AEROLITES. 105 



lowered the lines which had, perhaps with some degree of 

 temerity, been usually termed the boundaries of the atmo- 

 sphere ; but processes of light may be evolved independently 

 of the presence of oxygen, and Poisson conjectured that 

 aerolites were ignited far beyond the range of our atmosphere. 

 Numerical calculation, and geometrical measurement, are the 

 only means by which, as in the case of the larger bodies of our 

 solar system, we are enabled to impart a firm and safe basis 

 to our investigations of meteoric stones. Although Halley 

 pronounced the great fire ball of 1686, whose motion was 

 opposite to that of the Earth in its orbit,* to be a cosmical 

 body; Chladni, in 1794, first recognised, with ready acuteness 

 of mind, the connection between fire balls and the stones 

 projected from the atmosphere, and the motions of the former 

 bodies in space. f A brilliant confirmation of the cosmical 

 origin of these phenomena has been afforded by Denison 

 Olmsted, at Newhaven, Connecticut, who has shown, on 

 the concurrent authority of all eye-witnesses, that during the 

 celebrated fall of shooting stars, on the night between the 

 ,12th and 13th of November, 1833, the fire balls and shooting 

 stars all emerged from one and the same quarter of the 

 heavens, namely, in the vicinity of the star y in the con- 

 stellation Leo, and did not deviate from this point, although 

 the star changed its apparent height and azimuth during the 

 time of the observation. Such an independence of the Earth's 

 rotation shows that the luminous body must have reached our 



restrial attraction, although physically imponderable, and consequently 

 following our globe in its motion 1 According to this hypothesis, the 

 bodies of which we have been speaking would, on entering this impon- 

 derable atmosphere, decompose the neutral fluid by their unequal action 

 on the two electricities, and they would thus be heated, and in a state 

 of incandescence, by becoming electrified." (Poisaon, Rech. sur la Proba- 

 bilite des Jugements, 1837, p. 6.) 



Pkilos. Transact., vol. xxix. pp. 161-163. 



t The first edition of Chladui's important treatise, Ueberden Ursprung 

 der von Pallas gefundenen und anderen Eisenmassen (On the Origin cf 

 the masses of Iron found by Pallas, and other similar masses), appeared 

 two months prior to the shower of stones at Siena, and two years before 

 Lichtenberg stated, in the Gottingen Taschenbuch, that " stones reach 

 our atmosphere from the remoter regions of space." Comp. also Olbers 

 letter to Benzenberg, 18th NOT 183? in Ben/.enberg's treatise <w 

 Shooting Stars, p. 186. 



