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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

ELECTRICITY AND MATTER. By Joseph John Thomson, d.s c,
LL.D., PH.D., F.R.S., Fellow of Trinity College and Cavendish Professor of
Experimental Physics, Cambridge University.

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THE INTEGRATIVE ACTION OF THE NERVOUS SYSTEM. By
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fessor of Physiology, University of Liverpool.

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RADIOACTIVE TRANSFORMATIONS. By Ernest Rutherford, d.sc,
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EXPERIMENTAL AND THEORETICAL APPLICATIONS OF THER-
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and Director of the Institute of Physical Chemistry in the University of

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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, sc.d.,
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Director of the Physico-Chemical Department of the Nobel Institute,
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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,
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MAR LiNDGREN, FREDERICK LESLIE RaNSOME, AND WiLLIAM D. MATTHEW.

{Second printing.) Price $5.00 net.
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ORGANISM AND ENVIRONMENT AS ILLUSTRATED BY THE
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{Second printing.) Price $1.25 net.

A CENTURY OF SCIENCE
IN AMERICA

AV^'.El^o^^ -e.

l/ t), tJyl^L-^^'t^'^^'^-'-^t^Ct''-i^

CENTURY OF SCIENCE

IN AMERICA

WITH SPECIAL. REFERENCE TO THE

AMERICAN JOURNAL OF SCIENCE

1818-1918

BY

EDWARD SALISBURY DANA • CHARLES SCHUCHERT

HERBERT E. GREGORY • JOSEPH BARRELL • GEORGE OTIS SMITH

RICHARD SWANN LULL • LOUIS V. PIRSSON

WILLIAM E. FORD • R. B. SOSMAN • HORACE L. WELLS

HARRY W. FOOTE • LEIGH PAGE • WESLEY R. COE

AND GEORGE L. GOODALE

NEW HAVEN

YALE UNIVERSITY PRESS

LONDON • HUMPHREY MILPORD • OXFORD UNIVERSITY PRESS

MDCCCCXVIII

COPYEIGHT, 1918, BY
YALE UNIVERSITY PRESS

^

127

C3

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

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

y. A Century of Government Geological Surveys.

George Otis Smith 193

YI. On the Development of Vertebrate Paleontology.

Eichard Swann Lull 217

VII. The Kise of Petrology as a Science. Louis V.

Pirsson 248

VIIL 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

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

XIIL The Development of Botany since 1818. George L.

Goodale 439

PORTRAITS

Benjamin Silliman Frontispiece

rrom a painting by G. S. Hubbard, Esq., in possession of
Miss Henrietta W. Hubbard

Benjamin Silliman, Jr opposite page 28

James D. Dana * * ' ' 36

Edward S. Dana *' *' 48

Wolcott Gibbs '' *' 52

James Hall * ' " 84

G. K. Gilbert * '^ '* 140

Edward Hitchcock '* '* 156

O.C. Marsh *' '' 232

F. V. Hayden '' '' 196

J.W.Powell '' '' 204

Clarence King '' ** 208

George J. Brush " '* 276

J. Willard Gibbs " '' 324

H.A.Newton '' '' 336

James Clerk Maxwell '* *' 348

Louis Agassiz * * * * 404

Thomas H. Huxley *' " 410

A. E. Yerrill '' '' 412

Asa Gray * * * ' 444

Charles Darwin ^ * * * 452

A CENTURY OF SCIENCE
IN AMERICA

I

THE AMERICAN JOURNAL. OF SCIENCE
FROM 1818 TO 1918

By EDWARD 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 of
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 first, 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 early, 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 16

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 dowm to the time with which we are immediately 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 -rrov (ttw, 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 was
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
been almost established by our countryman. 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 Hufcton 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 Linnaeus 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 civilization ; 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 century, what seemed once a wild dream of

18 A CENTURY OF SCIENCE

the imagination has 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 by ether waves. While,
still further, the same electrical current now gives man
his artificial illumination and serves him in a thousand
ways 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 IJieir sciences
have been deduced. Many new elements have been dis-
covered, in fact nearly all called for by 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 photography 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 we are reaching out to
a knowledge of the ultimate nature of matter.

AMERICAN JOURNAL OF SCIENCE 19

In geology, vast progress has 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 ^* unexplored''
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
unknown 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 Secretorum Naturae.

1603. Rome, Accademia dei Lincei.

1651. Leipzig, Academia Naturas Curiosum.

AMERICAN JOURNAL OF SCIENCE 21

1657. Florence, Accademia del Cimento.
1662. London, Eoyal Society.
1666. Paris, Academie des Sciences.
1690. Bologna, Accademia delle Scienze.
1700. Berlin, Societas Eegia Scientiarum. This was the
forerunner of the K. preuss. Akad. d. Wissenschaften.

The Royal Society of London, whose existence dates
from 1645, though 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 (1710) ;
Upsala (1720); Petrograd, 1728; Stockholm (1739);
and Copenhagen (1743).

For the latter half of the eighteenth century, when 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. Academy 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
only 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.^

Early 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. (Geh-
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 Royal 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-. Linnaea, 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 der Chemie (und Pharmacie) often known
as Liebig's Annalen. Leipzig, Lemgo.

The Founder of the American Journal of Science,

The establishment of a scientific journal in this country
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 CENTURY 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

AMERICAN 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 own
labors contributed to its extension. Every year was a year of
expansion and onward development, and the grandeur 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 us, to enjoy the good he has done, and cheer us
by his noble and benign presence.*'

In addition to these words of Dana, mucli 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 Journal,

In no direction did Silliman 's enthusiastic activities in
science produce a more enduring result than in the found-

THE

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CONDUCTED BY

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TRAVELS 1» KNOLANn. SCOTLAND. AND BOLLAND, ETC

— •;*,',>;3'''>- —

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— ^v^^s^ —

ENGRAVING IN THE PRESENT NO.

Nevf apl^ratus Tor the combustion of Tar, &.c. by ihc vapoar of

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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 CENTIJEY 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 num-
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 unreasonably extended, that fact is to be taken not
only 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) :

'TLAN OF THE WORK.

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 wants; 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 Navigation.

/^Y OT^t4^

/ /\f^'V6/^U^^yi^

o^u-^

^'

AMERICAN JOURNAL OF SCIENCE 29

Notices, Reviews, and Analyses of new scientific works, and
of new Inventions, and Specifications of Patents;

Biographical 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 the ** 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 apology 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 Intkoductoky Remakks 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 arts, and to the
common purposes of life.

In every enlightened country, men illustrious for talent, worth
and knowledge, are ardently engaged in enlarging the bound-
aries of natural science; and the history of their labors and
discoveries is communicated to the world 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 1818 ^Svhich have long enjoyed a
high and deserved reputation." 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 by 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 influence
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 by 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
the first volume of this Journal, and one year and ten months
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, on 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 this view of

AMERICAN JOURNAL OF SCIENCE 33

the subject, and by the favour of many distin^ished men, both
at home and abroad, and supported by able contributors, to
whom the Editor again tenders his 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 tlie same year, the 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 country are sufficient to afford an unfailing
supply of valuable original communications and that nothing
but perseverance and effort are necessary 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 only an ephemeral existence. It has been his fortune to

34 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
afflictions. 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, only in
retrospect, and with 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 payment,
to such an extent, that it may fairly be considered as an estab-
lished work ; its patronage is regularly increasing, and we trust
it will 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 your 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 whole situation up to
1829. This preface (dated July 1, 1829), which is quoted
nearly in full, cannot fail to be found particularly inter-
esting 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.

When 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, occupied in 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, sufficiently 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 kindness, 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 doeeri,

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 whom 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 than the literature
of the country. '^ 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, that

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, which
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 statues 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 disgusted,
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.

The Close of the First Series,

The ** First Series," as it was henceforth to be known,
closed with the fiftieth volume (1847, pp. xx + 347).
This final volume is devoted to an exhaustive index to the

yicUws-^ ws). ^3-«*-^A^

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 first volume
(1818), which has been already reproduced almost
entire, and then goes on as follows (pp. xi et seq.) :

Such was the pledge which, on entering upon our editorial
labors in 1818, we gave to the public, and such were the views
which we then entertained, 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 but 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 years 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 gratifying 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 Museum hold forth many allure-
ments to the young naturalist, as well as to the archaeologist 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 the 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 Yale College) successful observations have been

AMERICAN JOURNAL 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,
v^e 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
day. 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 with 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 financial. — The editorial labors on the
Journal were carried by the elder Silliman alone for
twenty 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 the enterprise. With volume 34 (1838) the
name of Benjamin Silliman, Jr., is added as co-editor on
the title page. He was graduated from Yale College the
year 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 labored alone, although overtures for editorial co-opera-
tion had been made to him by gentlemen commanding his con-
fidence 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
the assistance of gentlemen eminent in particular departments
of knowledge. On the title page of No. 1, vol. 34, published in
July, 1838, a new name is introduced : the individual to whom
it belongs having been for several years 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, book reviews and the like
contained in the Miscellany 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 41

name. Very early Asa Gray 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, 1832; 24, 342, 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 July, 1818, and in June, 1819,
the first volume of four numbers and 448 pages was completed.
This scale of publication, originally 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 necessary 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 Eooms, Broadway, New York" and Howe
& Spalding, New Haven." For the second volume and
those immediately following the corresponding state-
ment * Sprinted and published by S. Converse [New
Haven] for the Editor. "

Silliman adds (p. iv) :

At the conclusion of vol. 10, in February, 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 control 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. xiv) :

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 colleagues 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 activity 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 beginning of

AMERICAN JOURNAL OF SCIENCE 43

the Journal in 1818, the Connecticut Academy freely
gave its support both in papers for publication 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 [Silliman's] undertaking, a vote had been
passed in February [1818], ''that the Committee of Publication
may allow such of the Academy's papers as they think proper,
to be published in Mr. Silliman's Scientific 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 j^ 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 -unlucky displacement of your letter of Mar 3 has been
the cause of delay in my answer, altho' 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 that 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 given
by Silliman of the contributors to the Journal and the
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 fifty 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, coeteris 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 risen, while a few
planetary orbs visible in every zone, have continued 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 few 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 regular 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 any.

