leadership of Pourtales and As:assiz. 
 
 The Challens-er explorations"( 1872-1876) added greatly 
 to the knowledge of marine life off the American coast 
 as well as in other parts of the world. 
 
 The explorations of the United States Fish Commis- 
 sion succeeded those of the Coast Survey in the collection 
 of marine life off our coasts and in our fresh waters. 
 These have continued since 1872 and have yielded most 
 important results from both the scientific and economic 
 standpoints. 
 
 Under the charge of Alexander Agassiz the Coast Sur- 
 vey Steamer "Blake," in 1877 to iSSO, was engaged in 
 dredging operations in three cruises to various parts of 
 the Atlantic. The U. S. Fish Commission Steamer 
 "Albatross," also in charge of Agassiz, made three expe- 
 ditions in the tropical and other loarts of the Pacific in the 
 years from 1891 to 1905. The study of these collections 
 has added greatly to our knowledge of systematic zoology 
 and geographical distribution. The reports on some of 
 the groups are still in course of preparation. 
 
 Period of Evolution, 1S70-1890. 
 
 The time from 1870 to 1890 may be appropriately called 
 the period of evolution, for although it commences eleven 
 years after the publication of the Origin of Species, the 
 importance of the natural selection theory was but slowly 
 receiving general recognition. The hesitation in accept- 
 ing this theory was due in no small degree to the opposi- 
 tion of Louis Agassiz. After the acceptance of evolution, 
 although morphological and embryological studies con- 
 tinued as before, they were prosecuted with reference to 
 their bearing on evolutionary problems. 
 
 Following closely the methods which had produced so 
 much progress during the life of Agassiz, the field of 
 zoology was now occupied by a new generation, among 
 whom the pupils of Agassiz were the most prominent. 
 
 The teaching of biology at this time was also strongly 
 influenced by Huxley, whose methods of conducting lab- 
 oratory classes for elementary students were adopted in 
 most of our large schools and colleges. This placed 
 
/^^^^^^:,te<^^<^^ /^ifi^^i^^^^k:^ 
 
A CENTURY OF ZOOLOGY IN AMERICA 411 
 
 biology on the same plane with chemistry as a means for 
 training in laboratory methods and discipline, with the 
 added advantage that the subject of biology is much more 
 intimately connected with the student's everyday life and 
 affairs. 
 
 This increasing demand for instruction in biology and 
 the consequent necessity for more teachers brought an 
 increasing number of investigators into this field. 
 
 Conspicuous in this period was the work of E. D. Cope, 
 best known as a paleontologist, but whose work on the 
 classification of the various groups of vertebrates stands 
 preeminent, and whose philosophical essays on evolution 
 had much influence on the evolutionary thought of the 
 time. He was a staunch supporter of the Lamarckian 
 doctrine. Alpheus Hyatt also maintained this theory, 
 and brought together a great accumulation of facts in its 
 support. He thereby contributed largely to our knowl- 
 edge of comparative anatomy and embryology. A. S. 
 Packard, whose publications cover a wide range of 
 topics, was best known for his text-books of zoology and 
 his manuals on insects. 
 
 W. K. Brooks was a leading morphologist and embry- 
 ologist. S. P. Baird, for many years the head of the 
 United States Fish Commission, was the foremost 
 authority on fish and fisheries and is also noted for his 
 work on reptiles, birds and manraials. The man of 
 greatest influence, although by no means the greatest 
 investigator, was C. 0. Whitman. It is to him that we 
 owe the inception of the Marine Biological Laboratory, 
 the most potent influence in American zoology to-day; 
 the organization of the American Morphological Society, 
 the forerunner of the present American Society of Zoolo- 
 gists; and the establishment of the Journal of Morph- 
 ology. G. B. Goode was distinguished for his work on 
 fishes and for his writings on the history of science. 
 
 E. L. Mark, C. S. Minot, and Alexander Agassiz were 
 acknowledged leaders in their special fields of research — 
 Mark in invertebrate morphology and embryology, and 
 Minot in vertebrate embryology, while Alexander Agassiz 
 made many important discoveries in the systematic 
 zoology and embryology of marine animals, and to him 
 
412 A CENTURY OF SCIENCE 
 
 Ave owe in large measure our knowledge of the life in tlie 
 oceans of nearly all parts of the world. 
 
 The knowledge of the representatives of the different 
 divisions of the American fauna had now become suffi- 
 cient to allow the publication of monographs on the vari- 
 ous classes, orders and families. At this time also par- 
 ticular attention was given to the marine invertebrates 
 of all groups. 
 
 Of the many investigators working on the various 
 groups of animals at this time only a few may be men- 
 tioned. The protozoa were studied by Leidy, Clark, 
 Eyder, Stokes ; the sponges by Clark, Hyatt; the coelen- 
 terates by A. Agassiz, S. F. Clarke, Verrill; the echino- 
 derms by A. Agassiz, Brooks, Kingsley, Fewkes, Lyman, 
 Verrill; the various groups of worms by Benedict, 
 Eisen, Silliman, Verrill, Webster, Whitman; the mol- 
 lusks by A. and W. G. Binney, Tryon, Conrad, Dall, San- 
 derson Smith, Stearns, Verrill ; the Brachiopods by Ball 
 and Morse; the Bryozoa by Hyatt; the Crustacea by 
 S. I. Smith, Harger, Hagen, Packard, Kingsley, Faxon, 
 Herrick; the insects by Packard, Horn, Scudder, C. H. 
 Fernald, Williston, Norton, Walsh, Fitch, J. B. Smith, 
 Comstock, Howard, Riley and many others ; spiders by 
 Emerton, Marx, McCook ; tunicates by Packard and Ver- 
 rill; fishes by Baird, Bean, Cope, Gilbert, Gill, Goode, 
 Jordan, Putnam; amphibians and reptiles by Cope; 
 birds by Baird, Brewer, Cones, Elliott, Henshaw, Allen, 
 Merriam, Brewster, Ridgway; and the mammals by 
 Allen, Baird, Cope, Coues, Elliott, Merriam, Wilder. 
 
 Interest in the evolutionary theory continued to 
 increase and eventually developed into the morpholog- 
 ical and embryological studies which reached their cul- 
 mination between 1885 and 1890 under the guidance 
 of Whitman, Mark, Minot, Brooks, Kingsley, E. B. Wilson 
 and other famous zoologists of the time. In these years 
 the Journal of Morphology was established and the 
 American Morphological Society was formed. 
 
 The morphological, embryological and paleontological 
 evidences of evolution as indicated by homologies, devel- 
 opmental stages and adaptations were the most absorb- 
 ing subjects of zoological research and discussion. 
 
^^^ 
 
 ^^ r 
 
 ^^^4- 
 
A CENTURY OF ZOOLOGY IN AMERICA 413 
 
 Zoology in the American Journal of Science, 
 1870-191S. 
 
 The_ third series of tlie Journal (1870-1895), likewise 
 including fifty volumes, embraces this period of zoologi- 
 cal aptivitj^ in morphological and embrj^ological studies, 
 culminating with the inception of the modern experimen- 
 tal methods. 
 
 In this period also occurred the greatest progress in 
 marine systematic zoology, due to the explorations of the 
 United States Fish Commission off the Atlantic Coast. 
 The Journal had an important share in the zoological 
 development of this period also, for A. E. Verrill,\vho 
 was now an associate editor, was in charge of the collec- 
 tions of marine invertebrates. Consequently most of the 
 discoveries in this field were published in the Journal in 
 numerous original contributions by Verrill and his asso- 
 ciates. The explorations of the U. S. Fish Commission 
 Steamer "Albatross" are described from year to year by 
 Verrill, with descriptions of the new species of inverte- 
 brates discovered. 
 
 The numerous original contributions by Verrill on 
 subjects of general zoological interest as well as on those 
 of a systematic nature give this third series of the Jour- 
 nal much zoological importance. Verrill 's papers cover 
 almost the whole field of descriptive zoology, but are 
 mainly devoted to marine invertebrates. Those which 
 were originally contributed to the Journal or summarized 
 by him in his literature re\T.ews include the following 
 topics : 
 
 Sponges, 16, 406, 1878. 
 
 Coelenterates, 37, 450, 1864; 44, 125, 1867; 45, 411, 186, 46, 
 143, 1868; 47, 282, 1869; 48, 116, 419, 1869; 49, 370, 1870; 3, 
 187, 432, 1872 ; 6, 68, 1873 ; 21, 508, 1881 ; 6, 493, 1898 ; 7, 41, 
 143, 205, 375, 1899 ; 13, 75, 1902. 
 
 Ecliinoderms, 44, 125, 1867; 45, 417, 1868; 49, 93, 101, 1870; 
 2, 430, 1871; 11, 416, 1876; 49, 127, 199, 1895; 28, 59, 1909; 
 35, 477, 1913; 37, 483, 1914; 38, 107, 1914; £9, 684, 1915. 
 
 Worms, 50, 223, 1870; 3, 126, 1872. 
 
 Mollusks, 49, 217, 1870 ; 50, 405, 1870 ; 3, 209, 281, 1872 ; 5, 
 465, 1873; 7, 136, 158, 1874; 9, 123, 177, 1875; 10, 213, 1875; 
 
 26 
 
414 A CENTURY OF SCIENCE 
 
 12 236 1876; 14, 425, 1877; 19, 284, 1880; 20, 250, 251, 1880; 
 2, 74, 91, 1896; 3, 51, 79, 162, 355, 1897. „. ,,. ^o, 
 
 Crustacea, 44, 126, 1867; 48, 244, 430, 1869; 25, 119, 534, 
 
 A^sciclians, 1, 54, 93, 211, 288, 443, 1871; 20, 251, 1880 
 Dreda-ina: operations and marine fauna, 49, 129, 18^0; 2, ibi, 
 
 1871; 5, l" 98, 1873; 6, 435, 1873; 7, 38, 131, 405, 409, 498, 
 
 608 1874; 9, 411, 1875; 10, 36, 196, 1875; 16, 207, 371, 18/8; 
 
 17, 239 258, 309, 472, 1879 ; 18, 52, 468, 1879 ; 19, 137, 187, 20, 
 
 390 1880; 22, 292, 1881; 23, 135, 216, 309, 406, 1882; 24, 360, 
 
 477, 1882; 28, 213, 378, 1884; 29, 149, 1885. 
 
 Miscellaneous, 39, 221, 1865; 41, 249, 268, 1866; 44, 126, 
 
 1867; 48, 92, 1869; 3, 386, 1872; 7, 134, 1847; 10, 364, 1875; 
 
 16, 323, 1878; 20, 251, 1880; 3, 132, 135, 1897; 9, 313, 1900; 
 
 12, 88, 1901; 13, 327, 1902; 14, 72, 1902; 15, 332, 1903; 24, 
 
 179, 1907 ; 29, 561, 1910. 
 
 S. I. Smith describes the metamorphosis of the Crus- 
 tacea (3, 401, 1872; 6, 67, 1873), species of Crustacea (3, 
 373, 1872 ; 7, 601, 1874; 9, 476, 1875), and dredging opera- 
 tions in Lake Superior (2, 373, 448, 1871). In this series 
 occurs also a series of papers on comparative anatomy 
 and embrj'ology from tlie Chesapeake Zoological Labora- 
 tory in charge of W. K. Brooks. In the 39th and 40th 
 volumes of the third series (1890) occur several papers 
 on evolutionary topics by John T. Gulick (39, 21 ; 40, 1, 
 437) which have attracted much attention. 
 
 Before the end of this period, however, the Journal 
 was relieved from the necessity of publishing zoologi- 
 cal articles by the establishment of several periodicals 
 devoted especially to the various fields of zoology. We 
 find, therefore, but few exclusively zoological papers 
 after 1885, although articles of a general biological inter- 
 est and the reviews of zoological books continue. 
 ' In the fourth series of the Journal, beginning in 1896, 
 occur also a number of articles on systematic zoology by 
 Verrill and others and several papers having a general 
 biological interest. Brief reviews of a smaU number of 
 zoological books are still continued, but at the present day 
 the Journal, which played so important a part in the 
 early development of American zoology, has been given 
 over to the geological and physical sciences in harmony 
 with the modern demand for specialization. 
 
A CENTURY OF ZOOLOGY IN AMERICA 415 
 
 Period of Experiinental Hiology, since 1890. 
 
