The hydraulic press. (North San Juan, Nev. Co., Cal.) 1858-18??, 1858-11-06
TAIL SLUICES.

great lengths of sluice boxes employed, am
ounting to many hundreds of feet, and the
use Of quicksilver, and all the ingenious APP
planes for arresting the precious metal,
| such as false bottoms of wooden or granite
blocks, and the many kinds of riff1es-though
| the latter are mostly discarded nova large
portion of gold ,cal escape, going to the en-
richment of ravine and river channels. 1t
asserted by some that at least half the
gold originally contained in the earth is lost
to the parties who do the first washing. Whe-
Their this be correct or not, the amount which
escapes is really very great. There are ma
ny reasons for this loss, the principal one of
which is the conceded impossibility of saving
all the gold even under the most favorable
circumstances, by reason of the extreme
lightness of much of it. The loss is greater
in the diggings surrounding San Juan than
1t would otherwise be on account of the stone
like hardness of some of the earth, which
rattles in Jumps along the sluices, and passes
off, great deal Of it, undi ssolved, with all
its auriferous particles. Strata of pipe clay
are also found, and the pieces of this as they
roll along are supposed to pick up gold and
steal off with it. To remove these causes If
loss as much as possible the miners long ago
concluded the best plan was to have great
length of sluice, it being reasonably sup
posed that the more friction and soaking the
difficulty soluble earth was subjected to the
less of it would escape undissolved. But at
he end of the longest sluices the tailings, as
the washed gravel and dirt are called after
they leave the boxes, are found to contain
gold in considerable quantities. These tail
ings accumulate in rsvines, and hollows, and
on hillsides in deep banks, though the lsrg
est portion of them find their way to the riv-
err channels and go down to impede the nav
igation Of the Yuba. Where the nature of
the ground admits Of it they are conducted
through another and longer set of sluices,
which are generally laid in sections, each
section being lower by many feet than the
preceding one, thus occasioning succession
VI ldliS QVnu WulCu luO StuDUOIu
cement is crumbled in great degree and
made to yield its treasures. me,imes it
"slacks' on exposure to the ar, an | when
reconducted into boxes dissolves readily
This re-washing Of escaped dirt constitutes
what is termed tail-sluicing, and has become
a very important branch of mining in this
district. The tailings are thus collected and
submittel to a second washing sometimesoy
those from whose claims they ran but more
frequently and Systematically by other par
ties who purchase the right to them either
for given period or in perpesuity.
The tailings Of several different sets of
claims commonly hud vent down the same
declivity or into the same ravinc, and are
then collected into one Get Of boxes, the wa
ter needed to wash them flowing with them
from the diggings.
Not unfrequently the sailings VIII ch fl W
into ravines or small water cou, SEES are kept
sluiced down to a uniform shallowness by
the natural action of running streams, and
as much of the gold remains behind, they
often prove to be richer than the original de-
Iosits from which they came. The chief ex-
pense the proprietors Of tail-sluices have to
incur is the cost ofconstructing and keeping
in repair their fumes, for when these are
once completed one or two men can general
ly attend them, no labor being necessary but
in occ0 sionally cleaning up and repairing or
extending. We do not know the number Of
tail.sluces which are running in this vicinity,
but it is considerable.
The most extensive one is owned by Win
ham, Mcdowell & Ewing. 1t is situated on
Sweetland Creek--which empties into the
North Yuba some two miles or more below
this town--and is really an enterprise
considerable magnitude. The fume is laid
along the bed of the creek below the town of
Sweetland. 1t is constructed of inch and
half and inch and quarter lumber, consis
Of two parallel sets of boxes which are laid
snugly side by side, and zach of which is four
and half feet wide by two and half deep,
making total width of nine feet, supported
on heavy posts and stringers, and banked in
solidly on either side by gravel, which has
been allowed to rise to level with the fume,
for the purpose of anchoring it, by means of
dams here and there. The total length of
fume is about l 800 feet, 600 feet of which
are laid through a tunnel which pierces q
point of land, thus saving considerable
distance; and the total cost is stated at from
$4,000 to $4,000. At one place point of
land has been cut down and washed off, re-
vealing indisputable evidences of slide at
some remote Period. Large cedars were
found entire under the mass of rock and
earth, and ON being chopped proved to be in
a tolerably sound condition, though in the
first stages of that transformation which
converts them, under the influence doubtless
| of sulphurous acid and iron, into black