the Fall of Meteorites on the Earth. 359 



cited instances the stones were formed by the bursting or explo- 

 sion of one large stone, but that they actually entered the atmo- 

 sphere as a group or swarm of separate individuals, surrounded, 

 as I have ventured to suggest, by what appears to us the lumi- 

 nous fireball*. I must here shortly allude to some peculiarities 

 common both to stone and iron meteorites. One is the " pitted" 

 or indented appearance usually presented on their surfaces. This 

 " pitted " surface is particularly evident on the meteoric stone 

 of Gross -Divina, which fell July 24th, 1837, in Hungary ; and 

 in the meteoric iron of Nebraska (Transactions of the Acad, of 

 Sciences of St. Louis, vol. i. no. 4, plate 21). They are best 

 developed on the side supposed to have lain backwards (see P in 

 fig. 1) . The side turned towards C is constantly more uneven and 

 rough, as though it had pressed against a homogeneous mass of 

 air, while air-currents may, like pointed flames, turn alternately 

 towards the plane P. Marginal seams, as on the stones of Stan- 

 nern, owing to the fusibility of the crust, give place to similar 

 conjectures. As for the general form, the centre of gravity must 

 have been in the forepart or front, as long as the meteorite was 

 moving through space. When rotation round an axis had once 

 commenced, and become accelerated in consequence of the pro- 

 pulsory movement diminishing, the point next in gravity must 

 have taken its place in the plane of rotation, so that an iron mass 

 of a flat form, as that of Agram is, could be propelled lying on 

 its flat side. This iron is indeed of very different aspect on each 

 of its broader planes ; the rougher of them was certainly directed 

 forward, as long as propulsion continued, the smoother surface 

 remained turned backward, and not acted upon by external agents. 

 The flat shape of the whole characterizes the Agram iron as having 

 originally filled up a vein-like narrow cavity. 



A disruptive explosion is only indubitable where, as in the 

 stone-fall of Pegu (December 27, 1857), two fragments of the 

 same stone, fitting each other exactly, have been found at a 

 certain distance (in the case in question, 10 English miles !)f ; 

 such a disruption may cause a sound, as would a millstone 

 under analogous circumstances, but certainly of less intensity 



* See Haidinger on "eine Leitfovm [typical form] der Meteoriten," 

 Vienna Acad. Proceedings, vol. xl. 1 860, page 525, note. It yet by no means 

 seems proved that meteorites do enter our atmosphere in groups, and 

 that then an explosion again scatters them as they fall to the earth; it 

 seems more probable, and certainly as possible, on the other hand, that 

 one large friable mass, constituting probably the nucleus of the single 

 fireball, as that of L'Aigle, bursts into many pieces, sometimes, no doubt, 

 into hundreds of small fragments, as well as occasionally into the finest 

 dust.— R. P. G. 



t Haidinger, vol. xlii. p. 301 of the Proceedings of the Imperial Aca- 

 demy of Vienna, "Die Meteoritenfalle von Quenggouk bei Bassein in Pegu." 



