ior Water Company apart, the total cost amounted to about
1,000,000 dollars, and we must note that the latter company sold water to
other mining companies.

The gross yield in gold of the Blue Gravel Company in four years was
837,399 dollars, and in the year 1866 the returns from the Blue Gravel
Company paid all the costs of the developments; but in 1867 assessments
were paid by the owners to meet the deficiency arising from the cost of
sinking two new shafts, and driving fresh tunnels on the lowest levels,
which evidently contain on the bed rock the richest concentrations.

In smaller mining adventures of this description, involving less capital,
large profits have been made in the gold-bearing zone treated of, by also
not having invested in costly canals, which would not have repaid the
latter investment; and thus it is evident that the water companies are
dependent blindly on the prosperity of the miners.

I will now more minutely describe the actual mining operations. The mining
ground being selected, a tunnel is projected from the nearest and most
convenient ravine, so that the starting-point on the bed rock toward the
face of the ravine shall approach the center of the material to be removed
at a gradient of 1 in 10 to 1 in 30. The dimensions of such tunnels are
usually 6 feet in width by 7 in height, and continuing in contact with the
hard river-bed, for the greater ease of excavation, collection of gold,
and conservation of quicksilver amalgam.

These tunnels vary in length from a few hundred feet to a mile, and some
of the longer ones occupying from one to seven years in execution, at a
cost of from 10 to 60 dollars per foot of frontage. The tunnel of the Blue
Gravel Company, with length of 1,358 feet, cost in labor alone 70,000
dollars, but it could now be driven for 35,000 dollars, as skilled labor
is cheaper now than then. The grade in this tunnel is about 12 per cent.,
and the end of the tunnel is designed to be 170 feet of elevation, and
reaching to a point beneath the surface of the gravel which is being
operated upon, and where a shaft or incline is sunk to or through the bed
rock or gravel, until it intersects the tunnel.

The object of this laborious operation is obvious, as the long tunnel
becomes a sluiceway, and through the whole length of which sluice boxes
are laid, for the double motive of carrying off the material and saving
the gold, and for this purpose a trough of strong planks is placed i