466 DR. W. FLIGHT, GREENLAND METEORITES. 



fall to the earth's surface, we may draw any couclusion respecting 

 the chemical constitution of these clouds of matter, it appears 

 possible that, as many of these stones consist partly, and the irons 

 almost entirely, of iron and nickel, the attenuated cloud-like 

 matter may also contain a considerable proportion of these 

 magnetic metals. 



Let such a cloud, the greater part of the constituents of which 

 have magnetic characters, approach our earth, which we have 

 been taught to regard as a great magnet : it will evidently be 

 attracted towards the poles of this magnet, and, penetrating our 

 atmosphere, the particles which have not been oxidised and are in 

 a state of extremely fine division will, by their oxidation, gene- 

 rate light and heat, the result being the phenomenon which we 

 term a polar aurora. Observations have shown that the seat of 

 these phenomena is about, not the geographical, but the magnetic 

 poles. Not a few facts, even at that time, could be advanced in 

 support of the theory, which assumes the occasional presence of 

 metallic particles in the higher regions of our atmosphere. More 

 than once such particles had been discovered in a fall of hail. 

 Eversmann * found in the hailstones which fell on the 11th June, 

 1825, at Sterlitamak, 200 wersts from Orenburg, Siberia, crystals 

 of a compound of iron and sulphur, in which Hermann found 

 90 per cent, of that metal, j In hail which fell in the province 

 of Majo in Spain on the 21st June 1821, Pictet J found metallic 

 nuclei which were proved to be iron ; and the hail which fell in 

 Padua on the 26th August 1834, was observed to contain nuclei 

 of an ashy grey colour. The larger ones were shown by Cozari § 

 to be attracted by the magnet, and to contain iron and nickel. 

 ** It would," wrote Baumhauer, " be very interesting, in verifica- 

 " tion of this theory of the origin of polar aurorae, to detect in 

 " the soil of polar areas the presence of nickel." This theory, 

 which at the time it was promulgated appeared so rash that it 

 met with severe criticism by the great Berzelius,|| has gained 

 support from recent researches ; among others, the discovery by 

 Heis of the simultaneity of boreal and austral aurorae, the relation 

 between the aurorae and the meteor-showers, the perturbations of 

 the telegraph-lines, which not only accompany, but forecast, an 

 auroral display ; and the identity of the light, principally that of 



* E. Von Eversmann, Archiv fur die gesmmnte Naturlehre, iv. 196. — A. 

 Neljubin, Archiv fur die gesammte Naturlehre, x. 378. — R. Hermann, Gilbert's 

 Ann., Ixxvi. 340. 



f Though Von Baumhauer cites this instance, it does not appear that the 

 metallic character of the " crystals " was fully established in this case. Nel- 

 jubin found them to consist of 70 per cent, iron-oxide, and 17*5 per cent, of 

 other metallic oxides. In fact, this substance appears to have been an impure 

 limonite, Uke that which fell at Iwan, in Hungary, on the 10th of August 

 1841, and was probably not meteoric. 



X Pictet, Gilbert's Ann., Ixxii. 436. 



§ D. L. Cozari, Ann. Sc. Reyn. Lomb., 1834, Nov. e Dec. ; New Ed. Phil. 

 Jour., xxxvii. 83. 



II Jahresbericht, xxvi. (1847), 386. 



