MAGNETIC EFFECTS OF ELECTRIC CURRENTS 231 



The lifting magnet is shown in figure 117. This type is 

 very common in steel mills. It is said that two men can 

 use two similar magnets 62 inches in diameter to unload as 

 much as 4,000,000 pounds of pig iron in ten and one-half 

 hours. Electric engines, street cars, subway trains, and 



The 



Used in lifting heavy iron and -steel such as pig iron and steel rails. A magnet 

 thirty-four inches in diameter may be made to lift four tons of solid iron 



the electric generators for power plants could not operate 

 without powerful electromagnets. 



237. The simple electric motor. The simple electric motor 

 (fig. 118) may be illustrated in two ways: The essential part 

 of the first apparatus is a heavy copper wire that is free to 

 swing between the poles of five U -magnets arranged side by 

 side. The north poles are placed above the wire. When a 

 current of about fifteen amperes is passed through the heavy 

 wire fro/n left to right, the wire quickly swings away from the 