 Zoological studies remained in large measure observa- 
 tional and comparative until about 1890 when the experi- 
 mental methods of Roux, Drieseh and others came into 
 prominence. Interest then turned from the accumulation 
 of facts to an analysis of the underlying principles of 
 biological phenomena. The question now was not so 
 much what the organism does as how it does what is 
 observed, and this question could be answered only by 
 the experimental control of the conditions. These exper- 
 imental studies met with such remarkable success that in 
 a few years the older morphological studies were largely 
 abandoned, the Morphological Society changed its name 
 to the Society of Zoologists, and in 1904 the Journal of 
 Experimental Zoology was established. The experimen- 
 tal methods were applied to all branches of biological 
 science, and while it must be freely admitted that little 
 progress has been made toward an understanding of the 
 ultimate causes which underlie biological phenomena, a 
 great advance has been made in the elucidation of the 
 general principles involved. 
 
 Experimental embryology, histology, regeneration, 
 comparative physiology, neurology, cytology, and hered- 
 ity have in recent years successfully adopted an experi- 
 mental aspect and have made significant progress 
 thereby. Biology has now taken its place beside chem- 
 istry and physics as an experimental science. 
 
 The latest' great advance in biology has been in the field 
 of heredity. "The rediscovery of the Mendelian principles 
 of heredity in 1900 brought "to light the_ most important 
 generalization in biolo,gy in recent times. The new 
 "science of genetics is essentially the experim.ental study 
 of heredity. 
 
 We are" at the moment in the midst of an effort^ to 
 establish in biology a few relatively simple laws by using 
 for the purpose the vast accumulations of observational 
 data gathered in past vears, supplemented by such exper- 
 imental data as have been provided by these more recent 
 investigations. Such h^qootheses as have been formu- 
 lated are for the most part only tentatively held, for their 
 
416 A CENTURY OF SCIENCE 
 
 validity is generally incapable of a critical test. But 
 wherever such tests have been possible, the laws of math- 
 ematics, physics and chemistry are found applicable to 
 biological phenomena. 
 
 The number of investigators has now become so great 
 and their activities so prolific that the list and synopses 
 of the zoological publications each year cover upwards 
 of 1000 to 1500 pages in the International Catalogue of 
 Scientific Literature. 
 
 American Leadership.— Dnring the first half of the 
 century the progress of zoology in America remained dis- 
 tinctly" behind that of Europe. At the beginning of the 
 century the science was farthest developed by the French . 
 and English,..although Linna:'us was a Swede and took his 
 degree in Holland. "iTnder the influence of VartBaer and 
 his^ monumental treatise .on._enibi'yology (Ueber Entwick- 
 lungsgeschichte der Thiere, 1828), and supported later 
 by ithe great physiologist, Johannes ]Muller. _ whose ' ' Ph y- 
 siologie des Menschen" (1846) forms^'tEelDasis of moderir 
 physiol<3£;5^,^_HieGermajL-Sj^^ ahead and 
 
 eventually^iisuinecrfhe leadership in zoology, as in sev- 
 eral other branches of science. 
 
 In the latter half of the century the influence of the 
 German iiniversities dominated in a large measure the 
 zoological investigations in America. The reason for 
 this is partly due to the fact that many of our young 
 zoologists, after finishing their college course, com- 
 pleted their preparation for research by a year or more 
 at a German universitv. The more mature zoologists, 
 too, looked forward with keen anticipation to spending 
 their summer vacations and sabbatical years in research. 
 in a German laboratory or at the famous Naples station 
 in which the German influence Avas dominant. 
 
 With the rise of experimental biology since 1890, how- 
 ever, the American zoologists have shown so high a degree 
 of originality in devising experiments, so much skill in 
 performing them, and such keenness in analyzing the 
 results, that they have assumed the world leadership in 
 several of the special fields into which the science of 
 zoology is now divided. 
 
A CENTURY OF ZOOLOGY IN AMERICA 417 
 
 Siological Periodicals. 
 
 Perhaps in no better way can the progress of biology in 
 America be illustrated than by a brief survey of the 
 origin and development of the more important biological 
 journals. For it will be seen that these publications have 
 become more numerous and more specialized as the sci- 
 ence has advanced in specialization. 
 
 The early publications — which as is well known, treated 
 mainly of the birds, mammals and other vertebrates, and 
 of insects, Crustacea and shells — consisted mainly of sep- 
 arate books or pamphlets, published by private subscrip- 
 tion. After the establishment of the so-called Academies 
 of Science, or of Arts and Sciences, toward the end of 
 the eighteenth and in the first quarter of the nineteenth 
 century, the reports of the meetings began to be pub- 
 lished as periodical Journals, supported by the acade- 
 mies. In these publications, and in the Journal which 
 was founded at the same time, appear papers on all 
 branches of science, including zoology. As soon as 
 zoology in America assumed its modern aspects through 
 the influence of Louis Agassiz and his followers the 
 earliest strictly zoological journals were established. 
 
 It should be noted, however, that the journals of the 
 scientific and natural history societies were more or less 
 fully devoted to zoological topics according to the nature 
 of the activities of the members and correspondents. 
 After the establishment of the IMuseum of Comparative 
 Zoology by Louis Agassiz came the founding in 1863 of its 
 Bulletin and later its Memoirs. These publications have 
 continued to the present day as a standard of excellence 
 for the reports of zoological investigations. In con- 
 nection with the systematic work on mollusks, the Amer- 
 ican Journal of Conchology was established in 1865. 
 The American Naturalist was founded in 1867 by four of 
 Louis Agassiz 's pupils, Hyatt, Morse, Packard and Put- 
 nam. It was later edited by Cope as a leading periodical 
 for the publication of biological papers, particularly 
 those relating to evolution, and is at present devoted to 
 evolutionary topics. It is now in the 52d volume of its 
 new series. 
 
418 A CENTURY OF SCIENCE 
 
 With the awakened interest in comparative anatomy 
 and embryology came the need for an American journal 
 which should supply a means of publication for the 
 reports of researches accomplished by the increasing 
 number of workers in these fields. This need was fully 
 met by the establishment of the Journal of Morphology. 
 in 1887. This publication, now in its 30th volume, has 
 equalled the best European journals in the character of 
 its papers. A few years later (1891) came the Journal 
 of Comparative Neurology for the publication of investi- 
 gations relating to the morphology and physiology of the 
 nervous system and to nervous and allied phenomena in 
 all groups of organisms. Twenty-eight volumes of this 
 journal have been completed. The Zoological Bulletin 
 was started under the auspices of the Marine Biological 
 Laboratory in 1897 for the publication of papers of a less 
 extensive nature and which could be more promptly 
 issued than those in the Journal of Morphology where 
 elaborate plates were required. After two years the 
 scope of the Bulletin was enlarged to include botanical 
 and physiological subjects. The name was correspond- 
 ingly changed to the Biological Bulletin. Of this import- 
 ant periodical 33 volumes have been issued. 
 
 For the publication of papers on human and compara- 
 tive anatomy and embryology, the American Journal of 
 Anatomy was established in 1901, and is now in its 
 twenty-third volume. 
 
 Meanwhile the trend of zoological interest was toward 
 topics connected with the ultimate nature of biological 
 phenomena. The meaning of these phenomena could be 
 determined only by the experimental method. Researches 
 in this field became more prominent and the adequate 
 publication of the numerous papers required the estab- 
 lishment of a new journal in 1904. This was named the 
 Journal of Experimental Zoology. It immediately took' 
 its place in the front rank of American zoological period- 
 icals. Twenty-four volumes have been published. 
 
 In spite of the constantly increasing number of 
 journals, the science grew faster than the means of pub- 
 lication. So crowded did the American journals become 
 that long delays often resulted before the results of an 
 mvestigation could be issued. This condition was met in 
 
A CENTURY OF ZOOLOGY IN AMERICA 419 
 
 part by the sending of many papers to be published in 
 European journals (a necessity most discreditable to 
 American zoology) and in part by the establishment 
 ef additional means of publication. Of the latter the 
 Anatomical Record, now in its fourteenth volume, was 
 begun in 1906 for the prompt publication of briefer 
 papers on vertebrate anatomy, embryology and histology 
 and for preliminary reports and notes on technique. 
 
 During the past few years has come a great advance in 
 the experimental breeding of plants and animals. Prob- 
 lems in heredity and evolution have taken on a new 
 interest since the importance and validity of Mendel's 
 discovery have been recognized. To meet this develop- 
 ment of biology the journal Genetics was begun in 1916 
 for the publication of technical papers, while the Journal 
 of Heredity, modified from the American Breeders Maga- 
 zine, is devoted to popular articles on animal and plant 
 breeding, and Eugenics. 
 
 On the whole, the science of zoology is now assuming 
 a closer relation to practical affairs. Entomology, for 
 example, is now represented by the Journal of Economic 
 Entomology, of which 10 volumes have been issued since 
 
 1907. The Journal of Animal Behavior covers another 
 practical field of research. The Proceedings of the Soci- 
 ety for Experimental Biolog}^ and Medicine, starting in 
 1903, the American Journal of Physiology, and several 
 other publications cover the physiological field. The 
 Journal of Parasitology, established 1914, now in its 
 fourth volume, is devoted to the interests of medical 
 zoology. The Auk, now in the 34th volume of its neAV 
 series (42dof old series), is the official organ of the Amer- 
 ican Ornithologists Union and is devoted to the dissemi- 
 nation of knowledge concerning bird life. The Annals 
 of the Entomological Society of America, established in 
 
 1908, and now in its 10th volume, is one of several import- 
 ant entomological journals. The Nautilus, of which 28 
 volumes have been issued, is one of the more successful 
 journals devoted to conchology. This list might be 
 extended to include numerous other periodicals of import- 
 ance, both technical and popular, which have been of great 
 service in the various fields of biology. 
 
 In addition to these are the many volumes of syste- 
 
420 A CENTURY OF SCIENCE 
 
 matic papers in the Proceedings of the United States 
 National Museum, the practical reports in the Bulletin of 
 the United States Fish Commission, the vast literature 
 issued yearly by the various divisions of the United 
 States Department of Agriculture, Public Health Service 
 and other Governmental departments, while the list of 
 publications by scientific societies, museums, and other 
 institutes is constantly increasing and covers all fields of 
 biological research. 
 
 At the present time facilities for the publication of 
 research on any branch of zoology are as a rule entirely 
 adequate. For this highly satisfactory condition the 
 science is indebted to the support given five of its most 
 important journals by the Wistar Institute of Anatomy 
 and Biology. 
 
 Biological Associations. 
 
 An important light on the history of biology in Amer- 
 ica can be thrown b}^ a glance at the rise and development 
 of societies or associations for the report and discussion of 
 papers relating to that branch of science. In the first half 
 of the nineteenth century natural history societies were 
 formed in most cities and centers of learning. These 
 were very important factors in the promotion of scientific 
 research as well as in the diffusion of popular knowledge 
 of living things. The aims and activities of twenty-nine 
 such scientific societies, many of which were devoted 
 especiallv to natural historv, are described in one of the 
 early volumes of the Journal (10, 369, 1826). The Con- 
 necticut Academy of Arts and Sciences, dating from 1799, 
 the Philadelphia Acaden^ of Natural Sciences from 1812, 
 and the New York Lyceum of Natural History (in 1876 
 name changed to New York Academy of Sciences) from 
 1817 are among the oldest of those which still exist. 
 
 Of national institutions the American Philosophical 
 Society was founded in 1743, the American Academv of 
 Arts and Sciences in 1780, and the National Academy of 
 Sciences in 1863. 
 
 The American Association for the Advancement of 
 Science, with its thousands of members, now has separate 
 sections for each of the special branches of science. This 
 
A CENTURY OF ZOOLOGY IN AMERICA 421 
 
 great association was organized in 1848, as the successor 
 of the Association of American Geologists and Natural- 
 ists. This was itself a revival of the American Geolog- 
 ical Society which first-met at Yale in 1819. Its meetings 
 have given a great supjaort to the scientific work of the 
 country. 
 
 The American Society of Naturalists was founded in 
 1883. The original plan of the society was for the dis- 
 cussion of methods of investigation, administration and 
 instruction in the natural sciences, but its program is 
 now entirely devoted to discussions and papers of a broad 
 biological interest. It also arranges for an annual din- 
 ner of the several biological societies and an address 
 on some general biological topic. 
 
 In 1890, toward the end of the period in which morpho- 
 logical studies vrere being emphasized, the professional 
 zoologists of the eastern states founded the American 
 Morphological Societ3^ This association held annual 
 meetings during the Christmas holidays for the presenta- 
 tion of zoological papers. This name became less appro- 
 priate after a few years because of the gradual decrease 
 in the proportion of morphological inA^estigations owing 
 to the greater attention being directed to problems in 
 experimental zoologj^ and physiology. Consequently the 
 name was changed to the American Society of Zoologists. 
 To be eligible for membership in this society a person 
 must be an active investigator in some branch of zoology, 
 as indicated by the published results. 
 
