CHAPTER XVIII 

 TRANSMISSION OF ELECTRICAL ENERGY 



250. Practical Uses of Electricity.---Mechanical energy 

 is transformed into electricity because in this form it can 

 be conducted very readily from a convenient place of genera- 

 tion or source of power, such as a waterfall, to any spot 

 within a reasonable distance and there be utilized as heat, 

 light, or power. 



Electric heating is only practicable when it is desirable 

 to use heat for a short time at a certain point. In small 

 quantities electric heat is used in cookers, welding processes, 

 foot-warmers, cigar-lighters, etc. The advantage of this 

 form of heat is that it is free from fumes, odor, and noises; 

 its disadvantage is that it is too expensive for general heating. 

 Electricity, when consumed in large quantities in a special 

 electrical furnace, produces a very high temperature ordi- 

 narily as high as 3500 C. without difficulty, while in the 

 case of a furnace used for smelting metals by the burning of 

 coke under a forced draught, the temperature hardly ever 

 exceeds 2000 C. 



The practical use of electricity gives employment to a 

 great many people. The various types of electrical work 

 include over two hundred occupations. Four types of 

 electrical work will be described in this chapter: (1) electrical 

 apparatus work; (2) inside wiring; (3) outside wiring; and 

 (4) power station work. 



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