28 EVOLUTION 



CHAPTER III 

 THE STORY OP THE EARTH 



THE first phase in the story of the earth is, then, a 

 large mass of semi-gaseous, semi-liquid matter that has 

 been detached in some form from the condensing nebula. 

 It consists broadly of the same material as the other 

 bodies that will make up the solar system, and is subject 

 to the action of the same forces. Let us take it as one 

 of the incandescent arms that reaches out spirally from 

 the centre, and is gradually cut off altogether. The 

 inexorable pressure of ether will not permit it to remain 

 spread out in its thin condition over hundreds of thou- 

 sands of miles of space. Some thicker knot, as we may 

 conceive it, in the fiery cloud becomes a centre of gravita- 

 tion, and the outstretched filmy mass slowly gathers into 

 a ball. There is nothing to arrest the movement round 

 the centre of the nebula which it had as part of its 

 structure, and the great ball now circles rapidly round 

 the parent ball. 



Still the enormous pressure of ether the reader will 

 remember that we are taking this, provisionally, as the 

 source of gravitation crushes the ball closer and closer 

 together. Every particle in it is oscillating rapidly, and 

 collisions between them increase as they are forced within 

 a smaller space. The temperature of the mass rises until 

 it reaches an incandescence far surpassing anything that 

 we can reproduce. Assuming that the detached mass 

 reaches in its development a temperature at all corre- 

 sponding to that of condensing stars, there would be a 

 phase of evolution of great interest 



