456 



KENNELLY AND AFFEL. 



diameter of the motional-impedance circle increases, as indicated in 

 Figure 18, in nearly simple proportion, until a torque of 250 gm-perp- 

 meters is attained. Beyond this torque, there is very little effect 

 on the circle diameter. After a torque of 20 gm-p-m had been ap- 

 plied, no appreciable effect was discovered on the resonant frequency 

 of this particular instrument. 



At the time that the above torque tests were taken, the method of 

 amplitude measurement had not been^developed ; so that an exact 



100 200 300 400 



CAP TORQUE GM. P. METERS 



Fig. 19. — Curves showing Values of A and r 

 FOR Different Cap Torques. 



determination of all four constants throughout the series is not possible. 

 If, however, we assume that the equivalent mass m of the diaphragm 

 remained constant throughout, since the resonant frequency remained 

 practically unchanged, we are able to evaluate the three other con- 

 stants A, r and s. Of these, the s constant must have remained un- 

 changed, and the only variations would be those of A and r, which are 

 plotted in Figure 19 as ordinates against torques as abscissas. It will 



