14 B. Siliiman on the Deep Placers of 
set like a cobble-stone pavement, the gold being deposited in 
the interstices. Most of the sluices are however paved wit 
rectangular wooden blocks as described. 
Standing at the mouth of one of these long bed rock tunnels 
in full action, one unaccustomed to the process is filled with a 
sense of amazement amounting almost to terror, as the muddy 
sweeps with great velocity onward, bearing in its course 
great boulders which add to the roar of the water, the whole 
being’ precipitated down a series of falls, at each of which it 
is caught up again by new sluices of timber lined like the first ; 
one, and so onward and downward many hundreds of feet, until 
the level of the river is reached at the distance perhaps of half 
a mile or more from the mouth of the first tunnel. At each of 
these new falls of twenty-five or fifty feet, the process of com- 
minution begun in the first shaft is carried forward and a new 
portion of gold is obtained. 
Another ingenious device to secure the gold is by means 
of what are called under currents. At the end of the last 
sluice box, and beyond the mouth of the tunnel a grating 
of iron bars is arranged lengthwise in the bottom through which 
a portion of the water and finer material falls upon a series of 
more gently graded sluices of double the width of the main 
sluice. ese sluices are placed at right angles to the other 
while the great body of the gravel with the large boulders go 
hing forward over the fail, while the finer part thus di- 
verted is more gently brought in contact with a new set of 
mercurial rifles, from which it rejoins the main torrent; and the 
same process is repeated at each succeeding fall, until the river 
is reached. 
Rude as this method of saving the gold appears, experience 
shows that more gold is saved by it than by any other method 
of washing yet devised, while the economical advantages it offers 
are incomparably greater than any other. In fact, it would be 
entirely impossible to handle so vast a body of poor material in 
any other way now known. 
'o show the enormous advantage gained by the present sys- 
tem of working, compared with those formerly in use, Mr. Black 
states that, taking a miner’s wages at four dollars per day, the 
cost of handling a cubic yard of auriferous gravel is as follows: 
With the pan,” - : ‘ . _ - $20.00 — 
5. 
Wite the ticker oor 8 
Wi oe6 O08 Mee ok ee LOU 
With the hydraulic process, : p : .20 
In fact, man has, in the hydraulic process, taken command of 
nature’s agencies, employing them for his-own benefit, compell- 
ing her to surrender the treasure locked up in the auriferous 
a ost 
o 
aes 
