Oxford Democrat. [volume] (Paris, Me.) 1833-1933, 1895-08-20
HYDRAULIC MINING IN CALIFORNIA


hydraulicking was impaired by Super
| intendent Radford, OF the North Bloom
field Gravel Mining Company Of Cali
fornia. He was New York boy,
graduate Of the Columbia School oi
Mines; Ia man OF extensive mining ex.
perience In South Africa as well as In
this country; and it is largely owing to
his engineering skill In providing for
the safe disposition Of "tailings" that
the North Bloomfield Mine has been
worked during all the years OF enforced
idleress from which other similar prop
critics have suffered.
The operations Of this company are
confined to the bed OF a pliocene river
lying between the south and middle
forks Of the Yuba in Nevada County
and among the rugged western foothills
of the Sierras. The company owns
1886 acres OF land lying along the course
Of the ancient river, but thus far, though
operations on large scale were begun
In 1872, they have washed away but 30o
acres, aud cleared out only 6OO0 lineal
feet of the old channel, which Is from
| 100 To GOO feet wide. At the same time
their giant monitors are tearing down
earth at the rate Of $500, 900 cubic yards
per year. The yield of gold from this
enormous amount Of dir Is in the re'gh-
borhood Of $1,000 day.
To provide the water necessary Tor
the attainment of these results the COM
pany was first Obliged to construct a
dam across the mouth Of valley high
| up in the Sierras, and thus form res
eryoir $50 acres In extent that holds
$50, 900. 900 cubic feet Of water, or enough
to supply the city Of San Francisco for
eight years. The dam Is built of gran
ite, Is 100 feet high, 400 feet long. and
has a bottom thickness OF l67 feet. The
ditch" carrying the water thus stored
10 North bloomfield Is IS miles 10
length, or half as long again as the
Croton aqueduct. 1t is divided into
eight-mile sections, each OF which Is In
charge of man who dwells in hut on
the ditch bank, and must carefully in
spect his entire section every day.
While much OF this ditch Is open canal,
other portions are heavy box fumes
carried across valleys on high trestles,
or suspended along the face OF precipi-
tous cliffs by iron brackets. The ditch
leads TO a distributing reservoir from
| which the water Is conveyed In sheet
iron pipes %, -, and II inches in
diameter to the brow Of the eroded cliffs
enclosing the ancient river bed, and
down their steep declivity to the scene
OF its labors. The original cost of thus
bringing water to this point was s1l6,OOO
while to keep dams, bitches, fumes, and
pipes In order involves an annual ex-
pense of about els, 900.
Down the face Of the water-worn cliffs,
yellow, white, and purple, or streaked
in black and reds, the pipe lines crawl
like gigantic reptiles. Two Of them end
in great cast iron nozzles, known as
monitors. The monitor is q marvel OF
simplicity, ingenuity, and concentration
of power. In general appearance II
resembles a piece Of artillery, as II is
nine feet long, has q heavy breech
swivelled to its feed pipe on universal
Joint that enables il 10 move freely In all
directions, and tapers To q muzzle diam
eter OF from four to nine inches. IL is
rifled like a gun, to give consolidating
twist to the stream that rushes from II
with the force OF cannon ball and
roar like that Of escaping steam. SO
powerful Is this torrent, driven by a
pressure head Of 500 feet, that should a
strong man attempt to cut IL with n
crow bar, the iron would be instantly
torn from his hands and whirled away
like a feather before gale. As the
water crashes against an opposing bank
toward which the monitor is directed,
the air Is instantly filled with flying
debris and a cloud of tawny spray.
Earth, sand, and gravel beds are swept
away as though by magic, while there Is
continuous avalanche OF powders and
masses Of indurated pipe clay.-Harper's
Weekly.