MINING. 943 
is not careful to catch all that he could. His purpose is to 
draw the largest possible revenue per day from his claim. He 
does not intend to spend many years in mining, or if he does 
he has become thriftless and improvident. In either case, he 
wishes to derive the utmost immediate profit from his mine. 
If his claim contain a dollar to the ton, and he can save five 
dollars by slowly washing only six tons in a day, while he 
might make ten dollars by rapidly washing fifteen tons in a 
day, he will prefer the latter result, though he will lose twice 
as niuch of the precious metal by the fast as by the slow mode 
of working. The object of the miner is the practical dispatch 
of work, and his success will depend to a great extent upon 
the amount of dirt which he can wash within a given space of 
time. He regrets that any of the gold should be wasted, but 
his reoret is because it escapes from his sluice and his pocket, 
rather than because it is lost to industry and commerce. 
_ $179. The Sluice-—-The board-sluice is a long wooden 
trough, through which a constant stream of water runs, and 
into which the auriferous dirt is thrown. The water carries 
away the clay, sand, gravel, and stones, and leaves the gold in 
the bottom of the sluice, where it is caught by its gravity and 
by quicksilver. The board-sluice is the great washing ma- 
chine, and the most important instrament used in the placer 
mining of California. It washes nearly all the dirt and catches 
nearly all the placer gold of the country. It was invented 
here, although it had previously been used elsewhere ; it las 
been more extensively employed here than in any other country, 
and it can be used here to more advantage than elsewhere. It 
is not less than fifty feet long, nor less than a foot wide, made 
of boards. The width is usually sixteen or eighteen inches; 
and never exceeds five feet. The length is ordinarily several 
hundred and sometimes several thousand feet. It is made 
in sections or “boxes” twelve or fourteen feet long. The 
boards are an inch and a half thick, and are sawn for that 
special purpose, the bottom boards being four inches wider at 
ene end than the other. The narrow end of one box therefore 
