M. A. Kimdt on (he Velocity of Sound in Tubes. 23 



lengths of the two sides gives directly the ratio of the velocities 

 of sound in the air in the two tubes. 



The results of the investigation are as follows : — 



(1) The velocity of sound in air is diminished when the dia- 

 meter of the tube is decreased. The diminution, however, only 

 becomes perceptible below a certain diameter ; in all wide tubes 

 the velocity of sound is equal. A decrease in the velocity is 

 sometimes perceptible when the diameter of the tube is equal to a 

 quarter wave-length of the tone used. The amount of the dimi- 

 nution of velocity with a decreasing diameter may be seen from 

 the Table under (2). 



(2) The diminution of the velocity of sound in air in tubes in- 

 creases with the wave-length of the tone used. The following 

 Table gives the velocities of sound of the air in five tubes of dif- 

 ferent diameters with three different notes, whose semiwave- 

 lengths are as 90, 45, and 30 millims. The velocity of sound 

 in the widest tube is equal to that in the open air =332*8 metres. 



Velocity of Sound for various Notes in glass tubes of varying 



diameter. 



Semiwave-length "1 

 of the note . . f 



— =90 millims. 

 2i 



=45 millims. 



2 



— =30 millims. 



Diameter of the 

 tube. 



Velocity of sound, that in the widest tube being 

 =332-8 metres. 



millims. 

 550 

 260 

 130 



6-5 



3-5 



metres. 

 332-80 

 332-73 

 329-47 

 323 00 

 305-42 



metres. 

 332-80 

 332-66 

 329-88 

 32714 

 318-88 



metres. 

 332-80 

 333-45 

 330-87 

 32814 



(3) Powder strewed in a tube leaves the velocity of sound un- 

 altered in wide tubes ; in narrow ones it diminishes it the more the 

 greater its quantity. This diminution may amount to 10 metres*. 



(4) The influence of the powder is increased when it is very 

 finely divided and is violently moved by the motion of the sound 

 — as, for instance, when silicic acid is used. 



(5) If the wall of the tube is roughened on the inside, or if a 

 larger or a rougher surface is exposed to the air by means of 

 paper or metal sheets inserted and fitting as close as posible the 

 wall of the tube, the velocity of sound in narrow tubes is thereby 

 materially diminished ; and this diminution is considerably more 

 than could be produced by the mere diminution in the section 



* In the above experiments the quantity of powder used was so small 

 that it could not appreciably influence the results. 