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 CENTUEY OF SCIENCE

technical 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 "Gypsies"
by J. Griscom (from the Revue Encyclopedique) in vol-
ume 24 (pp. 342-345, 1833), 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 he 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 within 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 voyage of the first Atlantic steam-
boat, the ^ ^ Savannah, ' ' which 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 number of interesting 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 Morey (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 submarine invented by
David Bushnell and used in the Revolutionary War in
August, 1776. An account is also given of a dirigible
balloon that mav 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 other. 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 anaesthetic (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
was 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 anything 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 ^^ readable'*
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 Quarterly Journal of Science,
&c. should be in form, inscribed among the titles of the work.

The Second, Third and Fourth Series,

The Second Seeies 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. From 1846 until the completion of an
additional fifty volumes in 1871, the Journal was made a
bimonthly, each of the two yearly volumes having three
numbers each. Furthermore, a general index was given
for each period of ^yq years, that is for every ten
volumes.

Much more important than this change 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 Wilkes Exploring Expedition in 1842; he
settled in New Haven, was married in 1844, and in 1850

(^^^^..^.w^^

^xt.C.^W'

AMEEICAN JOUENAL OF SCIENCE 49

was appointed Silliman professor of Geology in Yale
College. He was at this time actively engaged in writ-
ing his 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 Series, a volume
of about 350 pages, finally issued in 1847. From the
beginning of the Second Series 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-
raphy accompanying 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 Thied Sekies 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 FouKTH Sekies 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 years. In a note
dated Jan. 1, 1851 (11, 105), he says:

It is my intention in future to prepare for the columns of this
Journal abstracts of the more important physical and chemical
memoirs contained in foreign scientific journals, accompanied
by references, and by such critical observations as the 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 chemistry and physics,
and these subjects were carried together until 1873 when
they were separated and the physical notes were fur-

AMERICAN JOURNAL OF SCIENCE 51

nished, 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 cryptogamic 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 work of Asa Gray. It may not be out
of place, however, to call attention to the notice of Gray
written for the Journal by his life-long friend, James D.
Dana (35, 181, 1888). The opening paragraph is as
follows :

52 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, the accomplished writer, the just and
genial critic, and as Darwin has well said, ' The lovable man. ' ' '

The third associate editor, following Gray, was Louis
Agassiz, whose work 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 years, 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; Newton 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 filled the place in zoology which it so long
held. Much later the list of New Haven men was
increased by the addition of Henry S. Williams (1894),
and 0. 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

Mx^^utt^joj.

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 other gentlemen, whose names have not been
jDlaced 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 Nickles 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 very 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, 1851 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 " 35, 1888

Henry S. ■Williams '' 47, 1894

Henry P. Bowditch '' 49, 1895 to (4) 8, 1899

William G. Farlow " 49, 1895

Othniel C. Marsh " 49, 1895 to (4) 6, 1899

Henry A. Rowland (4) 1, 1896 " '' 10, 1900

Joseph S. Diller '' 1, 1896

Louis V. Pirsson '' 7, 1899

William M. Davis '' 9, 1900

Joseph S. Ames " 12, 1901

Horace L. Wells '' 18, 1904

Herbert E. Gregory '' 18, 1904

Horace S. Uhler '' 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 years 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 presentation 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 Chemical 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 Eeview.

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.
1904r- . Journal of Experimental Zoology.

1905- . Economic Geology.

1906- . Anatomical Eecord.

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 this country, 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 JournaP' 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 years 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 57

presented, in the 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 the editor and — as in years long past — a
silent partner 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 the 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 Silliman in 1818 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
which 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 different 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 which forms the frontispiece of
this volume has been reproduced from the plate in
volume 50 (1847). The original painting was made by
H. 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 Magazine, and was published in the num-
ber for December, 1839.

AMERICAN JOURNAL OF SCIENCE 59

It is interesting to quote the remarks with which the
editor introduces the portrait (50, xviii, 1847). He says :

The portrait prefixed to this volume was engraved for a very
different purpose and for others than the patrons of this Jour-
nah It has heen suggested hy 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 he 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 fuller information see Scudder's *' Catalogue of Scientific
Serials, 1633-1876," Cambridge, 1876; also H. Carrington Bolton's
*' Catalogue of Scientific and Technical Periodicals, 1665-1882" (Smith-
sonian Institution, 1885). The writer is much indebted to Mr. C. J. Barr,
Assistant Librarian of Yale 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 SCHUCHERT

Introduction,

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 194 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 geology'' (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

HISTORICAL 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 MerrilPs 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, afford 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 Mise of Geology 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

Cosmogonists. — 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 Giovanni
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 f ossilif erous 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 published **one of the classics of geological
literature," distinguishing clearly thirty successive 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 Ftichsel 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 Geognosy. — We come now to
the time of Abraham Gottlob Werner (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 pupils 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 CENTUEY 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-
buisson 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 lavas," says Geikie, *Hhey
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), *Hhe 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 Conformism. — 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 his Illustrations of the Huttonian Theory
of the Earth, of which Geikie says, **0f 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-

QQ 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 ^Westige 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-hoolcs. — In 1822 appeared 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, by 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 Eed 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 books 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

The 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 by 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

Psychozoic or Recent

Alluvial

QQ
02

QD

ci

Pleistocene

Diluvial

O

"i

3

.sa

S=l[Neogene

Upper Marine formation (Crag,

S

s

£•

o

Bagshot sand, and Isle of Wight)

r^

■|

B

Freshwater formations

K

O

6

&np«>-««-

London Clay
Plastic Clay

3

1

^

Cretaceous

Chalk

Beds between Chalk and Oolite

Comanchian 1887

Series (Chalk Marie, Green Sand,
Weald Clay, Iron Sand)

r

Upper Oolitic division (Purbeck

S

OQ

o

beds, Portland Oolite, Kimmer-

1

03

QQ

g

idge Clay)
Middle Oolitic division (Coral Rag,

o

m

c§

g

c3

J

o

1

Oxford Clay)

O

>»

Jurassic 1829

Lower Oolitic division (Cornbrash,

^

Stonesfield Slate, Forest Marble,

g

1

Great Oolite, Fullers' Earth, In-

O.

s

ferior Oolite, Sand and Marie-

S
Ul

ci

stone

Lias

Triassic 1834

New Red Sandstone

Magnesian Limestone
Coal Measures

n3

Permian 1841

1

o^^

.2

Pennsyivanian 1891

13 go

1

Mississippian 1869

Millstone Grit and Shale

i%^

fl

s

Devonian 1839
Silurian 1835

Old Red Sandstone

15 1

o

1

2

1

Ordovician 1879

H

(-Lower Silurian 1835)

1— H

Cambrian 1833

Unresolved
Submedial

>

.2

Keweenawan^ S

^

o

Animikian I g S

•|

I

^

Huronian \ U^

g

d

1

Sudburian J ^

and

■fi

6 -^ iS

^.S Keewatin 1 gS

Inferior Orders

g g Coutchiching j g g

HISTORICAL GEOLOGY 69

Early Geology in Philadelphia, — The oldest scientific
society is the American Philosophical 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 1803, 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.

Silliman, the Pioneer Promoter of Geology. — ^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

70 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. eTohn 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 geology. 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 U

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, who 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), *4n 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 lawyer and
land agent in Catskill, New 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 De 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 sown the idea

T2 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, 436, 1818). This is also noteworthy for its
geological map, the next one to be published after those
of Maclure of 1809 and 1817. In 1823 came a still
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,
particularly 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 days of labor he found that he
must necessarily be separated from his family, much to his dis-

HISTORICAL GEOLOGY 73

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 Silliman 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
Navy as instructor in mathematics, cruising oif 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 Wilkes Exploring Expe-
dition as mineralogist, returning to America in 1842 ; his
geological results of this expedition were published in
1849. In 1863, during the Eebellion, 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
be 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.

U A CENTURY OF SCIENCE

Wernerian Geology in North America,

The 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 River. The
classification was essentially the Wernerian system. All
of the strata of the Coastal Plain, now known to range
from the Lower Cretaceous 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 Secondary. 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 anywhere 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: '*! intend to demonstrate
. . . that all geological strata are arranged in ^ve 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 unrelated 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 shown by Finch 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 Geology, — 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.

T6 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
Bakewell," 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 MerrHl, 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 Eobert 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 says he is
*' neither Wernerian nor Huttonian," and yet his sum-
mary on pages 120 to 126 shows clearly that he was not
only a Wernerian but a pietist as well.

Unearthing of the Cenozoic and Mesozoic
in North America,

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

HISTOEICAL GEOLOGY 77

access to the horizontal and highly f ossilif erous 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 reliquiae, which the various accessible strata of
the earth present." Say fully realizes the difiiculties 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) DHuvial.

78 A CENTURY OF SCIENCE

The grandest of these early stratigraphic papers,
however, is that by Lardner Vanuxem (1792-1848}^ of
only three pages, entitled **Eemarks on the Characters
and Classification of Certain American Eock Forma-
tions" (16, 254, 1829). Vannxem, a cautious 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 the 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 secondary, 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

HISTORICAL GEOLOGY 79

same strata are highly inclined. *'The 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).

Timothy 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 by 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 Remarks'' (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: '*!
consider the marl of New Jersey as referable to the great
ferruginous sand series, which in Prof. Buckland'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 very much of the Msestricht 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 \ ^^l^^^a,!.
Moaem , ^ Diluvial.

