The San Francisco call., 1895-05-24

grounds, preparatory to arranging for the
resumption of work.
James D. Hague has outlined an active
campaign of mining his new properties,
for which he has paid $15o,0o0, and the
initial steps have already been taken.
Among the first questions considered was
as to the most feasible power to be used
and the method of transmission. After
careful study and research by his civil
engineer, Arthur d. Foote-during which
he visited the electric plant of the Calu-
met and Hecla copper mines in Michigan,
and other electric works-it has been de-
cided to use compressed air. A 20-inch
pipe will convey water from the South
Yuba ditch on Osborn Hill to a central
power station in Boston ravine, where
pressure OF 775 feet attained will drive
19-foot Pelton water-wheel, and this power,
estimated at 600 horsepower, will be con-
verted into compressed air, and thence
distributed along the mile and half of
mines, and applied to hoist engines,
pumps mills, Burleigh drills, etc., wher-
ever needed. To convey the water main
over Wolf Creek and afford firm anchor
age a heavy stone aqueduct will be con-
structed. The contract for the machinery
has been given to San Francisco foundry
and within three months the machinery
should be in place. Three to four hundred
men will find employment, and the entire
group of mines and mills will be under
the superintendency of II. P. Roberts, a
mining engineer who has operated at the
Atlantic copper mine, Michigan; in Ell
more, Idaho; Railroad district, Nevada;
at the Reiley-Bliss mine, California, and
lately in the State of Chiapas, Mexico.
Mining men, and especially those VINO
have studied electric power transmission
and its relations to mining, will be sur
prised to learn that Mr.. Foote'S investiga-
rions have resulted in the adoption of COM
pressed air. Electricians, though, acknowl-
edge that in transmission by electricity an
initial loss of 20 per cent is always incurred,
| while it is expected that the. loss by com
pressed air will not exceed Il per cent,
which can be reduced at little cost by heat
ing the air at the point of application, thus
! increasing its expansive power. An cleo
trio plant will be established to furnish
lights for the mills and mines.
While Hague is adopting distribution of
power by compressed air company has
been formed to bring electric power to the
mines from five miles to the north; thus
will Grass Valley enjoy the advantages to be
derived from the most scientific modes of
milling and mining known to man. At
the Rose Hill mill gasoline engine of six
horsepower, weighing a ton, has been
placed in position, and will furnish power
for three-stamp battery at an estimated
cost of ~ 25 in twenty-four hours.
The most complete milling outfit in
| Grass Valley is the North Star, containing
40 stamps, where ore is reduced at a cost of
| only so cents a ton, divided as follows
Labor 81 cents, power 80 cents, supplies 16
cents. The average weight of the stamps
OF the district is $50 pounds, with a drop
OF six inches, and eighty-four revolutions
minute. The ore is dumped from the
mine cars into ore bins, which lead to
rock breakers, and from rock breakers to
Challenge self-feeders into the batteries
and from copper-plates to concentrators
Sixty to eighty per cent of the assay value
is caught in the battery plates. The con-
centrators run from one to five per cent,
ranging in value from $50 to $400 per ton.
The sulphurets are treated at local chlori-
nations work or shipped to San Francisco
or Everett, Washington. But little slime
appears during the milling of the ore, thus
enabling the millmen to work the ore up
to S5 and so per cent without encountering
dlfieu lties met with in nearly every gold
mining region of the world. The United
States Bureau mining statistics state that
to produce $1723 in gold in Nevada
County has required an expenditure of
only $725.
The forty-five years of mining on the
veins of this district and the immense out
put therefrom surpass even in expecta-
ton the widest estimate of the "boomers''
of the South African blanket deposits.