Gold Mining Notes. 35 
Dirt is thrown in and carried forward by the water 
which is afterwards shut off when a sufficient quantity 
has been washed. The stones are then removed and the 
dirt washed in a rocker, long torn, or shorter sluice. 
Blasting is resorted to by the hydraulic miners to 
shatter the large boulders and masses of clay from which 
the surrounding dirt has been torn and washed by the 
stream of water directed against them, or when the 
gravel is too hard to be disintegrated by water. It is 
also extensively used by the quartz-miner. Where 
the material to be broken up presents a flat surface, a 
vertical shaft is sunk fifteen or twenty feet deep and a 
small chamber excavated at the bottom into which five 
of six kegs of gunpowder are placed, thoroughly tamped, 
and fired by electricity. Where a bank has to be blasted, 
a main tunnel or adit is run in for a distance one and a 
half times as great as the height of the bank to be 
broken down. From the end of this, cross adits are 
driven at right angles to the main adit. Kegs or boxes 
of powder are placed along the adits in rows, the tops 
of the middle row removed and wires laid along for con- 
nection with the battery. A bulkhead of timber is then 
placed across the main adit where the lateral arms 
intersedl it and the adit tightly packed with sand and 
gravel to the mouth. When all is ready, the conducting 
wires are connected with the electric battery and the 
charge fired from a safe distance. Large quantities of 
powder are used. The report mentions one of no less 
than 50,000 lbs. fired in a drift 275 feet long with cross 
drifts by means of which 150,000 cubic yards of earth 
were loosened ready for treatment by the hydraulic 
pipe. Gunpowder is not the only explosive used. The 
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