TOPOGRAPHY. 55 
chemical laboratories were then united under the official designation 
" division of chemical and physical researches." So little of the 
earlier equipment remained that all of the first year was spent in 
building and calibrating special apparatus and in general laboratory 
furnishing. Much more than usual difficulty was encountered in pre- 
paring for accurate physical measurements in the space assigned there- 
for, both on account of the location of the laboratory and on account 
of lack of the services of a skilled mechanic. 
In the two years during which the laboratory has been in operation 
three researches have been undertaken. The most important one is a 
thorough and systematic thermal investigation of the relations of the 
feldspars, their melting temperatures, conditions of crystallization, 
etc. This experimental work is now approaching completion, but no 
results have yet been published. There have also been made measure- 
ments of the elastic constants of an interesting artificial pseudo-solid 
formed by beating the white of egg into a stiff foam with a small 
quantity of sugar in solution, and of the linear force exerted by grow- 
ing crystals. 
For Survey publications relating to physics, see the Survey's list of 
publications. The physicists of the Survey have also made numerous 
contributions to other scientific periodicals and series. 
TOPOGRAPHIC BRANCH. 
The topographic branch is organized in two divisions — topography, 
and geography and forestry. 
DIVISION OF TOPOGRAPHY. v 
Eastern and Western Sections. 
The division of topography is divided for administrative purposes 
into two sections, the eastern and the western, but the work of the two 
sections is identical in character. The chiefs of these sections are the 
administrative heads, the one of all topographic surveys executed 
east of the one-hundredth meredian, and the other of all those executed 
west of that meridan. With the Director the} 7 form a committee hav- 
ing jurisdiction over all work of the division of topography. This 
includes a section of triangulation and computing, a section of inspection 
of topographic surveying and mapping, and thirteen subsections of 
topographic field work — three in the western section and ten in the 
eastern. 
The employees are procured through civil-service examinations held 
from time to time for the recruiting of the force. All appointments 
are to the minor position of topographic aid, and appointees are 
advanced by promotion through the grades of assistant topographer, 
topographer, and geographer, the latter title going with the larger 
administrative responsibilities. 
