At each of these new falls of 25 to 50 feet the process of comminution
begun in the first shaft is carried on, and a fresh portion of gold
obtained. Rude as this plan of saving gold appears to be, more gold is
procured by it than by any other method of washing yet devised for this
process of work, and the economical advantages obtained by it cannot be
surpassed, as it would be impossible to handle such vast quantities of
material in any other way, and we can compare the cost of washing and
handling a cubic yard of auriferous gravel by it as follows:
Dollars.
By manual labor with the pan 15.00
" " with rocker 3.75
" " with the long tom .75
By the hydraulic process .15
But this process, even if effective or profitable as a mining operation,
may be prejudicial to the interests of the general public, if conducted on
a large scale, as the vast quantity of material which it so suddenly
removes is merely shifted into the shallows beneath, to be redistributed
by every freshet to points lower and lower down until it reaches the
sea-coast, creating bars at the mouths of rivers in its course, and
changing the hydrography of harbors--as it has done with the Bay of San
Francisco by its silt.
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