each plate used, as thereby any essential difference in thickness could
be detected. Iron plates which have been subjected to the action of
salt water are undesirable.
The Spring Valley Water Company, of San Francisco, California, strain their pipes from 11,400 to 13,000 lbs. per sectional inch.
Virginia City and Gold Hill Water Company, of Nevada, has an inverted
siphon (of inferior English iron) with a maximum pressure of 1,720 feet
head, equal to 746 lbs. per square inch, No. o iron, with 5/8-inch
rivets, being used at the lowest point of depression and subjected to
a tensile strain of 13,310 lbs. The No. 9 iron is strained fully 15,000
lbs., and the No. 7 over 14,000 lbs., per sectional inch.
Texas Creek pipe, four miles below the Bowman Dam, Nevada County,
California, is an inverted siphon 4,438.7 feet long, 17 inches in
diameter, made of riveted plate iron. Its inlet is 303 leet above the
outlet, and with a full head it will discharge about 1,260 miner's
inches. It sustains a maximum pressure of 770 feet or 334 lbs. per square inch.*
Cherokee,f California, there is an inverted siphon of ordinary English
plate, 30 inches in diameter, with a maximum pressure of 887 feet head.
The maximum strains on the several sizes of iron used in practice are given in the following tables:
* See Official Report North Bloomfield Mining Co., 1878. t For further description see p. 172.