426 Dr. Moll’s account of the experiments on 
cited exactly at the same time on both ends of a basis, and 
let two observers stationed on these ends, measure the velo- 
city with which sounds travels from one end of the basis to 
the other. It is quite clear, that the action of the wind rppst 
necessarily accelerate the velocity of the sound excited at one 
end of the basis, as much as it will retard that at the other 
end, and thus the medium of these two velocities will give 
the velocity in tranquil air. This method was not adopted 
by the French Academicians of 1738, in their experiments 
between Monthlery and Montmartre. Cannon was fired at 
one of these stations, whilst the observers were at the other, 
and thus the results remained affected by the whole effect of 
the wind. It was found expedient therefore to repeat these 
experiments with more accuracy, and this was executed with 
great precaution on Mr. Laplace’s proposal* by Messrs. 
Arago, Prony, Mathieu, Bouvard, Humboldt, and Gay 
Lussac. The experiments were made in 1822, on the basis 
of Monthlery and Villejuif. In two successive days, the 
21st and 2 2d of June, 1822, seven shots were fired on both 
stations, and observed on the other ; the difference of time in 
which the corresponding shots were fired at both stations 
not exceeding five minutes, and from these seven corre- 
sponding shots the result was deduced. 
These experiments having never been made in this coun- 
try with any thing like sufficient accuracy, His Royal High- 
ness Prince Frederick, second son of His Majesty the King. 
of the Netherlands, and Master General of the Ordnance, 
was pleased to approve of our proposal of repeating the 
same, and to authorise Lieutenant-Colonel Kuytenbrouwer, 
J 
and the officers and men of the battalion of Artillery under 
