THE MINERAL DEPTHS 



in mining operations. The pioneer of this type of 

 locomotive seems to have been one built by Mr. W. M. 

 Schlessinger for one of the collieries of the Pennsylvania 

 Railroad about 1882, and which has remained in active 

 use ever since. The total weight of this locomotive 

 was five tons and it was equipped with thirty- two 

 horse-power electric motors. The current was supplied 

 through a trolley pole which took the current from a 

 T-shaped rail placed above and at one side of the track. 

 The train hauled by this locomotive consisted of fifteen 

 cars, carrying from two to three tons of coal each. 



Following this first mining-locomotive a great num- 

 ber were quickly produced. In Pennsylvania alone 

 something like four hundred are now in use, and in 

 Illinois two million tons of coal were hauled in this 

 manner in twelve mines in 1901. It was estimated 

 at the beginning of the present century that some 3,000 

 electric locomotives specially built for mining were in 

 use in the United States alone. 



The earlier types of mining-locomotives were much 

 higher and bulkier than those of more recent con- 

 struction, the motors being mounted above the trucks 

 and geared downward. Very soon, however, the 

 " turtle-back" or "terrapin-back" type was developed, 

 with the motors brought close to the ground, so that 

 even quite a heavy locomotive might not be much higher 

 than the diameter of its driving-wheels. When these 

 queer-looking machines were boxed in so that even the 

 wheels were covered, they lost all resemblance to loco- 

 motives or vehicles of any kind, appearing like low, 

 rectangular metal boxes placed upon the car tracks, 

 VOL. vi. 17 [ 257 ] 



