THE COMSTOCK MINES. 125 



The pipe or column in which the water is raised above the piston is 

 sometimes placed upon and directly over the cylinder, in which case the rod 

 to which the piston is attached passes up through it and is connected above 

 with the motive power; but commonly the pipe, or column of elevation, is 

 fixed at one side and connected by a short horizontal or curved piece, H, with 

 the cylinder, the top of which is then fitted with a stuffing-box, g. The pis- 

 ton-rod passes through the latter and is then connected with the main pump- 

 rod, R, working in the shaft, from which it receives its motion. 



The column may be of any desired height to which the strength of the 

 material is adapted. As the lifting pump is generally only employed in the 

 Comstock mines at the bottom of the shaft to raise the water to the force- 

 pump above, the height of its column varies according to circumstances. In 

 shafts where sinking is in progress the column of the lifting pump is con- 

 stantly being extended as the shaft deepens, until a sufficient depth, 200 

 feet or more, has been attained for the convenient establishment of a force- 

 pump, when the lifting pump is detached from the column, the force-j)ump 

 put in its place at a suitable distance above the bottom, and the lifting 

 pump again employed for sinking deeper with a short but gradually extending 

 column. 



The Force-Pump or Plunger-Puinp, Fig. 1, Plate IX, forces the water upward 

 in its column of elevation by the descent of the piston or plunger. This 

 pump consists of a cast-iron cylinder or "plunger-case" usually 10 or 12 feet 

 long and from 8 to 12 inches in diameter, in which a solid cylindrical piston, 

 P, nearly as long as the cylinder, is caused to play with an upward and down- 

 ward motion ; the piston passes through a stuffing box, g, at the top of the 

 cylinder, and is then connected with the pump-rod, R', that gives it motion. 

 Below the cylinder is a side or branch pipe, H, connecting the cylinder with 

 a valve-chamber, o, and the column of elevation, C. The valve, V, in the 

 chamber, o, retains the water drawn through it from the wind-bore or suction 

 pipe 8, which is immersed in the cistern. The valve, v, at the bottom of the 

 column of elevation, C, opens for the passage of the water into the column 

 and closes to retain it there. When the piston ascends, the valve, V, opens 

 and the space in the cylinder, below the piston, fills with water ; when the 

 piston descends, the valve, V, closes, the valve, v, opens, and the column of 

 water is forced upward to the point of discharge at any desired height. 



