156 REPORT OF THE CALIFORNIA EARTHQUAKE COMMISSION. 
CRYSTAL SPRINGS LAKE. 
Description of stations. — These monuments are about 7 miles northwest of San Mateo 
on the eastern shore of Crystal Springs Lake, the reservoir of the Spring Valley Water 
Company. The location is about a mile southeast of Camp Sawyer, which is on the west 
side of the lake at a point where the lake is very narrow and is spanned by a bridge, close to 
the northern end. 
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Fic. 48. — Monuments at Crystal Springs Lake. 
As will be seen from the leveling record, and from the accompanying rough sketch, fig. 
48, the ground is very uneven, and the measurement of a base-line was executed under 
considerable difficulty. The line measured, which was the only practicable one, crosses two 
ravines and comes up toward the southeast monument, over a very steep road embankment. 
Considerable clearing of brush was necessary in order to cross the ravine near the northwest 
monument. On account of the large differences of level between the base-line stakes in 
some places, the leveling had to be done with extreme care, there being at one place a rise 
of 11.5 feet in 50 feet, and, next to the road embankment, a rise of about 6 feet in 20 feet. 
