342 ELECTRICITY DURING THE NINETEENTH CENTURY. 



There is no need to dwell here upon the enormous saving of time 

 secured bv the telephone and the profound etiect its introduction has 

 had upon business and social life. The situation is too })alpable. 

 Nevertheless, few users of this wonderful invention realize how nmch 

 thought and skill have been employed in working out the details of 

 exchange switclit)()ards, of signaling devices, of underground cables 

 and overhead wires, and of the speaking instruments themselves. Few 

 of those who talk between Boston and Chicago know that in doing so 

 they have for the exclusive use of their voices a total of over 1,0(X),000 

 pounds of copper wire in the single line. There probably exist now 

 in the United States alone between 75.000 and 100.000 miles of hard 

 di'awn copper wire for long-distance telephone service, and over 

 150,000 miles of wire in underground conduits. There are upward 

 of 750.000 tele]>hones in the Inited States, and including both over- 

 head and underground lines, a total of more than 500.000 miles of 

 wire. Approximately, 1,000,000,000 conversations are annually con- 

 veyed. 



The possibility of suboceanic telephoning is frequently discussed, 

 but the problem thus far is not solved. It involves grave difficulties 

 and \vc may hope that its solution is to be one of the advances which 

 will mark the coming century's progress. The advent of the telephone 

 in 1876 seemed to stimulate invention in the electric field to a remark- 

 aide (legTee. Its inmiediate connneirial success probably acted also to 

 inspire contidence in other proposed electric enterprises. Greater 

 attention than ever before began to be given to the problem of electric" 

 lighting. An electric arc-lamp. prol)ably the only one in regular use, 

 had been installed at Dungeness light-house in 1862, after a long set 

 of trials and tests. It was fed by a Holmes magneto-electric machine 

 of the old type, very large and cum})rous for the work. Numerous 

 changes and improvements had before 1878 been made in arc lamps b}^ 

 Serrin. Duboscq, and many others, but the display' of electric light 

 during the Paris Exposition of 1878 was the first memorable use of 

 the electric light on a large scale. The splendid illumination of the 

 Avenue de I'Opera was a grand object lesson. The source of light was 

 the ''electric candle'' of Paul Jablochkotf, a Russian engineer. It was 

 a strikingh^ original and simple arc lamp. Instead of placing the 

 two carbons point to point, as had been done in nearly all previous 

 lamps, he placed them side by side with a strip of baked kaolin between 

 them. The candle so formed was supported in a suitable holder 

 whereby at the lower end the two pai-allel carbons were connected 

 with the circuit terminals. By a suitable device the arc was started 

 at the top and burned down. The electric candle seemed to solve the 

 problem of allowing complicated mechanism for feeding the carbons 

 to be discarded: but it survived only a short time. Owing to unfore- 

 seen difficulties it was graduall}- abandoned after having served a great 



