geologic
philosophy. These researches are experimental, and relate to the effect of
temperatures, pressures, etc., on rocks. This laboratory is under the
charge of the chief chemist.

LITHOLOGY.

There is a lithologic laboratory in the Survey, with a large corps of
lithologists engaged in the microscopic study of rocks. These lithologists
are field geologists, who examine the collections made by themselves.

STATISTICS.

There is in the Survey a division of mining statistics, with a large corps
of men engaged in statistic work, the results of which are published in an
annual report entitled "Mineral Resources." Mr. Albert Williams, Jr., is
the Chief Statistician of the Survey.

ILLUSTRATIONS.

There is in the Survey a division organized for the purpose of preparing
illustrations for paleontologic and geologic reports. Mr. W.H. Holmes is
in charge of this division. Illustrations will not hereafter be used for
embellishment, but will be strictly confined to the illustration of the
text and the presentation of such facts as can be best exhibited by
figures and diagrams. All illustrations will, as far as possible, be
produced by relief methods, such as wood-engraving, photo-engraving, etc.
As large numbers of the reports of the Survey are published, this plan is
demanded for economic reasons; but there is another consideration believed
to be of still greater importance; illustrations made on stone cannot be
used after the first edition, as they deteriorate somewhat by time, and it
is customary to use the same lithographic stone for various purposes from
time to time. The illustrations made for the reports of the Survey, if on
relief-plates that can be cheaply electrotyped, can be used again when
needed. This is especially desirable in paleontology, where previously
published figures can be introduced for comparative purposes. There are
two methods of studying the extinct life of the globe. Fossils are indices
of geological formations, and must be grouped by formations to subserve
the purpose of geologists. Fossils also have their biologic relations, and
should be studied and arranged in biologic groups. Under the plan adopted
by the Survey, the illustrations can be used over and over again for such
purposes when needed, as reproduction can be made at the small cost of
electrotyping. These same illustrations can be used by the public at large
in scientific periodicals, text-books, etc. All the illustrations made