On Aerolites. 41 



scliel thought he saw the gleam of a volcano on the lunar sphere; 

 and this being of the imagination has been received as currency, 

 and made the pedestal of the hypothesis which regards these 

 "children of the air" as of lunar fonnation. — Now here, methinks, 

 two difficulties are introduced ; namely, That the lunar mass is 

 composed of very different materials from any we find on our own 

 planet, — and a necessity of admitting the existence of volcanoes 

 in the moon gifted with powers of projection of the most extra- 

 ordinary description. Now, could the bright speck which our 

 eminent astronomer witnessed, proceed from no other source than 

 a lunar volcano ? — The celestial exhibitions which from time to 

 time greet the eye, should tend to mingle humility in our estimate 

 of the phsenomena of the stars. Besides, many eminent astro- 

 nomers have denied the assertion of Sir W, Herschel, and among 

 them we find the name of M. Arago. The existence of a lunar 

 atmosphere ^eems necessary for this position; and the occultations 

 of the stars clearly prove that such an atmosphere does not exist, 

 or at least that it does not possess a sensible density. Moreover, 

 on this supposition meteorolites ought to be confined to a given 

 range ; whereas, so far from being limited to any parallel of lati- 

 tude, they are not bounded by any prescribed lines. It seems 

 less difficult to say what they are not, than what they really are: 

 but I think a proper consideration of tiie phaenomena which 

 announce their presence and their fall, might in some measure 

 serve as a clue to guide us out of the difficulty. Their precipi- 

 tation from the atmosphere, though once deemed fabulous, is no 

 longer doubted, and the identity of their elements and peculiar 

 aggregations pronounces their common origin, and that they 

 are not terrestiial bodies. A black cloud, the splendours of the 

 thunder-storm, the apparition of light succeeded by tremendous 

 explosions, are the heralds of their fall; and when it occurs at 

 night, a luminous phaenomenon proclaims their passage through 

 the regions of the atmosphere. Mr. Brande thinks that " their 

 ignition may be accounted for either by supposing the heat ge- 

 nerated by their motion in our atmosphere sufficient to ignite 

 them ; or, b\- considering them as combustililes ignited by the 

 mere contact of air." It is very true, we may assume any thing; 

 and the rapidity of their progress, on the supposition that they 

 are launched from the surface of the moon and enter our atmo- 

 sphere with the velocity of" about 25,000 feet in a second," 

 might, by the extraordinary friction that would obtain, be suffi- 

 cient to ignite them ; — but to be inflamed by the mere contact 

 of cool air in passing through that rarefied medium, where even 

 aciucous vapour may lose its elasticity and become solid matter, 

 we must suppose that the meteoric stones are entirely composed 

 of some such body as polasiium: — now they are well known ag- 

 gregations 



