Weekly Trinity journal., 1878-11-23
RIVER MINING BY DREDGING

Inc / lacer argus Of last week has a
lengthy account Of what it terms sue.
cessfll enterprise on the American River,
near Auburn dredging boat for work
ing the river bed, which is thus describ.
ed.
AT first glance it seems TO resemble a
saw mill, as much rs it does boat. It's
design and purpose necessarily make it
something ofa nordescrIpt. A nearer
inspection serves to proposes one with it
more favorably, although from distance
it looks imposing, with its tall smoke
stack, mast and open roof, hosting gear
and cylinder. The vessel, as we suppose
it may be called, is eight feet long, and
thirty feet wide. The hull is scow. shap-
ed, the deck being bout four feet out Of
water, unpainted, but with its sides caulk-
ed and pitched. On tho whole, its op-
pesrance is favorable, though Of course
practical people only want to know what
it is capable of doing. But people will
want description of the craft, and n
description Of it, to bc compl etc, must
deal not only with its structure, bat with
its appearance. Tho hold has three lon
gltudinal compartments running its
whole length, not because the space was
needed tor any special plrpose, but
simply that the partition tim bers might
give greater staunchnoss to the hull.
which otherwise would Mt times be sub.
jected to straining and fitting, for great
power is often needed to raise the loads or
gravel, earth and rock which are taken
up at the end Of the boat, and placed
1 perpendicularly, which are raised aud
lowered by ratchet arrangement. They
are called "spuds," and serve the pIr-
/ pose of being lowered into the bed of the
river to keep the boat steady in position.
| There is an air of roomlness and light
someness about the deck, because the
roof covering it is lofty. 1t extends over
the width Of the boat and nearly from
end to end.
The machinery comprises a boiler of
fifty horse power centrifugal pump of
the VIM. p. Andrews make, conden-
ser, and the cage and cylinder. The es
sential part Of the apparatus is this cyin-
der, which being lowered into the river is
filled with steam. The steam is then
condensed BY cold water being forced in
to the cy Under; thus producing a vacuum,
in to which the gravel, sand or rocks at
the bottom are iDstantaneously forced.
The iongth Of this, great iron cylinder, is
45 feet, and its diameter, three feet. The
lengths OF hose are connected with the
top oft, one Of which supplies the steam;
the othor, water. Tho condenser is also
an upright hollow cylinder, Of about
three feet in diameter, and seven or eight
feet high, filed with water. 1t stands on
the deck. Steam is also let in this and
forces the water into the hosting cyln-
der. The centrifugal pump is one of the
best made, being the same as those usal
on the government monitors. It's pur-
pose IS 90 supply water to wash the gravel
in tn e dump-bo and sluices. IT is cap
able Of throwing $500 gallons 80 feet
high per minute, which is equal to about
300 miners inches. The cylinder, of
course, is in Il cage which is suitably |
gealcd for being swuAg around into any
desired position. BY means Of n wire
rope, the hosting engine raises and low
ers the cylinder. The dumpbox, into
which the gravel is deposited, is about
five feet square, and its bed slopes toward |
the head OF the sluice boxes. These are
ofthe ordinary size, supplied with the
regulation rifles, and about 100 feet in |
length. Their incline Is greater than the
average; their fall we should Judge, was |
about one foot in eight. The services of
a couple Of men are constantly needed 10 |
preventive sluices from being choked |
up with the bouiders which are washed |
down. The larger ones have to be lifted !
out Of the dumpbox and thrown out.
They seldom weigh over thirty or forty
pounds, although the machine will raise
these weighing hundreds. The whole !
apparatus consumes "A deal Of steam, for
not only Is tho hosting cylinder supplied !
with it, but also the condenser, the pump |
and the engine. About once every three
minutes "lif." is made the machinery
being worked most admirably and salts
faetorily by the engineer, Mr. E. II. Som
erviIle, and his assistants.
The top grave! contains little orno pay,
the main wealth Of the river remaining.
rs everybody believes, and as all old
miners know, in the old gravel at the
bottom. To reach this, vast guam titles
Of tho upper gravel have to be removed,
and as the pit is gradually deepened and |
enlarged, and sometimes slides occur, of
the gravel on the sides of this hole, that
serves further to delay reaching the SO
called old gravel. The day Il q dumpbox
went down, two or three ellis" OF this
rusty looking gravel were taken up that
gave Mr.. Chapman and his men great
encouragement.