t 424 2 
XXIII, An account of Experiments on the velocity of Sound , 
made in Holland. By Dr. G. Moll, Professor of Natural 
Philosophy in the University of Utrecht , and Dr. A. Van 
Beer, 
Read March 18, 1824. 
S i r Isaac Newton’s formula, expressing the velocity of 
has since his time been investigated and demonstrated by 
several first-rate mathematicians. Actual experiments how- 
ever on this velocity, instituted in various countries, and under 
different circumstances, went to prove that the celerity of 
sound, found by experimiment, is about one-sixth greater 
than can be deduced by theory. 
The celebrated Laplace accounted for this difference be- 
tween experiment and theory, by showing that it could be 
attributed to the heat evolved by the compression of the par- 
ticles of air which is effected by the undulations of sound. 
It was found impossible to determine the quantity of heat 
thus evolved, by the compression which sound occasions in 
the particles of the air ; and therefore it was deemed expe- 
dient to multiply Sir Isaac Newton's formula by a constant 
factor Vi k, the value of which was determined by expe- 
riment. Sir Isaac’s formula thus altered, became 
" = ■ rr+i. 
Thus, by the experiments of the French Academicians of 