 The American Association of Anatomists includes in 
 its membership investigators and teachers in compara- 
 tive anatomy, embryology, and histology as well as in 
 human anatomy. Many professional zoologists and 
 experimental biologists present their papers before this 
 society, or at the meetings of the American Physiological 
 Society. The Entomological Society of America and the 
 American Association of Economic Entomologists are 
 large and active societies. 
 
 These national societies have been of great service in 
 fostering a high standard of zoological research. A still 
 more important service, though generally less conspicu- 
 ous, is rendered by the journal clubs in connection with 
 all the larger zoological laboratories, and by local scien- 
 
422 A CENTURY OF SCIENCE 
 
 tific societies wliicli are now maintained in all the larger 
 centers of learning throughout the country. There are 
 also specific societies for some of the different fields of 
 biological work. 
 
 ' Siological Stations. 
 
 No insignificant factor in the development of biological 
 science has been the establishment of biological stations 
 where investigators, teachers and students meet in the 
 Summer vacation for special studies, discussions and 
 research. The most successful of these laboratories have 
 been located on the seashore and here the study of marine 
 life in Summer supplements the work of the school or uni- 
 versity biological courses. The famous Naples Station 
 was foundedin 1870, and was shortly after followed by 
 several others. Similar biological stations are now sup- 
 ported on almost every coast in Europe and in several 
 inland localities. 
 
 The first such American school was established by 
 Louis Agassiz at the island of Penikese on the coast of 
 Massachusetts in 1873, succeeding his private laboratory 
 at Nahant. During that Summer more than forty stu- 
 dents gained enthusiasm for the work of future years. 
 Unfortunately the laboratory so auspiciously started was 
 of brief duration, for the death of Agassiz occurred in 
 December of the same year, and the laboratory was dis- 
 continued at the end of the following Summer. Shortly 
 afterward Alexander Agassiz equipped a small private 
 laboratory at Newport, Rhode Island, and W. K. Brooks 
 established the Chesapeake Bay Zoological Laboratory. 
 
 At this time the United States Pish Commission was 
 engaged under the direction of Spencer F. Baird in a 
 survey of the marine life of the waters off the Eastern 
 Coast. Between 1881 and 1886 the Commission estab- 
 lished the splendidly equipped biological station at 
 Woods Hole, Massachusetts. Both here and at the Fish 
 Commission Laboratory at Beaufort, North Carolina, 
 much work in general zoology as well as in economic prob- 
 lems is accomplished. These laboratories are designed 
 particularly for specialists engaged in researches "con- 
 nected with the work of the Fish Commission. 
 
A CENTURY OF ZOOLOGY IN AMERICA 423 
 
 A need was soon felt for a marine laboratory along- 
 broader lines, and one available to the students and 
 teachers of the schools and colleges. To meet these 
 requirements the "Woods Hole Marine Biological Labora- 
 tory was started in 1887, as the successor to an earlier 
 laboratory at Annisquam, and has since become a great 
 Summer congress for biologists from all parts of the 
 country. It is safe to say that no other institution has 
 been of equal service in securing for biology the high 
 plane it now occupies in American science. The leading 
 spirit in the establishment of this laboratory and its 
 director for many years was Charles 0. AVhitman. 
 
 Successful marine laboratories are located also at Cold 
 Spring Harbor, Long Island; at Harpswell, Maine; and 
 at Bermuda. The Carnegie Institution maintains a lab- 
 oratory at Tortugas Island, Florida, for the investigation 
 of tropical marine life. 
 
 On the Pacific Coast marine laboratories are located 
 at Pacific Grove and at La Jolla, California, and at Fri 
 day Harbor, "Washington. Several other biological lab- 
 oratories are open each Summer on our coasts, as well as 
 a number of fresh-water laboratories on the interior 
 lakes. There are also several mountain laboratories. 
 The influence of these laboratories on American biology f 
 is immeasurable. 
 
 Natural History Museums. 
 
 Museums of Natural History or "Cabinets of Natural 
 Curios" as they were sometimes called, were established 
 in the first half of the nineteenth century in connection 
 with the various natural history societies. These were 
 of much service in stimulating the collection of zoological 
 "specimens" and in arousing a popular interest in 
 natural history. 
 
 The zoological museum of earlier daj^s consisted of 
 rows on rows of systematically arranged sioecimens, each 
 carefully labelled with scientific name, locality, date of 
 collection and donor — much like the pages of a catalogue. 
 All this has now been changed ; the bottles of specimens 
 have been relegated to the storeroom, and the great 
 plate glass cases of the modern museum represent indi- 
 vidual studies in the various fields of modern zoological 
 
 > 
 
424 A CENTURY OF SCIENCE 
 
 research, or individual chapters in the latest biological 
 text-books. Often the talent of the artist and the skill 
 of the taxidermist are cunningly combined to produce 
 most realistic bits of nature. 
 
 The United States National Museum, the American 
 Museum of Natural History, the Field Columbian Museum 
 and the Museum of Comparative Zoology are among the 
 finest museums of the world, while many of the states, 
 cities, and universities maintain public museums as a 
 part of their educational systems. 
 
 Systematic Zoology and Taxonomy. 
 
 The work in systematic zoology is now mainly carried 
 on by specialists in relatively small groups of animals. 
 This is necessitated both by the increasingly large num- 
 ber of species known to science and by the completeness 
 and exactness with which species must now be defined. 
 The majority of systematic workers are now connected 
 with museums where the large collections furnish mate- 
 rial for comparative studies. 
 
 Prominent in this field is the United States National 
 Museum, the publications of which are mainly taxonomic 
 and zoogeographic, and cover every group of organism. 
 The adequacy of this great museum for such studies 
 may be illustrated by the collection of mammals. This 
 museum has the types of 1135 of the 2138 forms (includ- 
 ing species and subspecies) of North American mammals 
 recognized in Miller's list,'' and less than 200 forms lack 
 representatives among the 120,000 specimens of mam- 
 mals. Systematic monographs of several of the orders 
 of mammals have been published. 
 
 Systematic study of the birds has brought the number 
 of species and subspecies known to inhabit North and 
 Middle America to above 3000. The most comprehen- 
 sive systematic treatise is the still incomplete report of 
 Eidgeways of which seven large volumes have already 
 been issued. 
 
 On the reptiles, the most complete monograph is that 
 by Cope" entitled "The Crocodilians, Lizards and Snakes 
 of North America." 
 
 The Amphibia have also been studied by Cope, whose 
 
A CENTURY OF ZOOLOGY IN AMERICA 425 
 
 report on the Batrachia of Nortli America^ is the stand- 
 ard taxonomic work. 
 
 The most comprehensive systematic work on iishes is 
 the "Descriptive Catalogue of the Fishes of North and 
 Middle America" by Jordan and Evermann.*^ 
 
 The invertebrate groups liave been in part similarly 
 monographed by the members of the U. S. National 
 Museum staff and others, and further studies are in prog- 
 ress. Other taxonomic monographs published by this 
 museum include the various groups of animals from 
 many different parts of the world. 
 
 A number of the larger State, municipal, and university 
 museums publish bulletins on special groups represented 
 in their collections as well as articles of general zoological 
 interest. 
 
 Expeditions, subsidized by museum and private funds, 
 are from time to time sent to various parts of the world 
 and their results are often published in sumptuous 
 manner. 
 
 The total number of living species of animals is 
 unknown, but considering that about a quarter of a mil- 
 lion new species have been described during the past 
 thirty years, it is probable that several million species are 
 in existence to-day. More than half a million have been 
 described. These are probably but a small fraction of 
 the number that have existed in past geological ages. 
 
 Thus, in spite of all the work that has been done in sys- 
 tematic zoology and as the number of known species con- 
 tinues to increase, there still remain many groups of 
 animals, some of Avhich are by no means rare or minute, 
 in which probably only a small proportion of the species 
 are as yet capable of identification. 
 
 It is only since the publication of Ward and Wliipple 's 
 "Fresh- water Biology" within the past year that the 
 amateur zoologist could hope to find even the names of 
 all the organisms which may be collected from a single 
 pool of water. And in many cases he will still meet with 
 disappointment, for many of our protozoa and other 
 fresh-water organisms have not yet been described as 
 species. 
 
 During the past few years there has been a tendency on 
 
43G A CENTUEY OF SCIENCE 
 
 the part of some of our biologists engaged in experimen- 
 tal work to disparage the studies of the systematists. It 
 must be granted, however, that both lines of work are 
 essential to the sound development of zoological science, 
 for experimental investigations in Avhich the accurate 
 dia.gnosis of species is ignored always result in confusion. 
 
 Ecology. — The marvelous modifications in structure 
 and instincts by which the various animals are adapted 
 to their surroundings now forms a special topic in biolog- 
 ical research and one of the most fascinating. The adap- 
 tations in habitat, time, behavior, appearance and even 
 in structure are found capable of a certain individual 
 modification when studied experimentally. 
 
 Zoogeograpliy. — Closely associated with systematic 
 zoology, and indeed a part of the subject in its broader 
 sense, is the study of the geographical distribution of 
 animal species and larger groups. 
 
 Paleontology. — The geological succession of organisms 
 embraces a field where zoologist and geologist meet. 
 The wonderful progress made by American investiga- 
 tors is well described in the preceding chapters on His- 
 torical Geology and Vertebrate Paleontology, 
 
 Bio^netry. 
 
 Since Darwin's theory of evolution postulated the 
 origin of new species by means of natural selection, it 
 was obviously necessary in order to apply a critical test 
 to determine the precise limits of a species. It w^as, 
 therefore, proposed to subject a given species to a strict 
 examination by the application of statistical methods to 
 determine the range of variation of its members and the 
 extent to which the species intergrades with others. 
 Other problems, particularly those concerning heredity, 
 were treated in similar manner. This branch of biolog- 
 ical science was particularly developed by the English 
 School, led by Sir Francis Galton, followed by Karl 
 Pearson and William Bateson. 
 
 In America the methods of biometrv have been utilized 
 extensively by Charles B. Davenport, Raymond Pearl, H. 
 S. .lennmgs and others in the solution" of problems in 
 genetics and evolution. Their work shows the great 
 
A CENTURY OF ZOOLOGY IN AMERICA 427 
 
 value of critical statistical analysis in the interpretation 
 of biological data. A thorough training in mathematics 
 is now found to be hardlj^ less important for the biologist 
 than is a knowledge of physics and chemistry, for the 
 science of biometry has become one of the most important 
 adjuncts to the study of genetics. 
 
 Comparative Anatomy and Emhryoloyt], 
 
 Comparative Anatomy. — Upon the foundations laid 
 down by Cuvier a century ago the present elaborate 
 structure of comparative anatomy of animals, both verte- 
 brate and invertebrate, has been developed. Vast as is 
 the present accumulation of facts and theories many 
 important problems still await their solution. Jeffries 
 Wyman was long a leader in this field, where many 
 workers are now engaged. 
 
 Embryology. — The embryological studies, so bril- 
 liantly begun by Von Baer early in the nineteenth cen- 
 tury, are still in progress. They have now been extended 
 to the groups more difficult of investigation and into the 
 earliest stages of fertilization and implantation in the 
 mammals. Artificial cultural methods have yielded 
 important results. Louis and Alexander Agassiz, Mark, 
 Minot, Brooks, Whitman, Conklin and E. B. Wilson have 
 taken prominent parts in this work. 
 
 In the early nineties embryological studies were 
 directed to the arrangement of cells in the dividing egg, 
 and there was much discussion of "cell lineage" in 
 development. Valuable as were these studies they threw 
 comparatively little light on the general problems of 
 evolution. 
 
 Experimental Embryology. — A more fertile field, 
 developed at the same period and a little later, was found 
 in experimental embryology. The discoveries made by 
 Driesch and others in shaking apart the cells of the divid- 
 ing egg or by destroying one or more of these cells gave 
 a new Insight into the potency of cells for compensatory 
 and regenerative processes. These studies attracted 
 many able investigators, who made still further advance 
 by subjecting the germ cells, developing eggs, embryos, 
 
to 
 
 428 A CENTURY OF SCIENCE 
 
 and developing organs to a great variety of artificial con- 
 ditions. 
 
