Page:Popular Science Monthly Volume 7.djvu/613

Rh A trace of manganese remains with the ferrous oxide—also a small amount of alumina. The trace of sodium is sufficient to give a brilliant line in the spectroscope; the lithium-line, while quite distinct, is not brilliant.

An extended report of my examination of the Iowa County meteorite will be published, as soon as the more careful investigation of the concretions shall have been completed, which examination is delayed for want of material. I am unwilling to sacrifice any of the fine specimens above enumerated for this purpose.

—The researches of Daubrée and Meunier, of Paris, have demonstrated that meteorites are fragments of one or more planetary bodies, which, by some great convulsion, has been broken to pieces. Furthermore, we possess abundant evidence that the earth, in its structure, corresponds, at different depths, to the different varieties of meteorites: from those without iron (Asydères), through the Oligosidères to those consisting exclusively of nickeliferous iron (Syssydères). Hence if our earth, through the action of some cause, should be broken to pieces, these pieces would be meteorites and describe orbits around the sun similar to and near by the orbit of the earth.

But the cosmical spaces are filled with a very rare, slightly-resistant medium. Hence, the fragments being different in density and in dimensions, would be differently affected by this resisting medium. The smaller fragments and those of less density would lose their velocity of revolution around the sun more rapidly than those of greater size and higher density. In other words, all fragments would, while revolving around the sun, also descend toward the same, bat at different rates: the smaller and lighter fragments would sink faster than the larger and heavier.

These terrestrial meteorites would, therefore, gradually reach the orbits of the inner planets. On Venus first would appear meteorites composed of the rocks of our earth's superficial crust, limestone, shales, quartz, granite, serpentine, etc. These would be associated with small meteorites of more dense materials derived from the deeper portions of the earth. At a later period, Venus would receive terrestrial meteorites from deeper portions of our earth, corresponding to Oligosidères. These would also be associated with small meteorites of denser materials, thus foreshadowing the third meteorite era, in which the dense masses of the interior metallic core of our earth would have sunk far enough toward the sun to reach the orbit of Venus. The mechanical problem herein involved I pretty completely solved about ten years ago.

Now, it is furthermore well understood that it will be a long time