{Upper Tertiary (Upper Marine).
Middle Tertiary (London Clay).
Lower Tertiary (Plastic Clay),
o , \ Calcareous Strata / Cretaceous group, or Ferrugi-

becondary j 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 Mountains was clearly

HISTORICAL GEOLOGY 81

developed by F. V. Hayden in 1855-1888 and by F. B.
Meek (1857-1876). Other workers in this field were
Charles A. White (1869-1891), and R. P. Whitfield (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 had been described
by Ferdinand Roemer 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 series 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 known 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. White 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 known as the Morrison beds. In 1896, 0. 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 accordingly referred
the strata to the Permian (3, 220, 1821 ; 6, 76, pi. 9, figs. 1,
2, 1823). The discerning Professor Finch in 1826
remarked that the red beds of Connecticut appear to
belong *Ho 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

HISTORICAL 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 bv
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 *Hhe 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 *Hhere is so
complete a blending of adjacent strata'' that it is only

84 A CENTURY OF SCIENCE

in Russia that the Permian has been distinguished from
the Triassic. This view of Owen's was not only correct
for Russia but even more so for the Alps and for India,
and it has taken a great deal of work and discussion to
fix upon the disconformable contact that distinguishes
the Paleozoic from the Mesozoic in these areas. In
other words, 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
Mesozoic evidence. ** These are certainly strong argu-
ments in favor of placing, not only the Permian, but also
the Carboniferous group in the Mesozoic period, and ter-
minating the Paleozoic division with the commencement
of the coal measures." To this harking backward 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 many reptiles in the red beds of Texas, and through
the work of C. A. White, published in 1891, The Texan
Permian and its Mesozoic Types 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 by 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 WHliam 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.
Pennsylvanian period.

Upper Productive Coal series. Monongahela series.
Lower Barren Coal Measures. Conemaugh series.
Lower Productive Coal Measures. Allegheny series.
Pottsville series.

The New York System, — We now come to the epochal
survey 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 who
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

86 A CENTURY OF SCIENCE

expensive, and do not give as clear and connected a view
of the 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 Torrey ; 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
Eegents of the State, so that it is safe to say that he
published 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 system. (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 New 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 system to the Mississippi
Eiver, 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 supposedly 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, arid
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.

{Alluvial division.
Quaternary division.
Drift division.

Tertiary system

These strata are included in the next
lower division.

Upper Secondary
system

New Ked system
>- of Emmons and
Hall.

Long Island division. Equals the Ter-
tiary and Cretaceous marls, sands,
and clays of the coastal plain of New
Jersey.
Trappean division.

The Palisades
Red Sandstone
division.

Coal system of Mather, and Carboniferous system of Hall.
Old Red system of Catskill Mountains of Emmons; Catskill
division of Mather and Hall ; and Catskill group of Vanuxem.

According to Hall 1843, and essentially Vanuxem 1842.

'' Chemung, Portage or Nunda (divided
into Cashaqua, Gardeau, Portage),
Genesee, Tully, Hamilton (divided
into Ludlowville, Encrinal, Moscow),
and Marcellus.

Erie division
[Devonian]

Helderberg series
[Devonian-
Silurian]

Ontario division
[Silurian]

Champlain division
[ Silurian-Ordovi-
cian-Upper
Cambrian]

'' Corniferous, Onondaga, Schoharie, Cau-
da-galli, Oriskany, Upper Pentame-
rus, Encrinal, Delthyris, Pentamerus,
Waterlime, Onondaga salt group.

Niagara, Clinton, and Medina.

Oneida or Shawangunk, Grey sandstone,
Hudson River group, Utica, Trenton,
Black River including Birdseye and
Chazy, Calciferous sandrock, and
Potsdam.

According to Emmons 1842, Mather 1843, Yanuxem 1842,

Hall 1843.

"^Tordovi^faTand / G^raiiular quartz, Stockbridge limestone,
Lower Cambrian] \ Magnesian slate, and Taconic slate.

Primary or Hypo-
gene system

Metamorphic and Primary rocks.

HISTORICAL GEOLOGY 89

aran, while the Middle Devonian about Columbus, 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 tvith 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 Hall 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 Middle 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
Eussia, 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 Verneuirs results were translated by Hall and with
his own comments were published in the Journal in 1848
and 1849 under the title *^0n 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 VerneuiPs 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 correlations
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, with 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 ^ve 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
HalPs 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 physical
conditions."

An analysis of the Paleozoic fossils of Europe and
America leads De Verneuil 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 *Hhe 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 Verneuil 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 unconf ormably 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 geology," 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, 1863) and for the altered
and deformed strata, the name Huronian series (1857,
1863). 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 (Schuchert and
Barrel!, 38, 1, 1914) :

Late Proterozoic era.

Keweenawan, Animikian and Huronian periods.
Early Proterozoic era.

Sudburian period or older Huronian.
Archeozoic era.

Grenville series, etc.
Cosmic history.

The Taconic Systeim Resurrected,

The Taconic system was 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 by 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 Taconic Ideas, aiid 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 typical area of the Taconic system, i. e., in Rens-
selaer County, Emmons in 1844-1846 produced the fossils
Atops trilineatus and Elliptocephala 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 part 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 typical 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 down through 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
interbedded sparry limestones, calciferous 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 *4n the sedimentation and succession of
the faunas which serve to draw a boundary line between
the Lower and IMiddle 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 system 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 Controversy,

Just as in America the 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, delayed 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 Sedgwick 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 — Synopsis of the Classification of the
British Palaeozoic Rocks, along with M 'Coy's Descriptions
of British Palaeozoic Fossils, did not appear until 1852-
1855. Sedgwick's original Upper Cambrian included the
greater part of the chain of the Berwyns, 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
Caernarvonshire, 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 yielding 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 Cambrian system upwards to include
the Bala, Llandeilo, and Caradoc, a proceeding not unlike
that of Murchison, who earlier had been extending his
Silurian downward through all of the fossiliferous Cam-
brian to the base of the LingTila 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 Murchison '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 Loiver 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

98 A CENTURY OF SCIENCE

Murchison, 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 system. 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 Murchi-
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 reco,2:nize 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 with the term Champlain, 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 :

.2

Upper or Silurian f Ludlowian (Murchison 1839).

(Murchison, re- < Wenlockian (Murchison 1839).
stricted, 1835). |^ Landoverian (Murchison).
Middle or Ordovician / Caradocian (Murchison 1839 ) .

(Lapworth 1879). {^^ IS^TlS'
Lower or Cambrian f Potsdamian (Emmons 1838).

(Sedgwick, re- < Menevian (Salter and Hicks 1865),

stricted, 1835). |^ Georgian (Hitchcock 1861).

Eegarding 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 faunal
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
chroliology 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:

Silurian period. Llandovery to top of Ludlow in Europe.
Alexandrian-Cataract-Medina to top of Manlius in America.

Champlain (1842) or Ordovician (1879) period, Arenig to top
of Caradoc in Europe. Beekmantown to top of Richmondian
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.

Taconic period. For the world-wide Olenellus or Mesonacidae
faunas.

Paleogeography,

When geologists began to perceive the vast significance
of Hutton's doctrine that *Hhe 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 Robert Etheridge in his presidential
address before the Geological Society of London in 1881.
Since Canu's use of the term in 1896, it has been fre-
quently seen in print, 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

HISTORICAL GEOLOGY 101

to outline the 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 paleogeographic 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
France, 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 Rekon-
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 Methoden 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 amounts 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 hypothetic 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.

Paleometeorology,

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 Perraudin in 1815
directed the attention of the engineer De Charpentier to
the fact *Hhat 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 'Hold 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 1821, 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 deeply 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 was 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 hypothesis, 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 CENTURY OF SCIENCE

power of quick perception, his 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 July, 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 Buch, 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 TyndalPs Glaciers of the Alps, 1860.

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 Eamsay, 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 Proterozoic
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
occur 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 *4ife 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 marine '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 marine 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 but 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 pliotherm periods of Eamsay.

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 varying
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.

Modern evolution, or the theory of life continuously
descending from life with change, may be said to have
had its first 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 Work, 1901, con-
cludes in regard to Buff on as follows :

'*The impression left on the mind, after reading Buff on, is
that even if he threw out these suggestions and then retracted
them, from fear of annoyance or even persecution from the
bigots oi 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
Buff on 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. Locy 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 acquired characters."

Georges Cuvier (1769-1832), 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

extinct forms, and later on that there was a succession
of wholly extinct faunas. This at first puzzling phenom-
enon he finally came to explain by assuming that the
earth 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, *Hhe 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 by directing attention to
James D. Dana's Thoughts on Species (24, 305, 1857).
After 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 they
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 **0n 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 v^^hich, 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 was to revolutionize the thought 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 consequence 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
lithography 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, sim-
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. 0.
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 *Hhe 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 Growth of Invertebrate JPaleontology,

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 Palasontological
Discovery (18, 323, 1879), and by Karl von Zittel in his
most interesting book, History of Geology and Palaeon-
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 about 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 me,*' 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 (1483-1553),
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 clearly 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 Linnaeus 's Systema Naturae, 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 saj^s 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-

HISTOEICAL 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 striking, 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
views 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 the Ordovician gastropod Maclurites
magna. All of the paleontologists of this time were sat-
isfied 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 been 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 making their appearance.

It had now become clearly evident, moreover, that 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 stock
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. Whitfield, 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 paleontoloerists Elkanah
Billings and, later on, J. F. Whiteaves. The ^'father of

120 A CENTURY OF 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 Hollick, 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 study of paleontology dur-
ing the evolutionary period 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.

Charles 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 synthetic period."

Synthetic Period. — Wliat is to be the next trend in
paleontology? Clearly it is to be the Synthetic period,
one that Marsh in 1879 indicated in these words: "But
if we are permitted to continue in imagination 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 Whole, 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 Climates
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 123

other will you arrive at a knowledge of things.'' But
the thorough-going ''diluvialisf' 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 Button working in the
ancient lavas of New Mexico ; and Whitney'^ 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. These 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 Backward,

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 French 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 English view for
the first quarter of the nineteenth century is expressed
in the reviews in this 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
** Reliquiae Diluvianse, " 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 Hutton'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 inadequate to their production;
nay, that such a supposition would involve a physical impossi-
bility. We do not believe that one-thousandth 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 summits 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 Englisli contemporary. 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)^^ 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 CENTUEY 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.

