292 Dr. Beatty and Mr. Gilmour on Measurement of 



glycerine) was placed in series with the grid and shunted by 

 a condenser C. The mutual inductance was iron-cored. The 

 oscillations were of audiofrequency. When K = C = R~ 0, 

 /= 420 cycles. 



In addition, a standard oscillation-circuit was set up which 

 could be tuned to unison with the experimental circuit by 

 varying the capacity of the main condenser. The standard 

 circuit was carefully calibrated by means of tuning-forks 

 and a curve drawn connecting capacity with frequency. 



2500 



200O 



| 1500 



1000 



500 



Results. 

 In fig. 2 the relation between /and Ris shown for different 

 values of the grid capacity C in the experimental circuit. 



Fie-. 2. 



/ c 



= 0-05rr 



.rT /c=0 



003 m.f. 



/c 



=0-00043 



/c =ooc 



04-m.f. 



(a)\ 

 I 







Jfb) 





/(c) 



(«)/ 





' 



















c=o-oc 



>0/9 f77.fi 



!//% 















(e)^ 





r ( eM 





^ / 

































i' 



T, 

 fa 



Us 



f 





tT" 











lOxfO* 



20X10' 

 Resistance > 



40xi0-* 



It will be seen that, as C decreases, the relation between/ 

 and R, at first approximately linear, becomes more involved. 

 A hollow appears in the curve, and the frequency descends 

 by a series of jumps to the bottom of this hollow, and rises 

 again continuously as R is further increased. Curve (d) 

 shows a separation into two parts with a silent region between 

 them, extending from R = 4'8xl0 4 &) to R = 6'7xl0 4 o). 



