The daily morning journal and courier. [volume] (New Haven, Conn.) 1894-1907, 1895-05-31
Hydraulic Mining in California.
[From Harper's Weokly.l

| [From Harper's Weekly.l
The foregoing information concerning
hydraulicking was impaired by Super
intendent Radford, of the North Bloom
field Gravel Mining company of Califor-
MIA. He was a. New York boy, a grad
uate OF the Columbia school Of mines;
is man Of extensive mining exper-
fence In South Africa as well as in this
country; and 1t is largely owing to his
Engineering skill i'm providing for the
safe disposition of "tailings" that the
North Bloomfield mine has been worked
during all the years of enforced idle
ness from which other similar proper
ties 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 foot
hills Of the SieTas. The company owns
1886 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
about 300 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 $780,
900 cubic yards per year. The yield of
gold from this enormous amount of dirt
is in the neighborhood of $1,000 a. day.
To provide the water necessary for
the attainment of these results the COM
pany was first obliged to construct a
dam across the mouth of a. valley high
up in the Sierras, and thus form res
ervoir $50 acres in extent that holds
100000 900 cubic feet of water, or enough
to supply the city of San Francisco for
eight years. The dam is built of gran
lite, is 100 feet high, 400 feet long, and
has a bottom thickness of 1877 feet.
The ditch" carrying the water thus
stored to Bloomfield Is forty-five miles
in length, or half as long again as the
Croton aqueduct. It is divided into
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 each 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 precipit-
Gus cliffs by iron brackets. The ditch
leads to a distributing reservoir, from
which the water is carried in sheet iron
pipes q, % and 10 Inches in diameter to
the brow of the eroded cliffs enclosing
the ancient river-bed, and down their
steep declivity to the scene of it's Iabors.
The original cost of thus bringing water
to this point was $716, 900, while 20 keep
dams, bitches, fumes and pipes in order
Involves an annual expense Of about
SIG, 900.
Down the face of the water-worn
cliffs, yellow, white and purple, or
in black and reds, the pipe |
lines crawl like gigantic reptiles. Two
Of them end I'm great cast iron MOBILES |
known as monitors. The monitor is a
marvel of simplicity, ingenuity, and |
Of power. In general APP
pearance it resembles a piece of artil- |
ery, as it is mine feet long, has heavy |
breech swivelled to it's feed-pipe on a |
universal Joint that enables 1t to move |
freely in all directions, and tapers to a
nuzzle diameter of from four to nine |
inches. Tt is rified like gun, to give
4 consolidating twist to the stream that |
-ushes from 1t with the force of a cam
non ball and a roar like that of es-
gaping steam. So powerful Is this tor
,ent driven by pressure head of 800 |
feet, that should man attempt to cut |
t with a crowbar, the iron would be
torn from his hands and
vhirled away like a feather before a
gale. AS the waiter crashes against AM
opposing bank toward which the moni- |
or is directed, the air is instantly filed |
With flying debris and a cloud of tawny |
spray. Earth, sand, and gravel-beds |
ire swept away as though by magic, |
while there Is a continuous avalanche |
# powders and masses of indurated |
oipe-clay