OC. K. Wead—Intensity of Sound. 189 
as the ear was at a point of maximum loudness, assume that the 
energy per second at that point is four times that due to a uni- 
form distribution of the energy : 
io: BON -8. 
table VI gives S=30010-8. 
_Some experiments were made bearing on the question of the 
division of the energy as already referred to; they indicate that 
with the Ut, fork only about /; of the total energy is used for 
the sound-wave; but the observations are too few to determine 
whether the theory used in their discussion is valid or not; so 
this matter must be deferred till another time. 
The only other experiments that I know of with which to 
compare the values of S in table VI are three in number, from 
which I have computed the values of S as follows: 
Tépler and Boltzman,* closed organ pipe, n=182 S= 10000 x 10°® 
Rayleigh,} open pipe, n=2730 S= 4500 x 10% 
Allard,t bells, steam syren, etc., at sea, n from 400 to 1500_-.-- S=nx 43x10 4 
Following Rayleigh’s formula we get the maximum velocity 
of the air particles at the limit of hearing, thus: v?=S+4ap, 
where a= the velocity of sound =34000 cm. and p=0013= 
ir v2=S+2 
Inn=V/S+80n. The smallest 
value of x to be obtained from table VI is 7010-8 em. for 
Ut, The formula computed from Allard’s data would give | 
for n=512, 2=31x10-8 cm. Rayleigh found for n=2730, 
*=8:110-8 cm. 
But the fuller discussion of these matters must be postponed 
to another part of this paper. 
* Pogg. Ann., cxli, 321, 1870, 
t Proc. Roy. Soc., xxvi, 248, 1877. i ‘ ; 
} Comptes Rendus, xev, 1062, 1862. I have not seen his longer memoir. 
