4 PRESIDENTS ADDRESS. 



intensely hot, though the existence of heat in the first instance 

 does not seem to be an absolutely necessary postulate, it being quite 

 conceivable that this immense mass of matter may have been 

 able to generate sufficient heat, by means of the internal motion 

 with which it was endowed. 



The matter in question was a homogeneous mass of atoms, each 

 being an exact counterpart of every other, all being in motion ; 

 but the homogeneity continued only until these atoms, in obedience 

 to a law impressed upon them, began to arrange themselves in 

 various manners, and thus to form molecules which, according to 

 their arrangement among themselves and their distances from 

 each other, formed the different elements with which we are 

 acquainted, and no doubt others which we have not yet 

 discovered. 



The whole nebulous mass began to part with its heat, but, as there 

 was at first no space not already filled with matter equally hot, it 

 is difficult to determine whether the lost heat became latent, or 

 was converted into motion, electricity, or light, or (if the theory 

 that heat is not a condition of matter, but an actual fluid sub- 

 stance, is tenable) into some other form of matter, or what 

 became of it. 



However this may be, the diffused matter gradually cooling 

 and shrinking, began to curdle into vast divisions, each of which 

 was the commencement of a system, such as our own solar system; 

 and these embryo systems, having acquired a circular motion, 

 and continuing to cool and consolidate, presently threw off rings, 

 which, on breaking and rolling themselves together, became 

 planets, and some of these again in due course threw off other 

 rings, which became secondary planets or moons. 



The earth, which was originally one of the rings thrown off by 

 thn sun, was at first a seething mass of intense heat, and, being then 

 self-luminous, shone like a star ; but, continuing to cool and con- 

 solidate, its surface, although racked for long ages by terrific 

 explosions, earthquakes, tornadoes, and other disturbances, con- 

 tinued to grow firmer, and, ultimately, as things became more 

 settled, and further consolidation made it possible, seaweeds, 



