52 THOMAS COMMERFORD MARTIN 



upon this loads up to 20,000 pounds in weight can be moved 

 at a speed of from 800 to 1,500 feet per minute. 



This telpherage method was first experimented with 

 several years ago in England and America, but only within 

 the last year or two has it been practically introduced in 

 this country and abroad. Its present feasibility is due to 

 improvements in motors which can stand exposure, in methods 

 of control, in contact devices, in brackets, etc. In an elec- 

 tric telpher system employed in a limestone quarry in the 

 island of Cuba, the telpher with its car travels upon cables, 

 except at eight curves, where solid rail is employed. The 

 buckets, loaded with limestone and carried below the telpher, 

 take along the cable a maximum load of 1,200 pounds, with 

 a speed of from 12 to 15 miles per hour. Current is derived 

 from a distant power plant, and to start the telpher all that 

 is necessary is to close the switches at the ends of the system. 

 This telpher travels automatically, but in the case of larger 

 apparatus a cab is provided for a telpher man, as on an elec- 

 tric crane, so that he can travel with the load of coal, sulphur, 

 phosphates, etc., and assist in loading and unloading. 



Electric hoisting is a growing feature of the use of elec- 

 tricity in mines, and a large amount of work has already 

 been done in this field with the object of replacing the steam 

 engine with the electric motor driven from a central plant. 

 To quote a paper read by Mr. F. O. Blackwell before the Amer- 

 ican Institute of Mining Engineers, at Albany, in February, 

 1903, '^The throttling of steam to control speed, the necessity 

 for reversing the engine, the variation in steam pressure, the 

 absence of condensing apparatus, the cooling and large clear- 

 ance of cylinders, and the condensation and leakage of steam 

 in pipes when doing no work are all against the steam hoisting 

 engine. One of the largest hoisting engines in the world 

 was recently tested and found to take 60 pounds of steam 

 per indicated horse power per hour. The electric motor, 

 on the other hand, is ideal for intermittent work. It wastes 

 absolutely no energy when at rest, there being no leakage 

 or condensation. Its efficiency is high, from one quarter 

 load to twice full load." As a matter of fact this class of 

 work touches closely that above referred to in connection 



