* 
278 RESOURCES OF CALIFORNIA. 
tunnels. After the excavation has extended twenty or thirty 
feet below the surface, it is usual to dig a perpendicular shaft, 
so as to strike the vein sixty or seventy feet below the surface, 
and from this point the miner or “ drifter” works upward, and 
as he loosens the rock it falls to the bottom of the shaft, where 
it is put in the bucket to be hoisted to the surface. Our quartz 
mines are generally in dry hills, so that they are not troubled 
much by water; but there are afew shafts where steam-pumps 
are constantly at work to carry off the water. 
Occasionally the miners find small quantities of auriferous 
quartz which are so easily broken up, and the pieces of gold in 
which are so coarse, that after the rock has been pounded a 
little in a mortar, the metal can easily be picked out with the 
fingers. 
§ 208. Arastra.—Quartz is pulverized either in an arastra, 
or Chilean mill, or by stamps. 
The arastra is the simplest instrament for grinding aurifer- 
‘ous quartz. It is a circular bed of stone, from eight to twenty 
feet in diameter, on which the quartz is ground by a large 
stone dragged round and round by horse or mule power. 
There are two kinds of arastras, the rude or improved. The 
rude arastra is made with a pavement of unhewn flat stones, 
which are usually laid down in clay. The pavement of the 
improved arastra is made of hewn stone, cut very accurately 
and laid down in cement. In the centre of the bed of the 
arastra is an upright post which turns on a pivot, and running 
through the post is a horizontal bar, projecting on each side to 
the outer edge of the pavement. On each arm of this bar is 
attached by a chain a large flat stone or muller, weighing from 
three hundred to five hundred pounds. It is so hung that the 
forward end is about an inch above the bed, and the hind end 
drags on the bed. A mule hitched to one arm will drag two 
such mullers. In some arastras there are four mullers and two 
mules. Outside of the pavement is a wall of stone a foot high 
to keep the quartz within reach of the mullers. About four 
hindred pounds of quartz, previously broken into pieces about 
