Page:Popular Science Monthly Volume 7.djvu/611

Rh inches thick; it weighs 75 pounds, or 33.6 kilogrammes, and is completely covered with a black crust, i. e., a complete stone. The smaller meteorite forms an irregular rhomboid, the diagonals of which are 16 and 10 inches, while it is 12 inches thick; it weighs 48½ pounds, or 21.1 kilogrammes. One of its sides has but a secondary crust, so that another piece of perhaps 20 pounds must be found in the neighborhood. The smallest complete stone is in the possession of Mr. William Moerschel; it is a lenticular stone, weighing two ounces only. The largest stone found weighs, therefore, 624 times as much as the smallest!

The two admirable specimens just described belong to the largest meteoric stones on record, as may be seen from the following table, which, however, is probably not quite complete below forty kilogrammes.

The Amana Society has confided these two remarkable specimens to me for study. They appear to have formed but one stone when the meteor first struck our atmosphere.

The number of meteorites thus far found in Iowa County is about one hundred; the total weight is over 500 lbs., or 225 kilogrammes.

The Iowa County meteorites are all alike, bounded by irregular plane surfaces, indicating the usual fragmentary nature of meteorites. They are all covered with a black crust, formed during the cosmical part of their motion through the earth's atmosphere. This crust is not due to fusion, but simply to the heating of the outer layer of the stone to a red heat, as has been proved by Meunier. Indeed, the gray mass of these meteorites turns very readily black by exposure to a red heat. The surface of these meteorites shows all the ordinary impressions of meteoric stones; the finger-marks, granulations, ripples simulating the flow of fused matter, etc. The anterior side is, as commonly, deeper black than the posterior side; the latter has the smaller finger-marks.