e auriferous gravel and region near Smartsville, and 2,000 feet
above the Yuba River, where snow is unknown, and near its terminus the
ancient river bed courses more westerly than it does above it, and crosses
Yuba below Timbuctoo, where the auriferous depositions disappear. The
whole distance of 40 miles has been ransacked by the earlier adventurers,
and around the village of Timbuctoo was a center famed for its wonderful
yield of gold, obtained chiefly in the ravines, in holes, and depressions
in the bed rock. These hollows detained the concentrations of the
denudated alluvium from the altitudes, and were generally closely beneath
the surface, and by such guidance and means of discovery the miners traced
the gold up the ravines to their sources in the lofty mounds and deposits,
or hills of cemented conglomerate, near Eureka in Nevada county; and by
constructing canals from a higher level began the new system of "hydraulic
mining" and washing, and gradually extended their operations over the area
of the metallic zone mentioned, of 40 miles long by 20 wide, using the
Yuba River below Timbuctoo to receive and discharge the tailings, or
refuse from their operations. The result in gold was considerable, but the
system is from its violent nature difficult to control, by presuming to
handle and remove such huge depositions in order to collect the richest
material. The idea was bold, being an anticipation of Nature's operations;
but the equitable disposal of the "tailings" in a cultivated country is
impossible, as the silt runs down the rivers, creating banks and bars in
their channels, obstructing navigation and agricultural arrangements.

_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 th