EFFECTS ON STRUCTUKES OUTSIDE OF SAN FRANCISCO. 19 
point for 50 feet. A brick conduit used for waste purposes extends 
across the fault. All the four rings, of hard-burned brick, are laid 
in first-class Portland-cement mortar, making a first-class piece of 
work in every way. This conduit, which is 9 feet 6 inches in diam- 
eter, was crushed together at the crossing. 
The Searsville dam, a structure similar to the San Andreas earth 
dam, 1 mile east of the fault line and parallel to it, was also found 
to be uninjured. 
Very little damage was done to the pumping stations, and the steel 
standpipes of this company were not injured. The Lake Honda 
reservoir was slightly damaged by a crack in its concrete lining. No 
damage was done to the Alameda Creek supply, except to the con- 
nection at the Belmont pumping station. 
The concrete dam near San Mateo, at the lower end of Crystal 
Springs Lake, parallel to the fault line and a few hundred feet east 
of it, was undamaged. This dam, a view of which is given in PL 
XI, Z?, is built of large blocks of concrete, thoroughly keyed together 
and molded in place, each block containing between 200 and 300 cubic 
feet. The dam is 680 feet long, with a present height of 146 feet. 
When completed it will be 170 feet high, 176 feet thick at the base, 
and 25 feet thick at the top. It is arched upstream to a radius of 
637 feet. 
The clay-core earth dam of the upper Crystal Springs Lake lies 
across the fault line at nearly right angles. This dam is now main- 
tained as a county causeway, equalizing pipes having been placed 
through it. At the time of the earthquake the water was at the same 
height on each side, and the absence of any " head " made it impos- 
sible to tell the extent of the damage. The dam moved about 6 feet, 
however, this fact being shown clearly by an offset of that amount in 
the fence which runs across it. The roadway over the dam also 
shows the same offset, although not so clearly. 
The water supply of San Francisco, as compared with that of other 
cities, w T as fairly good and had a rated capacity of 36,000,000 gallons 
per day. The failure to control the fire by reason of the crippling 
of the water supply was not due to the failure of the system outside 
of the city, but to the breaks in the distributing mains within the 
city, which rendered unavailable about 80,000,000 gallons of water 
stored within the city limits. These breaks occurred (see the map, 
PL LVI) wherever the pipes passed through soft or made ground. 
No breaks occurred where the cast-iron pipe was laid in solid ground 
or rock. It is evident that in earthquake countries water-supply 
pipes, at least, should be so laid as to avoid the action of slips, set- 
tling, and ground movements of all kinds. The pipe lines should 
also be arranged with gates and by-passes, making it possible to cut 
