OBSERVATIONS OF LUMINOUS METEORS. " 167 



doubtedly meteoric, and two such have been found in Great Britain. The 

 falls of eight stony meteorites have been recorded in this country, of which 

 the last happened at Killetcr, in Ireland, on the 29th of April, 1844. A 

 Section of the llowton siderite for analysis wiU shortly be made ; and the 

 foregoing description of the meteorite, and of the circumstances attending 

 its fall, are extracted from an account of the occurrence of the aerosiderite by 

 Professor Maskelync, in ' Nature ' of July 27th, 1876 (vol. xiv. p. 472). 



llegarding the origin of tho remarkable pittings of the surfaces of aerolites 

 and aerosidcrites, an opinion was lately expressed and advocated by Daubree *, 

 that in their flight through the air they undergo erosion and excavation by joint 

 effects of fusion and combustion, assisted mainly by air vortices attacking most 

 violently certain portions of their surface. An important paper on this subject, 

 by Professor Maskelyne, was published more recently in the ' Philosophical 

 Magazine ' of August 1876. It is true that pittings identical in appearance 

 with those of meteorites are found on the surfaces of certain large grains of 

 powder blown unconsumed from the mouths of tho large modern rifled 

 ordnance (excellent specimens of this kind received from Professor Abel 

 and Major Noble having been shown by Professor Maskelyne to Mr. 

 Daubree in the summer of 1875) ; but two important grounds for exception, 

 in regard to this explanation, are pointed out by Professor Maskelyne, 

 which must not be overlooked. The closest examination of the molten 

 glaze with which, like other parts of their surfaces, the pittings or depres- 

 sions of meteorites are coated over, shows no indications of vorticose action 

 of the air, although stream-lines of the glaze from front to rear are of 

 freqiient and conspicuous occurrence. The process of atmospheric combina- 

 tion, or combustion, is also rare, if not entirely absent, during the period of 

 most intense operation of the heat, as is shown by particles of metallic iron 

 which are occasionally found imbedded in the glaze, and even by cases 

 where the highly oxidizable mineral Oldhamite (calcium sulphide), occurring 

 in spherules in the Bustee meteorite, is glazed over equally with the Augite, 

 without offering any signs of combustion or of the production of cavities 

 where they are exposed. On the other hand, the readier fusibility of some 

 constituent minerals of meteorites appears to determine the formation of 

 depressions of the surface where they present themselves ; and among the 

 magnesian silicates which form the principal materials of stony meteorites, it 

 appears that the more ferruginous varieties are somewhat more fusible than 

 the more purely mngnesiferous silicates, which, with minor assemblages of 

 other minerals, enter, in very various proportions, into the composition 

 of the stony masses of aerolites. If the entire process of surface-melting 

 and abstraction which meteorites undergo is thus correctly represented, the 

 question of the amoimt of fracture and division into separate parts which they 

 may suffer by their collision with the atmosphere is one which is yet undecided ; 

 and many difficulties beset the inquiry if meteorites are single bodies, or if, 

 as numerous examples appear to testify, they sometimes enter the atmo- 

 sphere in swarms. An important dissertation on this question by F. Mohr 

 appeared during the past year in Liebig's ' Annalen'f ; and a paper by Yon 

 Tschermak (of which a brief abstract was presented in last year's Ilepoi*t), 

 on the same subject of the probable origin and of the original forms of 

 aerolites, is now translated in extenso in the Supplementary No. for June 

 1876 of tho ' Philosophical Magazine.' 



* ' Comptes Eeudus,' April 24tb, 1876, 

 t Vol. clxxix. pp. 257-282. 



