1865.] Cosmical and Geological Philosophy. - 125 



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 reasonably 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 characteristic element of the Sun, of 

 Meteorites, and of the Earth. 



In harmony with these views on the origin of Meteorites is a recorded 

 but perhaps hitherto unpublished opinion of Sir H. Davy, that they origi- 

 nally consist of the metallic and other combustible bases of the earths and 

 alkalies of which Meteoric 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 condensation proceeds, is a diffi- 

 cult 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 rela- 

 ting 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 consist 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 meteorites have derived any conside- 

 rable part of their oxygen from the atmosphere ; with which also the exist- 

 ence of sulphide of calcium in certain meteorites is inconsistent. 



In what part of Space between the Zodiacal Light and the Earth the final 

 condensation 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 Suri 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 until 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 fusibility are mingled in 

 meteorites, that their formation must have taken place in some physical 

 locality 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" *. 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 

 * Letter to the Author. 



