THE CONQUEST OF NATURE 



that glided along the rails in some mysterious manner. 

 The presence of the trolley pole helped to dispel this 

 illusion, but in some instances this is wanting, the power 

 being taken from a third rail. 



With these locomotives, some of them not more than 

 two and a half feet high, it was possible to haul trains 

 even in very low and narrow passages much lower, 

 in fact, than could be entered by the little mules used 

 in former years. This in itself was revolutionary in 

 its effects, as many thin veins were thus made workable. 



This type of low locomotive is the one that has come 

 into general use throughout the world. Such loco- 

 motives range in size from two to twenty tons, with 

 wheel gauges from a foot and a half wide to the stand- 

 ard railway gauge of four feet, eight and a half inches. 

 Locomotives weighing more than twenty tons are 

 not in general use on account of the small size of the 

 mine entrances. 



In the ordinary types the motorman sits in front, 

 controlling the locomotive with levers and mechanical 

 brakes placed within easy reach, but sunk as low as 

 possible. As a rule, the motors are geared to the truck 

 axles, either inside or outside the locomotive frame. 

 An overhead copper wire supplies the current by con- 

 tact with a grooved trolley wheel mounted on the end 

 of the regulation trolley pole. An electric headlight 

 is used, and the ordinary speed attained by the com- 

 pact motors is from six to ten miles an hour. 



The amount of work that can be performed by one 

 of these little, flat, box-like locomotives is entirely out 

 of proportion to its size. A lo-ton locomotive in a 



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