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XV . — On the theoretical investigation of the velocity of sound, as corrected 
from M. Dulong’s recent experiments, compared with the results of the obser- 
vations of Dr. Moll and Dr. Van Beek. By Dr. Simons, Assistant at the 
i-T has been demonstrated by the ever-to-be-lamented Laplace*, that in order 
to obtain the velocity of sound by calculation. Sir Isaac Newton’s original 
expression'!', 
must be multiplied by the square root of the ratio between the specific heats 
of atmospheric air under a constant pressure and under a constant volume. 
sound is transmitted ; the density of mercury being equal to 1. 
The coefficient, which is to multiply the Newtonian formula, has been de- 
duced by M. Laplace, first from MM. Laroche and Berardo’s^; experiments, 
next from those of MM. Clement and Desormes§, and finally from the more 
accurate investigations of MM. Gay-Lussac and Welter. 
By introducing this correction, the velocity as deduced from calculation, 
was found to differ but little from what is actually obtained by experiment. 
But this difference between calculation and experiment, however small, was 
always such, that the observed velocity constantly exceeded that which was 
deduced by calculation. 
* Annales des Physique et de Chimie, t. iii. p. 238. t. xxiii. p. 1. Mecan. Celeste, t. v. p. 119, seqq. 
f Princip. 1. ii. prop. 48. 
+ Annales de Chimie, t. lxxxv. p. 72. 
§ Journal de Physique, t. lxxxix. p. 333, seqq. 
Observatory of the University of Utrecht. Communicated by Captain Henry 
Kater, Vice-President. 
Read March 18, 1830. 
In this formula V is the velocity of sound, g the intensity of gravitating force, 
p the atmospheric pressure, and D the density of the medium through which 
2 e 
mdcccxxx. 
