86 



MINING INDUSTEY. 



Table showing Temperatures in the interior of the Comstock Lode — Continued. 



Mine. 



Locality. 



Temperature. 



Remarks . 















 





< 























Yellow Jacket - 



New shaft, 570 level . . . 



77 



- 



" 



Clay I foot wide, running with vein 2 

 feet wide. 





Do. 550-foot level 



75 



- 



- 



In vein, 100 feet south of shaft ; east 

 wall. 





Do. 450-foot level 



72 



. 





West drift, 350 feet from shaft. 





Do 



61 



. 



63 



20 feet from shaft. 



Imperial and Em- 

 pire. 



N e w shaft . 





93 





Tank at top of shaft. 











Do ■- 





96 



97 



From bottom. 







The Ophir works being inaccessible at the time of this study, we have 

 no very definite ideas relating to the thermal conditions of that part of the 

 lode; but such a uniformity exists in the relations of temperature and depth 

 that it cannot be doubted that the Ophir would repeat the conditions observed 

 so miiformly elsewhere. The vein-material is all wet with infiltrated waters, 

 which may be classed in two systems : those which owe their origin to surface 

 drainage, and percolate downward from the outcrop of the lode; and those 

 which rise from great depths, arriving at the lower mine-works in a more or 

 less heated condition. The former are dammed up by the various clay-seams, 

 penetrating to greater or less depths according as the clays pinch out or con- 

 tinue deeply downward; the upper portion of the lode, especially that which 

 has expanded in the V-form, is a continuous series of water chambers. As 

 mining developments have progressed, these chambers, one after another, have 

 been drained and pumped out. Within the main portion of the lode, subter- 

 ranean galleries tapped successively nearly all these water bodies, and there 

 are no longer any great isolated collections; but the constant influx necessitates 

 a very elaborate system of pumping machinery, as will hereafter be seen from 

 Mr. Hague's chapter. By referring to the table, the reader will see that the 

 average temperature of these waters, from the surface to 700 feet downward, is 

 about 70° to 75° Fahrenheit; while those which are found in the lowest work- 

 ings of the Empire, Crown Point, and Hale and Norcross, rise to a maximum of 