 Artificial Parthenogenesis. — Another question concerns 
 the nature of the process of fertilization and the agencies 
 which cause the fertilized egg to develop into an embryo. 
 In 1899 Jacques Loeb succeeded in causing development 
 in unfertilized sea-urchin eggs by subjecting them to con- 
 centrated sea water for a period and then returning them 
 to their normal environment. To this promising field of 
 experimental work came many of the foremost biologists 
 both in America and Europe. It was soon found that 
 the eggs of most groups of animals except the higher 
 vertebrates could be made to develop into more or less 
 perfect embrj^os and larval forms by treatment with a 
 great variety of chemical substances, by increased tem- 
 perature, by mechanical stimuli and by other means. 
 This artificial parthenogenesis, as it is called, has also 
 been successful in plants (Fucus), and recently Loeb has 
 reared several frogs to sexual maturity by merely 
 puncturing with a sharp needle the eggs from which they 
 were derived. Loeb, then, maintains that "the egg is the 
 future embryo and animal ; and that the spermatozoon, 
 aside from its activating effect, only transmits Mendelian 
 characters to the egg.'^'-^ 
 
 Further experimental analyses of the nature of the fer- 
 tilization mechanism have recently been made by Mor- 
 gan, Conklin, F. R. Lillie, and others. 
 
 Germinal Localisation. — The question as to whether the 
 egg contains localized organ-forming substances has been 
 studied experimentally particularly by means of the cen- 
 trifuge. The results indicate that neither of the older 
 opposing theories of "performation" or "epigenesis" is 
 applicable to all eggs, but that in certain organisms the 
 eggs possess a well-marked differentiation while in 
 others each part of the egg is essentially, although prob- 
 ably not absolutely, equipotential. 
 _ The Germplasm Cycle. — Since Weismann's postula- 
 tion of the independence of soma and germplasm in 1885 
 many attempts have been made to trace the path of the 
 hereditary sul)stance from one generation to the next. 
 A recent book by Hegner'" summarizes the success 
 attamed m various groups of animals. 
 
A CENTURY OF ZOOLOGY IN AMERICA 429 
 
 Cytology. 
 
 Another important field of investigation which has 
 attracted many workers is that wliicli pertains to the life 
 of the cell — the science of cytology. Although the cell- 
 theory was established as early as 1839, little advance 
 was made in this subject in America before 1880. Since 
 that time, however, Americans have been so successful in 
 cytological discoveries that they are now among the 
 world's leaders in this field. 
 
 These studies have been followed along both descrip- 
 tive and experimental lines. The most prominent of the 
 early workers in this field are E. L. Mark and E. B. Wil- 
 son. Mark's description of the maturation, fecundation, 
 and segmentation of the egg is the most accurate and 
 complete of the early cytological studies. Wilson's 
 discoveries concerning the details of fertilization and 
 his "Atlas of Fertilization and Karyokinesis," pub- 
 lished in 1895, have now become classic. Wilson, too, 
 has published the only American text-book on cytology ,^^ 
 and has more recently taken the lead in studies con- 
 cerning the relation between the chromosomes and sex. 
 Besides Wilson, Montgomery, Mark, McClung, Morgan, 
 Miss Stevens, Conklin and their associates and students 
 have now furnished conclusive evidence that the sex of 
 an organism is determined by, or associated with, the 
 nuclear constitution of the fertilized egg. This consti- 
 tution is moreover sho^vn to be dependent upon the chro- 
 mosomes received from the germ cells. 
 
 This explanation is in strict accordance with the results 
 of experimental breeding. It is also quite in harmony 
 with the Mendelian law of inheritance, and in fact forms 
 one of the strongest supports for the view that all Men- 
 delian factors are resident in the chromosomes. Recent 
 work has also discovered the mechanism which governs 
 the complicated conditions of sex which occur in those 
 animals which exhibit alternating sexual and parthenp- 
 genetic generations. These remarkable processes are in 
 all cases found to depend upon a definite distribution of 
 the chromosomes. 
 
 Other recent experimental work has shown that while 
 the sex is thus normally determined in the fertilized egg, 
 
 27 
 
430 A CENTUEY OF SCIENCE 
 
 it is in some animals not irrevocabh^ trsed, and the normal 
 effect of tlie sex chromosomes may be inhibited by 
 abnormal conditions in the developing embryo, as is 
 demonstrated by the recent work of Lillie and others. 
 
 The cytological basis for Mendelian inheritance has 
 been very extensivclj^ studied by Morgan and his pupils 
 in connection with their work on inheritance in the com- 
 mon fruit fly Drosopliila. The evidence supports Weis- 
 mann's earlier hj-pothesis that the chromosomes are the 
 bearers of the herital)le factors, and that these are 
 arranged in a series in the different chromosomes. This 
 theory is shown to be in such strict accord with both the 
 cytological studies and the results of experimental breed- 
 ing that Morgan has ventured to indicate definite points 
 in particular chromosomes as the loci of definite heri- 
 table factors, or genes. 
 
 Confirmation of this view is furnished by the behavior 
 of the so-called sex-linked characters, the genes for which 
 are situated in the same chromosome as that which 
 carries the sex factor. Many ingenious breeding experi- 
 ments indicate further that all the hereditary characters 
 in DrosopJiila are borne in four great linkage groups 
 corresponding with the four pairs of chromosomes which 
 the cells of this fly possess. 
 
 Comparative Physiology, 
 
 None of the experimental fields has been of greater 
 importance in zoological progress than that which con- 
 cerns the functions of the various organs. Without this 
 companion science morphology and comparative anatomy 
 would have become unintelligible. American investiga- 
 tors, among whom G. H. Parker stands prominent, have 
 taken a leading part in this field also. 
 
 Neurology.— T\\Q physiological analysis of the com- 
 ponents of the nervous system, both in vertebrates and 
 invertebrates, is another important branch of experimen- 
 tal biology The 28 volumes of the Journal of Compara- 
 tive Neurology attest the large influence that American 
 mTOstigators have had m the development of this science 
 
 Ee^r/enerai^wn.—Experimental studies on the powers 
 of regeneration m plants and animals have been made 
 from the earliest times. During the past few years how 
 
A CENTURY OF ZOOLOGY IN AMERICA 431 
 
 ever, there lias been made a concerted attempt to analyze 
 the factors which determine the amount and rate of 
 regeneration. Much jDrogress has been made toward the 
 postulation of definite laws applicable to the re,c;-enerative 
 processes of the parts of each orsjanism. The critical 
 analyses of Morgan, Loeb and Child have been particu- 
 larly stimulating. 
 
 Tissue Culture. — Another line of experimental work 
 which has been developed within the past few years by 
 Harrison, Carrell, and others is the culture of body 
 tissues in artificial media. These experiments have 
 included the cultivation in tubes or on glass slides of the 
 various tissues of numerous species of animals. They 
 have yielded much information regarding the structure, 
 growth and multiplication of cells, the formation of tis- 
 sues, and the healing of wounds. 
 
 Trans plant ation and Grafting. — Closely associated 
 experiments consist in the transplantation of organs or 
 other portions of the body to abnormal positions, to the 
 bodies of other animals of the same species or of other 
 species. In this way much has been learned about the 
 potentiality of organs for self-differentiation, for regula- 
 tion, for regeneration and for compensatory adaptations. 
 The experiments have shown, further, the independence 
 of soma and germplasm and have revealed the nature of 
 certain organs whose functions were previously obscure. 
 
 Tropisms and Instincts. — Another field of experimen- 
 tal biology concerns the analysis of behavior of organ- 
 isms in response to various forms of stimuli. These 
 studies are being prosecuted on all groups of organisms, 
 including the larval stages of many animals, and are 
 yielding most remarkable results. The success in this 
 field of research is largely due to stimulating influence of 
 Jacques Loeb, Parker, Jennings, and their co-workers. 
 
 Biological Chemistry. — Still another experimental field 
 which has developed into one of the most important of 
 the biological sciences relates to the fundamental^ chem- 
 ical and physical changes which underlie all organic phe- 
 nomena. A knowledge of both physiological and physi- 
 cal chemistry is to-day essential for all advanced 
 biological work. The peculiar nature of life itself, of 
 growth, disease, old-age, degeneration, death and dissolu- 
 
432 A CENTURY OF SCIENCE 
 
 tion are presumably only manifestations of chemical and 
 physical laws. The ultimate goal of all experimental 
 biology, therefore, will be reached only when the basic 
 physico-chemical properties of life are understood. At 
 that time only will the perennial controversy between 
 vitalism and mechanism be ended. 
 
 Economic Zoology. 
 
 A moment's reflection will show that economic 
 biology is the most essential of all sciences to the human 
 welfare and progress. For man's relation to his envi- 
 ronment is such that the penalty for ignorance or neg- 
 lect of the biological principles involved in the struggle 
 for existence quickly overwhelms him with a horde of 
 parasites or other enemies. 
 
 It is only by the intelligent application of biological 
 knowledge that our food supplies, our forests, our domes- 
 ticated animals and our bodies can be protected from the 
 ever ravenous organisms which surround us. 
 
 The losses to food supplies and other products by 
 insects alone amounts to 100 millions of- dollars a month 
 in the United States. And the parasites cause losses in 
 sickness and premature deaths each year of many mil- 
 lions more. Then there are the destructive rodents and 
 other animals which add largely to our burdens of sup- 
 port. These enemies next to wars and fungi are the most 
 destructive agencies on earth. Could they but be elim- 
 inated man's struggle against opposing forces would be 
 in large measure overcome. The results of recent work 
 in economic zoology, both in regard to the destruction of 
 enemies and protection of useful mammals, birds and 
 fishes, furnish a bright outlook for the future. 
 
 Protozoology. — Partly as an experimental field for the 
 solution of general biological problems and partly 
 because of its practical applications the study of protozoa 
 has now developed into a special science. 
 
 The results of the investigations of Calkins, Woodruff, 
 Jennings and others have greatly supplemented our 
 understanding of the signification of such important 
 biological phenomena as reproduction, sexual differen- 
 tiation, conjugation, tropisms, and metabolism. 
 
A CENTURY OF ZOOLOGY IN AMERICA 433 
 
 From an economic standpoint tlie protozoa have 
 recently been shown to be of the greatest importance 
 because of the human and animal diseases for which they 
 are responsible. 
 
 Parasitology. — The animal parasites of man, domesti- 
 cated animals and plants include numerous species of 
 protozoa, worms, and insects. Together with the bac- 
 teria and a few higher fungi they cause all communicable 
 diseases. When we consider that not only our health 
 but also our entire food supply is dependent upon the 
 elimination of these organisms we must admit that para- 
 sitology is the most important economically of all the 
 sciences. 
 
 The reports of the investigations of Stiles and his 
 associates in the Hygienic Laboratory and of Ransom 
 and his staff in the Bureau of Animal Industry are widely 
 distributed by the federal government. The systematic 
 studies so ably begun by Joseph Leidy in the middle of 
 the last century have been continued by Ward, Linton, 
 Pratt, Curtis and others on the parasites of many groups 
 of animals. 
 
 Economic Entomology. — Another extremely important 
 biological science, the practical applications of which are 
 second only to those of parasitology in importance, is 
 entomology. In the last few years economic entomology 
 has exceeded any of the other branches of biology in the 
 number of its investigators. The American Association 
 of Economic Entomologists has a membership of about 
 five hundred. The work of most of these is supported by 
 appropriations from the State and federal governments, 
 and the results of their investigations are widely 
 published. 
 
 It is now well known that some of the protozoon par- 
 asites are conveyed from man to man only through 
 the bites of insects. The local eradication of several 
 of our most fatal diseases has recently been brought 
 about by the application of measures to destroy such 
 insects. This is the greatest triumph of economic 
 zoology. 
 
 Economic Ichthyology. — The U. S. Fish ^Commission 
 has for many years been actively engaged in investiga- 
 tions on the food fishes, including methods for increasing 
 
434 A CENTURY OF SCIENCE 
 
 the food supply by suitable protection and artificial 
 propagation. The work includes also edible and other- 
 wise useful mollusks and crustacea. Their marine and 
 fresh-water laboratories have also been of great service 
 to general biological science. 
 
 Economic Ornithology and Mammalogy. — In addition 
 to the local bird clubs and the American Ornithologists 
 Union for the study and preservation of bird and mam- 
 mal life, the Bureau of Biological Survey has_ for some 
 years conducted investigations on the economic import- 
 ance of the various species. The publications of this 
 Bureau are of great value both in determining the 
 economic status of our birds and mammals, and also m 
 recommending means for the protection of the beneficial 
 species and the destruction of the injurious. Several of 
 the States issue similar publications. 
 
