DAR W1NISM AND OTHER BRANCHES OF SCIENCE. 34^ 



rupture again takes place and a second planet is pro- 

 duced. 



Again, and still again, the same process is repeated, un- 

 til at length we recognise the central mass as our great and 

 glorious sun, diminished by incessant contraction, though 

 still vast and brilliantly hot. One of the lesser fragments 

 which he cast oiF has consolidated into our earth, while 

 other fragments, greater and smaller, have formed the 

 rest of the host of planets. There are many features in 

 the planets which seem to corroborate this view of their 

 origin. They all revolve around the sun in the same 

 direction ; they all rotate on their own axes in the same 

 direction, that direction being also coincident with the 

 sun's rotation on its axis. Most astronomers are agreed 

 that the history of the solar system has been something of 

 the kind that I have ventured to describe. Astronomers 

 were thus the first evolutionists ; they had sketched out a 

 majestic scheme of evolution for the whole solar system, 

 and now they are rejoiced to find that the great doctrine 

 of Evolution has received an extension to the whole domain 

 of organic life by the splendid genius of Darwin. 



At its first separation from the shrinking central nebula, 

 our earth was probably a mass of glowing gas, of far 

 greater volume than it is at present. Gradually the 

 earth parted with its heat by radiation, and commenced 

 to shrink also. The temperature was so high, that iron 

 and other still more refractory substances were actually in 

 a state of vapour, but, as the temperature fell, these sub- 

 stances could not remain in the gaseous form ; they con- 

 densed first into liquids, these liquids coalesced into a vast 

 central mass, and still that mass went on cooling until ita 



