ILLUSTRATIONS. 109 
etc.), geologic and other maps, photographic prints, geologic and 
paleontologic specimens, thin sections, and references or citations. 
The material belonging to the first and second classes is generally crude, 
and is used merely as a guide in preparing more elaborate and finished 
drawings. Each illustration is prepared with the twofold purpose of 
expressing the fact intended by the author and securing the best pos- 
sible result in its reproduction by one of the numerous processes in 
use. This section decides upon the most suitable process of reproduc- 
tion, writes specifications for the reproduction of each class, examines 
critically all proofs, keeps complete records and files, and gives atten- 
tion to all other matters that pertain to the illustration of the various 
reports of the Survey. 
In the early days of the section, as at the present time, drawings 
were prepared in accordance with the demands of the various repro- 
ductive processes in vogue. Photography had not reached its present 
perfection, and up to the year 1884 the majority of such illustrations 
were engraved on wood. On referring to any of the reports published 
prior to that date one will observe a marked deficiency in the scien- 
tific value of the illustrations engraved by that process, as compared 
with more recent reproductions of similar subjects — a lack of value due 
to the fact that hand work entered too largely into the former. More- 
over, the woodcut process was relatively expensive. The 76 wood- 
cuts used in the Seventh Annual Report of the Survey cost $4,825, 
whereas similar illustrations reproduced by the half-tone process 
would probably cost less than $600. But as artistic illustrations in the 
broader sense, many of the woodcuts in the earlier reports stand as 
examples of exceptional merit in selection and execution. 
The half-tone process began to be used for the reproduction of 
photographs and drawings in 1881. This process has gradually 
worked into favor, and has revolutionized the illustration of all kinds 
of literature. Its use has also effected many changes in methods of 
preparation, and at the present time photographs are used (whenever 
suitable prints can be obtained) in preference to drawings. It is also 
used in numerous ways when drawings must be made, and is not only 
a timesaver, but adds to the element of accuracy in the finished draw- 
ing. In other words, new conditions have so modified methods of 
preparation of illustrations that complete new drawings of certain 
classes of subjects rarely become necessary. There is still, however, 
abundant need for skill in the artistic treatment of illustrations, 
whether in preparing new designs or in "building up" or retouching 
photographic prints. 
During the calendar year 1903 illustrations were prepared and trans- 
mitted for the following publications: Three annual reports, 2 mono- 
graphs, 9 bulletins, 10 water-supply papers, 12 professional papers, 
and 2 volumes on mineral resources; in all, 1,168 illustrations, many 
