256 KESOUECES OF CALIFORNIA. 



a total expenditure of six hundred and forty dollars: and the 

 gold obtained \vas three thousand dollars, leaving a clear profit 

 of twenty-three hundred and fifcy dollars. The dirt contained 

 one cent and a fifth of cold in a cubic foot. The greater the 

 amount of water used, the greater tlie proportionate amount 

 of dirt that can be washed, and the greater the pi-o])ortionate 

 profits. It is far more profitable to have a large sluice than a 

 little one, if the water and dirt can be obtained in abundance. 



Usually, in a hydraulic claim, the dirt is washed down to 

 the bed-rock; but in some places the washing stops far above 

 the bed-rock, because there is no outlet for the water. 



§ 186. Blasting, — In some hydraulic claims, the dirt, in dry 

 seasons, is blasted, so as to loosen it. A drift or hole is cut 

 into the bottom of a hill one or two hundred feet high, and a 

 number of kegs of j^owder (from twenty to two hundred) are 

 introduced, and they are fired with a slow match. The explo- 

 sion makes an earthquake in the vicinity ; and the ground is 

 loosened to such an extent that there is a great saving of labor. 

 The breaking up of the dirt and the exposure to the air are 

 supposed to facilitate the washing greatly. 



More water is required for piping down banks than for 

 washing the dirt ; ?.nd often the sluice is almost idle for want 

 of dirt, while the water, after being thrown against the hill- 

 side, runs away without doing any service at washing. Blast- 

 ing, therefore, by loosening the earth, enables the hydraulic 

 miner to have an abundant and regular supply of dirt in his 

 sluice, at an expense much less than the cost of manual labor 

 to dig the bank down with pick and shovel. 



§ 187. Tail-Sluice. — The tail-sluice is a large sluice made 

 for rewashing the tailings or dirt which has previously passed 

 through other sluices. It is placed ordinarily in the bed of a 

 ravine or creek through which tailings run, and it receives no 

 attention for weeks or months at a time, save to keep it from 

 choking. The sluices emptying into it furnish both dirt and 

 water, and in the dirt there is always a large amount of fine 

 gold, as is plainly proved by the fact that some of the tail- 



