AEROLITES. 223 



my fellow-travelers saw the greatest swarm of shooting stars 

 between half past two and four o'clock. A very meritorious 

 observer of the phenomena of meteors, Coulvier-Gravier, con- 

 tributed an important essay to the Institute at Paris upon la 

 variation horaire des etoiles Jilantes. It is difficult to con- 

 jecture the cause of such an hourly variation, an influence 

 of the distance from the hour of midnight. If, under differ- 

 ent meridians, the shooting stars do not become especially 

 visible until a certain early hour, then, in the case of their 

 cosmical origin, we must assume, what is still but little prob- 

 able, viz., that these night, or, rather, early morning hours, 

 are especially adapted to the recognition of the shooting stars, 

 while in other hours of the night more shooting stars pass 

 by before midnight invisible. We must still long and pa- 

 tiently collect observations. 



The principal characters of the solid masses which fall 

 from the air I believe I have treated of with tolerable com- 

 pleteness (Cosmos, vol. i., p. 129), in reference to their chem- 

 ical relations and the granular structure, especially investi- 

 gated by Gustav Rose in accordance with the state of our 

 knowledge in the year 1845. The successive labors of How- 

 ard, Klaproth, Thenard, Vauquelin, Proust, Berzelius, Stro- 

 meyer, Laugier, Dufresnoy, Gustav and Heinrich Rose, Bous- 

 singault, Rammelsberg, and Shepard, have afforded a rich 

 material,* and yet two thirds of the fallen meteoric stones, 

 which lie at the bottom of the sea, escape our observation. 

 Although it is striking that, under all zones, at points most 

 distant from each other, the aerolites have a certain fthys- 

 iognomic resemblance in Greenland, Mexico, and South 

 America, in Europe, Siberia, and Hindostan still, upon a 

 closer investigation, they present very great differences. 

 Many contain yW of iron; others (Siena) scarcely y|^ ; 

 nearly all have a thin black, brilliant, and, at the same time, 

 veined coating : in one (Chantonnay) this crust was entire- 

 ly wanting. The specific gravity of some meteoric stones 

 amounts to as much as 4-28, while the carbonaceous stone 

 of Alais, consisting of crumbling lamellae, showed a specific 

 gravity of only 1'94. Some (Juverias) have a doleritic struc- 

 ture, in which crystallized olivin, augite, and anorthite are 

 to be recognized separately ; others (the masses of Pallas) 

 afford merely iron, containing nickel arid olivin ; and others, 



* The metals discovered in meteoric stones are nickel, by Howard; 

 cobalt, by Stromeyer; copper and chromium, by Laugier; tin, by Bcr- 

 ze'.ius. 



