THE MINERAL DEPTHS 



first cost of the battery is no more than the outlay on 

 trolley wires and supports. It is also claimed that the 

 cost of maintenance is relatively low, but it is doubtful 

 if it equals the trolley or third- rail systems in this respect. 



Closely allied to the systems of traction by electric 

 locomotives, is the modern electric telpherage system. 

 Until quite recently the haulage of ores and other raw 

 materials used in mining, when done aerially, has been 

 by means of travelling rope or cable. When distances 

 to be travelled in this manner are short, such as across 

 streams or valleys, where no supports are used, the 

 term " cable way" is generally applied; but where the 

 distance is so long that supports are necessary, the term 

 "tramway cable" is used. It is to these longer systems 

 that electric telpherage is particularly applicable. 



The advantage of such an electric system over the 

 older method is the same as the advantages of the trol- 

 ley road over the cable, all ropes and cables being 

 stationary, the electric motor, or "telpher," travelling 

 along on one cable and taking its current by means of 

 a trolley pole from a wire above. For heavier work 

 metal rails supported between posts are employed in 

 place of a flexible cable, and over such systems loads 

 of several tons can be hauled. 



Such an electric telpher system is used in one of the 

 Cuban limestone quarries, the telpher and cars travel- 

 ling a long distance upon cables, except at some of the 

 curves, where solid rails are substituted, hauling a 

 load of a thousand pounds at a speed of from twelve 

 to fifteen miles an hour. The current comes from a 

 distant source, and the telpher is so arranged that it 



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