ORIGIN OF COMETS AND METEORS. 53 



With a wide choice as to a starting-point, I take first the results of 

 M. Daubree's analysis of meteorites in regard to chemical composition 

 and physical structure ; and I combine the positive evidence he has 

 obtained with Professor Newton's argument very just and of great 

 negative weight that no theory can reasonably be accepted with re- 

 gard to meteorites which may not be extended in its general sense to 

 all orders of meteoric bodies. 



M. Daubree tells us, then (nay, he shows by demonstrative experi- 

 mental evidence), that meteorites resemble so closely in composition 

 and structure volcanic products such as are only found deep below the 

 earth's crust, that we may be assured they were formed under similar 

 conditions of temperature and pressure. He constructs masses of mat- 

 ter under such conditions which the most experienced student of me- 

 teorites could not distinguish from true meteoric masses ; and he points 

 out how the earth in her interior laboratories has constructed and pres- 

 ently ejected bodies which in like manner deceived the most experi- 

 enced, taking their place for a long time in museums as " the Ovifak 

 meteorites." 



M. Daubree very naturally draws the inference that meteorites 

 were actually formed under such conditions. But a mass formed as 

 such volcanic products are being now formed, deep beneath the crust 

 of the earth, could not possibly escape from such a birthplace except 

 by such energetic extrusion as a body like our earth, now or during the 

 ages recorded in the geologic strata, could not possibly have effected. 

 Hence, M. Daubree infers (again, quite naturally) that meteorites were 

 ejected from the interiors of stars. 



Applying to this result the principle indicated by Professor 

 Newton, we see that it requires to be at once generalized and modi- 

 fied, for there are classes of meteoric bodies which can not possibly 

 be regarded as coming from any of those orbs which we call stars. 

 Among these may be specially mentioned, first, those orders of mete- 

 oric bodies which Stanislas Meunier and Tschermak have been led to 

 regard as ejected from the earth. Without for the moment attaching 

 any specific importance to this idea as involving a positive theory of 

 the origin of these meteors, it is certain that the evidence adduced by 

 Tschermak and Meunier, confirmed also by the mathematical inquiries 

 of Sir Robert Ball, definitely negatives the idea of an origin outside 

 the sun's special domain. In like manner we must exclude those me- 

 teor-streams which, like the Leonides, the Perseids, and the Bielids, 

 travel in closed paths, indicating an origin within the solar system. I 

 have myself adduced evidence which is really demonstrative, and ad- 

 mitted (even by those who think there may be some escape from it) 

 to be for the present unanswerable, to show that these meteor-streams 

 can not have been captured as meteor-flights by the giant planets, as 

 Schiaparelli suggested. But, apart from this, I believe that no one 

 who considers the nature of these streams, or the character of the or- 



