Velocity of Sound Waves in Tubes. 207 
In the second place the sound produced by a pistol or cannon is, near 
the source, a pulse whose wave curve is short and steep. As the dis- 
tance from the source increases the wave type changes. This change 
of wave form would of itself cause a variation in the time lag of the 
device. However, the unavoidable sources of error in Regnault’s work 
are not sufficient to cast doubt on his conclusions that the velocity of 
sound decreases as the intensity decreases. Indeed, other experimenters 
using other methods have arrived at a similar conclusion, a conclusion 
in accord with theory. 
Referring to Rink’s table of Regnault’s results from which Rink 
eoncludes that the velocity of sound in a pipe 110 em. in diameter is 
practically constant, one may conclude that the apparent constancy is 
due to the fact that, in such a tube, the intensity of the sound wave 
varies very slowly with the distance from the source. In very small 
iubes and in tubes with rough walls or with walls of material capable 
of absorbing some of the energy of the waves, the intensity would vary 
more rapidly with increasing distance from the source, and one would 
expect a greater variation in the velocity. Experiments confirm this 
conclusion. 
TABLE II. 
ees $ , Diameter and Velocity 
Observer Method Freauency Mciteclton aise lel aces 
Wrertiternns §8440 0 ce os aa cecal OrrankPipe serene eeelt shea cece 1.0 em. Brass... 329.12 
2.0 em. Brass......] 330.11 
2.0 em. Glass..... 330.23 
4.0 em. Brass......| 332.10 
Regnault. Mem. de l’Acad...... See Fig. 2 and explana- 
Paris. 37. I. 3. 1868. C. R. tion. 
B 66. s 209, 1868. 
Rink, Pogg. Ann. B 149......... See Fig. 2 and explana-| Explosion..| 110 em. Iron....... 330.5 
s 533. 1873. tion. 
Kundt. Pogg. Ann. B 135....... Double Kundt’s tube. . ? 3.0 cm. Glass... ... 305.42 
s 333 u. 527. 1868. 6.5 em. Glass......| 323.00 
1380'em) Glass?.-.-- 329.47 
Seebeck. Pogg. Ann. B139...... Kung ts tube sss. 4- 320 .84 em. Glass..... 317.26 
s 104, 1870. 320 .9 em. Glass... 328.02 
320 1.75 cm. Glass..... 329.24 
512 .34 em. Glass..... 322.98 
512 .9 em. Glass..... 328.44 
512 1e7a.eme Glasses: 330.92 
Le Roux. Ann. Chem. Phys.... . Similiar to Regnault’s | Explosion..| 7.0em............ 330.66 
LA) est a7 Ey Re ee ee eo method.... Ef Soll ais 0 gs an 
laikley. Phil. Mag. V 16 ......| Special form of organ 105 1.17 cm. Brass....| 324.56 
p. 447, 1883. pipe. 1.95 em. Brass 326.90 
3.25 em. Brass 328.78 
5.41 em. Brass... 329.72 
8.82 em. Brass....| 330.13 
