898 Scientific Intelligence. 
air in the interior of the cloud becomes heated, by its numerous 
contacts with those globules which are susceptible of being 
heated. Hence the air will dilate, and the cloud will rise in 
the atmosphere, to a height depending on the fineness of the 
particles of the cloud, and on the intervals which separate them. 
—See the Bull, de la Soc . Math, in Oct. 1822, p. 159. 
14. On the Cause of the Suspension of Clouds. — M. Gay Lus- 
sac, in the Ann. de Chim ., vol. xxi. p. 59-, ascribes the suspen- 
sion of clouds to ascending currents, which push them upwards, 
until this force of impulsion is balanced by the weight of the 
cloud. A soap bubble, he remarks, will not rise in a room, but 
will descend directly when left to its own weight ; but if the 
bubble is blown in the open air above a heated soil, it will rise to 
a height more or less considerably. It remains, however, to be 
determined, how much of this effect is owing to the cause assigned 
by M. Fresnel, and how much to the mere mechanical force of 
the current of heated air. It is quite obvious, that both causes 
must operate to a certain extent. 
15. Meteoric Stone in the department of the Vosges . — On the 
18th September 1822, a meteoric stone fell in the commune of 
la Buffe, during a thunder storm, accompanied with intense 
lightning. At 7 a. m., a noise was heard like that of a carriage 
descending over a rough road ; it lasted seven minutes, and be- 
came at last terrific. The meteor then exploded on the ground, 
and fragments of a meteoric stone were found in a round hole.— 
Ann. de Chim ., vol. xxi. p. 17- 
HYDRODYNAMICS. 
16. Perkins ’ New Steam-Engine of great Power.— Id our last 
Number, p. 186., we inserted a short notice of this great inven- 
tion, which we copied from a letter written by the inventor’s 
own hand to a scientific friend in Edinburgh. We have seen 
various letters from individuals of great scientific zeal and intel- 
ligence, who have had repeated communications with Mr Per- 
kins himself, and we cannot doubt that Mr Perkins’ invention 
will turn out one of great value, even if it shall not realise all 
the expectations which have been entertained from it. One of 
Mr Perkins’ engines is probably by this time in actual operation. 
“ This engine,” says the editor of the London Journal of Arts, 
