124 MINING INDUSTEY. 



Accidents sometimes occur, but they are usually the results of carelessness on 

 the part of the sufferers, either in climbing upon or crowding the cage, or 

 otherwise violating the simple rules of safety. 



The winding apparatus and other machinery employed at the surface in 

 hoisting and pumping will be described after reference to the pumps placed in 

 the shafts. 



Pumping Machinery. — The pumps usually employed in the several 

 deep shafts of the Comstock lode are all of the same general character, and 

 do not differ essentially in principle from those used in deep mines in other 

 countries. They are either lifting pumps or force-pumps. In a complete set 

 of deep pumps the two kinds are combined, the former being applied to rais- 

 ing the water from the bottom of the shaft to a height adapted to the capacity 

 of a single pump, the latter for forcing the water thence upward to the point 

 of discharge. 



The Lifting Pump, Fig. 7, Plate IX, consists of a cast-iron cylinder, or 

 "working barrel," from 8 to 12 inches in diameter and from 8 to 12 feet long, 

 smoothly turned inside, in which a closely-fitting piston, P, that has an upward- 

 opening valve, V, may be caused to move up and down by means of a rod to 

 which it is attached. At the bottom of the cylinder is a valve, V, opening 

 upward, by means of which the water once drawn from below into the cylin- 

 der is retained there. Below the cylinder is the suction pipe, S, dipping 

 below the surface of the water to be lifted. Above the cylinder is an iron 

 pipe or column of elevation, C, in which the water is raised, by the upward 

 movement of the piston, to any desired height. When the piston in the 

 cylinder is moved upward, its valve remaining closed, and the lower end of 

 the suction pipe being immersed in the water, the pressure of the exterior 

 air causes the water to rise in the suction pipe, S, and to pass through the 

 retaining valve, F, at the bottom of the cylinder, in accordance with the well- 

 known principle involved in all suction pumps. On the downward stroke of 

 the piston the retaining valve, V, at the bottom of the cylinder, closes, while 

 the valve, v, in the piston, opens and the water passes through the piston. On 

 the succeeding upward stroke the water, now above the piston, is lifted by it, 

 while a new supply is drawn into the cylinder in the manner just described, 

 to be lifted by the next upward stroke. 



