226 THE NEW WORLD OF SCIENCE 



was necessarily very heavy. It comprised not only all the 

 telegraph and telephone communications between different 

 depots and headquarters in France ; but nearly all those between 

 the army and America. It has been estimated that the tele- 

 graph system carried in all more than five million army 

 messages before the Armistice. The average army message is 

 much longer than the average telegram of commercial and 

 civil peace. It may be taken as sixty words in length. This 

 represents an average of about 10,000 telegrams or 600,000 

 words a day. The highest record was 47,500 telegrams or 

 2,850,000 words in one day. 



In order to carry this heavy traffic, the wires had to be worked 

 by specially rapid signalling methods. One of the trunk lines 

 was from Paris to General Headquarters at Chaumont, and 

 consisted of four parallel copper wires on poles. These wires 

 naturally formed two pairs, say A, B and C, D. Over each pair 

 a separate telephone circuit was arranged in the ordinary way. 

 On these two parts an additional telephone circuit was made 

 up of the type known as the " phantom circuit." This pro- 

 vided, in all, three sets of telephonic communications between 

 Paris and Chaumont. Moreover, each of the four wires was 

 worked as a telegraph wire without interfering with the tele- 

 phonic conversations. Wire A had a synchronous three- 

 channel multiple printing telegraph system in operation over it, 

 permitting three messages to be sent simultaneously in each 

 direction. Wires B, C and D were also each worked duplex, or 

 simultaneously in opposite directions, telegraphically. As the 

 result, twelve streams of telegrams six each way were ob- 

 tained over these four wires, day and night, in addition to the 

 telephonic conversations. 



To operate these telegraph lines, a number of American 

 operators were brought over to France in the Signal Corps, 

 and a number were also trained in special schools overseas. 



Telephone Service with A. E. F. While the heavy traffic 

 of main army communications was carried on by telegraph, a 

 vast amount of local communication was conducted by tele- 



