Evening star., 1904-03-11
WHERE MUDl Is GOLD
DREDGING FOR PRECIOUS METAL
IN CALIFORNIA RIVERS.
Considering Outlay, the Annual Yield
Is Great-How Machines
Work.

From the Chicago Record Herald
One of the strangest nqthods of mining in
the world is being carried on in the Feather
River Meadows, below the city of Oroville
in Butte county. Cal. 1t consists In remov-
ing thousands of tons of goid-bearing mud
and gravel from the bottom of Feather
river, which in some places is more than
twenty feet in depth.
From fifteen to tweny great dredges are
employed in the Oroville district, each hav-
ing a capacity Of from 1900 to 1906 cubic
yards every twenty-four hours. Some of
the great floating mines burrow down iato
the river bottom as far as twenty-five feet,
fifty feet from the surface being the lowest
depth at which the big shovels operate.
For many years mining men in that dis
trict In California which was made fa-
nous in the days Of 40. have been trying
to devise a scheme to get the gold which
lay far beneath the surface of the rivers.
In 1893 Capt. Couch put upon the Feather
rivers the Pioneer. the first dredger con-
structed after s50.0G0 had been expended
in experiment. At the present time there
are thirty-four dredgers in the gold streams
Of California. each especially constructed to
suit the locality in which 1t Is to be work.
ed.
Produce Almost 81 900, 900.
The success Of the dredgers has been phe-
duced almost 81. 100000. This year the min
ers expect to double that record. The
ground worked averages from 10 to 70
cents, and often more. per cubic yard, but
the cost of operating the dredges, includ-
ing an allowance for wear and tear on
machinery. is in many Of the dredges only
cents per cubic yard and in none of them
does it exceed u cents.
1t is only from twenty to thirty feet
to bed rock, and as this is sedimentary
deposit of many years 1t is easily eXca-
waited. The dredgers at work at the pres
ent time taking out 25.000 to 10000
cubic yards of gravel daily. 1t is a strange
sight to these great dredgers nosing
along the river like huge amphibian
monsters, while often the river banks are
bordered by orange orchards or waving
grain fields. A great deal of the low land
bordering on the Feather river has been
purchased by miners. and the dredgers rap
idly eat the land away until the water,
rushing in reduces it to a soft and easily
worked mass
Two classes Of dredgers are used The
more popular form consists of an endless
chain of buckets. These lift the auriferouS
gravel on an inclined plain to the head of
the sluices and concentrating tables at
tached to the dredger. The machinery
which operates the bucket belt also pumps
! the water used in the concentrator in sepa-
rating the precious contents from the dross.
Same Principle as in 40.
| The principle in extracting the gold flakes
| and minute nuggetsGis identical with that
adopted by the old placer miner in the days
| of 40. when he washed the gold in his
cradle in some of the,vsry localities where
| the dredgers are now operating.
| The other type of dredgers is the scoop
dredger, in which great shovel is directed
| beneath the surfaceJ DfIthe water by a huge
| beam. which movesf Bpe and down upon
rotating axis. This fshqNel works in much
the same way that ah oftdinary shovel does
| in human hands. V4iseHothe shovel is filed
with gravel beneatnf hesTiver bed the bot
tom of the SCOOP opens and the gold-bearing
detritus falls upon the fponcentrator. At
temptS have been made to work these
river beds with sHc5ion.siredgers, but these
have not been successful the high spe-
cifc gravity of the gold enables it to escape
from the suction whssI the cutter breaks
down the pay dirt. szfz rs sa,, 1az,S- -se
Placer dredging: is. yielding excellent
profits. One outfit with two dredgers aver
aged net profit of 5000 "a day for three
weeks 1t is estimated that there is
invested in California almost S3.000,00O in
this branch of mining.
Ready for the Mint.
AT the close of the days work the gold
dredged has all been separated from the
river bed gravel and is ready for the mint
at San Francisco. The value of the ground
worked is ascertained by systematic drilling
before operations are begun, and the esti-
mated profits ten years operation.
counting the original cost of the land and
plant and making liberal allowances for
wear and tear on machinery, repairs, loss
of time and other incidental expenses, are
figured at IS per cent the first year and up
on steady increase to $50 per cent at the
end of ten years.
No other branch of placer mining has
ever given such magnificent returns to the
average miner, and the fact that this dis
trict is in the very locality where Marshall
first discovered gold and started the rush
to California in 40 promises that these
dredgers will be in operation for many
years.
In addition to the dredging below Oro-
vile ii is also being prosecuted on the Kla-
math river and some of it's tributaries in
Siskiyou county. and on the Trinity. Bear.
MOkelume and American "a tributary of the
Sacramento) rivers. All these localities
were known to forty-niners. but. strange to
say, while the gold is found in steady and
paying quantities, few of the great nuggets
that once made these regions famous have