David Forbes — On Meteorites. 233 



thrown up from terrestrial Yolcanos which had subsequently fallen 

 down again, independent of the fact that no such volcanic products 

 as meteorites are known, and that the force required to project 

 masses to such an altitude as meteorites are known to descend from 

 is far beyond that developed by known volcanos. A century ago, 

 ■when European philosophers seem rather to have shirked the inves- 

 tigation of many of the more abstruse natural phenomena, it was 

 customary to regard meteorites as mere atmospheric appearances, 

 like, for example, lightning, — an explanation which, in face of so 

 much evidence to the contrary, is no longer entertainable ; so that we 

 must proceed to the consideration of the only remaining explanation 

 of these phenomena, one which also had its root in the suggestion of 

 the ancient Greeks, that they originated in celestial space as heavenly 

 bodies which had long remained invisible, a supposition which was 

 but little modified when, at the end of the last century, Chladni de- 

 clared meteorites to be an accumulation of matter, originally created as 

 such or fragments of larger masses, moving in space. This view was 

 accepted by most later men of science, by whom it became gradually 

 more and more developed, and of late years especially so, by the 

 labours of Schiaparelli, so that the united results tend to demon- 

 strate that falling stars, meteors, and meteorites or aerolites, are all 

 similar bodies, differing in size, but not in composition, and that the 

 numerous meteors which traverse the celestial space are furnished by 

 certain if not all the comets, and probably identical with the comets 

 themselves. These bodies, owing to the remarkable elongation of 

 their orbits, do not appear to have formed part of our system as at 

 first constituted, but to have been wandering nebulee brought within 

 the influence of the sun's action. Meteors do not belong to the 

 planetary system, but to the stellar regions beyond, and are in 

 reality falling stars, which bear the same relation to comets that 

 asteroids do to planets ; in both cases the smaller size is made up 

 by the greater numbers. 



The structure of aerolites shows them not to be mere masses of 

 previously molten matter, for not only is the external vitrified glaze 

 extremely thin, but the structure itself, instead of being homogeneous 

 or crystalline throughout, as would have been the case had the whole 

 been in a state of fusion, is, as a rule, seen by the eye or under the 

 microscope to be an aggregation of fragmentary matter resembling 

 a volcanic ash or breccia, in which, whilst some of the particles have 

 been in a molten state (the presence of both glass and air cavities in 

 them indicating that they were in the molten state when gases or 

 vapours were being given off), others show no signs of fusion; so 

 that the structure of meteorites confirms the views that they have 

 been formed out of the debris of some previously existing larger 

 mass, or even out of the ruins of some planetary body. 



When the vastly elongated elliptical paths extending far beyond 

 our system into stellar space, in which these bodies move, happen to 

 cross or approach closely to our sphere, those meteors which are 

 nearest to the earth may be drawn towards it by its attraction ; and 

 once brought within its atmosphere, their cosmical course would be 



