RADIO COMMUNICATION 279 



speakers with megaphone horns are also employed so that a 

 group may enjoy a musical program without each person being 

 required to listen to the music from a small telephone receiver. 

 Government regulations require radio telephone broadcast- 

 ing stations to employ wave-lengths or frequencies which are 

 assigned to them on such a schedule that no large stations near 

 each other will be sending on the same wave-length. Thus 

 when two broadcasting stations operate in the same city, one 



FIG. 130. A modern receiving set. The tubes (amplifying and detector), 

 condenser, coupler-coil, and tuner are shown mounted behind the panel. 



station might have a wave-length of 411 meters while the other 

 might be operating on a wave-length of 260 meters. This 

 difference in wave-length, or frequency, enables the person receiv- 

 ing to choose one or the other, so that the musical programs or 

 signals from one station will not be confused with those from the 

 other station. 



Development in radio transmission and receiving has been 

 so rapid in the few years succeeding the war that any predic- 

 tion as to its future use may easily be exaggerated. It seems 

 quite within reason, however, to expect the radio methods of 



