18 THE SAN FRANCISCO EARTHQUAKE AND EIRE. 
ried 27 miles, crossing San Francisco Bay through submarine pipes, 
and thence passing through the Crystal Springs conduit to the city; 
that from Lake Merced is pumped into the Pilarcitos conduit and 
thence to the city. 
In company with Herman Schussler, chief engineer of the Spring 
Valley Water Company, the writer made a detailed examination of the 
principal conduits and reservoirs. On the San Bruno marsh the 44- 
inch line to the University Mound reservoir had been thrown off the 
trestle for a distance of 1,300 feet; and, while the pipe was readily 
repaired, the trestle had to be rebuilt, as many of the timbers had 
rotted. Near Baden the line had been telescoped 42 inches, shearing 
off an 8-inch gate valve. The reservoir itself was undamaged, yet its 
three days' supply was rendered useless by the breaks in the cast-iron 
distributing mains. 
The only damage done to the conduit between San Andreas Lake 
and the College Hill reservoir was at Baden, where the slip joint had 
been broken, tearing out the four cast-iron lugs — an effect indicating 
a force of at least 2,000,000 pounds. 
The principal breaks in the Pilarcitos conduit, which was so badly 
damaged that the company decided to abandon it, were examined. 
This conduit had been located for convenience in one of the long, nar- 
row valleys, and therefore on the line of an old fault. It is evident 
that it would be futile to attempt to build this conduit strong enough 
to withstand a slip on the fault line. The breaks in this 30-inch 
wrought-iron pipe ranged from 30 inches to 6 feet in length. At 
other points it was telescoped and twisted beyond repair. (See PI. 
IX.) The Pilarcitos conduit crosses Frawleys Gulch on a trestle. 
The movement of the earth produced a compression in the pipe line 
at this point, which threw it off and wrecked the trestle, and the water 
in the conduit leading to the trestle line was released so rapidly that 
it formed a vacuum, which caused this conduit to collapse, as shown 
in PI. X, .1. The conduit crosses and recrosses the fault for a dis- 
tance of 6 miles south of Frawleys Gulch. The 30-inch wrought- 
iron pipe line was torn and twisted at each crossing, Avhile the earth 
dam of Pilarcitos Lake was uninjured. 
The San Andreas earth dam lies across the fault, the crossing being 
about 100 feet from its east end, and the dam shows a disturbance for 
a distance of more than 100 feet. One of the worst cracks runs diag- 
onally across a culvert 4 feet G inches in diameter, which appears to 
be uninjured. Although San Andreas Lake had considerable water 
in it, no appreciable loss of head was observed. There is a roadway 
over the dam, along which runs a fence. Both were offset at the 
fault line about 3J feet. A wooden flume used for diverting storage 
water to the reservoir lines crosses the fault, and was wrecked at that 
