138 MINING INDUSTEY. 



either direction, independently of the motion of the shaft. They may be 

 made to revolve with the shaft by the clutches, (7, v^^hich, being fixed to the 

 shaft by a feather, may slide tow^ard or from the pinions. If the clutch, C, be 

 moved into gear with the pinion, P, the latter receives the motion of the 

 engine-shaft and transmits it to the reel; if the clutch be withdrawn from its 

 contact with the pinion, the reel may turn in the opposite direction while the 

 motion of the engine is uninterrupted. The reel may therefore be moved by 

 the engine for hoisting, and, when reversed for lowering, may be controlled 

 by the brake. The clutches are moved in and out of gear by the levers 

 L, L ; the brakes are applied by similar levers I, I. If it be desired to 

 lower a cage under control of steam, as is usually the case when men are de- 

 scending, it is only necessary to leave the clutch in gear and reverse the 

 engine. It will be seen that both reels may hoist at the same moment ; or 

 by fixing both clutches permanently in gear and reversing the engine for each 

 operation, one reel may hoist while the other lowers, using the descending 

 cage as a counter- weight for the ascending one, as already described. It will 

 also be seen that by this arrangement, the single engine, E, may not only 

 do all the hoisting, but drive the pump also. The engine-shaft extends be- 

 yond the reels and, by the wheel H, if the latter be moved into gear with the 

 pinion, J, of the pump wheel, K, may set that in motion. The pumping 

 engine, F, is commonly used for this purpose, but, in case of necessity, its 

 work may be done by the hoisting engine, E. Hoisting may also be per- 

 formed by the pumping engine, if the wheel, H, be put in gear with the pinion, 

 J. Thus, if desired, either engine may serve as a substitute for the other. 



The cables commonly employed in the hoisting works of the Comstock 

 mines are either flat ropes of steel or iron wire, or heavy, round hemp ropes. 

 Chain is used very rarely, if at all. Flat ropes are generally preferred, 

 especially for great depths, because they possess greater strength in propor- 

 tion to their size, winding themselves compactly upon a reel and withstand- 

 ing, better than the hemp, the wear and tear of the work. They are usually 

 from 3J to 6 inches wide, and vary in thickness according to the character 

 of the material of which they are made. If of iron wire they are from 

 ^-inch to f -inch thick ; if of steel they are usually §-inch in thickness. The 

 latter is preferred on account of its lighter weight, less bulk, (an important 



