THE GREAT IOWA METEOR. 



593 



inches thick; it weighs V5 pounds, or 33.6 kilogrammes, and is com- 

 j)letely 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 48^ 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 Moer- 

 schel ; 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 kilo- 



grammes. 



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. 



' Of meteoric irona many of much greater weight are found in museums. The largest 

 of all is the Cranhourne iron, Australia, of 4,000 kilogrammes, at the British Museum. 

 Next in weight is the Charcas iron, weighing 780 kilogrammes, at the Museum of the Jardin 

 des Plantes in Paris. The largest iron in the K. K. Hof-Mineralienkabinet at Vienna is 

 from Elbogen, Bohemia, and weighs 78 kilogrammes. 

 VOL. TII. 38 



