134 report — 1865. 



silicon, which, in union with oxygen as silica, is an abundant and equally charac- 

 teristic element of meteorites, is absent in the Sun, according to our present know- 

 ledge, in which also other elements of meteorites, including oxygen itself, are not 

 known to be present"*. It cannot be doubted, however, that by the further pro- 

 secution of spectrum-analysis, other elements will be discovered in the Sun. It 

 must be remembered also that our knowledge of meteorites is confined to a few only 

 of those which have fallen upon the Earth, and that during a very small space of 

 time, physically speaking, not exceeding a few thousand years, or perhaps even not 

 many centuries ; while the synthesis of ponderable matter in the Sun may reason- 

 ably be supposed to vary from time to time as to the particular chemical elements 

 produced. A remarkable and instructive fact, in the actual condition of science on 

 this subject, is that the metal iron is now known to be an abundant and character- 

 istic element of the Sun, of Meteorites, and of the Earth. 



In harmony with these views on the origin of meteorites is a recorded, but per- 

 haps hitherto unpublished opinion of Sir H. Davy, that they originally consist of 

 the metallic and other combustible bases of the earths and alkalies of which me- 

 teoric stones are principally composed. But whether the oxidation of these bases 

 is effected in the Earth's atmosphere, as he also suggested, or whether in some cases, 

 though not in all, oxygen is present in the original assemblage of elementary 

 vapours, and combines with certain bases, and with portions of others, as the con- 

 densation proceeds, is a difficult question. The latter theory may be thought to 

 agree better with the entire series of phenomena presented by meteors, and with 

 the constitution of meteorites as a peculiar class of mineral aggregates ; but some 

 facts relating to either branch of the subject tend to support the former. Both 

 may be true to a certain extent. The facts, however, that scarcely any oxidation 

 of the iron meteorites has taken place, and that there are no meteorites which con- 

 sist principally of oxide of iron, while there are some in which metallic iron and 

 earthy matter (oxides) are present in nearly equal proportions, but that even in 

 these no excess of oxide of iron occurs, are opposed to the supposition that meteor- 

 ites have derived any considerable part of their oxygen from the atmosphere ; with 

 which also the existence of sidphide of calcium in certain meteorites is incon- 

 sistent. 



In what part of space between the zodiacal light and the Earth the final conden- 

 sation takes place is not at present determinable. It would seem that these masses 

 must retain much of their original heat, and therefore to a great extent an aeriform 

 or vaporous condition (though one of greater density than that in which they left 

 the Sun, or even the zodiacal light, and mingled with liquid or solid matter as just 

 suggested) in the interplanetary spaces where the ether alone exists, and that 

 their entire conversion into a liquid and finally a solid form may not occur imtil 

 their arrival in a region of positive cold in the vicinity of the Earth or other planets. 

 Mr. Sorby has lately inferred, from the equable manner in which mineral ingredients 

 greatly differing in specific gravity as well as fusibdity are mingled in meteorites, 

 that their formation must have taken place in some physical iocality where the 

 force of gravitation is small ; " that they come either from the outside of a very 

 small planet much less than the moon, or else from the interior of a larger planet 

 since broken up"f. The first inference is in perfect accordance with the theory of 

 meteorites announced in this paper ; for it is evident that the force of gravity in 

 the original meteoritic masses must be very small, quite inadequate to interfere with 

 the disposition within them, and among one another, of their proximate elements, 

 however discordant in fusibility or specific gravity. It will follow also that the 



* Companion to the Almanac for 1865, p. 65. 



t Letter to the author [dated July 29, 1864. At the Meeting of the British Association 

 in September 1864, Mr. Sorby stated his inference in a somewhat different form, suggesting 

 " that the fusion and cooling " of metallic meteorites (such as the Pallas Iron) " might have 

 taken place in the metallic centre of small independent bodies, where the specific gravity was 

 nil, the meteorites being fragments of such bodies entering subsequently within the earth's 

 attraction, or that each meteorite had been itself a separate small body cooled in space." — 

 Quart. Journ. of Science (Oct. 1864) vol. i. p. 747. The last alternative, it will be seen, is 

 exactly the description of a meteoritic mass as contemplated in this paper. The equable 

 diffusion of proximate elements is equally characteristic of meteoric stones]. 



