hydraulic pump now coming, and which will be set up as mate to that
now in operation at the 3,000 foot level, will be 5,200,000 gallons.

The water which feeds the pressure pipe of the three sets of hydraulic
pumps is brought from near Lake Tahoe, in the Sierra Nevada Mountains.
The distance is about thirty miles, and the greater part of the way
the water flows through iron pipes, which at one point cross a
depression 1,720 feet in depth. The pressure pipe takes this water
from a tank situated on the eastern slope of Mount Davidson, 3,500
feet west of the shaft. At the tank this pipe is twelve inches in
diameter, but is only eight inches where it enters the top of the
shaft. The tank whence the water is taken is 426 feet higher than the
top of the shaft, therefore the vertical pressure upon the hydraulic
pump at the 3,000 foot level is 3,426 feet. The pressure pipe is of
ordinary galvanized iron where it receives the water at the tank, but
gradually grows thicker and stronger, and at the 3,000 level it is
constructed of cast iron, and is 2½ inches in thickness. The pressure
at this point is 1,500 pounds to the square inch.

In the early days of hydraulic mining in California the miners thought
that with a vertical pressure of 300 feet they could almost tear the
world to pieces, and not a man among them could have been made to
believe that any pipe could be constructed that would withstand a
vertical pressure of 1,000 feet; but we now see that a thickness of
two and a half inches of cast iron will sustain a vertical pressure of
over 3,400 feet.

There is only one pressure pipe for all the hydraulic pumps. This
extends from the tank on the side of the mountain to the 3,000 foot
level. It is tapped at the points where are situated the several sets