 Genetics. 
 
 One of the most interesting chapters in biology relates 
 to the development of the modern science of heredity, 
 or genetics. 
 
 Previous to the year 1900, when the Mendelian princi- 
 ple of inheritance was re-discoA'ered, the relative import- 
 ance of heredity and of environment in the development 
 of an organism was little understood. It is true that 
 Weismann had insisted on the independence of soma and 
 germplasm some years earlier (1883), but the body of, 
 the individual was still generally considered the key to 
 its inheritance. 
 
 The recognition of the general application of IMendel's 
 discovery gave a great impetus to experimental breeding 
 both in plants and animals. Wliile heretofore it had been 
 necessary to depend upon the somatic characters as evi- 
 dence of the hereditary constitution of an individual, it 
 now became possible, knowing the hereditary constitution 
 of the parents of any pair of individuals, to predict with 
 almost mathematical certainty the characters of their 
 possible offspring. 
 
 In general, the laws of possible chance combinations of 
 any group of characters determine the probabilitv of any 
 particular offspring possessing one or many of those 
 
A CENTURY OF ZOOLOGY IN AMERICA 435 
 
 cliaracters. The physical basis for sucli Mendelian 
 inheritance is evidently the chance combinations of 
 chromosomes which result from the processes of matura- 
 tion and union of the germ cells. 
 
 Certain limitations to the law are met with because 
 the relatively small number of chromosomes involves 
 linkage of genes, because of the occasional interchange of 
 groups of genes between homologous chromosomes, and 
 because the relative activity or potency of any partic- 
 ular gene may differ in different races, and, finally, 
 because the normal activity of any given gene may be 
 modified or inhibited by the action of other genes. It is 
 by no means certain, however, that all inheritance is 
 Mendelian, for there still remains much evidence that the 
 hereditary basis of certain characters may be resident in 
 the cytoplasm, rather than in the chromosomes. A 
 recent book by Morgan, Sturtevant, Miiller and Bridges 
 (1915), entitled "the mechanism of Mendelian heredity" 
 gives the cytological explanation of Mendelian inher- 
 itance. 
 
 Americans have from the first taken a leading part m 
 this field of research and have been quick to recognize its 
 practical applications to the improvement of breeds in 
 both animals and plants. This prominent position is 
 largely due to the experimental work of Castle, Daven- 
 port, Morgan, Jennings, Pearl, and their co-workers on 
 animals and that of East, Emerson, Davis, Hayes and 
 ShuU on plants. 
 
 The geneticist now realizes that the appearance of the 
 bodv (phenot^T^e) gives but little clue to the inheritance 
 (genotype). That two white flowers produce only pur- 
 ple offspring, or two white fowls only deeply colored 
 chickens, or ^that a pair of guinea pigs, one of which is 
 black and the other white, have only gray agouti off- 
 spring, while other apparently similar white flowers or 
 white animals produce offspring like themselves, is now 
 readily comprehensible and mathematically predictable. 
 
 The most important application of our newly acquired 
 knowledge of inheritance is in the improvement of the 
 human race. The wonderful opportunity in this direc- 
 tion must be apparent to all. The welfare of humanity 
 depends upon the immediate adoption of eugenic princi- 
 
436 A CENTUEY OF SCIENCE 
 
 pies. The Eugenics Kecord Office has secured many of 
 the essential data. 
 
 With the destruction of the world's best germ plasm 
 at a rate never equalled before, the outlook for the future 
 race would be appalling were it not for the hope that with 
 the advent of a righteous peace will come a realizationof 
 the necessity of applying these new biological discoveries 
 to improving the races of men. That the discoveries 
 have been made too late in the world's history to be of 
 such use to humanity must not be thought possible. 
 
 Evolution, 
 
 Previous to the publication of Darwin's ''Origin of 
 Species" in 18.59, American zoologists were generally 
 inclined toward special creation, in spite of the evidences 
 for evolution which had been presented by Erasmus Dar- 
 win, Buffon, Lamarck, and Geoffroy St. Hilaire. This 
 attitude of mind continued for some years after the pub- 
 lication of the natural selection theory of Darwin and 
 Wallace. This was in part due to the powerful influence 
 of Louis Agassiz and others who bitterly opposed the 
 Darwinian theory. The influence of Asa Gray in gaining 
 a general acceptance for this theory is explained in the 
 following chapter. 
 
 A modified Lamarckian doctrine was widely accepted 
 in the last quarter of the century, due largely to the 
 influence of Cope, Hyatt and Packard. The inheritance 
 of "acquired characters" demanded by this theory seems 
 incompatible with the discoveries of recent times, so that 
 "today the theory has few followers amongst trained 
 investigators, but it still has a popular vogue that is wide- 
 spread and vociferous. '"- 
 
 The origin of new varieties and species by accidental 
 and fortuitous modifications (mutations) of the germ- 
 Wlasm is now the most widely accepted theory of evolu- 
 lion. 
 
 Some of the most important discoveries regarding the 
 origin_ of new forms have been recently made by Morgan 
 and his pupils. From a stock of the common fruit fly 
 (Drosophila ampelophila) more than 125 new types have 
 arisen within six years. Each of these types breeds true. 
 "Each has arisen mdependently and suddenly. Every 
 
A CENTURY OF ZOOLOGY IN AMERICA 437 
 
 part of the body has been affected by one or another of 
 these mutations." To arrange these mutations arbi- 
 trarily into graded series would give the impression of an 
 evolutionary series, but this is directly contrary to the 
 known facts concerning their origin, for each mutation 
 "originated independently from the wild type." "Evo- 
 lution has taken place by the incorporation into the race 
 of those mutations that are beneficial to the life and 
 reproduction of the individual." This evolutionary 
 process is usually accompanied by the elimination of 
 those forms which have remained stable or which have 
 developed adverse mutations. 
 
 A question that is being vigorously debated at this 
 time concerns the possible effects of selection on the 
 hereditary factors. Are the genes fixed both qualita- 
 tively and quantitatively or does a given gene vary in 
 potency under different conditions and in different indi- 
 viduals? In the former case selection can only separate 
 the existing genes into separate pure strains. But if the 
 gene be quantitatively variable, then selection will result 
 in the establishment of new types. 
 
 Castle has long stoutly maintained the effect of such 
 selection, and his forces have recently been augmented by 
 Jennings. The experimental work now in process will 
 doubtless yield a decisive answer. 
 
 Conclusion. 
 
 A comparison of the simple descriptive natural history 
 of a century ago with the foregoing manifold develop- 
 ments of modern biology will indicate the wonderful 
 progress which has occurred during this period. The 
 path has led from the crude methods of the almost 
 unaided eye and hand to the applications of the most 
 delicate experimental apparatus. For the marvelous 
 success which zoology has attained has been possible only 
 by the skillful use of scalpel, microscope, microtome and 
 other mechanical devices and by the refined methods of 
 the chemist and physicist. 
 
 The central truth to which all these discoveries consist- 
 ently point is the unity and harmony of all biological 
 phenomena, and indeed of all nature. No longer does the 
 zoologist find any demarcated line separating his field of 
 
438 A CENTURY OF SCIENCE 
 
 research from that of the botanist or the chemist or even 
 of the physicist, for all the natural sciences obviously deal 
 with closely associated phenomena. The aim of the 
 future will be both to complete fields of study already 
 marked out and to derive a comprehensive explanation 
 of the general principles involved. 
 
 Notes, 
 
 • Proc. Biol. Soc. Washington, 3, 35, 1SS6. 
 
 "Ibid, 4, 9, 18S8. Both of these papers are reprinted in Ann. Eept. 
 Smithsonian Inst., 1897, U. S. Nat. Mus., Pt. 2, pp. 357-466, 1901. 
 
 'Louis Agassiz: his Life and Correspondence, by Elizabeth Carey 
 Agassiz, p. 145, 1885, 
 
 'List of North American Land Mammals in the United States National 
 Museum, 1911. Bull. 79, U. S. Nat. Mus., 1912. 
 
 "Birds of North and Middle America, Bull. 50, parts I-VII, U. S. Nat. 
 Mus., 1901-1916. 
 
 "Report U. S. Nat. Mus. for 1898, pp. 153-1270, 1900. 
 
 'Bull. 34, U. S. Nat. Mus., 1889. 
 
 'Bull. 47, parts I-IV, U. S. Nat. Mus., 1896-1900. 
 J. Loeb, The Organism as a "Waiole, p. 126, 1916. 
 "The Germ-cell Cycle in Animals, 1914. 
 1 Tt"^ '-^''" m" Development and Inheritance, 1896 ; second edition, 1900. 
 
 Morgan, T. H. A critique of the theory of evolution, p. 32, 1916. 
 
XIII 
 
 THE DEVELOPMENT OF BOTANY SINCE 1818 
 
 By GEORGE L. GOOD ALE 
 
 "Our Botany, it is true, has been extensively and 
 successfully investigated, hut this field is still rich, and 
 rewards every new research with some interesting dis- 
 covery." 
 
 SUCH are the words with which the sagacious and 
 far-sighted founder of tlie American Journal of 
 Science and Arts, in his general introduction to the 
 first volume, alludes to the study of plants. It is plain 
 that the editor, embarking on this new enterprise, appre- 
 ciated the attractions of this inviting field and sympa- 
 thetically recognized the good work which was being done 
 in it. It is not surprising, therefore, to find that he wel- 
 comed to the pages of his initial number contributions to 
 botany. 
 
 Early Botanical Works. — The collections of dried and 
 living North American plants, which had been carried 
 from time to time to botanists in Europe, had been 
 eagerly studied, and the results had been published in 
 accessible treatises. Besides these general treatises, 
 there had been issued certain works, wholly devoted to 
 the American Flora. Among these latter may be men- 
 tioned Pursh's "Flora" (1814) and Nuttall's "Genera" 
 (1818). There were also a few works which were rather 
 popular in their character, such as Amos Eaton's "Man- 
 ual of Botany for North America" (1817), and Bigelow's 
 "Collection of the Plants of Boston and environs" 
 (1814). These handbooks were convenient, and pos- 
 sessed the charm of not being exhaustive ; consequently 
 a botanist, whether professional or amateur, was stimu- 
 lated to feel that he had a good chance of enriching the 
 list of species and adding to the next edition. 
 
UO A CENTURY OF SCIENCE 
 
 The marly Years of Botany in the Journal. 
 
 At that time, the botanists had no journal in this 
 country devoted to their science. Here and there they 
 found opportunity for publishing their discoveries in 
 some medical periodical or in a local newspaper. Hence 
 American botanists availed themselves of the welcome 
 extended by Silliman to botanical contributors to place 
 their results on record in a magazine devoted to science 
 in its wide sense. Specialization and subdivision of 
 science had not then begun to dissociate allied subjects, 
 and, consequently, botanists felt that they would be at 
 home in this journal conducted by a chemist. Botanists 
 responded promptly to this invitation with interesting 
 contributions. 
 
 It is well to remember that the appliances at the com- 
 mand of naturalists at the date when the Journal began 
 its service, were imperfect and inadequate. The botanist 
 did not possess a convenient achromatic microscope, and 
 he was not in possession of the chemical aids now deemed 
 necessary in even the simplest research. Hence, atten- 
 tion was given almost wholly to such matters as the 
 forms of plants and the more obvious phenomena of 
 plant-life. In view of the poverty of instrumental aids 
 in research, the results attained must be regarded as sur- 
 prising. 
 
 In the very first volume of the Journal, bearing the date 
 of 1818, there are descriptions of four new genera and of 
 four new species of plants ; certainly a large share to 
 give to systematic botany. Besides these articles, there 
 are some instructive notes concerning a few plants, which 
 up to that time had been imperfectly understood. There 
 are four Floral Calendars which give details in regard 
 to the blossoming and the fruiting of plants in limited 
 districts, a botanical subject of some importance but 
 likely to become tedious in the long run. Just here, the 
 skill of the editor in limiting undesirable contributions is 
 shown by his tactful remark designed to soothe the feel- 
 ings of a prolix writer whose too long list of plants in a 
 floral calendar he had editorially cut do-wn to reasonable 
 limits. The editor remarks, "such extended observa- 
 tions are desirable, but it may not always be convenient 
 
DEVELOPMENT OF BOTANY SINCE 1818 441 
 
 to insert very voluminous details of daily floral occur- 
 rence. " It is convenient to consider by themselves some 
 of the botanical contributions published in the first series 
 of volumes of the Journal during a period of twenty 
 years, the period before Asa Gray became actively and 
 constantly associated with the Journal. 
 
