1870.] 3IISCELLANE0US. 461 



remarking, that astronomy had shown us that the planetary- 

 bodies are worlds like our earth. This has its astronomical 

 history, and the others have doubtless their geological one. 

 Having briefly defined the province of geological science, 

 and shewed that it investigates the developement of our planet in 

 obedience to physical, chemical and biological laws, the lecturer 

 proceeded to argue that these laws were doubtless applicable, 

 mutatis mutandis, to the other bodies of this and other solar sys- 

 tems. The nebular hypothesis, which sought to explain the deri- 

 vation of a solar system from the condensation of a vaporous mass, 

 was briefly explained ; and the history of the nebulae, as made 

 known to us by the telescope and spectroscope, was noticed. The 

 sun is to be looked upon as a partially condensed mass of nebulous 

 matter, in which we have by spectroscopic examination been able 

 to detect most of the chemical elements of our own earth. 



The history of cooling and condensing nebulous matter and its 

 conversion into solid matter, like our globe, was explained : as was 

 also the doctrine of the internal heat of the earth, and its inevi- 

 table slow refrigeration and final reduction to the temperature of 

 the intcrplanetry spaces. The moon is conceived from its small 

 size to have already reached that condition, or at least to have 

 arrived at such a point that the air and ocean which once sur- 

 rounded it had been absorbed into the cold and porous mass. The 

 question of the probable identity of chemical and vital phenomena 

 in other worlds than ours was then touched upon, and the history 

 of uranolites or meteoric stones briefly noticed. It was contended 

 that in their chemical and and mineralogical constitution we see 

 evidence that they were found under conditions very like those of 

 crystalline rocks of our own globe, and that we have every reason 

 to conclude that vegetable and probably animal life played a part 

 in the celestial bodies from which these uranolites have been 

 derived. These matters are generally crystalline, but we shall 

 possibly find one day among them uncrystalline sedimentary rocks, 

 in which we may hope to find organic forms. Such materials, 

 however, make up but a very small proportion of the mass of our 

 planet, and have, moreover, much less resistance than the harder 

 crystalline rocks, so that the chances of finding them among ura- 

 nolites are comparatively small. The history of the seemingly 

 earthy and hydrocarbonaceous meteoric stones was then briefly 

 noticed. The intense heat which is developed in the flight of 

 these bodies through our atmosphere afi"orded the lecturer occasion 



Vol. V F * No. 4. 



