Outlines of Meteoric Astronomy. 219 



(14.) Some meteorites, called aerosiderites, are metallic 

 iron, more or less alloyed with nickel. These kinds are 

 generally found fossil, two only having been observed to 

 fall from the sky, and these nearly a century apart. The 

 first occurred at Agram in Croatia, on the 26th of May, 

 1751, weighing 72 lbs., and is preserved in the Imperial 

 Museum at Vienna, where is also exhibited the aerosiderite 

 of Braunau, that fell on the 14th of July, 1847. The largest 

 fossil iron remains immoveably fixed in the desert of Bahia, in 

 the Brazils. Another from La Plata, weighing 7 cwt., is 

 exhibited in the British Museum. One was found at Var, in 

 France; and recently a specimen, weighing 33 lbs., was dug 

 up near Melrose, in Scotland. The iron of these blocks is 

 nearly as regularly crystallized as a piece of ordinary spar, as 

 may be shown by etching their polished surfaces with acid. 

 Some meteorites (a good specimen is the meteorite of Hain- 

 holtz) are composed partly of iron and partly of stone. They 

 are called siderolites, and the meteorite of Butsura, already 

 mentioned, is not far removed from this class. 



(15.) By far the greater majority of meteorites are aerolites, 

 or stones resembling grey lava, with scattered grains of iron and 

 pyrites, etc., and covered, as above described, with a shining or 

 dull black crust. In their form they are rough, unshapen pieces, 

 weighing from one to' two hundredweights in the largest, and 

 one or two ounces in the smallest specimens. The mixed 

 minerals, mostly crystalline, of which they consist, have been 

 studied with the microscope, and in the laboratory by chemical 

 analysis. By the microscope they are shown to have been 

 slowly consolidated from a state of fusion ; and by analysis they 

 are hardly to be distinguished from terrestrial lavas, excepting 

 that iron, carbon, phosphorus, and nickel are present in a state 

 uncombined with oxygen. Aerolites are, therefore, erupted or 

 unerupted foreign lavas — specimens of the igneous frame of some 

 unknown planet, melted in mountains, cooled in rocks, roughly 

 broken off and projected into space. It deserves to be men- 

 tioned, as a curious coincidence, that the earliest well-known 

 historical aerolite in existence, that of Bnsisheim, fell upon the 

 earth in the same year, and within a month of the same day, as 

 that on which America was discovered by Columbus. The 

 minerals brought back by Columbus and his contemporaries to 

 the court of Spain did not furnish with more positive proofs of 

 the existence in the Atlantic of a "New World," than the 

 presence of a meteorite upon the globe supplies to astronomers, 

 that planets are to be found in the vicinity of the earth, of 

 which the positions and capabilities are not yet computed, even 

 by Le Verrier and his most accomplished adherents. That 

 bolides and shooting- stars owe their existence to belts of 



