322 Gold in California. | July, 
gullies, on the bars and in the beds of modern rivers, and in shallow 
flats; in the latter, as before stated, the pay-dirt is often at great 
depths from the surface, and not unfrequently covered by thick 
beds of lava or volcanic ash. 
The appliances made use of in the shallow diggings are usually 
very simple, suchas the pan, rocker, long-tom, and sluice, whilst for 
the deeper deposits hydraulic mining is now generally resorted to. 
Among the most remarkable objects that first strike the atten- 
tion of the visitor to the mining regions of California, are the lofty 
aqueducts constructed of trestle work for conveying water across 
valleys and ravines. ‘These, and the various canals with which they 
are connected, are usually the property of companies who supply 
the miners, whose claims lie along their course, with the amount 
of water they may require, charging for it at rates varying from a 
shilling to five pence per miner’s inch. ‘The miner’s inch is usually 
reckoned as the amount of water which will flow through a hole of 
an inch square, under a mean head of six inches, during ten hours. 
In hydraulic mining the water from a canal is brought, by side 
flumes or aqueducts, to the head of the ground, with an elevation 
of from 120 to 150 feet, where it is conducted into a wooden box 
into which it constantly flows. This is provided with a valve, and 
from it the water is conveyed to the bottom of the claim by means of 
a strong sheet-iron pipe. At the lower extremity of this is a thick 
cast-iron chamber, in the sides of which are apertures, provided with 
slide-valves, to which flexible hose, terminating in bronze nozzles, 
can be attached by means of union joints. Jets of water are 
directed from these against the bank, by which means it becomes 
rapidly disintegrated and washed down through a sluice, in which 
are wooden or stone riffles charged with mercury, with which the 
gold becomes amalgamated and is thus retained. 
The illustration shows the method of conducting the operations 
of hydraulic mining. Some tail-sluices employed for this purpose 
are as much as from fifteen to twenty feet in width, and several 
hundred yards in length. The more ordinary width of a hydraulic 
sluice is, however, from four to eight feet. When it is desired to 
collect the gold, the sluice is cleaned up, the mercury strained, and 
the amalgam retorted. ‘To give an idea of the amount of work 
done in a hydraulic claim in the course of twenty-four hours, it may 
be mentioned that 350 miner’s inches of water, with a head of 160 
feet, will remove and wash above 4,000 tons of gravel per diem, 
leaving a small profit on the working of stuff affording gold to the 
value of only three half-pence per ton. Some of the aqueducts are 
carried across valleys at a height of 125 feet, and the aggregate 
length of the different ditches belonging to the Eureka Company 
alone exceeds 200 miles. 
The largest yield of gold during any one year was in 1853, 
