Transatlantic Radio Telephony 



By RALPH BOWN 



MANY of the technical and scientific features of Transatlantic 

 Radio Telephony have been discussed individually in consider- 

 able detail in engineering papers. Furthermore, through the agency 

 of the newspapers much general information has been published 

 regarding the development of commercial telephone service between 

 the old world and the new. Most of this published material either 

 is sketchy in nature or is concentrated upon some detail of the system 

 and it is difficult to gain from it a connected picture of how the final 

 result was built up through several years of continued effort. The 

 following has been written in an attempt to provide such a connected 

 story. 



As soon as the successful experiments carried out by the Bell System 

 engineers in 1915 had resulted in the reception of intelligible speech 

 in Paris and Honolulu transmitted from near Washington, D. C, 

 it became a foregone conclusion that sooner or later a serious attempt 

 would be made to bridge the Atlantic Ocean by radio telephone 

 service which would be available to the public at large. 



While the 1915 experiments were successful, they also served to 

 emphasize the tremendous difficulties which had to be overcome. 

 The onset of war activities prevented continuing a direct attack on 

 these difficulties but the developments incidental to the wartime use of 

 radio had a profound effect on the instrumentalities necessary to their 

 solution. In particular the development of vacuum tubes for trans- 

 mitting purposes made considerable progress. Other radio develop- 

 ments carried out immediately subsequent to the war also aided the 

 program. 



When transatlantic telephony was taken up again for active con- 

 sideration, it was obvious that the first requirement was for a trans- 

 mitting station which would be sufficiently powerful to deliver satis- 

 factory signals on the other side of the ocean. Since the amount of 

 power which would be required to do this was unknown, it was decided 

 to construct a transmitter which was sufficiently large to approach the 

 economic limit of what it seemed it could be worth while to attempt to 

 employ in a commercial undertaking. For this purpose there were 

 available water-cooled vacuum tubes ^ each capable of handling about 



1 "A New Type of High-Power Vacuum Tube," W. Wilson: Bell System 

 Technical Journal, Vol. 1, No. 1, July 1922, pp. 4-17. 



248 



