WORLD-WIDE TELEPHONY 487 



opened In 1928. Two years later came the transcontinental telephone 

 line in Australia. 



Overseas radio telephone experiments, in 1915, successfully trans- 

 mitted the human voice from Washington to Paris and from Washing- 

 ton to the Hawaiian Islands. Commercial development of inter- 

 continental telephony, however, followed somewhat slowly both 

 because of the war and because of the tremendous inherent technical 

 difficulties. However, as an interesting fore-runner of what would 

 come later, a public service radiotelephone system was opened in 

 1920 linking Catalina Island, off the coast of California, with the wire 

 telephone network of North x^merica. In 1927, after a period of 

 intensive experimentation and development work, commercial service 

 between Europe and North America was opened to the public. This 

 was the first step in the expansion of telephone service from a conti- 

 nental scope to a world-wide scope. 



Present Situation and Plans for Future Development 

 Intercontinental telephony has naturally been dependent upon and 

 been preceded by the development of large networks of telephones to 

 which the intercontinental circuits could be connected. The most 

 highly industrialized parts of the earth's surface today are provided 

 with extensive networks of telephone lines covering great areas and 

 interconnecting large numbers of telephones. This is indicated in 

 Fig. 1 which shows the principal national and continental wire tele- 

 phone networks, and all individual cities not connected to an extensive 

 interurban network which according to latest reports have more than 

 10,000 telephones. As a result of the improvements which have 

 been made in these wire networks in the last 15 years, both as to 

 transmission and speed of service, they are today generally available 

 and satisfactory for use in connection with intercontinental service. 



For the purpose of this paper circuits of less than 600 miles (1000 kilo- 

 meters) even if they cross continental boundaries will not be considered 

 intercontinental circuits. In the consideration of world-wide tele- 

 phony we are interested in the long circuits between distant parts of 

 different continents or between continental areas and distant islands, 

 for which the technique developed for long continental telephone lines 

 is not directly applicable. 



The extent to which the continents of the world are already inter- 

 connected by telephone circuits and the additional connections 

 contemplated by plans now under way are indicated in Fig. 2. These 

 are such as to make possible conversations between any two continents 

 of the earth either by direct circuit or by switching in Europe or in 



