ELECTRICITY DURING THE NINETEENTH CENTURY. 341 



electrotyping, and, most novel and interesting of all, one Gramme 

 machine driven bv power was connected to another by a pair of wires 

 and the second ran as a motor. This in turn drove a centrif uoal pump 

 and raised water which flowed in a small fall or cataract. A year or 

 two previously the Gramme machine had been accidentally found to be 

 as excellent an electric motor as it was a generating dy namo. The crude 

 motors of Jacobi, Froment. Davenport. Page, Vergnes, Gaume, and 

 many others, were thus rendered obsolete at a stroke. The first public 

 demonstration of the working of one Gramme machine by another was 

 made by Fontaine at the Vienna Exhibition of 1873. 



Here, then, was a foreshadowing of the great electric power trans- 

 mission plants of to-day; the suggestion of the electric station furnish- 

 ing power as well as light, and to a less degree the promise of future 

 railways using electric power. Replace the centrifugal pump of this 

 modest exhibit b}^ a turbine wheel, reverse the flow of water so as to 

 cause it to drive the electric motor so that the machine becomes a 

 dynamo, and in like manner make of the dynamo a motor, and we 

 exemplify in a simple way recent great enterprises using water power 

 for ihe generation of the current to be transmitted over lines to distant 

 electric motors or lights. 



The Centennial Exhibition also marks the beginning, the very birth, 

 it may be said, of an electric invention destined to l)ecome. before the 

 close of the century, a most potent factor in human aflairs. The speak- 

 ing telephone of Alexander Graham Bell was there exhibited for the first 

 time to the savants, among whom was the distinguished electrician and 

 scientist, Sir William Thomson. For the first time in the history of 

 the world a structure of copper wire and iron spoke to a listening ear. 

 Nay. more, it both listened to the voice of the speaker and repeated 

 the voice at a far-distant point. The instruments, were, moreover, 

 the acme of simplicity. Within a year many a boy had constructed a 

 pair of telephones at an expenditure for material of only a few pennies. 

 In its first form the transmitting telephone was the counterpart of the 

 receiver, and they were reversible in function. The transmitter was 

 in reality a minute dynamo driven by the aerial voice waves; the 

 receiver, a vibratory motor, worked by the vibratory currents from 

 the transmitter and reproducing the aerial motions. This arrange- 

 ment, most beautiful in theory, was only suited for use on short 

 lines, and was soon afterwards replaced by various forms of carbon 

 microphone transmitter, to the production of which many inventors 

 had turned their attention, notably Edison, Hughes. Blake, and Hun- 

 nings. In modern transmitters the voice wave does not furnish the 

 power to generate the telephone current, but only controls the flow of 

 an already existing current from a battery. In this way the effects 

 obtainable may be made sufficiently powerful for tmusmission to 

 listeners 1,500 miles away. 



