WIRELESS TELEGRAPHY 



At the present time at least a dozen systems of wire- 

 less telegraphy are in use, in various parts of the world. 

 These all resemble one another closely, although each 

 has some features specifically different from any other. 

 Thus the DeForest system, the invention of the Amer- 

 ican, Lee DeForest, which made such a good record in 

 the Far East during the Russo-Japanese war in the 

 service of the London Times, employs alternating- 

 current generators as a prime source of electric oscilla- 

 tions. In this the filings-coherer is not used, but in place 

 of it a "responder" which utilizes a telephone at the 

 receiving end. 



Among the other well-known systems in general use 

 are the Lodge-Muirhead system, employed in Great 

 Britain; the Slaby-Arco system, the Braun-Siemens- 

 Halske system, in Germany ; the Branley-Popp system, 

 used extensively in France, the Rochefort system, used 

 in the French navy, the Ducretet-Popoff system of Rus- 

 sia, the Fessenden system, and numerous systems 

 operated by ambitious amateurs, which sometimes inter- 

 fere with the workings of the regular commercial lines. 



Four different wireless systems are in use by various 

 departments of the United States government. The 

 navy uses the Slaby-Arco system ; the army, the Braun 

 system; the Army Signal Corps, the Wildman system; 

 and the Weather Bureau, the Fessenden system. 



VOL. VIII.- 



[65] 



