606 ELECTRICAL ENGINEERING 



telephone, the electric arc and incandescent light, the electric furnace, 

 the electric railway, and the electric wireless telegraph have all come 

 into existence. These industrial applications have jointly created an 

 applied science and an art with a large and rapidly growing literature, 

 language, and technology. In the United States alone it is estimated 

 that these industries have a total investment of three billions of 

 dollars and employ 400,000 workers. 



The most significant difference between electrical engineering and 

 all other engineering lies in the fact that electrical engineering deals 

 with the application and control of wave-movements propagated 

 through the universal ether with the speed of light ; whereas all other 

 engineering deals with the mutual relations between material sub- 

 stances. In other words, electrical engineering is the controlled 

 operation of the immaterial upon the material. All other engineering 

 is the controlled operation of the material upon the material. 



A projectile may be fired from a cannon over a thirty-kilometer 

 range at an initial velocity of about one kilometer per second. A 

 locomotive may be driven over a smooth level track at a speed of 

 fifty or sixty meters per second; but an electric impulse will travel 

 over a wire at a speed of 300,000 kilometers per second. Both the 

 projectile and the locomotive must displace the air through which 

 they move, producing violent frictional disturbance of the medium. 

 The electric impulse moves through the air without friction or 

 appreciable disturbance. Hence the wonderful adaptability of elec- 

 tricity to play the part once assigned to the winged Mercury among 

 the gods on Mount Olympus, and by its enormous speed to annihilate 

 distances. 



In nearly all industrial electrical applications, energy is trans- 

 mitted over wires, and it is the transmissibility of electrical energy 

 which gives its principal value. The energy is transmitted from con- 

 venient sources, or points of generation, to sinks or consumption 

 points, where the energy is abstracted and converted. In some cases 

 it is directly converted by electric motors into mechanical w r ork. In 

 other cases, it is converted into heat, as in electric furnaces for heating, 

 or in electric lamps for lighting. In yet other cases it is converted 

 into mechanical energy, not for doing work, but for communicating 

 intelligence, as in the telegraphic receiving-instrument. But in all 

 these cases the electric energy is carried to the point of consumption 

 and delivery through the ether, guided by the wire or wires. The 

 interior of the wire is the only place where the transmitted energy 

 does not flow, for whatever energy enters the ware is w ; asted therein 

 as heat, and fails to reach its destination. 



Prior to the introduction of the steam engine, men worked in two 

 w r ays; first, as intelligent beings exercising skill and judgment; second, 

 as muscular machines, or peripatetic sources of brute force, like beasts 



