TOPOGRAPHIC SURVEYS. rr 
SURVEYS IN SHEN-SI AND SSI-CH’UAN. 
CHOU-CHI -HIEN TO TS’IN-LING SUMMIT. 
Graphic Triangulation.—After traveling rapidly from T’ai-ytian-fu in 
Shan-si, along the well known highway to Si-an-fu, Shen-si, without exe- 
cuting any surveys, the topographic surveying was recommenced at the 
little city of Chéu-chi-hién in the Wei valley, about 65 kilometers west of 
Si-an-fu and 13 kilometers from the base of the great Ts’in-ling mountains. 
Our route lay across these mountains to the city of Shi-ts’tan-hién on the 
Han river, and we attempted to carry out an extensive topographic sur- 
vey by graphic triangulation, as had been done in the northern mountains. 
Although high water and heavy rains interposed serious obstacles, we suc- 
ceeded in this object as far as the summit of the Ts’in-ling range, but 
south of that divide the vegetation and forest cover, extending over even 
the highest summits, made it impossible to pursue the method without 
excessive loss of time in clearing the outlook around stations. 
The survey from Chéu-chi-hién to the summit of the Ts’in-lings was 
begun by measuring a base line 1,773.7 meters long, in the creek bottom 
3 kilometers south of the city. This base was measured twice and the two 
measurements differed .25 meters. Using the theodolite, the triangulation 
was expanded to the mountain summits near the front of the range, and 
their computed positions were platted on the plane-table sheet. The 
graphic triangulation was then expanded from the positions determined. 
The area thus surveyed is shown by the contours on atlas sheets a1 
and @ 2. 
The p'ane-table work required 8 days. There were 583 square kilo- 
meters of country mapped, 14 triangulation stations were occupied, 393 
intersections were made, and about 375 elevations were ascertained. 
TS’IN-LING SUMMIT TO SHI-TS’UAN-HIEN. 
Stadia Traverse.—At Won-kung-miau,on the main divideof the Ts’in- 
ling range, we were able for the first time to see the country south of us, 
and the obviously unfavorable conditions led us immediately to abandon 
the graphic triangulation and begin the stadia traverse at that point. 
This traverse was confined to the route traveled, our rate of progress being 
too rapid to permit the topographer to occupy any side stations, except 
in the vicinity of San-ho-k’6u, where the complex relations of the valleys 
made a slight expansion of the work desirable. The traverse was run 
with the plane-table, which was oriented by a compass needle 10 centime- 
ters long. Distances were measured by stadia and elevations by vertical 
