806 The Outline of Science 



is reconverted into mechanical energy and made to do work. 

 Thanks to the ease with which the electric motor can be con- 

 nected to an electric circuit, to its cleanliness, compactness, and 

 generally accommodating nature, it finds countless uses, which are 

 being added to every day. In size and power the electric motor 

 ranges from the tiny units attached to the dentist's drill, the desk 

 fan, or the carpet-sweeper, to the great machines which drive roll- 

 ing mills and propel huge ships. It has given navigators the 

 revolutionary gyroscopic compass, which remains quite unaffected 

 by the proximity of iron and steel. In mines it cuts, ventilates, 

 drains, and hauls, penetrating whithersoever a man can go. 

 Attached to pumps, it accompanies the diver into the holds of 

 ships; during the war the submersible electric pump kept afloat 

 many ships that without it would have foundered, and then and 

 since has brought many sunken ships back to the surface. In the 

 gold-mines of the South African Rand great economies have been 

 effected by installing electrically-driven turbine pumps at the 

 bottom of the shafts to force water to the surface in one case 

 through a sheer half-mile. 



In California, electric motors developing 190,000 horse- 

 power are used in agriculture alone, and the rice industry is 

 almost entirely dependent on irrigation by electrically-driven 

 pumps. In many factories complicated systems of belts and 

 shafting have given way to motors connected directly to machine 

 tools. The electric crane toys with loads up to a hundred or more 

 tons. The electric navvy scoops up several tons of earth or 

 broken rock at a bite, two or three times a minute. Electric 

 windlasses work the largest ships easily through the locks of the 

 Panama Canal; and haul boats, trains, and waggons up inclines. 

 Electric traction, which has revolutionised transport in many 

 respects, and thereby affected our daily lives to no small 

 extent, is based on the electric motor. In short, wherever mo- 

 tion is required the electric motor is, if possible, pressed into 

 service. 





