The Bell System Technical Journal 



Vol. XVI July, 1937 No. 3 



Scientific Research Applied to the Telephone Transmitter 



and Receiver * 



By EDWIN H. COLPITTS 



LET us recall a scene at the Centennial Exhibition in Philadelphia 

 in 1876. Across a room had been strung wires connecting crude 

 instruments, at one end of the room a transmitter and at the other end 

 of the room a receiver. Dom Pedro, Emperor of Brazil, takes up the 

 receiver and listens while Alexander Graham Bell speaks into the 

 transmitter. The Emperor, astonished at hearing Mr. Bell's voice in 

 the receiver, exclaims in amazement, "My God, it talks." 



When at the same place. Sir William Thomson (later Lord Kelvin) 

 took up the receiver and listened to Mr. Bell, the words of this dis- 

 tinguished scientist were, "It does speak," and continuing, "it is the 

 most wonderful thing I have seen in America." 



Sixty years have passed and, as a result of continued effort, the 

 use of the telephone has become such an everyday matter that even 

 the ability to talk from Tokyo in your country to New York in my 

 country scarcely excites comment or wonder. It is not surprising that, 

 to the layman, the element of distance seems the most striking factor 

 in the technical development of the telephone art. As a matter of 

 fact, while the conquest of distance has involved much scientific effort, 

 and very ingenious and highly developed methods for the transmission 

 of speech currents, the magic of the telephone still resides in the 

 instruments which provide for the conversion of mechanical energy, 

 namely speech sounds of highly complex wave form, into electrical 

 currents of corresponding wave form, and the reverse process of 

 converting these electrical currents into speech sounds. These instru- 

 ments, the transmitter and the receiver, are basic to the whole tele- 

 phone art. As they have been improved by development and design, 

 it has become possible not only to render a higher grade of service but 

 to effect economies in other portions of the plant. For example, the 



* Another of three Iwadare Foundation lectures deHvered during this past spring in 

 Japan by Dr. Colpitts. One lecture was published in the April 1937 issue of this 

 Journal. 



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