INDUCTANCE AND CAPACITY 



421 



The oscillating circuit ACE contains an adjustable condenser, 

 C, and the inductance of the two deflecting coils, and can there- 

 fore be tuned. The secondary coil from which the current 

 is taken to the bridge is in the magnetic field of the deflecting 

 coils which thus serve the double purpose of causing the arc to 

 oscillate between D and A and D and B and of acting as the 

 primary of. the air-core transformer. 





FIG. 246.: Vreeland sine wave oscillator. 



If the arrangement were perfectly symmetrical the arc would 

 divide equally between the two anodes, the potentials of A and 

 B would be equal and no current would flow through the circuit 

 ACB. If from any cause the arc to B is the stronger, this equality 

 of potentials is disturbed, the potential of B is lowered relatively 

 to that of A, and a current begins to flow in the oscillating circuit 



