VIBRATIONS IN TONE GENERATOR 
87 
flection of the Rayeigh disc, then any other membrane placed in 
the same position and vibrating with the same frequency that gave 
the same deflection would have the same amplitude. Thus it was 
possible by means of the receiver to calibrate the deflection of the 
Rayleigh disc in terms of the amplitude of the vibrating membrane 
under the tube. Calibration curves were obtained for four differ- 
ent frequencies. Figure 12 shows the one obtained for a frequency 
of 3700. 
The amplitude of the diaphragm of the tone generator was de- 
termined by this means for frequencies of 1440, 1600, 2200, and 
3700. These amplitudes were measured for larger values of cur- 
rent and then reduced to values for a direct current of 1.0 ampere 
and an alternating current of 0.1 ampere. The amplitude was 
not the same at different distances from the edge of the dia- 
phragm. Figures 13 and 14 show the value of the amplitude 
for different positions on the diaphragm for frequencies of 
2200 and 3700. The other two frequencies gave similar curves. 
The mean value of the amplitude was obtained by taking the 
ij'requency = 3700 
!D,'C,s= 1,0 Airypere, A,c,= 0,lJimp*etre 
Mean Amplitude's 4,32 10“^ cm'. 
Fig. 14 