Valleys Formed hy Mivers,

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 by Darwin as type 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 -.2^

''Like the great canons of the Colorado, the broad valleys
bounded by high and perpendicular walls belong to a vast system
of erosion, and are wholly due 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 Caiion 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 Mivers,

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 beds 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) j'-"^ 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
peneplains 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. Geikie (1865), Foster and Top-
ley (1865), Maw (1866), Wynne (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 directly 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. ' '

PowelPs 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 gystematic 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 Resulting 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 :3«

''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 the 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-cathedra 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)^^ as resting on limestone,
Finch (1824)^2 says: '4t 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 Deluge,

In the seventh volume of the Journal (1824)^^ we read:

''After the production of these regular strata of sand, clay,
limestone, &c. came a terrible irruption of water from the north,

INTERPRETATION OF LAND FORMS 133

or north-west, which 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
convulsion which has lacerated and partly broken 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),^^ a volume which deserves a prominent place in
American geological literature. Hayden clearly dis-
tinguished 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. While 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 physical 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 which, 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, which collectively,
or even singly, might well contain much more than all our
oceans, seas, and other superficial waters, none of which 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

134 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, Struder, and Hubbard, and many Europeans.
They found a champion in Jackson, who states (1839) :^^

'^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 be represented by the following remarks of Phil-
lips (1832) :38

''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 be admitted to have happened, because it has left
full evidence in plain and characteristic effects upon the surface
of the earth/'

However, the theory of deluges, whether of ocean or
land streams, did not hold the field unopposed. In 1823,
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

INTERPEETATION OF LAND FORMS 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 usually 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 hypothesis 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 Murchison, in
1842,^1 paid his respects to the remarkable work 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 CENTURY 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 (1834), 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 places 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, Whewell, 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

INTERPEETATION OF LAND FORMS 137

third and fourth meetings of the 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 equal 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 his 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 *Svere 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 i^"^

*'In view of the whole subject, it appears reasonable to con-
clude that the Glacier theory affords the best and fullest
explanation of the phenomena over the general 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 was
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 icebergs. . . .
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."

INTERPEETATION OF LAND FORMS 139

Matthew (1871)^^ reached the same conclusion 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 hypo-
thetical ice sheet would lower the ocean-level 350 feet — •
an early form of the glacial control hypothesis (see
Daly^O.

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 type 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-known 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
Hall (1876).^* Stevens (1873)^^ 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 Beche compared

140 A CENTURY OF SCIENCE

the drift of Jamaica with that of New England, and
Agassiz interpreted soils of Brazil as glacial.

The first 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
south west ward 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.

South of the St. Marys river are other and numerous moraines
accompanied by glacial striae. 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
(1864) Whittlesey interpreted 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.

INTERPRETATION OF LAND FORMS 141

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 bulk large
in the pages of the Journal for the last two decades.

Epochs of Glaciation,

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 *4ower'' diluvium
by Scandinavian geologists suggested two epochs, and as
the examples of such deposits i^icreased in number and
it became evident that the plant fossils represented forms
demanding a genial climate and that the phenomena
w^ere 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 1883 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 interglacial periods

142 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 glaciation 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 had 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 :^*

''Recognizing from personal observation the 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 143

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, geologically 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

lU A CENTURY OF SCIENCE

by the agency of wind in a region of steppe vegetation is
now all but universal.

Glacial Sculpture,

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 powerfully in
direct and heavy contact with and across the rocks to scoop out
deep hollows, the situations of which might either be determined
by unequal hardness of the rocks, by extra weight of ice 'in
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 geologists, 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 which has not received adequate recognition.
He says:

**...! 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
hewing and planing.

If Yosemite were unique, we might suppose that it was
formed by violent cataclysms; 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 verticahty 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 1 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 tho
beds carving immense amphitheatres with basin bottoms con-
taining numerous Alpine lakes. . . . Post-glacial erosion has done

146 A CENTURY 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),
Ruskin (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 the
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 Gilbert. 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 well 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
Button, 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.
Button 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 German, but Lamarck's
*^Hydrogeologie" 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
B. 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.

INTERPEETATION 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 fluviatile 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 *Hhis 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, 1802.

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 diluviansB, this Journal, 8, 150, 317, 1824.
' Phillips, John, Geology of Yorkshire, this Journal, 21, 17-20, 1832.
*Scrope, 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., valley 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, O. 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, 216-219, 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.

""Silliman, 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.

** Hall, 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 j 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, 44, 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. C, 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, Raphael, Geological researches in China, Japan, and Mon^
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 River,
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, aarence, U. S. Geol. Expl. 40th Par., 1, 459-529, 1878.

"Davis, W. M., Glacial erosion, Proc. Boston Soc. Nat. Hist., 22, 58,
1882.

'^ Sabine, Sir Edward, Address of the president of the Royal Society,
this Journal, 37, 108, 1864.

IV

A CENTURY OF GEOLOGY THE GROWTH OF

KNOWLEDGE OF EARTH STRUCTURE

By JOSEPH BARREL.L

Introduction
The Intellectual Viewpoint in 1818,

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 object to illustrate
American Natural History, and especially our Mrs-
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 Maillet and Buffon
had been less instrumental in developing science than in
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 imagiuation, 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 Outgrown 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 **driff
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
1823 (6, 74) 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 convulsion. Such irregularity
in the dip of coal fields is no uncommon occurrence."

In Hitchcock's Geology of Massachusetts, published in
1833, 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
forces. 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
while 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 subsequently 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 Science Monthly.

C ^^^^^^^-^-^-^^^^^ ^:^^^c^^^^^C^6^t>-^

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 by, 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 almost 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 Igneous Rocks,
Opposed Interpretations of Plutonists and Neptunists,

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 by 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
^ve pages to the subject of ** Greenstone Dykes in Old
Red Sandstone" (6, 56-60, 1823) and makes the follow-
ing statements :

"Professor Silliman 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 I feci to taking a side in 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 mind to invent a system more repugnant to
existing facts.'

On 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 amygdaloi-
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 quite 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 EAETH STRUCTURE 161

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 TriassLc 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 physical 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.

Views 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

162 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. Where 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) :

Eeport 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 Revue 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. France has
the greater cause to regret her being distanced in this race by

164 A CENTURY OF SCIENCE

America, from her having a corps of mining engineers, who
if they had the means, would, in a very 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, up 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 MantelPs 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.

Rise and Decline of the Metamorphic Theory of Chranite,

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 STRUCTURE 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 severely reviewed by **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 known to be altered strata of newer
Secondary and Tertiary ag^. 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 EABTH 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 the 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 in
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. R. 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 isogeotherms 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 OP EARTH STRUCTURE 169

Orogenic Structures,
Views of Flutonists and Neptunists»

Orogenic structures are, as the name implies, those
connected with 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 varying 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 by 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.

ITO 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.'' In a
couple of pages he confuses and dismisses the whole sub-
ject of deformation. He states f

*'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.

Recognition of Appalachian Structures,

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 Producing Folding,

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 without 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 STEUCTURE 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 the 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
actually 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 the 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 hypothesis 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 us 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 STEUCTURE 176

sufficiently powerful? Finally, such forces do exist in nature,
and have often been in operation.''

The advanced nature of these conceptions may he
appreciated by 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 nniformitarian 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-
mum thickness of between 30,000 and 40,000 feet, showed

KNOWLEDGE OF EARTH 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 fully 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 were 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 hypothesis 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 HalPs hypothesis,
especially as the folding took place not during, but after
the close of the vast Paleozoic deposition. Dana states
in conclusion on HalPs hypothesis (42, 209, 1866) that
* ^ It is a theory of the origin of mountains with the origin
of mountains left out.''

The Theory of Geosynclines and Geanticlines,

The fact that systems of folded strata lie along axes of
especially thick sediments and that this implied subsi-
dence during deposition was HalPs 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 view, 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 HerschePs principle cannot be doubted.
But the question 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 STRUCTURE 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 yet 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 next contribution to the theory of orogeny was a
series of papers published in 1873 by Dana, entitled **0n
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 Mountains,^^

** 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 polygenetic chain; it
consists, like the Kocky and other mountain chains, of several
monogenetic ranges, the more important of which are : 1. The
Highland range (including the Blue Kidge or parts of it, and
the Adirondacks also, if these belong to the same process of
making) pre-Silurian in formation; 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-
paratory, 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
geosynclinal 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 6po<s,
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 hy 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 polygenetic 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 underneath. 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
geanticlinal, parallel with it ; and that both movements demanded
the existence beneath of a great sea of mobile rock."

The recognition of regional warping 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 downf old 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 synclinorium, 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 Crustal Compression,

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 hypothesis." 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 CENTUEY 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 contractional 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. Regarding these as the main and
underlying premises of the contractional 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 contractional 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 contractional 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 contractional 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 small, 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. '*

Dutton's criticisms robbed the current hypothesis of
mountain-making of its conventional basis without 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 CENTUEY OF SCIENCE

of the compressive forces it is necessary to seek another
cause. Two years later, in 1876, Dutton 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 Dutton presents in this paper the views brought out
in his article in volume 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 Dutton 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 Hhe 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:
'Wlierever 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 anticlinals. '

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 says 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 before 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 Dutton attempted to link to it the
horizontally compressive forces which have produced
folding and overthrusting. 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 Dutton. 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 h^^othesis 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

through 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 Interpretation 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 Appalachians. 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 out 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, the thirteenth
annual 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 Movements as Revealed hy 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.

12

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 PowelPs 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.

Melations of Crust Movements 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 Dutton 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 Dutton, has taken the lead.

Conclusion on Contributions of America to Theories of

Orogeny,

The sciences atose 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 whole 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, 1840.

« H. D. Rogers, Geology of Pennsylvania, 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, U. 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 Geogno'sy, 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.

^'W. N. Rice, On the use of the words synclinorium 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.

" B. Willis, Research in China, vol. 2, 1907.

"Joseph Barren, 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 CENTURY OF GOVERNMENT GEOLOGICAIi

SURVEYS

By GEORGE OTIS SMITH

Director of the United States Geological Survey

EVEN 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 geologic science to industry.

