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
characters, it was logical to include everything under the single head.
There were some writers in the early centuries 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 knowledge and it was not until the beginning
of the sixteenth 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
properties. Unfortunately, he also did not realize the fundamental
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 mineralogy 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 considered 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 Haüy, the “father of crystallography,” had before this date
discovered 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 crystal 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 light was discovered by
Malus in 1808, and in 1813 Brewster first recognized the optical
differences between uniaxial and biaxial minerals. The modern science of
chemistry was also just beginning to develop at this period, enabling
mineralogists to make analyses more and more accurately and thus by
chemical means to establish the true character of minerals, and to
properly classify them.
Franz von Kobell, on page 372 of his “Geschichte der Mineralogie,”
somewhat poetically describes the condition of the science at this
period as follows: “With the end of the eighteenth and the commencement
of the nineteenth 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 accidental, to discover definite laws, and to
learn the relations 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 publication of the last number
of the Repository an Association has been formed in the city of New York
‘for the investigation of the Mineral and Fossil bodies which compose
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 subjects, but especially on the following: 1,
concerning stones suitable for gun flints; 2, concerning native
brimstone or sulphur; 3, concerning salt-petre; 4, concerning mines and
ores of lead.” Further the society asks “that 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 interest in things
mineralogical was clearly manifest. An important stimulus to this
increasing knowledge and discussion 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 probably 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 college. This was
quickly accomplished and in 1810, 1811 and 1812 the collection was
transferred to New Haven 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 University has been formed.
There is no doubt but that the presence at this early date of this large
and unusual mineral collection had a great influence upon the
development 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 Mineralogical Journal, being a Collection of Facts and
Observations tending to elucidate the Mineralogy and Geology of the
United States of America, together with other Information 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 instituted. 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 inclusive it has always published many articles on
mineralogical 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-established mineral species have been described since the
year 1800, of which approximately 150 have been from American 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 important part of
mineralogical investigation, still these figures 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 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 descriptions 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
indefatigable than Charles U. Shepard. He was graduated from Amherst
College in 1824, at the age of twenty. In 1827 he became assistant to
Professor Silliman in New Haven, continuing in this position for four
years. Later he was a lecturer in natural history at Yale, and was at
various times connected with Amherst College and the South Carolina
Medical College at Charleston. His articles on mineralogy were very
numerous. He assigned a large number of new names to minerals, although
with the exception of some half dozen cases, these have later been shown
to be varieties of minerals already known and described, rather than new
species. In spite, however, of his frequent hasty and inaccurate
decision as to the character 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, natural 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 Journal (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 classifying minerals. The German school, led by Werner,
classified minerals according to their external characters while the
French school, following Haüy, put the emphasis 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 composition and using the accurate description of the
physical 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
individual species, the arrangement here being an alphabetical 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 Haüy, 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 undesirability 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 System of Mineralogy started in this way in 1837, has
continued by means of successive editions to be the standard 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, formation 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 covered the years from
1846 through 1870. This period was characterized by great activity in
the study of the chemical 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
fundamental characters and relationships in minerals. He published many
articles in these years which were concerned chiefly with the
classification and grouping of minerals, with similarities in the
crystal forms of different species, with relations between chemical
composition 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);
various notes and articles on homœomorphism 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).
A great many new mineral names were proposed between 1850 and 1870, a
large number of which have continued to be well-recognized species. But
there was also a tendency, which has not wholly disappeared even now, to
base a mineral determination upon insufficient evidence, and to propose
a new species with but little justification for it. In this connection a
quotation from the introduction by J. D. Dana to the 3rd Supplement to
the System of Mineralogy (4th edition) published in the Journal (=22=,
page 246, 1856), will be of interest. He says:
“It is a matter of regret, that mineral species are so often brought
out, especially in this country, without sufficient investigation 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 growing 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 of his contributions are the “Memoir on Emery” (1850), a
series of papers on the “Reëxamination of American Minerals” (1853)
written with the collaboration of George J. Brush, and his “Memoir on
Meteorites” (1855).
[Illustration: Ge. J. Brush]
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 mineralogy never flagged.
His papers on mineralogical subjects 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 Mineralogy 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
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 painstaking
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 published fifty-four successive
articles, the greater part of which appeared in the Journal, which were
entitled Contributions 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 species. 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 tellurides, the species coloradoite,
melonite and calaverite being first described by him. A long and
important investigation was recorded on Corundum, “Its Alterations and
Associate Minerals,” published in the Proceedings of the American
Philosophical Society in 1873 (=13=, 361). Dr. Genth died in 1893.
The period from 1860 until 1875 was not very productive in mineralogical
investigations. The first ten volumes 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
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 publishing 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 mineralogy during this
period was that of Samuel L. Penfield. 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 mineral 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 protractors and
scales to make possible the rapid and accurate 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 strikingly 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
geology, even that of palaeontology, have all contributed articles
distinctly mineralogical in character. For this reason the number of
American writers who have published 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 petrographers is shown by the long list of
papers concerning it that have been published in the Journal; it should,
therefore, be considered briefly here. Many of these papers are short
and of a general descriptive nature but others which give more fully the
chemical, mineralogical and physical details are numerous. Among the
earlier writers on this subject Benjamin Silliman, Jr., and C. U.
Shepard should be mentioned. The latter was the first to recognize a new
mineral in the Bishopville meteorite which he called chladnite. The same
substance was afterwards found in a terrestial occurrence and was more
accurately described by Kenngott under the name of enstatite. J.
Lawrence Smith later showed that these two substances were identical.
Smith did a large amount of important chemical work on meteorites. He
was the first to note the presence of ferrous chloride in meteoric iron,
the mineral being afterwards named lawrencite in his honor. The
iron-chronium sulphide, daubreelite, was also first described by him.
Other names that should be mentioned in this connection are those of A.
W. Wright who studied the gaseous constituents of meteorites, G. F.
Kunz, W. E. Hidden, A. E. Foote and H. A. Ward, all of whom published
numerous descriptions of these bodies. Among the more recent workers in
this field the names of G. P. Merrill and O. 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 considered complete. All the commoner minerals had
certainly been discovered and exhaustively studied. Little 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 minerals. 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 Laboratory of the Carnegie
Institution of Washington has been of the greatest importance. This
laboratory was established 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 crystalline structure upon X-rays.
Through the refraction or reflection of the X-ray by means of the
ordered arrangement of the particles forming the crystalline network, we
are apparently going to be able to discover much concerning 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
constitution 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
possible 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
investigation.
IX
THE WORK OF THE GEOPHYSICAL LABORATORY OF THE CARNEGIE INSTITUTION OF
WASHINGTON