Amador ledger., 1900-03-23


is about the length of the shaking
grizzly y"-from twelve to fifteen feet
and on this seventy-five per cent of the
product is caught. Afterward the
pulp is carried the entire length of the
boat over other rifles and is finally re-
turned to the water about ten feet back
of the boat and at it's level. The
shovel is alternately filed and emptied
from seventy y-five to eighty times an
hour when all is moving well. To
operate the machinery of a dredge
of this pattern requires from
eighty to one hundred horsepower,
which is generated by use OF wood and
coal. The furnaces, boiler and ma
chinery, stand on the boats deck and
are covered by proper houses. This
pattern. of dredge is kept in place while
at work by ''set" or ''speed" an
iron-shod timber, which is driven into
the river bed at the boats corners.
The continuous bucket type of dredge
differs very materially from the shovel
dredge. The boat, which is thirty
feet wide and seventy feet long, is con-
structed with we'll hole five feet across
extending from the front, back about
three-fourths of the boats length.
The buckets are generally thirty
eight in number of three and one
quarter cubic feet capacity, fastened, on
an endless chain and working on. lad
der in the wellhole in such a manner
that they can dig vertically under the
boat, thirty feet below the surface of
the water or at any angle in front of
that. The top end of the ladder is hung
on bar, and the lower end is sus-
pended by blocks and tackle and by
means of a winch can be lowered as re-
quired. The continuous bucket chain
moves up the top side of the ladder
and down on the under side.
1t is given its motion by rope
transmission at the top end. When in
operation the ladder is held firmly so
that every bucket digs into the sand,
gravel or bedrock with great force and
is filed, after which it passes up the
ladder and emptles into delivery
plate. 1t is closely followed by its fell
lows, and the motion of the continuous
chain of buckets gives practically a
continuous discharge of material into
the delivery plate. From the delivery
plate it moves by gravity into a revolv-
ing screen or grizzly" in which water
for washing is conveyed through per-
forated pipe in many small jets under
great pressure. The water washes the
| fine material through the holes in the
| grizzly" The water, the finer wash
dirt, and the gold drops into distri-
| buting box, which distributes the ma
terial to either side and on to gold
ing tables. These tables are divided
into sections and are covered with
cocoa mating and expanded iron
which catch the gold. From them the
pulp is conveyed through sluice boxes
with rifles to the stem of the boat and
| returned to the stream. The heavier
material is discharged by the ''griz-
zly," at its lower end, down stone
chute and from thence onto a stOcker
which carries it out beyond the boat
forty or fifty feet and at an elevation of
from twenty-five TO thirty feet above
the water level.
By the method of goldsaving in use
on the continuous bucket dredges more
than seventy-five per cent of the gold
is recovered within three feet from the
point at which it leaves the distribu-
tor. The expanded iron over the
cocoa mattipg gives to the water COM
ing onto it with mach force, MOTION
which seems to preeipitate the parti-
cles of gold into the interstices of the
cocoa mating where they rest until the
mating is taken up and washed in the
cleanup tub. In this process of gold
saving no quicksilver is used and
cleanups can he made every day with a
machine.
This style of dredge has on
it six winches which operate one line at
each CORNER of the boat, one head line
and one to raise and lower the ladder.
The corner lines and the head line are
used to keep the dredge in place while
working and 10 altar its position at
will.
One of these dredges req uires from
thirty to forty horsepower to operate
it to its full capacity.
Electricity is being introduced on
theW as a power and seems to be in
great favor among the men who oper-
ate the dredges, and, wiil doubtless
soon become the power in general use
in this class of gold-saving. Its ad-
vantages are many, for in the use
of steara SO much room is required on
the boat that everything is er0Wded
and quite force of men is required on
shore to keep the furnaces going;
with electricity the current is carried
aboard the boat by wire and when
properly installed requires but little
attention.
To operate a dredge requires crew
consisting of a dredge superintendent,
(who, when quicksilver is used is occas-
ionaily also the amalgamatorl a roust-