236 B. Davis — Stationary Sound- Waves, 



By substitution and integration I obtain, 



n p, L V P, J J 



where n = - — 



7 



I I I I 1 



/t t 



1 t 



I 



111! l 



The cylinder is in the moving air as shown in fig. 4 ; u x is 

 the velocity of the vibrating air outside of the cylinder, u 3 is 

 the vilocity inside the cylinder near the closed end. P 2 and 

 p x are the pressures on the two sides of the closed end of the 

 cylinder. If the air in the cylinder next to the closed end is 

 at rest, then u 2 becomes zero. 



By expansion and reduction, the above equation becomes ; 



U > =2 P-P> 

 P~ 



Pi~Pi i s t ne quantity measured on the torsion balance. The 

 absolute value of the pressure as determined from the experi- 

 ments gave a force of 21 dynes on an area of one sq. cm . 

 This gives a linear velocity to the vibrating air of 187 om per 

 second. The amplitude so obtained is 2"61 mm . This value for 

 the amplitude is somewhat less than a corresponding value 

 obtained by means of the sound-wave anemometer recently 

 devised by myself, an account of which will be shortly pub- 

 lished. 



Physical Laboratory, Columbia University, 

 June 1st, 1900. 



