﻿Values of pt 



for electrons which 



return to grid. 



Work. 



Y-4 



165° to 345° 



negligible. 



1040 cm. 



150° „ 330° 



-•47 



520 „ 



135° „ 315° 



-•85 



347 ., 



120° „ 300° 



-•36 



260 „ 



90° „ 180° 



-•32 



130 , 



174 .Messrs. E. W. B. Gill and J. H. Morrell on Short 



to the grid in each oscillation, the third gives the total 

 work done per second by the oscillating potential in 

 arbitrary units for a fixed value of V and of emission, 

 and the fourth gives the corresponding wave-lengths for 

 the particular value, V = 44, for which T — 4*3 x 10"^ second 

 (see next paragraph) : — 



r ~ 4T 



7T 



3;r 



7T 



2tt 

 P = y 



In all these cases the work is negative and oscillations 

 can be theoretically sustained, though in practice the 

 dissipation losses in the oscillatory circuits are such that 

 generally only those wave-lengths corresponding to the 

 larger values of the work exist. 



For all values of the ratio T : ljp outside the range of 

 the table the work is small. The larger the work the 

 greater the amplitude of oscillation that will be sustained, 

 and the periodic time 2ir/p of the oscillation of maximum 

 amplitude for a given value of T is seen to be in the region 

 of § T. In general, the wave-length corresponding to this 

 will be sustained, and also a certain range of wave-lengths 

 on both sides of it, the limits of the range being determined 

 by the dissipation losses in the. oscillatory circuit. The 

 theoretical result is in good agreement with several of the 

 experimental results of paragraph 6. 



In the particular case recorded there for V = 44 the 

 range of wave-lengths sustained was from 320 to 451 cm., 

 with a maximum amplitude for 323 cm. Increase of 

 emission broadened the range of wave-lengths sustained, 

 which is in accordance with the fact that for a given V 

 the work put into the oscillatory system is proportional 

 to the emission current. 



The fact that the wave-length of maximum amplitude 

 of oscillation was near to the short wave-length end of 

 the range also agrees with the calculated fact that the 