The earlier stages in industrial evolution mentioned by
Hess^ — exploitation, development, 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 in this
country 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
inferentially 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,
69) 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 SUEYEYS 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 Major 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 MerrilPs 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 surveys 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, Moore, 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 Geology '

by George P. 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
promptly, 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. Geolo-
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 survey of the Lake Superior district.
The execution of these surveys under Jackson and under
Foster and Whitney 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 Survey with the Federal officials
would 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 added 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, was
sent out **for boring Artesian Wells along the line
of the 32d Parallel'' in New Mexico. The pub-

200 A CENTURY OF SCIENCE

lished reports varied greatly in scientific value and in
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 by 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 surveys 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 known 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 Wheeler.
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 CENTURY OF SCIENCE

marks, in the history of national geological work, a turn-
ing point, when the science ceased to be 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. Y. 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 was 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 Shasta, Rainier, 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 with
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 use 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 Survey." An earlier influence in the sci-
entific study of ore deposits had come from Von Richt-
hofen's investigation of the Comstock Lode in 1865 and
his subsequent work with Whitney 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-

^rvv^Jj,

GOVERNAiENT GEOLOGICAL SUEVEYS 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
Wheeler's own claim for the work 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 Academy considered all the work
relating to scientific surveys^ and reported to Congress
a plan prepared by a speciarcommittee, 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, surveys of mensuration and surveys of
geology. At that time -^ve 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

GOVERNMENT GEOLOGICAL SURVEYS 207

wliich 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
office 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 Division 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 Wheeler, and five with the King Survey.

In planning the initial work of the United States

tkMei/v h.

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 f ramers 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, which 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
ore deposits, which may be said to have begun with the
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 first 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.^^ 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. This 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
Wj^oming, for instance — detailed geologic surveys which
form the basis for the 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 mark 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 in 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 Survey 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

GOYEENMENT GEOLOGICAL SURVEYS 215

the 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 surveys 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 CENTURY 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,

^ Hess, B. H., Foundations of National Prosperity, p. 100.

'Eeport Nat a Museum, 1904, pp. 189-733.

« Featherstonhaugh, J. D., Am. Geol., 3, 220, 1889.

* Whitney, Mineral Wealth of the United States, pp. 248-250.

■* Foster and Whitney, 31st Cong., 1st session. House Doc. 69, pp. 13-14,
1850.

' First Annual Kept. U. S. Geol. Survey, p. 4.

^Wheeler, Keport 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 U. 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. Kept., 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 Board of the Geological
Survey: Proceedings 2d Pan-American Sci. Cong., 1915-16, 3, 761.

VI

ON THE DEVELOPMENT OF VERTEBRATE
PALEONTOLOGY

By RICHARD SWANN LULIi

Introduction*

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 type 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 with 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 evolutionary 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.

Mise 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

VERTEBRATE 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 living, 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 affirm the unlikelihood of any further discovery
of unknown forms among the great mammals 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 CENTUEY 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 Richard Owen, possessed his breadth 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 Woodward of the British Museum is
considered the highest living authority upon fossil fishes.

Of the Amphibia, the most famous foreign students
were Brongniart, Jaeger, Burmeister, Von Meyer, and
Owen, although Owen'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 Archceopteryx
as the earliest known bird and not a reptile 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, by 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 Hipparion; this horse, together with the
remarkable proboscidean Dinotherium, 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 Palaeontology, 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 Reliquiae Diluvianae ; Falconer, co-author
with 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-Major 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 Fayum 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 Proboscidea 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 ^ve of the mammalian orders, those men-
tioned above, together with the Embrithopoda, a group
unknown elsewhere. This theory had been advanced
independently by Tullberg, 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, Florentino

224: A CENTUEY OF SCIENCE

Ameghino, 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.

Vertebrate Paleontology 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 World 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. When 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, displaying therein for
study the bones of proboscideans and their contempora-
ries which the Big Bone Lick of Kentucl^ 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 the 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 quarto 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

Hitchcock'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
dilBficult 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 work was contemporaneous with that
of Hitchcock, but one, W. C. Redfield, 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
Pennsylvania 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 Clepsysaurus, 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(?) 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 CENTUEY 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 with 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 Leidy (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 w^ere based upon the fruits of organized
research. Leidy began his publication in 1847 and con-
tinued to issue papers and 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-
tJierium'' {=T it another ium 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 Nebraska 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 hi§ 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 types.
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
much 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 Hadrosaurus, 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 Eoyal 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 were
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 years, 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, Wyoming, geologically older

VERTEBRATE PALEONTOLOGY 231

than the Nebraska and Dakota formations. This,
together with specimens from the Green River and
Sweetwater River deposits of Wyoming and the John
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 Marsh (1831-1899).

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 Yale University. These parties explored Kansas,
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 by 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, Marsh 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. Marsh 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 advance of 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

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 CENTUEY 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.
They also were published first in the Journal, although
they have subsequently been reproduced in text-books
and other works the world over. Part of Marsh'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 Marsh
collection has reflected the fame of its maker.

Edward DrinJcer Cope (1840-1897).

The third great name in American vertebrate paleon-
tology, that of Edward Drinker Cope, stands out in sharp
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 years 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
Amphihamus 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 years 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 Wyoming 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 well 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 Leidy alone was engaged in research in the
AVest, 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
him 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 ** Cope's 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 CENTURY 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 marks 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, while far less logical
than Huxley, he was more creative and constructive, his meta-
physics ending in theism rather than agnosticism."

1870-1880.

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 University 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 ill 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
1878, 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 paleontologio
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 Wortman 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, filling 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 OAvn 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 Mammalia, man, neurology and embry-
ology, biographies, and the theory of education.

In paleontology, Osborn's researches have been largely
with 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 Patagonia for the E. and M. Museum, 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 Haplocanthosaurus 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, morphology, 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.

Summary,

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 variety. 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

researcli 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 heavy, 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 and 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
things 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 Marsh

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 the 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 * * Palaeothere " 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 the 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 1815, Cordier by a
process of washing separated the components of a basalt
and by 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 and analyses of
rocks were made in 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
reviewed 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 naturally 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 field and made inci-
dental reference to them, but investigations of the rocks
themselves was very little attempted. An inspection of
the first 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 was
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 !

The Thin 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. When 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 whose 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 were 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

EISE 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 petrography.

The twenty years following the publication of the
texts of Rosenbusch and Zirkel may be characterized as
the era of microscopical petrography. 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, especially of igneous
and metamorphic rocks, in addition to their mineral
constitution, were more studied and gained greater recog-
nition, petrography 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 otfered 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, Lacroix 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 slowly, 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 TealPs 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. Dana^^ 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
Rosenbusch 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,
G. 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 lithophysae; 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.

The 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
assemblages 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 the ^* 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 J whereas in the second volume (1892-1900)
they are grouped under petrology 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
work of ZirkeP^ began to appear, which sums up so com-
pletely the results of the petrographic era. 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
** Physiographic 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 analogy 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

which we owe so largely to Rosenbusch 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 Bayley, Bascom, Cushing, 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 diiferentiation. 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-
erable fraction, have indeed been of great weight in
shaping the development and future of the science.

By referring to the files 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
crystallization, and on diiferentiation; by Cross on
classification; by Adams on the physical properties of
rocks ; by Daly on the methods of igneous intrusion ; by
•Wright on schistosity; by Fenner on the crystallization
of basaltic magma; by Bowen on differentiation by
crystallization; by the writer on complementary rocks
and on the origin of phenocrysts ; by Smyth on the origin
of alkalic rocks ; by Murgoci on the genesis of riebeckite
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

EISE OF PETROLOGY AS A SCIENCE 259

Hague on the lavas of the Yellowstone Park; by Pogne
on ancient volcanic rocks from North Carolina ; by 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. Hawes,
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 works 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
Rosenbusch with 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 w^hich 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, the work in mineralogy of Pen-
field, noticed in the accompanying 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 hydroxy!
in a variety of species, and thereby the perception of their pneumatolytic
origin. His papers have been published almost entirely in the Journal.

260 A CENTURY OF SCIENCE

quent improvements in them and in ways of using them,
as exemplified 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 year, 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 who are not able
to use the microscope special manuals of petrology have
been prepared in which rocks are treated from the
megascopic standpoint.^^

Metamorphic 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
way. The inaugural work of Lehmann, Lossen, 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 resrion became the chief place
of study of the metamorphic rocks in this country.
Irving soon obtained the assistance of G. H. Williams,
who had been engaged in the study of such rocks, and the

RISE OF PETROLOGY AS A SCIENCE 261

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, Leith, 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 Hocks,

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 1861, 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. Whitney and two by European chemists, one of
whom 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 was prob-
ably 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
petrographio 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 especially 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 W. 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 quality 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 previously 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 new edition of Washington's Tables has recently been
published, listing some 8600 analyses of igneous rocks
made up to the close of 1913.^^

RISE 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.

Physico-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
synthesis 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,*^ ^nd 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 be 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

264 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 hypothetical 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 outlines
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.

What 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 265

Bihliography,

^W. Cross, Jour. Geology, 10, 451, 1902.

' Ihid., p. 45.

" Sorby, Quart. Jour. Geol. Soc, 14, 453, 1858.

*Zirkel, Einfiihrung des Mikroskops in das mineralogisch-geologische
Studium, 1881.

^ Williams, G. H., Modern Petrography, 1886.

' Zirkel, Mikroskopische Beschaffenheit der Mineralien und Gesteine.

' Rosenbusch, Mikroskopische Physiographie der petrographisch wichtigen
Mineralien.

* Zirkel, Mikroskopische Gesteinstudien, Sitzung vom 12 Marz, 1863.

'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. Rocky Mts. Rep. on Black Hills of Dakota, 469-527. The
separate copies issued bear the imprint 1876; the complete report 1880.

^* Dana, E. S., Igneous Rocks in the Judith Mts. Rep, of Reconnaissance
Carroll, Mont., to Yellowstone Park in 1875. Col. Wm. Ludlow, War
Dept., Washington, 105-106.

" Hawes, G. W., Rocks 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 silurischen 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, 1882;

, 23, 302-308, 1882.

Cross, 27, 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, 36-45, 1887.

Williams, 31, 26-41, 1886; 33, 135-144, 191-199, 1887; 35, 433-448,
1888; 36, 254-259, 1888.

, 34, 137-145, 1887.

DUler, 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 Rosenbusch, Ueber Monchiquit, etc., Min. petr. Mitth., 11,
445, 1890. Rosenbusch, Ueber Structur und Class, der Eruptivgesteine,
ibid., 12, 351, 1891.

^Iddings, Origin of Igneous Rocks, Bull. Phil, Soc Washington, 12,
89-213, 1892. , , s » -»

J^Brogger, Mineralien der Syenit-pegmatit-gange, etc., Zs. Kryst., 16,
1890.

