_General Description of Hydraulic Mining._
The first work to be accomplished, after calculating that the amount or
value of the material to be operated upon is sufficient to guarantee the
cost of the undertaking in general, is the construction of a canal or
canals, to convey the requisite volume of water from the fountain-head,
and of sufficient elevation to command the ground to be worked upon,
having also in view the levels of the necessary tunnels and shafts as
outlets for the discharge of the gravel through them, these being
engineering operations requiring much skill and labor to avoid useless
after-cost.
Aqueducts of considerable elevation have to be constructed across deep
valleys, and the speculation is at all times problematical, as the ground
cannot be properly tested until the water arrives upon it, and disputes
may arise between the shareholders of the canal and the mining company,
ending frequently in the one devouring the other, unless the two interests
be quickly amalgamated.
The starting point should be the lowest level, or "bed rock," on the white
cement in the ancient channel, which is probably the original silt
collected in it, and is harder than the conglomerate above it, which is
more easily removed.
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