 In systematic and geographical botany one finds com- 
 munications from Douglass and Torrey (4, 56, 1822) 
 on the plants of what was then the North-west ; Lewis C 
 Beck (10, 257, 1826; 11, 167, 1826; 14, 112, 1828) contri- 
 buted valuable papers on the botany of Illinois and Mis- 
 souri ; there is a literal translation by Dr. Ruschenberger 
 (19, 63, 299, 1831; 20, 248, 1831; 23, 78, 250, 1833) of a 
 very long list of the plants of Chili ; WoUe and Huebener 
 (37, 310, 1839) gave an annotated catalogue of botanical 
 specimens collected in Pennsylvania; Tuckerman (45, 27, 
 1843) presented communications in regard to numerous 
 species which he had examined critically; Darlington 
 (41, 365, 1841) published his lecture on grasses ; Asa Gray 
 (40, 1, 1841) gave an instructive account of European 
 herbaria visited by him, and he contributed also a charm- 
 ing account (42, 1, 1842) of a botanical journey to the 
 mountains of North Carolina. The most extensive series 
 of botanical communication at this time was the Caricog- 
 raphy by Professor Dewey of Williams College, pre- 
 sented in many numbers of the Journal ; the first of these 
 in 7, pp. 264-278, 1824. There were also descriptions of 
 certain new genera, and species, and critical studies in 
 synonjTUS. 
 
 Crj'ptogamic botany is represented in the first series 
 of volumes of the Journal by L. C. Beck's (15, 287, 1829) 
 study of ferns and mosses, by Bailey's (35, 113, 1839) 
 histology of the vascular system of ferns, by Fries' Sys- 
 tema mycologicum (12, 235, 1829), and by De Schweinitz 
 (9, 397, 1825) and Halsey, who had in hand a crj^Dtogamic 
 manual. There are two important papers by Alexander 
 Braun, translated by Dr. George Engelmann, one on the 
 Equisetaceas of North America (46, 81, 1844) and the 
 other on the Characefe (46, 92, 1844). 
 
 Vegetable paleontology had begun to attract attention 
 in many places in this country, and therefore the trans- 
 lated contributions by Brongniart on fossil plants were 
 
443 A CENTUEY OF SCIENCE 
 
 given space in the Journal. Plant-physiology received 
 a good share of attention either in short notices or m 
 longer articles. Such titles appear as, the respiration of 
 plants, the circulation of sap, the excrementitious matter 
 thrown off by plants, the effects of certain gases and 
 poisons on plants, and the relations of plants to different 
 colored light. One of the most important of the notes 
 is that in which is described the discovery by Robert 
 Brown (19, 393, 1831) of the constant movement of 
 minute particles suspended in a liquid, tirst detected by 
 him in the fovilla of pollen grains, and now known as the 
 Brownian (or Brunonian) movement. The heading 
 under which this note appears is of interest, ' ' The motion 
 of living particles in all kinds of matter." 
 
 One side of botany touches agriculture and economics. 
 That side was represented even in the first volume of the 
 Journal hy a study of ' ' the comparative quantity of nutri- 
 tious matter which may be obtained from an acre of land 
 when cultivated with potatoes or wheat." Succeeding 
 volumes in this series likewise present phases which are 
 of special interest regarded from the point of view of 
 economics ; for example, those which treat of rotation of 
 crops and of enriching the soil. Probably the economic 
 paper which may be regarded as the most important, in 
 fact epoch-making, is the full account of the invention by 
 Appert of a method for preserving food indefinitely 
 (13, 163, 1828). We all know that Appert 's process has 
 revolutionized the preservation of foods, and in its mod- 
 ern modification underlies the vast industry of canned 
 fruits, vegetables and so on. There are suggestions, 
 also, as to the utilization of new foods, or of old foods in 
 a new way, which resemble the suggestions made in these 
 days of food conservation. For example, it is shown 
 that flour can be made from leguminous seeds by steam- 
 ing and sulisequent drying, and pulverizing. There are 
 excellent hints as to the best ways of preparing and using 
 potatoes, and also for preserving them underground, 
 where they will remain good for a year or two. It is 
 shown that potato flour can be made into excellent bread. 
 Another method of making bread, namely from wood, is 
 described, but it does not seem quite ' so practicable. 
 
DEVELOPMENT OF BOTANY SINCE 1818 M3 
 
 There are interesting notes on tlie sugar-beet as a source 
 of sugar, and here appears one of the earliest accounts of 
 the Assam tea-plant, wliich was destined to revolutionize 
 the tea industry throughout the world. Cordage and tex- 
 tile fibers of bark and of wood should be utilized in the 
 manufacture of paper. In fact one comes upon many- 
 such surprises in economic botany as the earlier volumes 
 of the Journal are carefully examined. 
 _ Early numbers of the Journal present with suffi- 
 cient fulness accounts of the remarkable discovery by 
 Daguerre and others of a process for taking pictures by 
 light, on a silver plate or upon paper (37, 374, 1839; 38, 
 97, 1840, etc.). Before many years passed, the Journal 
 had occasion to show that these novel photographic 
 delineations could be made useful in the investigation of 
 problems in botany. In the pages of the Journal it would 
 be easily possible to trace the development of this art in 
 its relations to natural history. Silliman possessed 
 great sagacity in selecting for his enterprise all the nov- 
 elties which promised to be of service in the advancement 
 of science. In 1825 (9, 263) the Journal republished 
 from the Edinburgh Journal of Science an essay by Dr. 
 (afterwards Sir) William Jackson Hooker, on American 
 Botany. In this essay the author states that "the 
 various scientific Journals" which "are published in 
 America, contain many memoirs upon the indigenous 
 plants. Among the first of these in point of value, and 
 we think also the first with regard to time, we must name 
 Silliman 's Journal of Science." The author enumerates 
 some of the contributors to the Journal and the titles of 
 their papers. 
 
 It has been a useful practice of the Journal, almost 
 from the first, to transfer to its pages memoirs which 
 would otherAvise be likely to escape the notice of the 
 majority of American botanists. The book notices and 
 the longer book reviews covered so wide a field that they 
 placed the readers of the Journal in touch with nearly all 
 of the current botanical literature both here and abroad. 
 These critical notices did much towards the symmetrical 
 development of botany in the United States. _ Andas we 
 shall now see, the Journal notices and reviews in the 
 
444 A CENTURY OF SCIENCE 
 
 hands of Asa Gray continued to be one of the most 
 important factors in the advancement of American 
 botany. 
 
 Asa Gray and the Journal, 
 
 In 1834 there appears in the Journal (25, 346) a 
 "Sketch of the Mineralogy of a portion of Jefferson and 
 St. Lawrence Counties, New York, by J. B. Crawe of 
 Watertown and A. Gray of Utica, New York." This 
 appears to be the tirst mention in the Journal of the 
 name of Dr. Asa Gray, who, shortly after that date, 
 became thoroughly identified with its laotanical interests. 
 In the early part of his career both before and imme- 
 diately after graduating in medicine. Gray gave much 
 attention to the different branches of natural history in 
 its w4de sense. He not only studied but taught "chemis- 
 try, geology, mineralogy, and botany," the latter branch 
 being the one to which he devoted most of his attention. 
 Among his early guides in the pursuit of botany may be 
 mentioned Dr. Hadlej^ "who had learned some botany 
 from Dr. Ives of New Haven," and Dr. Lewis C. Beck of 
 Albany, author of Botany of the United States North of 
 Virginia. At that period he made the acquaintance 
 of Dr. John Torre}^ of New York, with whom he later 
 became associated in most important descriptive work. 
 During the years between his graduation in medicine and 
 1842, the year when he came to Harvard College, his 
 activities were diverse and intense; so that his prep- 
 aration for his distinguished career was very broad and 
 thorough. His first visit to Europe, in 1838, brought him 
 into personal relations with a large number of the botan- 
 ists of Great Britain and the Continent. This extensive 
 acquaintance, added to his broad training, enabled him 
 even from the outset to exert a profound influence upon 
 the progress of his favorite science. He made the 
 Journal tributary to this development. His name first 
 appears as associate editor in 1853, but there are articles 
 in the Journal from his pen which bear an earlier date. 
 The first of these early botanical papers is the following: 
 "A Translation of a memoir entitled 'Beitrage zur Lehre 
 von der Befruchtung der Pflanzen,' (contributions to the 
 doctrine of the impregnation of plants, by A. J. C. 
 
DEVELOPMENT OF BOTANY SINCE 1818 445 
 
 Corda:) with prefatory remarks on the progress of dis- 
 covery relative to vegetable fecundation; by Asa Gray, 
 M. D." (31, 308, 1837). Dr. Gray says tliat he made the 
 translation from the German for his own private use, 
 but thinking that it might be interesting to the Lyceum, 
 he brought it before the Society, with ' ' a cursory account 
 of the progress of discovery respecting the fecundation 
 of flowering plants, for the purpose of rendering the 
 memoir more generally intelligible to those who are not 
 particularly conversant with the present state of botan- 
 ical science." The translation occupies six pages of the 
 Journal, while the prefatory remarks fill nine pages. 
 The prefatory remarks constitute an exhaustive essay on 
 the subject, embodied in attractive and perfectly clear 
 language. The translator shows complete familiarity 
 ■with the matter in hand and gives an adequate account of 
 all the work done on the subject up to the date of 
 M. Corda 's paper. A second important paper by him 
 near this period is his review of "A Natural System of 
 Botany: or a systematic view of the Organization, Natu- 
 ral Affinities, and Geographical Distribution of the whole 
 Vegetable Kingdom; together with the use of the more 
 important species in Medicine, the Arts, and rural and 
 domestic economy, by John Lindley. Second edition, 
 with numerous additions and corrections, and a complete 
 list of genera and their sjmonjmis. London: 1836" (32, 
 292, 1837). A very brief notice of this work in the first 
 part of the volume for 1837 closes with the words, "A 
 more extended notice of the work may be expected in the 
 ensuing number of the Journal." The extended notice 
 proved to be a critical study of the work, signed by the 
 initials A. G. which later became so familiar to readers 
 of the Journal. Citation of a few of its sentences will 
 indicate the strong and quiet manner in which Dr. Gray, 
 even at the outset, wrote his notices of books. In speak- 
 ing of the second edition of Professor Lindley 's work, 
 he says : 
 
 "It is not necessary to state that a treatise of tliis kind was 
 greatly needed, or to allude to the peculiar qualifications of the 
 learned and industrious author for the accomplishment of the 
 task, or the high estimation in which the work is held in Europe. 
 But we may properly offer our testimony respecting the great 
 
 28 
 
446 A CENTUEY OF SCIENCE 
 
 and favorable influence which it has exerted upon the progress 
 of botanical science in the United States. Great as the merits 
 of the work undoubtedly are, we must nevertheless be excused 
 from adopting the terms of extravagant and sometimes equivocal 
 eulogy employed by a popular author, who gravely informs his 
 readers that no book, since printed Bibles were first sold in Paris 
 by Dr. Faustus, ever excited so much surprise and wonder as 
 did Dr. Torrey's edition of Lindley's Introduction to the Natural 
 System of Botany. Now we can hardly believe that either the 
 author or the American editor of the work referred to was ever 
 in danger, as was honest Dr. Faustus, of being burned for witch- 
 craft, neither do we find anything in its pages calculated to 
 produce such astonishing effects, except, perhaps, upon the 
 minds of those botanists, if such they may be called, who had 
 never dreamed of any important changes in the science since the 
 appearance of good Dr. Turton's translation of the Species 
 Plantarum, and who speak of Jussieu as a writer who has greatly 
 improved the natural orders of Linngeus. " 
 
 In the Journal for 1840 tliere is a large group of 
 unsigned book reviews under tlie heading, "Brief notices 
 of recent Botanical works, especially those most inter- 
 esting to the student of North American Botany. ' ' The 
 first of these short reviews deals with the second section 
 of Part VII of Be CandoUe's "Prodromus." In 1847 
 the consideration of the "Prodromus" is resumed by 
 the same author and the initials of A. G. are appended. 
 This indicates that Br. Gray was probably the writer of 
 some of the unsigned book-reviews which had appeared 
 in the Journal between 1837 and 1840. Boubtless Silli- 
 man availed himself of the assistance of his associates, 
 Eli Ives and others, in New Haven, in the examination 
 of current botanical literature, and it is extremely prob- 
 able that he early secured help from young Br. Gray 
 who had shown himself to be a keen critic as well as a 
 pleasing writer. The notices of botanical works from 
 1840 bear marks of having been from the same hand 
 Ihey cover an extremely wide range of subjects. While 
 tliey are good-tempered they are critical, and they had 
 much to do with the development of botany, in this 
 country, along safe lines. 
 