" > Basic Eruptive Rocks of Gran, Quart. Jour. Geol. Soc, 50,

15, 1894; Grorudit-Tinguait-Serie, Vidensk. Skrift. 1 Math. nat. Kl., No.
4, 1894.

266 A CENTURY OF SCIENCE

^ Weed and Pirsson, e. g. Shonkin Sag, the Journal, 12, 1-17, 1901.

-* The references for the articles mentioned (all in the Journal) are as
follows :

Becker, 46, 1893; 4, 257, 1897; 3, 21-40, 1897.

Cross, 39, 657-661, 1915.

Adams, 22, 95-123, 1906; 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 HHl, 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 Rocks, vols. 1 and 2, J. P. Iddings, New York, 1909 and 1913.

Problem of Volcanism, Iddings, New Haven, 1914.

Natural History of Igneous Rocks, Alfred Harker, London, 1909.

Igneous Rocks 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.

Winchell, 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 Rocks, 3d ed., New York, 1904. Pirsson, Rocks
and Rock-Minerals, New York, 1910.

""Williams, G. H., U. S. Geol. Surv., Bull. 62, Washington, 1890.

^ Van Hise, Treatise on Metamorphism, U. S. Geol. Surv., Monograph 17.

"^ F. W. Clarke, U. 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 Rocks (1884-1900), U. S. Geol. Surv.,
Prof. Paper, No. 14, 1903.

"^Osann, Beitr. zu chem. Petrogr., II Teil. Anal. d. Eruptivgest., 1884-
1900, Stuttgart, 1905.

^^ Washington, ibid., 2d ed., U. S. Geol. Surv., Prof. Paper 99, pp. 1216,
1917.

EISE OF PETROLOGY AS A SCIENCE 267

«« Clarke, V. S. Geol. Surv., Bull. 616, 1916.

"'Fouque and Michel-Levy, Synthese des Mineraux et des Eoches, Paris,
1882.

*" Morozewicz, Exper. Untersuch. u. Bildung der Min. im Magma, Min.
petr. Mitt., 18, 1898.

*»Doelter, Synthetische Studien, N. Jahrb. Min. 1897, 1, 1-26. AUg.
chem. Mineralogie, etc.

*^ Tamman, Krystallisieren und Schmelzen, 1903.

*^St. Meunier, Les Methodes de Synthase en Mineralogie, Paris, 1891.

^'Vogt, Mineralbildung in Smelzmassen, Christiania, 1892; Silikatschmelz-
losungen, 1 and 2, 1903, 1904, and various other papers, esp. in Min. petr.
Mitt., vols. 24 and 25, 1906.

*H. E. Boeke, Grundlagen der physikaliseh-chemischen Petrographie,
Berlin, 1915.

VIII

THE GROWTH OF MINERALOGY FROM
1818 TO 1918

By WILLIAM E. FORD

MINERALOGY to-day would certainly be generally
considered one of the minor members of the
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 first
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 crust 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
forms of minerals. During many succeeding centuries
little was added to the general store of geological knowl-
edge and it was 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 physical 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 shown that rational relations existed between
the intercepts upon the axes of the different faces of a
crystal. It was not until 1809, however, that Wollaston
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 Mains 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 laws, 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

GROWTH OF MINERALOGY 271

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 frequency 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 the
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
Rozamonsky, a Russian nobleman, long resident in Switzerland.
To which the 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, the 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 the latter 's editorship. Although the field of the
Journal at the very beginning was made broad and inclu-
sive it has always 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. More 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. Bhepard. 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
exhaustive 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
U. 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 this way in 1837, has
continued by means of successive editions to be the 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 crystallographic 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 only 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:

*'Tt 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 introduction of a new name in the
science. The publication of factitious species, in 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 Turkey 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

J'u>9k'JD

GROWTH 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 scientific 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. His 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 figure 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 great many writers contributed to the pages of
the Journal, more than fifty different names being
counted for the volumes 41 to 50 of the Third Series.
Many 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 palaeontology, 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. TJ.
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,
daubreeiite, 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 iDodies. Among the more recent
workers in this field the names of G. P. Merrill 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

282 A CENTUEY 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 noteworthy.

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, however, it was felt that an authoritative,
although necessarily, 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 unorganized 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 CARXEGIE Il^STITUTION
OF WASHINGTON

By R. B. SOSMAN

THERE are three methods of approach to the great
problem of rock formation. The first 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 aifect such
relations.

It is to this third method of investigation of the prob-
lems of the rocks that the Geophysical Laboratory has
iDeen 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 accessibility
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. Two-component systems: silica-alumina, includ-
ing sillimanite and related minerals; silica-magnesia,
including the tetramorphic metasilicate MgSiOg ; silica-
lime, including wollastonite ; 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, complete, 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: SiOg-AlgOg-MgO-CaO : the in-
complete system anorthite-f orsterite-silica ; SiOs-AlgOg-
CaO-NaaO: the series of lime-soda feldspars (albite-
anorthite), and the series nephelite (carnegieite)-anor-
thite; SiOg-AlgOg-NaaO-KsO: the sodium- potassium
nephelites.

V. Five components: SiOg-AlaOg-MgO-CaO-NagO:
the ternary system 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 hydrated oxides of iron have been studied chemically
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 DURIIVG THE
PAST ONE HUNDRED YEARS

By HORACE L.. WELLS and HARRY W. FOOTE

Introduction,

AS we look back to the time of the founding of the

\ Journal in 1818, we see that the science of chem-
JIJL. 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.

Davy 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 year s^ 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 CENTURY OF SCIENCE

mentioned that all three of them and also Benjamin Silli-
man, the founder of the Journal, were born within 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 without giving him proper credit. He begins (2,
281, 1820) by saying: ^^Dr. Clark has published a book
on the gas blowpipe in 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 FeaOg he regarded as
FeOg and Fe03, 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 hydrogen as unity, or even still closer
when based upon oxygen as 16.

With our present knowledge Front's hypothesis 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 cases, 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 HUNDRED 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 Front'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
caesium 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 countryman 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 Chemistry,

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 * * Zeitschrif t fiir 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 analysts 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, particularly in Ger-
many, was so much absorbed by organic chemistry that

ONE HUNDRED YEARS OF CHEMISTRY 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 work 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. P. 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 in some of his researches upon minerals and one of
us bee:an 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 Journal 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, L
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 hjs name into everyday use in all
chemical laboratories.

Volumetric 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 in 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.

While 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-Lussac 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 hydrogen 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 Chemistry,

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 N2O5. 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 symbols to represent
oxygen, and commas to represent sulphur atoms. Exam-
ples of these are :

• ••• >»

CaS, calcium sulphate ; Fe, iron disulphide

ONE HUNDRED 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, H2O
for water, ZnClg for zinc chloride, N2O5 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 Gay-Lussac in Prance
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 NO5,
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. ,

The Law of Atomic Beats. — 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 polymorphism 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^Sg and FcuSia, 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 Zn3Sb and ZuoSb, 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 Avogadro'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 hydro-
gen sulphide. Berzelius saw clearly that the results
pointed to the existence of such molecules as Sg, 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.

Electro-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 arrived at
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.N2O5, CaO.COs and
H2O.SO3 where we now write KNOg, CaC03 and H^SO^,
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 *4ons" for the parti-
cles that were supposed to '* wander" towards the elec-
trodes to be set free there.

This term *4on" 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.

Cannizzaro^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

HO, HO, or H,0

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.SOg, 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 Davy
that *4odic acid," I2O5, showed no acid reaction until it
was combined with water, the accumulation of similar
facts led to the formulation of sulphuric acid as H2SO4
instead of SO3 or HgO.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 NagO.HgO, 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 'Haw of octaves" in 1863. This was
at the time when the atomic weights were being modified
and 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.

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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 R2O in Group I to R2O7 in
Group VII, while in Group VIII two oxides (of ruthen-
ium and osmium) are known which carry the progression
to RO4.

It was pointed out by Mendeleeff 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 caesium, 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 VIII and 0.

The periodic law has been useful in rectifying certain
atomic weights. At the outset Mendeleeff was obliged to
change beryllium from 14-5 (assuming BcoO^) 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.

Mendeleeif 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 CENTURY 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 five 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, where 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 heavy-metal 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-metallic elements, 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.

The Isolation of Elements. — In the year 1818 about
53 elements were 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 known 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 aluminmm 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 year 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 formitlas 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 very 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 Claus. 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 CENTURY OF SCIENCE

phuric acid industry, while other important applications
of platinum as a ** catalytic agenf have also been made.
Wolcott Gibbs 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, PtAss, 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 caesium by Bunsen and Kirchoif 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 caesium, thus cor-
recting Bunsen *s determination which was unsatisfac-
tory on account of the small quantity and impurity of his
material. Pollucite, a mineral rich in caesium, 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 YEARS 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 cassium 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

314 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, except 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.

The Inactive Gases. — As long ago as 1785, Cavendish,
that remarkable Englishman who first weighed the world
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 where 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 YEARS OF CHEMISTRY 315

mineral as much as 2-5 per cent of an inactive gas.
Hillebrand examined the gas spectroscopically but, just
missing an important discovery, he 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 yellow 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 radioactive 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 always 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 sho^vn 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 uranium, which shows the genetic relation between
the two.

In the case 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. All of the radio-
active changes that we know proceed from higher to
lower atomic weights, and we are entirely ignorant of the
process by 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.

Physical 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
extremely high temperatures were determined with inter-
esting results. For instance, it was found that iodine
vapor, which shows the molecule Ig at lower tempera-
tures, gradually becomes monatomic with rise in tem-
perature, that sulphur vapor dissociates from Sg to Sg
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 319

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 I2 and the metals
are monatomic.

