USE OF ARC IN WIRELESS TELEPHONY 151 



reached, the condenser will cease taking current from the 

 arc, the arc will require less voltage, and the condenser will 

 begin to discharge through it. This added current will cause 

 the voltage of the arc to drop still more until it reaches 

 the value shown by the line cc' . Eventually a limit will 

 be reached in this direction also. As the current from the 

 condenser ceases to flow through the arc, its voltage begins 

 again to increase and the process will be repeated. 



Energy is used in the condenser circuit both to produce 

 the heat due to the resistance of the circuit and to radiate 

 electrical waves. This energy is given to the condenser 

 circuit, because the potential difference is higher when the 

 current is flowing into the condenser than it is when it is 

 flowing out, so that more energy is delivered to the circuit 

 than is received from it. The steeper the characteristic 

 curve of the arc the more the energy that will be delivered 

 to the condenser circuit. 1 It has also been shown by 

 Simon 2 that the greater the hysteresis of the " dynamical'* 

 characteristic curves, the greater will be the amount of 

 energy delivered to the condenser. 



In general, arcs having steep characteristics are those 

 having terminals which cool off quickly, or those whose 

 resistance is in some way artificially increased. Thus it 

 has been found that an arc between copper terminals can 

 be used for producing oscillations to better advantage 

 than one between carbons and that deflecting the arc with 

 a magnet is advantageous. 3 Increasing the pressure of the 



1 Granqvist, Mitt. d. konigl. Ges. D. Wiss. zu Upsala, (4), i, 62; 1906. 

 Beib., 31, 840; 1906. 



2 Phys. ZS., 4, 737; 1903, 6, 297; 1905, and 7, 433; 1906. 

 Elektrot. ZS., 26, 818 and 839; 1905, and 28, 295; 1907. 

 Jahrbuch der drahtlesen Telegraph, und Teleph., i, 16; 1907. 



1 Poulsen, Elektrot. ZS., 27, 1040; 1906. 



