THE COMSTOGK MINES. 137 



ing; nor can either hoisting engine be applied to the pump, in the arrange- 

 ment indicated. 



Another method of arrangement is one by which the motion of the 

 hoisting reel may be reversed without reversing or arresting the motion of 

 the engine. 



In some cases where this method is in use, as at the Ophir and Empire- 

 Imperial works, the winding reels are supported upon the reel-shaft, not 

 keyed to it, but turning freely upon it in either direction. The reel-shaft re- 

 ceives its motion from the engine by means of a pinion and spur-wheel, but 

 may turn freely without imparting motion to the reels except when the latter 

 condition is desired. In such case a reel is caused io revolve with the shaft, 

 by throv^dng into contact with it a clutch that slides upon a feather on the 

 shaft. As the clutch always has the motion of the shaft, it causes the reel to 

 turn with it, while in contact, and on being withdrawn from contact the reel 

 is free to be reversed, for lowering the cage, while the motion of the engine 

 shaft is continuous. Such reels are cast with a flange or rim for a brake- 

 strap, by which the reverse motion is controlled. This method of arrange- 

 ment requires but one hoisting engine for two or more reels. The latter are 

 all upon the same reel-shaft, but work independently of each other, and as 

 the reel-shafl moves continuously in one direction the engine may be applied 

 to other work, such as pumping, or driving other machinery that requires con- 

 tinuous motion. If desired, however, two reels may be permanently clutched 

 to the shaft and revolve with it, one winding and raising a loaded cage from 

 the mine, while the other is unwinding and lowering an empty cage, gaining 

 in this case the advantage of the weight of the descending cage and rope. 

 In the last case, the engine must, of course, be reversed for each operation of 

 hoisting and lowering ; and the ropes must be wound upon the reels in oppo- 

 site directions. 



In the Hale and Norcross works, a plan of which is shown on Plate XIII, 



this method is in use, with some modifications, that appear in the drav/ing. 



In this case each of the two reels, R, R, is keyed to a separate reel-shaft with 



a spur-wheel W, and brake-rim, B. The reels are entirely independent 



of each other. There are two pinions, P, P, one for each reel, on the engine - 



shaft, S. These pinions are not keyed to the engine-shaft but turn freely in 

 18 