 Gray as Editor. -Qy^j^^ name as associate editor of 
 
 ontribX '?P'"'\"^ ^^^^- H^ ^^^ ^-^^ ^ welcome 
 contributor, as we have seen, for many years. His 
 
DEVELOPMENT OF BOTANY SINCE 1818 447 
 
 influence upon the progTess of botany in the United 
 States was largely due to his connection with the Journal. 
 His reviews extended over a very wide range, and supple- 
 mented to a remarkable degree his other educational 
 work. It must be permitted to allude here to his sagacity 
 as a writer of educational treatises. In his first ele- 
 mentary text-book, published in 1836, he expressed wholly 
 original views in regard to certain phases of structure 
 and function in plants, which became generally adopted 
 at a later date. His Manual of Botany was constructed, 
 and subsequent editions were kept, on a plan which made 
 no appeal to those who wanted to work on lines of least 
 resistance ; in fact he had no patience with those who 
 desired merely to ascertain the name of a plant. In the 
 Journal he emphasizes the desirability of learning all the 
 affinities of the plant under consideration. At a later 
 period, when entirely new chapters had been opened in 
 the life of plants, he sought by his contributions in the 
 Journal to interest students in this wider outlook. 
 
 Professor C. S. Sargent has selected with good judg- 
 ment some of the more important scientific papers by 
 Professor Gray and has re-published them in a con- 
 venient form.i Many of these papers were contributed 
 to the Journal in the form of reviews. These reviews 
 touch nearly every branch of the science of botany. As 
 Sargent justly says, "Many of the reviews are filled with 
 original and suggestive observations, and taken together, 
 furnish the best account of the development of 
 botanical literature during the last fifty years that has 
 yet been written." In these longer reviews in the 
 Journal, Gray was wont to take a book under review as 
 affording an opportunity to illustrate some important 
 subject, and many of the reviews are crowded with- 
 his expositions. For example, in his examination of 
 vonMohl's "Vegetable Cell" (15, 451, 1853) he takes up 
 the whole subject of microscopic structure, so far as 
 it was then understood, and he points out the probable 
 errors of some of Mohl's contemporaries, showing what 
 and how great were Mohl's own contributions to his- 
 tology. Such a review is a landmark in the science. The 
 physiology of the cell and the nutrition of the plant were 
 favorite topics with Professor Gray, and he brought 
 
448 A CENTURY OF SCIENCE 
 
 much of his knowledge in regard to them into such a 
 review as that of Boussingault (25, 120, 1858) on the 
 "Influence of nitrates on the production of vegetable 
 matter." 
 
 As a systematic botanist, Gray was naturally much 
 interested in the vexed question of nomenclature of 
 plants. One of his most important communications to 
 the Journal is his review, in the volume for 1883 (26, 
 417), of DeCandolle's work on the subject. He deals 
 with this strictly technical matter much as he did in a 
 contribution to the Journal which he made in 1868 (46, 
 63). In both of these papers he states with clearness the 
 general features of the code of nomenclature. He says 
 explicitly that the code does not make, but rather 
 declares, the common law of botanists. The treatment 
 of the subject at his hands would rightly impress a gen- 
 eral reader as showing a strong desire to have common 
 sense applied to doubtful cases, instead of insisting on 
 inflexible rules. For this reason, his rule of practice was 
 not alwaj's acceptable to those who were anxious to 
 secure conformity to arbitrary rules at wdiatever cost. 
 As he said in a paper published in the Journal in 1847 
 (3, 302), "The difficulty of a reform increases with its 
 necessity. It is much easier to state the evils than to 
 relievo them; and the well-meant endeavors that have 
 recently been made to this end, are, some of them, likely, 
 if adopted, to make confusion worse confounded." This 
 feeling led him to be very conservative in the matter of 
 reform in nomenclature. 
 
 This subject of botanical nomenclature illustrates a 
 method frequently employed by Professor Gray to elu- 
 cidate a difficult matter. He would find in the treatise 
 under review a text, or texts, on which he would build a 
 treatise of his own, and in this way he made clear his own 
 views relative to most of the important phases of botany. 
 When he faced controverted matters, his attitude still 
 remamed judicial. While he was tolerant of opinions 
 which clashed with his own, he was always severe upon 
 charlatanism and impatient of inaccuracy. The pages 
 of the Journal contain many severe criticisms at his 
 hands, but an unprejudiced person would say that the 
 severity is merited. 
 
DEVELOPMENT OF BOTANY SINCE 1818 U9 
 
 Sometimes, however, instead of reviewing a book or an 
 address, he would follow the custom inaugurated early in 
 the history of the Journal, of making copious extracts, 
 and thus give to its readers an opportunity of examining 
 materials which otherwise might not fall in their way. 
 
 Gray's contributions to the Journal comprise more 
 than one thousand titles, without counting the memorial 
 notices and the shorter obituary notes. In these notices 
 he sums up in a few well-chosen words the contributions 
 made to botany by his contemporaries. Even in the few 
 instances in which he felt obliged to note with disap- 
 proval some of the work, he expressed himself with per- 
 sonal friendliness. The necrology, as it appeared from 
 month to month, was a labor of love. All of the longer 
 memorial notices are what it is the fashion now-a-days 
 to call appreciations, and these are so happily phrased 
 that it would seem as if the writer in many a case asked 
 himself, "Would my friend, about whom I am now writ- 
 ing, make any change in this sketch?" 
 
 Gray on Darivinism. — In October, 1859, Darwin's 
 epoch-making work, "The Origin of Species," was pub- 
 lished. An early copy was sent to the editor of the Jour- 
 nal, Professor James D. Dana. This arrived in New 
 Havemon December 21, but it was preceded by a personal 
 letter which is of so much interest that it is here tran- 
 scribed in full. It should be added that Dana was at this 
 time in Europe where he was spending a year in the 
 search for health after a serious nervous breakdown. 
 In his absence the book was noticed by Gray as stated 
 below. The letter is, as follows : 
 
 Down, Bromley, Kent. 
 
 Nov. 11th, 1859. 
 My dear Sir, 
 
 I have sent you a copy of my Book (as yet only an abstract) on 
 the Origin of Species. I know too well that the conclusion, at 
 which I have arrived, will horrify you, but you will, I believe 
 and hope, give me credit for at least an honest search after the 
 truth. I hope that you will read my Book, straight through; 
 otherwise from the great condensation it will be unintelligible. 
 Do not, I pray, think me so presumptuous as to hope to convert 
 you ; but if you can spare time to read it with care, and will then 
 do what is far more important, keep the subject under my point 
 
450 A CENTURY OF SCIENCE 
 
 of view for some little time occasionally before your mind, I have 
 hopes that you will agree that more can be said in favour of the 
 mutability of species, than is at first apparent. It took me many 
 long years before I wholly gave up the common view of the sep- 
 arate creation of each species. Believe me, with sincere respect 
 and with cordial thanks for the many acts of scientific kmdness 
 which I have received from you, 
 
 My dear Sir, 
 Yours very sincerely, 
 
 Charles Darwin. 
 
 In ]\rarch, 1860 (29, 1.53), Gray published in the Journal 
 an elaborate and cautious review of Darwin's work. He 
 alluded to the absence of the chief editor of the Journal 
 in the following words : 
 
 "The duty of reviewing this volume in the American Journal 
 of Science would naturally devolve upon the principal editor 
 whose wide observation and profound knowledge of various 
 departments of natural history, as well as of geology, particu- 
 larly qualify him for the task. But he has been obliged to lay 
 aside his pen to seek in distant lands the entire repose from 
 scientific labor so essential to the restoration of his health, a 
 consummation devoutly to be wished and confidently to be 
 expected. Interested as Mr. Dana would be in this volume, he 
 could not be expected to accept its doctrine. Views so idealistic 
 as those upon which his 'Thoughts upon Species' are grounded, 
 will not harmonize readily with a doctrine so thoroughly natur- 
 alistic as that of Mr. Darwin . . . Between the doctrines of 
 this volume and those of the great naturalist whose name adorns 
 the title-page of this Journal [Mr. Agassiz] the widest diver- 
 gence appears." 
 
 Gray then proceeds to contrast the two views of Dar- 
 win and Agassiz, "for this contrast brings out most 
 prominently and sets in strongest light and shade the 
 main features of the theory of the origination of species 
 by means of Natural Selection." He then states both 
 sides with great fairness, and proceeds : 
 
 "Who shall decide between such extreme views so ably main- 
 tained on either hand, and say how much truth there may be 
 in each. The present reviewer has not the presumption to under- 
 take such a task. Having no prepossession in favor of natur- 
 alistic theories, but struck with the eminent ability of Mr. 
 Darwin's work, and charmed with its fairness, our humbler duty 
 will be performed if, laying aside prejudice as much as we can, 
 
DEVELOPMENT OF BOTANY SINCE 1818 451 
 
 we shall succeed in giving a fair account of its method and argu- 
 ment, offering by the way a few suggestions such as might occur 
 to any naturalist of an inquiring mind. An editorial character 
 for this article must in justice be disclaimed. The plural pro- 
 noun is employed not to give editorial weight, but to avoid even 
 the appearance of egotism and also the circumlocution which 
 attends a rigorous adherence to the impersonal style." 
 
 In this review he moves slowly and thoughtfully, but 
 not timidly, over the new paths. There is no clear indi- 
 cation in the review that he has yet made up his mind as 
 to the validity of Darwin's hypothesis. But, in a sec- 
 ond article appearing in the Journal for September of 
 the same year (30, 226), under the title "Discussion 
 between two readers of Dar-win's treatise on the origin 
 of species upon its natural theology" Gray plainly begins 
 to incline to take a very favorable view of the. Darwinian 
 theory, and makes use of the following ingenious illus- 
 tration to show that it is not inconsistent with theistic 
 design. A few paragraphs here quoted show the felicity 
 of his style in a controverted matter : 
 
 "Recall a woman of a past generation and show her a web 
 of cloth ; ask her how it was made, and she will say that the 
 wool or cotton was carded, spun, and woven by hand. When 
 you tell her it was not made by manual labor, that probably no 
 hands have touched the materials throughout the process, it is 
 possible that she miglit at first regard your statement as tanta- 
 mount to the assertion that the cloth was made without design. 
 If she did, she would not. credit your statement. If you 
 patiently explained to her the theory of carding-machines, spin- 
 ning-jennies, and power-looms, would her reception of your 
 explanation weaken her conviction that the cloth was the result 
 of design? It is certain that she would believe in design as 
 firmly as before, and that this belief would be attended by a 
 higher conception and reverent admiration of a wisdom, skill, 
 and power greatly beyond anything she had previously conceived 
 possible. ' ' 
 
 By this review Gray disarmed hostility to such an 
 extent that some persons who had been antagonistic to 
 Darwinism accepted it with only slight reservation. 
 It may be fairly claimed that the Journal bore a leading 
 part in influencing the views of naturalists in America 
 in regard to the Darwinian theory. 
 
452 A CENTURY OF SCIENCE 
 
 Dr. Gray soon put the Darwinian hypothesis to a 
 severe test. In the Journal for 1840 he had called atten- 
 tion to the remarkable similarity which exists between 
 the flora of Japan and a part of the temperate portion of 
 North America. The first notice of this subject by him 
 occurs in a short review of Dr. Zuccarini's "Flora 
 Japonica," a work based on material furnished by 
 Dr. Siebold, who had long lived in Japan. In this 
 review (39, 175, 1840), he enumerates certain plants com- 
 mon to the two regions, and says, "It is interesting to 
 remark how many of our characteristic genera are repro- 
 duced in Japan, not to speak of striking analogous 
 forms." In a subsequent paper (28, 187, 1859), he recurs 
 to this subject, and, after alluding to geological data fur- 
 nished by J. D. Dana, he says : 
 
 ' ' I cannot resist the conclusion that the extant vegetable king- 
 dom has a long and eventful history, and that the explanation, 
 of apparent anomalies in the geographical distribution of species 
 may be found in the various and prolonged climatic or other 
 vicissitudes to which they have been subject in earlier times; 
 that the occurrence of certain species, formerly supposed to be 
 peculiar to North America, in a remote or antipodal region, 
 affords in itself no presumption that they were originated there, 
 and that interchange of plants between eastern North America 
 and eastern Asia is explicable upon the most natural and gener- 
 ally received hypothesis (or at least offers no greater difficulty 
 than does the arctic flora, the general homogeneousness of which 
 round the world has always been thought compatible with local 
 origin of the species) and is perhaps not more extensive than 
 might be expected under the circumstances. That the inter- 
 change has mainly taken place in high northern latitudes, and 
 that the isothermal lines have in earlier times turned northward 
 on our eastern and southward on our northwest coast, as they 
 do now, are points which go far towards explaining why eastern 
 North America, rather than Oregon and California, has been 
 mainly concerned in this interchange, and why the temperate 
 interchange, even with Europe, has principally taken place 
 through Asia." 
 
