256 



Common Science 



FIG. 144. A toy electric motor that goes. 



piece of iron and letting this pull on another piece of 

 iron. And the iron is magnetized by letting a current 

 of electricity flow around and around it. 



The making of various kinds of electromagnets and 

 putting currents of electricity to work is becoming one 

 of the great industries of mankind. Waterfalls are being 

 hitched up to dynamos everywhere, and the water 

 power that once turned the mill wheels now turns mil- 

 lions of coils of wire between the poles of powerful mag- 

 nets. The current generated in this way is used for 

 all kinds of work not only for furnishing light to cities, 

 and cooking meals, heating homes, and ironing clothes, 

 but for running powerful motors in factories, for driving 

 interurban trains swiftly across the country, for carrying 



