110 THE UNITED STATES GEOLOGICAL Sl'KVEY. [bull.227. 
of which represented groups of separate drawings. In addition to 
these, hundreds of drawings were prepared within the year which still 
await transmittal to the engravers. 
The processes at present used for the reproduction of illustrations 
for Survey reports arc chromolithography, photolithography, photo- 
gelatin, half-tone, zinc etching, wax engraving, and the three-color 
process, in the preparation of illustrations both economy in prepara- 
tion and economy in reproduction must be considered. Some processes 
call for carefully prepared drawings, while others require only the 
crudest kind of copy. The total cost to the Government is approx- 
imately the same whether the drawing is elaborated and refined in the 
office or the elaboration is left to the reproducer. In deciding the 
question in any given case the points considered are urgency in getting 
out the report, quality of result desired, and character of subject. 
An important feature in connection with illustrations is that of cen- 
sorship. An author, thoroughly imbued with his subject, is apt to 
submit originals, especially photographs, in excess of the needs of his 
paper. In order to correct this tendency, a committee composed of 
officers of the Surve/v, and of which the chief of the section of illustra- 
tions is chairman, examines the original material submitted by authors, 
with a view to the elimination of all superfluous or irrelevant matter. 
Section of Photography. 
Photography has always been an important adjunct in the work of 
the United States Geological Survey, and its scope and usefulness have 
constantly increased. Before dry plates and paper films came into use' 
the work in photography was largety that of recording exploratory 
and scenic views. The wet-plate process required such bulky appara- 
tus, so much time and labor, and such skill in manipulation of camera 
and chemicals that its use was practically confined to large parties and 
to comparatively accessible localities. However, in spite of these dis- 
advantages, a large amount of valuable work, both in field and in office, 
was done. Indeed, it is not too much to say that many of these early 
negatives are unsurpassed in scenic value. 
With the advent of dry plates and small cameras the use of photog- 
raphy in the field work of both geologist and topographer rapidly 
increased. Instead of the one photographer with his glass plates and 
his array of bottles and pans and cumbrous developing tent or box- 
barely tolerated in a geologic party and abominated in a topographic 
party— almost every party chief now has his dry-plate or film camera, 
and is encouraged to photograph every subject germane to his work, 
thus adding immense^ to the volume, accuracy, and value of his field 
observations. 
As great improvement has been made in office or laboratory methods 
as in field. This is especially the case in the development of negatives, 
