Page:Popular Science Monthly Volume 31.djvu/63

Rh With a wide choice as to a starting-point, I take first the results of M. Daubrée'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 regard to meteorites which may not be extended in its general sense to all orders of meteoric bodies.

M. Daubrée tells us, then (nay, he shows by demonstrative experimental 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 matter under such conditions which the most experienced student of meteorites could not distinguish from true meteoric masses; and he points out how the earth in her interior laboratories has constructed and presently ejected bodies which in like manner deceived the most experienced, taking their place for a long time in museums as "the Ovifak meteorites."

M. Daubrée 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. Daubrée 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 modified, 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 meteoric 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 meteor-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 admitted (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