498 Prof. Gr. Tschermak on the Formation of 



read of the planetary nature of meteorites, experiences no 

 little astonishment, on inspecting a collection of them, to find 

 that they are not rounded as the planets are, but are angular, 

 often exhibit sharp edges, and possess, even in their interior, 

 no concentric structure. 



Haidinger, who examined with much care the surfaces of 

 meteorites, arrived at the conviction that their dark-coloured 

 crust and the rounded nature of their edges were not original 

 characteristics, but that the thin crust was developed during 

 transit through the atmosphere, the sharpness of the edges 

 being at the same time abraded. A meteorite, in short, before 

 .entering the atmosphere possesses an angular form ; the greater 

 number are acutely angular. The faces of the angular masses 

 are surfaces of fracture ; each meteorite is a fragment, and in 

 fact owes its form to the disruption of a larger mass. 



Any collection, in which complete meteorites are preserved, 

 will furnish examples which conclusively demonstrate this 

 fact ; and among the specimens at Vienna attention may 

 especially be directed to the meteoric iron of Agram, that of 

 Ilimae, and the stones of Knyahinya, Seres, Lance, Chan- 

 tonnay, Orvinio, Tabor, Pultusk, Stannern, and others. The 

 external form of these and other meteorites bears no relation 

 whatever to the constitution of their interior ; it is purely 

 accidental. 



It may perhaps be maintained that the disruption took 

 place in the atmosphere ; and there are unquestionably a few 

 instances where an inspection of the crust shows that the 

 meteorite had been sundered during its flight through the 

 atmosphere ; the fact, however, remains that meteorites enter 

 our atmosphere in the form of fragments. After the aerolitic 

 fall which took place near Butsura, India (May 12th, 1861), 

 five fragments w^ere discovered, some of them as much as six 

 miles apart ; by fitting these pieces together Maskelyne was 

 able to reconstruct in London the meteorite in the form which 

 it originally bore, and which appears to have been that of a 

 comparatively thin slab somewhat bent. The irregular heating 

 to which such a body would be subjected during its fall would 

 lead to its disruption. With this example, it is scarcely ne- 

 cessary to direct attention to other cases which establish 

 the fact that meteorites when they enter our atmosphere do 

 not have the rounded form of planetary bodies. 



Meteorites, then, always reach us in the shape of fragments, 

 as flattened masses, or as fine particles, which have their origin 

 in one or more larger planetary masses. Whether the source 

 be one or many, the dimension of this mass or these masses 

 must have been not inconsiderable. 



