Oscillations in Straight Wires and Solenoids. 



267 



determining- the high frequencies obtained in electric os- 

 cillations in terms of the frequency of a standard fork. 

 There is a considerable advantage, however, in using the 

 short wave as a standard, as it is easily adjusted to any 

 required length. 



4. The arrangement of a short-wave generator having a 

 fundamental oscillation which may be measured by a pair of 

 parallel wires is shown in fig. 1. The oscillatory circuit 



Fig, l. 



X, 



it 



r 



6g 



•2 f 



K 



'2 



-irr-±r 



O 



2 JT 



consists essentially of two rods AjA 2 , BjB 2 , 75 centimetres 

 long and a mica condenser C 2 of about one millimicrofarad. 

 Its exact capacity is unimportant, provided it is large com- 

 pared with the capacity of the rods. The condenser is of 

 small dimensions, and two short wires are connected to its 

 terminals and slide on the rods, so that the condenser may 

 be placed at any distance from the valve. The end A t of the 

 upper rod is connected to the anode of the valve and the end 

 A. 2 is connected through a choke coil to the positive terminal 

 of a high-tension battery. The end B x of the lower rod is 

 connected to the grid and B 2 through a choke coil to the 

 filament and to the negative terminal of the high-tension 

 battery. 



The oscillatory current flows from A { to B x through the 

 condenser C 2 , and the wave-length is adjusted by moving fche 

 condenser along the rods. The tine adjustment of the wave- 

 length is made by a small adjustable condenser d connected 

 to the ends A t , B x . 



It was found that the system did not oscillate when the 



T2 



