DH. W. FLTGHT, GREENLAND METEORITES. 4G5 



important part in the economy of nature in supplying phosphorus 

 to soils already exhausted by the growth of crops. His observa- 

 tions, moreover, are of value through the light they throw on the 

 theories of star-showers, aurora3, &c. The small but continuous 

 increase of the mass of our planet, which appears to take place, 

 may lead students of geology to modify the view at present held, 

 that from the time of the first appearance of vegetable and animal 

 life upon our planet it has undergone no cliange, in a quantitative 

 sense ; in other words, that the geological changes which have 

 occurred have been confined to a difference in the distribution of 

 material, and not to the introduction of new material from without. 



When the instances of the fall of soot-like particles, blood-rain, 

 sulphur-showers, &c., which have from tim.e to time been de- 

 scribed, are considered, the view pronounced by Chladni, that 

 these phenomena are due to the precipitation of large quantities 

 of cosmical dust, appears of great import. The black carbona- 

 ceous substances which fell with the Hessle meteorites, and coated 

 some of them, may be quoted as an illustration. Some meteo- 

 rites, moreover, are so loose and friable in texture that they are 

 very readily reduced to powder, as the Ornans meteorite (1868, 

 July 11th), while that which fell at Orgeuil (1864, May 14th) 

 breaks up when placed in water. If this stone had not fallen on 

 a day when the atmosphere was dry, portions, if not the whole of 

 it, would probably have reached the earth's surface in the form 

 of powder. These atmospheric deposits may have a very varied 

 composition. The dust which fell in Calabria, in 1817,* con- 

 tained chromium. The red rain that fell at Blankenberg, in 

 Flanders,! in 1819, owed its colour to the presence of cobalt- 

 chloride. 



In 1872 three papers were published in the Comptes Rendus,\ 

 on the origin of polar aurorse, which called forth one from 

 Baumhauer,§ where he refers to a theory as to their origin pro- 

 pounded in his thesis De ortu lapidum meteoricormn (Utrecht, 

 1844). After having shown the connexion which apparently 

 exists between the planets, their satellites, the comets, the shoot- 

 ing-stars, the meteorites ('* qui, pour 7noi, sont de petites planetes^^), 

 and the zodiacal light, a disc of asteroids or cosmical matter massed 

 together near the sun, he gives expression to the following views 

 respecting the polar aurorae : Not only solid masses, large and 

 small, but clouds of " uncondensed " matter probably enter our 

 atmosphere (probabile etiam est nebulas materiel primigeniae sine 

 nucleo condensato in atmosphseram venire). If from our know- 

 ledge of the chemical composition of the stones and irons which 



* L. Sementini. Atti della Beale Acad, delle Scienze, 1819, i. 285 ; 

 Gilbert's Ann., Ixiv. 327. 



f Meyer and Van Stoop, Gilbert's Ann., Ixiv. 335. 



J LeMarechal Vaillant, Compt. Rend., Ixxiv. 510 and 701. — J. Silbermann, 

 Compt. Rend., Ixxiv. 553, 638, 959, and 1 182.— H. Tarry, Compt. Rend., Ixxiv. 

 549. 



§ E. H. Vou Baumhauer, Compt. Rend., Ixxiv. 678. 



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