TRANSATLANTIC TELEPHONING." 



THE REMARKABLE INVENTION BY WHICH DR. M. I. PUPIN HAS REVO- 

 LUTIONIZED THE TRANSMISSION OF ELECTRICITY. 



By William A. Anthony, 



Former President of the American Institute of Electrical Engineers. 



At last the problem of telephoning over long-distance lines and 

 ocean cables has been solved, and we may hope soon to be able to talk 

 across the ocean and recognize the voice of a friend as he replies to us 

 from London or Paris. 



Dr. M. I. Pupin, of Columbia University, after years of patient 

 labor, has pointed out the way where others had failed, and has accom- 

 plished what many had believed to be impossible. 



To appreciate the importance of what Dr. Pupin has done, it is well 

 to contrast the two problems of transmitting telegraph messages on 

 the one hand, and of transmitting telephone messages on the other. 

 In transmitting a telegraph message, the sender closes and opens a key 

 that makes and breaks an electric circuit, sending to the line electric 

 impulses that magnetize little pieces of soft iron, and so operate a 

 lever in the receiving instrument in unison with the key. The alpha- 

 bet is a combination of dots and dashes. When the key is closed for 

 an instant only, a very short electric impulse travels along the line, 

 causing a momentary attraction and depression of the lever, which is 

 recognized as a dot. When the key is held closed for a little time the 

 lever is held down for a corresponding period and records a dash. 

 When the line is long and the electric impulses become weak, so that 

 the lever responds feebly, a new source of current is introduced; a 

 new "circuit" is established, extending on to the more distant point, 

 and the lever of the receiving instrument in the first circuit is made to 

 open and close this second circuit exactly as did the key at the begin- 

 ning. So the message is given to the new circuit with renewed energy, 

 and goes on again to produce a legible record at double the distance 

 from the sending station. When the receiving instrument is made 



"Reprinted, by courtesy of Doubleday, Page & Co., from Everybody's Magazine, 

 Vol. IV, April, 1901. Copyrighted. 



