OBSERVATIONS OF LUMINOUS METEORS, 383 



Ibbenbiihren, Germauy, 1870, June 17, 2 p.m. (local time). — In the same 

 No. of Poggendorif 's 'Aunalen ' as that last cited (of July 1872) is contained 

 the analysis by Dr. tr. vom Eath, and the microscopic examination of thin 

 sections by Dr. 0, Biichuer, of a meteorite which fell in Westphalia in Juno 

 1870. The principal meteorite, weighing- 2| lbs., struck the earth some 

 distance from a coimtryman who heard it fall, and, when passing by the same 

 place two days afterwards, observed the hole where it had penetrated the earth 

 of a well-trodden footpath to a depth of 2^ feet. It was almost uninjured, 

 being covered, except at some corners, by the usual black crust. It was 

 brought, several months after its discovery, to Dr. Heis at Miinster, by whom 

 some of the particulars attending its fall are related. A lightning-like flash, 

 followed in about one minute by thunder, preceded the faU of the stone, 

 which was heard striking the earth about three minutes after the flash. A 

 small fragment, weighing about 1 oz., was found 300 or 400 paces from the 

 larger stone ; and no other fragments (the ground having since been tilled) 

 could be afterwards discovered. The black crust is dull and extremely thin, 

 its rippled texture and penetration into fine crevices of the stone being only 

 discernible by means of a magnifying lens. As seen at the fractures, the 

 interior mass is greyish white, compact, and contains no grains of metallic 

 iron (which, with ckrome-iron, are absent in this meteorite), but interspersed 

 yellowish crystalline grains, generally minute, but at one of the exposed sur- 

 faces reaching to ^ inch, and even to 1 inch in diameter. The microscopic 

 sections show that this structure is continuous, the whole mass being com- 

 posed of the same crystalline ingredients in larger or smaller grains. The 

 specific gravity of the grains is about 3-425, and that of the matrix about 

 3-405, Chemical analysis also leads to the same conclusion, the separate 

 crystals being found to have the composition — 



Oxides of manga- 

 Silica. Iron protoxide. Magnesia, nese and calcium. Alumina, Total. 



54-51 17-53 26-43 1-33 1-26 101-06 



Oxygen 29-07 14-82 0-59 



which is also the composition of the matrix. Classing the manganese with 

 the iron, and the calcium oxide with the magnesia, the mineral substance is 

 a bronzite, or enstatite (EO, Si 0,), in which the atomic proportion of ii-on 

 oxide to magnesia is as 4 : 11. This simple composition is almost unique 

 among meteorites; but the aerolite of Shalka (India, November 30th, 1850), 

 as analyzed by G. Eose and Eammelsberg, consists mainly of a bronzite 

 (86-43 per cent., together with olivine 10-92, and chrome-iron 2-11 per cent,), 

 having almost identically the same composition, viz, : — 



Silica. Iron protoxide. Magnesia, Calcium oxide. Sodium oxide. Total, 

 55-55 16-53 27-73 0-09 0-92 100-82 



The single-silicate composition of the Ibbenbiihren meteorite occurs again 

 remarkably in the nearly pure bronzite or enstatite materials of the aerolite 

 of Menegaum (India, June 29, 1843), as determined by Eammelsberg and 

 Maskelyne, the analysis of the crystalline portion of which (as given by 

 Maskelyne), fi'om which that of the matrix scarcely differs, was as follows : — 



Silica. Iron protoxide. Magnesia. Calcium oxide. Total. 

 55-70 20-54 22-80 1-32 100-36 



differing only slightly in its specific gravity (3-198), and in a rather higher 



