102 ■ MmiNG IKDUSTEY. 



Shafts of this character, designed for permanent and extensive operations, 

 liberally planned and constructed in the most substantial manner, and furnished 

 with the best of machinery for pumping and hoisting, are now being sunk by 

 the Ophir, Gould and Curry, Savage, Hale and Norcross, Chollar-Potosi, and 

 Empire-Imperial companies. The depths attained by these several shafts vary 

 from 700 to about 1,300 or 1,400 feet. The deep mines further south, the 

 Bullion, Yellow Jacket, Kentuck, and Crown Point, are still working through 

 the shafts originally sunk near the croppings of the vein, but in the vicinity of 

 the last-named mines the west wall is only encountered at a much greater 

 depth than in the more northerly portions of the lode. 



At the present day the greater part of the ore extracted from the vein is 

 brought from a depth exceeding 500 or 600 feet, and the underground work 

 of the leading mines is necessarily prosecuted through these deep shafts. As 

 the sinking of these progresses, stations are established at successive distances, 

 usually at intervals of about 100 feet, and from these stations, levels or tun- 

 nels are driven from the shaft to the vein for purposes of exploration or extrac- 

 tion. The ore-body being reached, it is stoped out overhand ; that is, the 

 level is driven under the body of ore to be worked out, and the ground over- 

 head is thrown down and carried in cars from the stope to the shaft, where it 

 is raised to the surface. 



The drainage of the deep workings must, of course, be effected by means 

 of the shafts. The adits or tunnels, driven in from the surface to the upper 

 portion of the lode, serve to drain the ground above them, but as operations 

 are now carried on far below their level, the accumulating water must be col- 

 lected at the shaft and raised to the surface or to an adit-level. For this pur- 

 pose the deep shafts are provided with pumps of adequate capacity, and the 

 water encountered in the various parts of the mine, finding its way to the 

 shaft, is thus discharged at the surface. 



The various operations included in this work, comprising the sinking and 

 timbering of the shafts, the construction of the drifts or tunnels, the working 

 and timbering of the stopes, the extraction of the rock, the machinery em- 

 ployed for hoisting, pumping, and ventilation, and the arrangement of these 

 works on the surface, will now be reviewed somewhat in detail. 



Mine Shafts. — The deep shafts of the several leading mines on the 



