Stationary Sound Waves. 



131 



Anemometer No. 5. 

 Position in pipe. Rate of rotation. 







5 1-27 



10 4-28 



15 6-07 



20.- 8*51 



25 8'7 



30.. _ 8-16 



35 _. 7*38 



40.. 5-17 



45 2-26 



52 _ 



These tables are plotted in the figures below. The abscissae 

 are distances along the wave and the ordinates are rates of rota- 

 tion per second. The fall lines are the observed curves and 

 the broken lines are sine curves. 



These curves correspond quite closely to the sine curves 

 near the middle of the loop, where the amplitudes of vibration 

 have considerable magnitude ; hence one may infer that the 

 rate of rotation is proportional to the amplitude when such 

 amplitude is sufficiently great. The depressions in the curves 

 near the nodes indicate that the anemometers are not so 

 strongly affected when the amplitudes are small in comparison 

 to the radii of the cups. The rate of rotation is nearly the 

 same for both the No. 00 and the No. 2 anemometers, from 

 which one concludes that there is a definite relation between 



