MEASUREMENTS OF THE AMPLITUDE OF VIBRA- 
TION OF THE DIAPHRAGM OF THE HEWLETT 
TONE GENERATOR 
{ABSTRACT) 
C E. LANE 
The “New Tone Generator'' ^ designed by Dr. C. W. Hewlett 
promises to be a very valuable instrument for use as a precision 
source of sound. The operation of the instrument has been in- 
vestigated mathematically by its designer ^ and a method is given 
for calculating the amplitude of vibration of its diaphragm from 
the electrical input. The writer herein describes a method whereby 
it has been possible to make actual measurements of the amplitude 
by mechanical means for comparison with the calculated ampli- 
tudes. 
The tone generator was used in a vacuum tube oscillatory circuit 
from which the desired frequencies of alternating current were 
obtained. 
For the purpose of making these measurements an electrical 
micrometer was constructed (Fig. 9). This micrometer operated 
Fig. 9 
on the same principle as the one described by P. E. Shaw in the 
Proceedings of the Royal Society, Vol. 76, page 350. The small- 
est divisions of this micrometric arrangement measured distances 
of 10.6 cm. and estimations could be made to tenths of a division. 
1 Physical Review, Vol. XVII, p. 257. 
2 Work not yet published. 
