short branches, 7 inches in diameter, were extended to the several shafts.
It was in one place carried across the stream by a light suspension
bridge, some 150 feet long, the trunk of a tree on each side forming a
convenient tower. The aggregate length of the main and branches was 9,960
feet, with some 2,500 feet additional, for the branch to the diamond
drills. The pipe was laid on the surface of the ground, its only
protection being in places a couple of 11/2-inch planks tacked together, and
placed over it; the range of temperature was from 10 degrees to 107
degrees Fahr. (in the shade). It was inspected by the foreman of the
tunnel-work as he daily walked over the line; besides the occasional
driving of a few wedges and putting on a band or two, it gave no trouble
from leakage, which probably for its entire length did not amount to more
than an average of 3 or 4 cubic feet a minute; from time to time, a little
sawdust was put into the pen-stock. Three stop-gates were placed on the
main, and a separate stop-gate at each shaft, operated by a fine-threaded
screw, so that the water could be cut off when desired.

[Illustration: FIG. 13.]

Fig. 13 shows the arrangement of the machinery for hoisting and pumping,
which was identical at the several shafts, except that the hurdy-gurdies
varied from 161/2 feet in diameter at the upper shaft to 21 feet at the
lowest shaft. The water-wheel moved only in one direction; the pinion on
the wheel-shaft drove the spur-wheel, to which the pitman of the pump-bob
was attached. On the spur-wheel shaft was a friction-gear, driving the
hoisting-reel; this reel was mounted on sliding blocks, so that hoisting
was done by putting it in gear, the empty load being dropped by a
friction-band. Changing the size of the water-wheel as the pressure
increased permitted the use of the same pattern of machinery at the
different shafts. The water was brought to the wheel by a discharge-pipe,
some nine feet long, having a vertical movement by ball-and-socket joint,
so that at pleasure, by dropping the pipe, the machinery could be run at
various speeds, or entirely stopped. At the end of this discharge-pipe
was a cast tapered nozzle, about 31/2 inches in diameter, in which was
inserted a ring of saw-plate steel having the desired diameter, and which
was held in place by an annular screw-cap. By changing the ring, which
only required a few moments' time, any desired amount of water, up to 3 or
4 cubic feet