534 MINING INDIJSTEY. 



one 14-foot boiler to supply steam. From, the main engine-shaft the power 

 is transmitted by a belt to a line-shaft, 60 or 70 feet long, by means of which 

 both winding spools are driven and from which another belt communicates 

 power to the pumping gear. 



The rock, when brought from the mine to the surface, is first assorted, 

 selecting the first-class ore for smelting, and separating the waste-rock, that is 

 thrown away, from the low-grade ore, that is sent to the stamps. 



The company have a 24-stamp mill, which is situated in the valley di- 

 rectly below the shaft-house, so that a gravity tram-road, a few hundred feet 

 in length, is laid on the hill-side, by which means the ore is conducted in cars 

 from the shaft-house to the mill, the descending loaded car bringing the light 

 one up by its greater weight. The 24 stamps, weighing about 500 pounds 

 each, have an average capacity of 16 to 18 tons per day. The yield of the 

 rock, which will be stated with more detail in a following paragraph, is about 

 six ounces of crude bullion to the cord, equal to f 13 or $14, in coin, per ton. 

 In addition to this is the product derived from the tailings, which, as may be 

 seen further on, is considerable. The treatment of tailings will be more fully 

 described after discussing more particularly the general features of the milling 

 process. 



The superintendent of this mine. Colonel Greorge E. Randolph, deserves 

 much credit for the systematic and careful method of account-keeping intro- 

 duced by him. The data furnished here from his books, concerning the ope- 

 rations of the company, are especially valuable, because so little attention is 

 generally paid in Colorado to acquiring and preserving the statistics of costs 

 in the various departments of mining and milling ; or to recording such results, 

 obtained from month to month in the progress of the work, as may enable 

 one to form an intelligent judgment of the future by an accurate knowledge of 

 the past. Colonel Randolph took charge of the work in April, 1868. The 

 following statement shows the number of fathoms stoped, the quantity and 

 class of the ore produced, and the costs of mining and milling the same, dur- 

 ing the succeeding five months : 



