EVOLUTION: WHAT IT IS NOT, AND V/HAT IT IS. 641 



plest terms and most elementary dimensions, lias received many hard 

 knocks from later astronomers, and has been a good deal bowled over, 

 both on mathematical and astronomical grounds, by recent investi- 

 gators of nebulae and meteors. Observations on comets and on the 

 sun's surface have lately shown that it contains in all likelihood a 

 very considerable fanciful admixture. It isn't more than half true ; 

 and even the half now totters in places. Still, as a vehicle of popu- 

 lar exposition the crude nebular hypothesis in its rawest form serves 

 a great deal better than the truth, so far as yet known, on the good 

 old Greek principle of the half being often more than the whole. The 

 great point which it impresses on the mind is the cardinal idea of the 

 sun and planets, with their attendant satellites, not as turned out like 

 manufactured articles, ready made, at measured intervals, in a vast 

 and deliberate celestial orrery, but as due to the slow and gradual 

 working of natural laws, in accordance with which each has assumed 

 by force of circumstances its existing place, weight, orbit, and motion. 



The grand conception of a gradual becoming, instead of a sudden 

 making, which Kant and Laplace thus applied to the component bodies 

 of the universe at large, was further applied by Lyell and his school to 

 the outer crust of this one particular petty planet of ours. While the 

 astronomers went in for the evolution of suns, stars, and worlds, Lyell 

 and his geological brethren went in for the evolution of the earth's 

 surface. As theirs was stellar, so his was mundane. If the world be- 

 gan by being a red-hot mass of planetary matter in a high state of 

 internal excitement, boiling and dancing with the heat of its emotions, 

 it gradually cooled down with age and experience, for growing old is 

 growing cold, as every one of us in time, alas ! discovers. As it passed 

 from its tiery and volcanic youth to its staider and soberer middle age, 

 a solid crust began to form in filmy fashion upon its cooling surface. 

 The aqueous vapor that bad floated at first as steam around its heated 

 mass condensed with time into a wide ocean over the now hardened 

 shell. Gradually this ocean shifted its bulk into two or three main 

 bodies that sank into hollows of the viscid crust, the precursors of At- 

 lantic, Pacific, and the Indian Seas. Wrinklings of the crust, produced 

 by the cooling and consequent contraction, gave rise at first to baby 

 mountain-ranges, and afterward to the earliest rough drafts of the still 

 very vague and sketchy continents. The world grew daily more com- 

 plex and more diverse ; it progressed, in accordance with the Spen- 

 cerian law, from the homogeneous to the heterogeneous, and so forth, 

 as aforesaid, with delightful regularity. 



At last, by long and graduated changes, seas and lands, peninsulas 

 and islands, lakes and rivers, hills and mountains, were wrought out by 

 internal or external energies on the crust thus generally fashioned. 

 Evaporation from the oceans gave rise to clouds and rain and hail- 

 storms ; the water that fell upon the mountain-tops cut out the val- 

 leys and river-basins ; rills gathered into brooks, brooks into streams, 



VOL. XXXII. — 41 



