t. of the theoretic
power of the water is obtained on the main driving-shafts of the
machinery. The substitution of water for steam-power has resulted in a
large saving of expense. Although the hills near by are covered with fine
forests, thus making wood cheap, and although a round price is charged for
water by the company furnishing it, the cost of the water is considerably
less than that of the wood formerly used as fuel. The cost of attendance
is altogether in favor of the water-wheels, which hardly require any
attention. The cost of the change from steam to water-power was
$46,496.32.

* * * * *

TEXAS CREEK PIPE AND AQUEDUCT.

A description of this work will be of interest in showing the general
practice followed in California for carrying water across deep mountain
gorges. In order to augment its water supply, the North Bloomfield Gravel
Mining Company desired to conduct water from a stream known as Texas
Creek, in Nevada County, California, across the Big Canon branch of the
South Yuba River into the main Bloomfield flume or aqueduct, which was
located on the side of Big Canon Creek, at a vertical elevation of 620
feet above the bed of the latter stream. The quantity of water to be
carried was about 32 cubic feet a second (1,250 miner's inches), which
could be diverted from Texas Creek at a point 480 feet vertical above the
Bloomfield flume. An aqueduct about 4,000 feet long, partly of ditch and
partly of flume, was needed to bring the water from the catchment dam on
the creek to the brow of the gorge. The vertical head for the pipe could
therefore be from a maximum of 460 feet down to any lesser head; with a
head of 460 feet, the pipe would be 4,790 feet long; and with a head of
220 feet, the length would be 4,290 feet. Assuming a maximum tensile
strain upon the iron of 16,500 pounds per square inch, with the formula
for the greatest head of about

d = (.359 l/h)^{1/5}, [or, v = 68 (dh/l)^{1/2}, and Q = 32],

and a lower value of the coefficient in the last equation for the lesser
heads, it was found, by calculation, that the least cost could be obtained
with a head from 300 to 350 feet. The head fixed upon was 303.6 feet, with
a length of 4,438.7 feet. A profile of the pipe, with nearly the same
horizontal and vertical scales (horizontal scale, showing slope lengths),
is given in Fig. 14; details are given in Figs. 15 and 16. The pipe was of
double riveted sheet iron