 This paper was communicated in 1859, on the eve of 
 the publication of Darwin's "Origin of Species." At a 
 later date he applied the Darwinian theory to the possi- 
 ble solution of the problem, and came to the conclusion 
 that the two floras had a common origin in the Arctic 
 
a. J 
 
 / 
 
 a^r^u^x^ 
 
 From " Life and I,c-Uers ot riinrles Darwin " liy Francis Darwin. 
 
DEVELOPMENT OF BOTANY SINCE 1818 453 
 
 zone, during the Tertiary period, or the Cretaceous which 
 preceded it, and the descendants had made their way 
 down different lines toward the south, the species vary- 
 ing under different climatic conditions, and thus exhib- 
 iting similarity but not absolute identity of form. Before 
 the American Association for the Advancement of Sci- 
 ence, in his Presidential address, in 1872, he used the 
 following language : 
 
 "According to these views, as regards plants at least, the 
 adaptation to successive times and changed conditions lias been 
 maintained, not by absolute renewals, but by gradual modifica- 
 tions. I, for one, cannot doubt that the present existing species 
 are the lineal successors of those that garnished the earth in the 
 old time before them, and that they were as well adapted to 
 their surroundings then, as those which flourish and bloom around 
 us are to their conditions now. Order and exquisite adaptation 
 did not wait for man's coming, nor were they ever stereotyped. 
 Organic Nature — by which I mean the system and totality of 
 living things, and their adaptation to each other and to the 
 world — with all its apparent and indeed real stability, should 
 be likened, not to the ocean, which varies only by tidal oscilla- 
 tions from a fixed level to which it is always returning, but 
 rather to a river, so vast that we can neither discern its shores 
 nor reach its sources, whose onward fiow is not less actual 
 because too slow to be observed by the ephemeras which hover 
 over its surface, or are borne upon its bosom." 
 
 Gray's active interest in the Journal continued until 
 the very end of his life. There were many critical 
 notices from his pen in 1887. His last contribution to its 
 pages was the botanical necrology, which appeared post- 
 humously in volume 35, of the third series (1888). His 
 connection with the Journal covered, therefore, a period 
 of more than a half a century of its lif e.- 
 
 The changes that were wrought in botany by the 
 application of Darwinism were far reaching. Attempts 
 were promptly made to reconstruct the system of botan- 
 ical classification on the basis of descent. The more suc- 
 cessful of these endeavors met with welcome, and now 
 form the groundwork of arrangement of families, genera, 
 and species, in the Herbaria in this country, in the man- 
 uals of descriptive botany, and in the text-books of higher 
 grade. This overturn did not take place until after 
 
454 A CENTURY OP SCIENCE 
 
 Gray's death, although he foresaw that the revolution 
 Avas impending. 
 
 One of the most obvious changes was that which gave 
 a high degree of prominence in American school treatises 
 to the stud}' of the lower instead of the higher or flower- 
 ing plants, these latter being treated merely as members 
 in a long series, and with scant consideration. But of 
 late years, there has been a renewed popular interest in 
 the phEcnogamia, leading to a more thorough investiga- 
 tion of local floras, and also to the examination of the 
 relations of plants to their surroundings. The results 
 of a large part of this technical work are published in 
 strictly botanical periodicals and now-a-days seldom find 
 a place in the pages of a general journal of science. 
 
 Cryptogamic Botany in the Journal since 1846, 
 
 In glancing rapidly at the First Series it has been seen 
 that a fair share of attention was early paid by the Jour- 
 nal to the flowerless plants. So far as the means and 
 methods of the time permitted, the fern^, mosses, lichens, 
 and the larger algfe and fungi of America were studied 
 assiduously and important results were published, chiefly 
 on the side of systematic botany. 
 
 The Second Series comprises the years between 1846 
 and 1871. In this series one finds that the range of' 
 cryptogamic botany is much widened. Besides inter- 
 esting book notices relative to these plants, there are a 
 good many papers on the larger fungi, on the sdgse, and 
 mosses. Here are contributions by Curtis, by Ravenel, 
 by Bailey, and by Sullivant. The lichens are treated of 
 in detail by Tuckerman, and there are some excellent 
 translations by Dr. Engelmann of papers by Alexander 
 Braun. Some of the destructive fungi are considered, as 
 might well be the case in the period of the potato famine. 
 It is in these years that one first finds the name of 
 Daniel Cady Eaton, who later had so much to do with 
 developing an interest in the subject of ferns in this 
 country. He was a frequent contributor of critical 
 notices. 
 
 Cryptogamic Botany, as it is now understood, is a 
 comparatively modern branch of science. The appli- 
 
DEVELOPMENT OF BOTANY SINCE 1818 455 
 
 ances and the methods for investigating the more obscure 
 groups, and especially for revealing the successive stages 
 of their development, were unsatisfactory until the latter 
 half of the last century. Gray recognized this condition 
 of affairs, and appreciated the importance of the new- 
 methods and the better appliances. Therefore he viewed 
 with satisfaction the pursuit of these studies abroad by 
 one of his students and assistants, William G. Farlow. 
 Dr. Farlow carried to his studies under DeBary and 
 others unusual powers of observation and great indus- 
 try. He speedily became an accomplished investigator in 
 cryptogamic botany and enriched the science by notable 
 discoveries, one of which to-day bears his name in botan- 
 ical literature. On his return to the United States, 
 Farlow entered at once upon a successful career as an 
 ■inspiring teacher and a fruitful investigator. He 
 became a frequent contributor to the Journal, keeping its 
 readers in touch with the more important additions to 
 cryptogamic botany. He had wisely chosen to deal with 
 the whole field, and consequently he has been able to pre- 
 serve a better perspective than is kept by the extreme 
 specialist. The greater number of cryptogamic botanists 
 in this country have been under Professor Farlow 's 
 instruction. 
 
 Systematic and Geographical Sotany of Late Years. 
 
 The usefulness of the Journal in descriptive systematic 
 botany of phanerogams is shown not only by its accept- 
 ance of the leading features of DeCandoUe's Phytog- 
 raphy, where very exact methods are inculcated, but by 
 the very numerous contributions by Sereno Watson and 
 others at the Harvard University ]3erbarium, as well as 
 from private systematists. It is in the pages of the 
 Journal that one finds the record of much of the critical 
 work of Tuckerman and of Engelmann, in interesting 
 Phanerogamia. Of late years the Journal has had the 
 privilege of publishing a good deal of the careful work of 
 Theo Holm, in the difficult groups of Cyperacea?, and also 
 his admirable studies in the morphology and the anatomy 
 of certain interesting plants of higher orders. 
 
 Attention was called, in passing, to Gray's deep inter- 
 
456 A CENTURY OF SCIENCE 
 
 est in geographical botany. In this important branch, 
 besides his contributions, one finds, among many others, 
 such papers as LeConte's "Flora of the Coast Islands of 
 California in Relation to Recent Changes of Physical 
 Geography" (34, 457, 1887), and Sargent's "Forests of 
 Central Nevada" (17, 417, 1879). Examination reveals 
 a surprising number of communications which bear indi- 
 rectly upon this subject. 
 
 Paleontological Botany. 
 
 When the Journal began its career, the subject of fossil 
 plants was very obscure. Brongniart's papers, espe- 
 cially the Journal translations, enabled the students in 
 America to undertake the investigation of such fossils 
 and the results were to a considerable extent published 
 in the Journal. Since the subject belongs as much to 
 geology as to botany, it finds its ajopropriate home in the 
 pages of the Journal. The recent papers on this topic 
 show how great has been the advance in methods and 
 results since the early days of the Journal's century. 
 Under the care of George R. Wieland, the communica- 
 tions and the bibliographical notices of paleontological 
 treatises show the progress which he and others are mak- 
 ing in this attractive field. 
 
 Economic Botany, Plant Physiology, etc. 
 
 At the outset, the Journal, as we have seen, devoted 
 much attention to certain phases of economic botany, and, 
 even do-\\Ti to the present, it has maintained its hold upon 
 the subject. The correspondence of Jerome Nickles from 
 1853 to 1867 brought before its readers a vast number of 
 valuable items which would not in any other way have 
 been known to them. And the Journal dealt wisely with 
 the scientific side of agriculture, under the hands of S. W. 
 Johnson and J. H. Gilbert, and others, placing it on its 
 proper basis. This work was supplemented by Norton's 
 remarkable work in the chemistry of certain plants, the 
 oat, for example, and certain plant-products. In fact it 
 might be possible to construct from the pages of the 
 Journal a fair synopsis of the important principles of 
 agronomy. 
 
DEVELOPMENT OF BOTANY SINCE 1818 457 
 
 Physiology has been represented not only by the 
 studios which had been inaugurated and stimulated by the 
 Darwinian theory, such as the cross-fertilization and 
 the close-fertilization of plants, plant-movements, and 
 the like,_ but there have been a good many special com- 
 munications, such as Dandeno on toxicity. Plowman on 
 electrical relations, and ionization, and "W. P. Wilson on 
 respiration. 
 
 There are many broad philosophical questions which 
 have found an appropriate home in the Journal, such as 
 "The Plant-individual in its relation to the species" 
 (Alexander Braun, 19, 297, 1855; 20, 181, 1855), 
 and ''The analogy between the mode of reproduc- 
 tion in plants and the alternation of generations 
 observed in some radiata" (J.D.Dana, 10,341, 1850). 
 Akin to these are many of the reflections which one 
 finds scattered throughout the pages of the Journal, 
 frequently in minor book-notices. As might be expected, 
 some attention has been paid to the very special branch of 
 botany which is strictly called medical. For example, 
 early in its history, the Journal published a long treatise 
 by Dr. William TuUy (2, 45, 1820), on the ergot of rye. 
 This is considered from a structural as well as from a 
 medical point of view and is decidedly ahead of the time 
 in which it was written. There are a few references to 
 vegetable poisons, and there is a fascinating account of 
 the effect of the common white ash on the activities of 
 the rattlesnake. In short it may be said that the editor 
 did much towards making the Journal readable as well 
 as strictly scientific. 
 
 The list of reviewers who have been permitted to use 
 the pages of the Journal for notices of botanical and 
 allied books in recent years is pretty long. One finds the 
 initials of Wesley R. Coe, George P. Clinton, Arthur L. 
 Dean, Alexander W. Evans, William G. Farlow, George 
 L. Goodale, Arthur H. Graves, Herbert E. Gregory, 
 Lafayette B. Mendel, Leo F. Rettger, Benjamin L. Robin- 
 son, George R. Wieland, and others. 
 
 At the present time, in the biological sciences, as in 
 every department of thought, there is great specialization, 
 and each specialty demands its own private organ of 
 
458 A CENTURY OF SCIENCE 
 
 publication. Naturally this has led to a falling off in the 
 botanical communications to the Journal, but it cannot be 
 forgotten that the history of North American Botany has 
 been largely recorded in its pages. 
 
 2f^otes. 
 
 ' SeientLfic Papers of Asa Gray. Selected by Charles Sprague Sargent. 
 Two volumes, Boston, 1889 (see notice in vol. 38, 419, 1889). 
 
 ° A notice of Gray 's life and works is given by his life-long friend, J. D. 
 Dana, in the Journal in 1888 (35, 181-203). 
 
458 A CENTURY OF SCIENCE 
 
 publication. Naturally this has led to a falling off in the 
 botanical communications to the Journal, but it cannot be 
 forgotten that the history of North American Botany has 
 been largely recorded in its pages. 
 
 Notes. 
 
 ' Scientific Papers of Asa Gray. Selected by Cliarles Spra^e Sargent. 
 Two volumes, Boston, 1889 (see notice in vol. 38, 419, 1889). 
 
 ° A notice of Gray's life and works is given by his life-long friend, J. D. 
 Dana^ in the Journal in 1888 (35, 181-203). 
 
 Erratum for "A CENTURY OF SCIENCE." 
 
 Pafce 51, line ."iO, and page .54, line 2. For "George W. Goodale" road 
 'George L. Goodale." 
 
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