Shepherdstown register. [volume] (Shepherdstown, Va. [W. Va.]) 1849-1955, 1895-06-06
HYDRAULIC Mining in California.

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Superintendent Radford, of the North
Bloomfield Gravel Mining Company
of California. He was New York
boy, graduate of the Columbia School
of Mines is man of extensive mining
experience 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 idleness from which other
similar properties have suffered.
The operations of this company are
confined to the bed of pliocene river
living between the south and middle
forks of the Yuba, in Nevada county,
and among the rugged western foot
hills of the Sierras. The company
owns 1885 acres Of land lying along
the course of the ancient river, but
thus far, though operations on a large
scale were begun in 1872, they have
washed away but 800 acres, and cleared
out only 5000, lineal feet of the old
channel, which is from 400 to 600 feet
wide. At the same time their giant
monitors are tearing down earth at
the rate of 100000 cubic yards per
year. The yield of gold from this
enormous amount of dirt is in the
neighborhood of 81 ,000a day.
To provide the water necessary for
the attainment of these results the
company was first obliged to construct
dam across the mouth of a valley
high up in the Sierras, and thus form
a reservoir $50 acres in extent that
holds 93O,000,O00 cubic feet of water,
or enough to supply the city of San
Francisco for eight years. The dam
is built of granite, is 100 feet high,
400 feet long, and has bottom thick
ness of 1877 feet. The "ditch" carry
ing the water thus stored to North
Bloomfield is 45 miles in length, or
half as long again as the Croton aque-
duct. 1t is divided into eight-mile
sections, each Of which is in charge Of
a man who dwells in a hut on the
ditch bank, and must carefully inspect
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 sus-
pended along the face of precipltous
cliffs by iron brackets The ditch
leads to distributing reservoir, from
which the water is conveyed in sheet
iron pipes q, % and Is inches in d.
ameter to the brow of the Proded cliffs
enclosing the ancient river-bed, and
down their steep decHvity to the scene
of its labors. The original cost of thus
bringing water to this point was $716,-
900, while to keep dams, bitches,
fumes and pipes in order involves an
annual expense of about $4,000.
Down the face Of the water
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 a
marvel of simplicity, ingenuity and
concentration Of power. In general
appearance it resembles piece of ar
tillery, as it is nine feet long, has a
heavy breech swivelled to its feed-pipe
on a universal joint that enables it to
move freely in all directions, and ia
pers to muzzle diameter of from four
to nine inches. 1t is rihed like a gun,
to give a consolidating twist to the
stream that rushes from it with the
force of cannon ball and roar like
that of escaping steam. So powerful
is this torrent, driven by pressure
head of 500 feet, that should a strong
man attempt to cut it with crowbar,
the iron would be instantly torn from
his hands and whirled away like a
feather before a gale. As the water
crashes against an opposing bank to-
ward which the monitor is directed -,
the air is instantly filled with flying
debris and cloud of tawny spray.
Earth, sand and gravel-beds are swept
away as though by magic, while there
is a continuous avalanche of powders
and masses of indurated pipe-clay.-
Hmper's Weekly,
"
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