IOWA ACADEMY OF SCIENCE Voi.. XXVIII, 1921 
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Frequency 
Os C^icu fated 
Fig. 15 
root-mean-square of the amplitude over the instrument weight- 
ed with the area to which the different amplitudes corresponded. 
In figure 15 a curve is given which shows how near the measured 
amplitudes lie to the curve of the calculated amplitudes. 
These measured values of amplitude agree as well as might be 
expected with the calculated values for the chance of experimental 
error in the method used is fairly great. In conclusion, it would 
seem that one is safe in assuming that the method for calculating 
the amplitude of vibration of the diaphragm of the tone generator 
as provided by Doctor Hewlett will give the true amplitude nearly 
enough for practical purposes. 
Physics Department 
State University oe Iowa. 