VanH 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 behavior of salts, strong acids and strong bases by
assuming that they dissociate spontaneously into ions
Avhen 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
Hoif '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 NH4 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 hypothesis 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 colloi(J and the fine-
ness of division. By preparing filters with pores of
varying degrees of fineness, Bechold has been able to

ONE HUNDRED YEARS OF CHEMISTRY 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 iii 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 shown 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 haemoglobin,
starch, proteins, rubber and milk are examples of 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 Berthollet 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,
Berthollet 's law in its other applications received no
immediate attention. Mitchell, however, pointed out
in the Journal (16, 234, 1829) the importance of
Berthollet '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 was 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 simpler
aspect in applying only to the concentrations of the
gaseous substances. For example, in the reversible
reaction

3Fe + 4Hp:;=±Fe,0, + 4H„

which takes place at rather high temperatures, a definite
mixture of steam and hydrogen at a definite temperature
will 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 + 4H,0 > SFefi^ + 4X1, and

Fe,0, + 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 was 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 HgO,
for instance, whether as ice, water or vapor, contains but
one component, while a solution of salt and water con-
tains two. Letting P, F. and C stand for the three terms,
the phase-rule is simply

F = C-f2 — 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, /t^^iZ^^:4.^^i.^c^ yS^,

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 + 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 water 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 diiferent
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. The law, how-
ever, requires a knowledge of the molecular condition of

326 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 which 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 energy 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 for 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).
Using 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 this 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 Cheinistry,

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
found to be very numerous in many cases. For instance,
three pentanes with the formula C5H12 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 C13H28 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, GJIq,
which 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 years. In

ONE HUNDRED YEAES 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, who 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 putrefaction 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 subsequently did much service for agricultural chem-
istry in this country, by his investigations, his teaching,
and his writings. His book, **IIow Crops Grow," pub-

ONE HUNDEED YEARS OF CHEMISTRY 331

lished 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 with 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 first converting the latter into the
sulphate by 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 which 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
Journal 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
JournaPs 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 excellent 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 volimies of hydrogen combine with one
volume of oxygen.

XI

A CENTURY'S PROGRESS IN PHYSICS

By LEIGH PAGE

DYNAMICS. — At the beginning of the nineteenth
century mechanics was the only major branch of
physical 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 laws 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 dynamical 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 dynamical 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 France 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 communicated 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 !

V. ^ yhu..^^tz;z^

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 nebulae, 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 TempePs
comet.

Electromagnetism. — During the eighteenth century
much interest had been manifested in the study of elec-
trostatics and magnetism. Du Fay, Cavendish, Michel!
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-
sylvania 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 electrodynamics."

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
with 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 CENTURY'S PROGRESS IN PHYSICS 341

plete account of all experimental methods available for
inducing a current in a closed circuit.

While 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 into a
helix ; it seems to depend in some measure on the length
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 Ruhmkorif 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, 1838) greatly increased its efficiency.

Conservation of Energy. — Perhaps the most important
advance of the nineteenth century has been the estab-
lishTnent 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-
forniing 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 Eumford 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
*^0n 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 physical principles. As early
as 1850 Jeremiah Day (10, 174, 1850), late president of
Yale College, admitted the improbability of constructing

A CENTURY'S PROGRESS IN PHYSICS 346

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 energy, 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 concisely the princi-
ple toward which Carnot 's work had been leading, when
he asserted that *4t 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
thermodynamic 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

346 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 unfortunate 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
in making 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 combined with the
low temperature is sufficient to bring about liquefaction

A CENTURY'S PROGRESS IN PHYSICS 347

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 through 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
in 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
of nodes and loops determined by a detector composed of
a movable loop of wire containing an air gap. Thus the

■^.:-^

-^m^

A CENTURY'S PROGRESS 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
determined with a bolometer. Preliminary experiments
indicated the existence of a pressure of the order

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 nearby 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
carrying 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 HalPs 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 CENTURY 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 photographic plate.

The Electron. — The atomic theory of electricity dates
from the time of Faraday. His experiments on 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 363

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

in

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 easily 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 weighed 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)-^^ electrostatic units for the

364 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 of all
matter is attested by the fact that charge and mass are
the same regardless of the source or manner of produc-
tion. Whether 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

856 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 agreement 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
positively 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 hypothesis, 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.

X-Rays. — In 1895, on developing a plate which had
been lying near a vacuum tube, Rontgen^^ 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 PROGRESS 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
Laue 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 Lane'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 rays are elec-
tromagnetic pulses of the same nature as X-rays 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 hypothesis 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

360 A CENTURY OF SCIENCE

recent measurements by Miss Gleditsch (41, 112, 1916)
agree more closely with the value 1760 years obtained by
Rutherford and Geiger from the number of alpha parti-
cles emitted.

Under the action of X-rays or the radiations from
radioactive substances, gases acquire a conductivity
which has been attributed by Thomson and Rutherford
to the formation of ions. Zeleny has found that ions of
opposite sign have somewhat different mobilities in 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.)
has 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 nearly 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 was
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

362 A CENTUEY OF SCIENCE

particles shot out from the luminous body with enormous
velocities. So great was his 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 Copernican 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 lay in the discovery
of aberration by the British astronomer Bradley in 1728.
Bradley noticed that stars near the pole of the ecliptic
describe small circles during the course of a year, while
those in the plane of the ecliptic vibrate back and forth
in 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
all cases exactly a year. Bradley concluded that the
phenomenon is in 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 in observing a star at the pole of the ecliptic

A CENTURY'S PROGEESS 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 by 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, Michelson (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 luminif erous 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 absolute velocity greater than
that when the medium is at rest by an amount

i'-^h

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 FresnePs coefficient of entrainment was found by
Michelson and Morley to be less than one percent, which
'was about their experimental error. Thus FresnePs
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 known 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 was 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-

366 A CENTURY OF SCIENCE

ized light these vibrations are confined to a single
direction. This supposition explained so many of the
puzzling results of experiment, that it was accepted at
once and led to the complete vindication of the undula-
tory theory.

Elastic Solid Theory. — Shortly afterwards Poisson
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 types 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

|/i+±? and |/^

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 dynamical
explanation of the ether, should have proposed in a paper
read before the Cambridge Philosophical Society in
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 infinite 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 FresnePs theory, but the same rigidity,
certain of these coefficients fail to give the values

A CENTURY'S PROGRESS 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 electrodynamics. 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 CENTURY OF SCIENCE

logues to illustrate the phenomena of electromagnetism,
he was never enthusiastic over the speculations of the
advocates of a dynamical ether. The electrodynamic equa-
tions provided an accurate representation of the electric
and magnetic fields, and bevond 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 of 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 djoiamics
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 New Point of View. — While tTie 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. Kirchhoif'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 CENTURY 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
position 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

Fig. 1.

Fig. 2.

Fig. 3.

at the point under consideration at the instant for which
the intensity of the electromagnetic field is to be deter-
mined. This solution of the electrodynamic equations
led in turn to rigorous expressions for the electric and
magnetic intensities produced by a very small charged
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
radially from the charge, but are crowded in the equato-
rial plane and spread apart in the polar regions. The
dissymmetry 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 shown that fig. 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

^1 — ^» : 1, where p~-.

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 — mf, where / stands for the acceleration and m
is a positive constant, and we have the fundamental

equation of dynamics •

F — mf = 0

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 with 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 being 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 2^1, where the small
quantity (3 is the ratio of the earth's velocity to the
velocity of light. Hence the length of the path traversed
by this ray is approximately

2/(1 +

i&

The other ray will reach the mirror c after the latter has
moved forward a distance

A CENTURY'S PROGRESS IN PHYSICS 373

and on returning find m at m'. Hence its path has a
length of roughly 21 (1 + /?^). The difference in path of
the two rays is (3- 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 ^^ I.
This quantity is of course small, — p^ 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 b 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-

374 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 time 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' theory, 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

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

2l{ 1 +

:-")■

which is just that of the other ray. Of course when the
apparatus is rotated through 90°, the distance of this
mirror from m 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 paths of high speed 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

Vi - /8' : 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 justify 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 point 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 electrodymanic 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. What 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 electrodjoiamic 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 shorter 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 0
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 may 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 def orm-
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 every 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 symbols as

380 A CENTURY OF SCIENCE

electric and magnetic intensities. These modes of repre-
sentation liave T3een 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.

Finally 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
ditferentiation 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 analysis.

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 without 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 PEOGRESS 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
appropriated 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

34

382 A CENTURY OF SCIENCE

the laws which govern the motions of electrons and pos-
itively charged particles inside the atom.

Black Radiation. — The significance of the problem was
first brought to light through the study of black radia-
tion. By a 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, 1847.)

Farther than this general thermodynamical 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 hv, 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 hv.)
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-1

384 A CENTURY OF SCIENCE

cation of the energy of vibration which is permitted to
each 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 be 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 Atom. — The generally accepted model
of the atom is that due chiefly to Rutherford.^ ^ He con«

A CENTURY ^S PROGRESS 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-
trodynamic 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 hydrogen would be expected to give off 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.
Formulae 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^s 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 -| 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 taken 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 h 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 w^hich 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 JournaVs Part in Meteorology,

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 statenient
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. '* While 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, Redfield 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 FerrePs (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 PROGRESS 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, and 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
obtained 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.

Kotes,

» 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. Eev., 13, 307, 1901 et seq.
»J. J. Thomson, PhU. Mag., 44, 293, 1897.

• R. 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. Rontgen, Wied. Ann., 64, 1, 1898 et seq.

390 A CENTURY OF SCIENCE

"W. Friedrieh, P. Knipping, and M. Laue, Ann. d. Phys., 41, 971, 1913.
^ H. G. J. Moseley, Phil. Mag., 26, 1024, 1913, and 27, 703, 1914.
" E. W. Morley and D. C. MiUer, 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.

" R. A. Millikan, Phys. Rev., 7, 355, 1916.
" E. Rutherford, Phil. 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 text-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 IJnited 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 CENTUEY 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 world. 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 higher
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 Regno Animal,'' and Lamarck's * * Philosophie
Zoologique" had then aroused a new interest in classi-
fication and comparative anatomy from an evolutionary
standpoint. E. Geoffroy 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 Linnaeus by the
publication of the modern system of classification in the
tenth edition of his *^Systema Naturae" in 1758. The
influence of Linnaeus 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 CENTUEY 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 Linnaeus 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 untU

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 Xatural History,— Previous to 184:7 •

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. MitchilPs 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-
can work on mammals.

