Ball — Speculations on the Source of Meteorites. 227 



XXXVII. — Speculations on the Source of Meteorites. By Egbert 



S. Ball, LL.D., F.E.S., Koyal Astronomer of Ireland. 



[Read January 13, 1879.] 



I HAVE recently read M. Gr. Tschermak's most interesting memoir 

 "Die Bildung der Meteoriten und der Ynlcanismus."^ I am not 

 competent to offer any opinion on the mineralogical questions involved 

 in his discussion, but the numerous arguments he has advanced 

 appear to me to justify his conclusion, that " the meteorites have had 

 a volcanic source on some celestial body." These arguments are 

 briefly as follows : — 



Meteorites are always angular fragments, even before they come 

 into our atmosphere. 



Most meteoric irons have a crystalline structure, which, according 

 to Haidinger, requires a very long period of formation at a nearly 

 constant temperature. This condition could only have been fulfilled 

 in a large mass. 



Many meteoric stones show flutings resembling those see: on 

 terrestrial rocks, and which are due to the rubbings of adjacent 

 masses. 



Other meteorites have a structure produced by the union of 

 several fragments, so as to be analogous to breccia. 



Many meteorites arc composed of very small particles analogous 

 to volcanic tufas. 



After glancing at the old theory of the volcanoes in the moon, and 

 rejecting as untenable the hypothesis that meteorites have any con- 

 nexion with the ordinary shooting star showers, Tschermak con- 

 cludes, " We may suppose that many celestial bodies, of considerable 

 dimensions, are still small enough to admit of the possibility that 

 projectiles driven from them in volcanoes shall not return by gravity. 

 These would really be the sources of meteorites." Similar views 

 having been put forward by Mr. J. Laurence Smith and other 

 authorities, it seems not unreasonable to discuss the following 

 problem : — 



If meteorites have been projected from volcanoes, on what hody or 

 bodies in the Universe must these volcanoes have been located? 



Let us first take up a few of the principal celestial bodies seriatim, 

 and consider their claims to the parentage of the meteorites. "We 

 begiu with the sun. It has been shown that there exists upon the 

 sun tremendous explosive power. It is not at all unlikely that the 

 power would be sufficiently great under certain circumstances actually 

 to drive a body from the sun never to return. We might, therefore, 

 find upon the surface of the sun adequate explosive power for the 

 volcano, but the projectiles are here the difficulty. There are a 



1 Sitzungsbericlite der Mathematisch-Naturwissenscliaf tlichen Classe der Kaiser- 

 lichen Akademie der Wissenschaften, Wien, 1875. Band Ixxi., Abtheilung 2, 

 pp. 661-674. 



11. I. A. I'ROC, VOL. II., SEll. III. — SCIENCE. S 



