108 CELESTIAL PHENOMENA. 



have been shewn, among many other instances, by the fulls 

 of aerolites observed at Barbotan, in the Departement des 

 Landes in France (24th July, 1790), at Sienna, (16th 

 June, 1794), at Weston in Connecticut (14th December, 

 1807), and at Juvenas in the Departement derArdeche, (15th 

 June, 1821). In other instances, a small and very dark 

 cloud forms suddenly in a perfectly clear sky, and the 

 stones are hurled from it with a noise resembling repeated 

 discharges of cannon. Such a cloud, moving over a whole 

 district of country, has sometimes covered it with thousands 

 of fragments, very various in size, but similar in quality. 

 A phenomenon of still more rare occurrence took place on 

 the 16th September, 1843, when a large aerolite fell at 

 Kleinwenden, not far from Mulhausen, accompanied by a 

 thundering noise, but with a clear sky in which no cloud 

 was formed. As further evidence of the affinity between 

 fire-balls and shooting stars, it should be noticed that fire- 

 balls, from which meteoric stones have descended, have some- 

 times been seen, as at Angers, on the 9th of June, 1822, of 

 a diameter hardly equal to that of the small Roman candles 

 in our fire-works. 



"We have as yet scarcely any knowledge in regard to the 

 physical and chemical processes which contribute to the 

 formation of these phenomena. Whether the particles, of 

 which the compact meteoric masses are composed, exist 

 originally in a fluid form (as in comets) and only begin to 

 condense within the fire-ball at the moment when it becomes 

 luminous to our sight, or what takes place within the 

 bosom of the dark cloud from which sounds resembling 

 thunder are sometimes heard for minutes before the stones 

 are precipitated from it, or whether, in the case of smaller 



