TRANSATLANTIC TELEPHONY 185 



system that is expected to give conversations over this radio channel a 

 sufficient degree of privacy. Certain features of the new privacy 

 method will probably be in experimental use within a few months. 

 It will be at least six months and possibly a year before the complete 

 privacy system is in full operation. 



The feature of this whole transatlantic service which worries the 

 engineer most, however, is the matter of reliability. After the engineer 

 has done the best possible in transmitting and receiving stations he is 

 confronted by the fact that transmission through space and noise 

 conditions vary so much that thousands of times as much transmitting 

 power as would be sufficient under good conditions may be inadequate 

 to get through under poor conditions. His only defense is to use a 

 considerable number of wave-lengths which tend not to get into diffi- 

 culties at the same times or under the same conditions. 



Considering first the short waves we find as already noted there is 

 sufficient difference between the transmission characteristics of differ- 

 ent parts of the range, between say 10 meters and 30 meters, so that the 

 reliability is considerably improved by designing the stations to use 

 any one of three or more frequencies in this range. 



We shall be very happy if by such use of a number of short wave- 

 lengths and by further improvements in technique the reliability of 

 short wave channels can be made such as to some day eliminate al- 

 together the necessity of the long wave channel with its much more 

 extensive plant. There are a number of projects going ahead in the 

 world for the establishment of long distance transoceanic telephone 

 circuits employing short waves alone. With a reasonable further 

 development of the short wave art such service will undoubtedly prove 

 well worth giving. 



Telephone service is, however, necessarily an exacting service, 

 particularly since the subscribers participate directly in each connec- 

 tion. Moreover we are dealing here with the joining of North America 

 and Europe which, commercially and otherwise, is of so large impor- 

 tance as to justify perhaps much more exacting technical requirements 

 than any other transoceanic connection. 



So far, the data available regarding the short waves do not suggest 

 that they ever will give a reliability of service comparable to that for 

 similar distances over land wire circuits. It is our present expectation, 

 therefore, that the giving of suitable service between America and 

 Europe will require the continuation of the long waves even though 

 such waves demand a much more extensive and complicated plant than 

 do the short waves. In addition to the long waves we shall also want 

 the very best we can get from the short waves. By the combination 



