LXI. Some Consideratiom respecting the Lunar Oriqin of Aero- 

 lites. By R. P. Greg, Esq.^ 



JY: I^AWRENCE SMITH of Louisville University, U.S, has 

 -S->^ just published m the American Journal of Science, Second 

 Series, vol. xix. May ISoS/an interesting memoir on Meteorites, 

 which deserves attention even from those who may not agree with 

 the theory of their lunar origin. He directs attention to the phy- 

 sical, chemical as well as mineralogical, characteristics of aerolites, 

 pointing out the volcanic and igneous nature which some of them' 

 possess. He agrees with me in the importance of separatino- 

 these bodies from shooting stars and periodic luminous meteors^ 

 a circumstance which no astronomer except Olmsted has noticed 

 or valued. He rejects their atmospheric origin, and considers 

 them as certainly belonging to, or as having proceeded from, 

 a larger whole, and not to have resulted from the condensa- 

 tion of so many independent cosmical particles. He then comes 

 to the /«.«»/• theory, and after giving its history and naming the 

 principal advocates of itf, lays down the following i)roposi- 

 tions : — 



" 1st. That all meteoric masses have a community of orio-in, 

 ^"2nd. At one period they formed parts of some large body.' 

 " 3rd. They have all been subject to a more or less prolonged 

 igneous action corresponding to that of terrestrial volcanoes. 

 " 4th. That their source must be deficient in oxygen. 

 " 5th. That their average specific gravity is about that of the 

 moon. 



"From what has been said under the head of common charac- 

 ters of meteorites, it would appear far more singular that these 

 bodies should have been formed separately from each other, than 

 that they should have at one time or another constituted parts of 

 the same body : and from the character of their formation, that 

 body should have been of great dimensions. Let us suppo'se all 

 the known meteorites assembled in one mass, and regarded by 

 the philosopher, mindful of our knowledge of chemical and phy- 

 sical laws. Would it be considered more rational to view them as 

 the great representatives of some one body that had been broken 

 into fragments, or as small specks of some vast body in space 

 that at one period or another has cast them forth ? Tlic latter, it 

 seems to me, is the only opinion that can be entertained in re- 

 viewing the facts of the case. 



"As regards the igneous character of the minerals composing 

 meteorites, nothing remains to be added to what has already 

 * Communicated I)y the Author. 



t It was proposed by an Itahau philosopher, Terzago, in 16fiO, and has 

 been at different times, and for various reasons, supported hy Olbers, Biot, 

 Brandes, Poisson, Quetelet, Arago, Benzenburg and Laplarc. 



