130 MINING INDUSTEY. 



eter. In the Savage mine the pumps are 10 and 12 inches in diameter. The 

 water is raised from the bottom of the shaft, about 1,000 feet deep, to an adit- 

 level, which is about 120 feet below the surface, where it is discharged. For 

 this purpose two plunger or force-pumps are in use, one above the other, each 

 raising the water about 300 feet. Below the lower one of these pumps a lift- 

 ing pump is employed, which is extended in depth as the sinking proceeds. 

 The latter pump lifts the water from the bottom to a cistern above in which 

 the windbore of the lower plunger or force-pump is placed ; thence it is 

 forced by the last-named pump to a cistern 300 feet higher, and thence again 

 by the upper force-pump to the adit-level, where it is discharged. 



The ordinary working capacity of the pumps thus employed in the deep 

 mines is about 250 gallons per minute, though when required they can be 

 worked up to a considerably higher duty than that. It is not often that they 

 are required to perform their full duty. It is the liability to which the mines 

 on the Comstock are subject, of encountering at any time a great influx of 

 water, that makes the provision of large pumps necessary. 



The clay-seams of the vein appear to act as dams, effectually retaining 

 the water in certain places, and preventing the regular drainage of the 

 ground. 



Thus in the Yellow Jacket, the so-called North Mine being idle, was 

 filled with water during one or two years, which was not drained off by the 

 South Mine, which was much deeper, even when the drift from the latter, on 

 a level 100 or 200 feet lower, had been carried north so far as to be directly 

 under the water of the North Mine. Similar cases are reported in other 

 parts of the lode. It is said that years ago the Gould and Curry mine was 

 much deeper than the Savage without draining it. 



The Ophir company, in sinking their deep shaft during the winter of 

 1867 and 1868, met with large quantities of water, to remove which pumps 

 of large capacity were provided and steadily employed until, on reaching a 

 depth of several hundred feet, the sources of the water appeared to be 

 exhausted and the influx ceased almost entirely. The work remained exceed- 

 ingly dry until, in the autumn of 1869, a new body of water was tapped by 

 the drift on the 700-foot level. 



In some of the mines where sinking is in progress the pumps must be 



