" Skin "-effect in Electrical Oscillators. 



% 



The interrupter was that used by Gr. "W, Pierce with his 

 radio-micrometer.* It consisted of a platinum-tipped rod 

 which, by means of a fan-motor, was rapidly plunged into and 

 withdrawn from a cup of mercury, the surface of which was 

 kept clean by a stream of water continually flowing over it. 

 In series with the interrupter was a pendulum contact-maker. 

 The metallic rod of the pendulum carried a platinum wire 



soldered to its lower end, which, as the pendulum swung to 

 and fro, dipped into a mercury trough. By raising or lower- 

 ing the pendulum, the time during which it was immersed in 

 the mercury was shortened or lengthened. This was so 

 adjusted that whilst the pendulum made circuit during a 



single semi-oscillation, the motor-break made about six inter- 

 ruptions. In addition an ordinary key was in circuit. This 

 was pressed down while the pendulum made any desired num- 



* This Journal, vol. ix, p. 252, 1900. 