Peck has the distinction of writing the first paper on
systematic zoology published in America. This was a
description of new species of fishes and was printed in

396 A CENTURY 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.

Such 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 were published in
England, with later editions of smaller plates in America.
NuttalPs 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 Geography,
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 (1826-1828), 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 systematic 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 proniinent 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.l33) :
**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 afford him time 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

398 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 (Zoophytes) and to
the Crustacea. In 1846 the report on the Zoophytes 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
additional years (1854). These reports describe and
beautifully 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: Mollusca 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; Mollusca, Crus-
tacea, Annelida and Radiata'' was published by A. A.
Gould in 1841, which contains all the New England
species of these groups known 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
XI 17, 1846). In this article F. Y. 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 CENTUEY OF SCIENCE

their colored illustrations in 1859. The 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 Journal of Science,
1818-1846.

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 by 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 country. 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 Silli-
man in the preface to vol. 50 (page ix), 1847 :

*'Our zoolo^ 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 JournaPs
readers.

The Influence of Louis Agassiz,

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
similar 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 CENTUEY 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 CENTURY 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 Journal (6, 151, 1848) indicates clearly
the broad modern principles underlying the new era
which 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) ; VI, Of Nutrition; VII, Of the Blood
and Circulation ; VIII, Of Respiration ; IX, Of the Secre-
tions ; X, 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 Geologise"
by the Ray Society, beginning with 1848. The publica-
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 STich 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 summarized 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 in 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 master 's ideals.

Period of Morphology and Embryology , 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 reptiles; J. Leidy, protozoa,
coelenterates, worms, anatomy of mollusks ; 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, Dall, Jay, Lea,
S. Smith, Tryon, mollusks; E. S. Morse, brachiopods,
mollusks ; J. I). 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;
Audubon, 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. W. Tryon in
the Journal (33, 13,1862).

Jeffries Wyman 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 mucli 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 tu 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-
lished by Dana in other periodicals. His most conspicu-
ous zoological works, however, are his reports on the
Zoophytes 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, while 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 many 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 southeastern coasts and Gulf of Mexico under the
leadership of Pourtales and Agassiz.

The Challenger 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 1880, 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 parts 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, 1870-1890,

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

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. F. 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 mammals. 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

we owe in large measure our knowledge of the life in the
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,
Ryder, 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 Dall
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, Coues, 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.

^^^

s.^-^-^^

^^^

"^^Vf '

A CENTURY OF ZOOLOGY IN AMERICA 413

Zoology in the American Journal of Science^
1870-1918.

The third series of the Journal (1870-1895), likewise
including fifty volumes, embraces this period of zoologi-
cal activity in morphological and embryological 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, who
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. VerrilPs 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 reviews 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.

Echinoderms, 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; S9, 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;

414 A CENTUEY 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.

Crustacea, 44, 126, 1867; 48, 244, 430, 1869; 25, 119, 534,
1908.

Ascidians, 1, 54, 93, 211, 288, 443, 1871; 20, 251, 1880.

Dredging operations and marine fauna, 49, 129, 1870 ; 2, 357,
1871; 5, 1, 98, 1873; 6, 435, 1873; 7, 38, 131, 405, 409, 498,
608, 1874; 9, 411, 1875; 10, 36, 196, 1875; 16, 207, 371, 1878;
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. Smitli 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 embryology from the 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 small 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 Experimental Biology , since 1890,

Zoological studies remained in large measure observa-
tional and comparative until about 1890 when the experi-
mental methods of Roux, Driesch 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 biology in recent times. The new
science of genetics is essentially the experimental 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 years, supplemented by such exper-
imental data as have been provided by these more recent
investigations. Such hypotheses 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. — During 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 Linnasus was a Swede and took his
degree in Holland. Under the influence of Von Baer and
his monumental treatise on embryology (Ueber Entwick-
lungsgeschichte der Thiere, 1828), and supported later
by the great physiologist, Johannes Miiller, whose **Phy-
siologie des Menschen^' (1846) forms the basis of modern
physiology, the German school forged rapidly ahead and
eventually assumed the leadership in zoology, as in sev-
eral other branches of science.

In the latter half of the century the influence of the
German universities 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 university. 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 was 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

Biological 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 Museum 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
investigation could be issued. This condition was met in

A CENTUEY 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 MendePs
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 Biology 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 new
series (42d of 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 conehology. 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 by 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
especially to natural history, 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 Academy 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 Academy 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 support 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 were being emphasized, the professional
zoologists of the eastern states founded the American
Morphological Society. 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 investigations owing
to the greater attention being directed to problems in
experimental zoology 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 which 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.

Biological 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 founded in 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 Fish 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. Whitman.

Successful marine laboratories are located also at Cold
Spring Harbor, Long Island ; at Harp swell, 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
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 days consisted of
rows on rows of systematically arranged specimens, 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 CENTUEY 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
Eidgeway^ 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 North America'^ is the stand-
ard taxonomic work.

The most comprehensive systematic work on fishes is
the ^'Descriptive Catalogue of the Fishes of North and
Middle America'' by Jordan and Evermann.^

The invertebrate groups have 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 which 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 Whipple '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

426 A CENTURY 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 which the accurate
diagnosis 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.

Zoogeography. — 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.

Biometry,

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 was,
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 Bate son.

In America the methods of biometry have been utilized
extensively by Charles B. Davenport, Raymond Pearl, H.
S. Jennings 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 hardly 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 E^nhryology,

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,

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 embryos 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 Localization. — 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 substance from one generation to the next.
A recent book by Hegner^^ summarizes the success
attained in various groups of animals.

A CENTURY OF ZOOLOGY IN AMERICA 429

Cytology.

Another important field of investigation which has
attracted many workers is that which 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 ^gg 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 ^gg. This consti-
tution is moreover shown 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 partheno-
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 eggy

27

430 A CENTURY OF SCIENCE

it is in some animals not irrevocably fixed, and the normal
effect of the 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 extensively studied by Morgan and his pupils
in connection with their work on inheritance in the com-
mon fruit fly Drosophila. The evidence supports Weis-
mann's earlier hypothesis that the chromosomes are the
bearers of the heritable 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 Drosophila 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. — The 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
investigators have had in the development of this science.

Regeneration. — Experimental studies on the powers
of regeneration in 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 has been made a concerted attempt to analyze
the factors which determine the amount and rate of
regeneration. Much progress has been made toward the
postulation of definite laws applicable to the regenerative
processes of the parts of each organism. 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.

Transplantation 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, Woodru:ff,
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 the 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 gre^t value both in determining the
economic status of our birds and mammals, and also in
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-discovered, 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 Mendel 's
discovery gave a great impetus to experimental breeding
both in plants and animals. While 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 probability of any
particular offspring possessing one or many of those

A CENTURY OF ZOOLOGY IN AMERICA 435

characters. The physical basis for such 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 *Hhe mechanism of Mendelian heredity''
gives the cytological explanation of Mendelian inher-
itance.

Americans have from the first taken a leading part in
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
Shull on plants.

The geneticist now realizes that the appearance of the
body (phenotype) 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 CENTURY OF SCIENCE

pies. The Eugenics Eecord 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 realization of
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 1859, 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-
plasm is now the most widely accepted theory of evolu-
tion.

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
{Drosopfiila ampelophila) more than 125 new types have
arisen within six years. Each of these types breeds true.
**Each has arisen independently 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 wiU 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 wiU
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, 1886.

* Ibid, 4, 9, 1888. 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 Whole, p. 126, 1916.
*° The Germ-cell Cycle in Animals, 1914.

" The Cell in 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 the 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 Early Tears 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 down 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 ; Wolle 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
synonyms.

Cryptogamic 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 cryptogamic
manual. There are two important papers by Alexander
Braun, translated by Dr. George Engelmann, one on the
Equisetacese of North America (46, 81, 1844) and the
other on the Characeae (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

M2 A CENTURY OF SCIENCE

given space in the Journal. Plant-physiology received
a good share of attention either in short notices or in
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, first detected by
him in the f ovilla of pollen grains, and now known as the
Brownian (or Brunonian) movement. The heading
tinder 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 by a study of *Hhe 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 subsequent 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 443

There are interesting notes on the sugar-beet as a source
of sugar, and here appears one of the earliest accounts of
the Assam tea-plant, which 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 otherwise 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. ^ And as 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 first mention in the Journal of the
name of Dr. Asa Gray, who, shortly after that date,
became thoroughly identified with its botanical 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 wide 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. Hadley, **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 Torrey 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.

s

t-s^

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 that 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 synonyms. 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 this 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 CENTURY 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 Linnaeus.''

In the Journal for 1840 there is a large group of
unsigned book reviews under the 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 De Candolle'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 Dr. Gray was probably the writer of
some of the unsigned book-reviews which had appeared
in the Journal between 1837 and 1840. Doubtless 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 Dr. 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.
They cover an extremely wide range of subjects. While
they 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. — Gray's name as associate editor of
the Journal appears in 1853. He had been a welcome
contributor, as we have seen, for many years. His

DEVELOPMENT OF BOTANY SINCE 1818 447

influence upon the progress 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
afiinities 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.^ 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
vonMohPs *^ 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 MohPs contemporaries, showing what
and how great were MohPs own contributions to his-
tology. Such a review is a landmark in the science. The
physiology of the cell and the nutrition of th© 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 always acceptable to those who were anxious to
secure conformity to arbitrary rules at whatever 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
relieve 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
remained 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 449

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 T '

Gray on Darwinism. — 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
Haven* on 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 kindness
which I have received from you,

My dear Sir,
Yours very sincerely,

Charles Darwin.

In March, 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 ha? 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 Darwin'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 might 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 anomaUes 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. jr.

ayn^\^^

From " Life and Letters ot Charles Darwin" by 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 tlie 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 has 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 flow is not less actual
because too slow to be observed by the ephemerge 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 life.^

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 OF SCIENCE

Gray's death, although he foresaw that the revolution
was impending.

One of the most obvious changes was that which gave
a high degree of prominence in American school treatises
to the study 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 phsenogamia, 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 ferns, mosses, lichens,
and the larger algae 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 algae, 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 Botany 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 DeCandolle's Phytog-
raphy, where very exact methods are inculcated, but by
the very numerous contributions by Sereno Watson and
others at the Harvard University Herbarium, 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 CjnP^raceae, 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,
snch 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 appropriate 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 down 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
studies 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 Tully (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.

Notes,

* Scientific 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).

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