Dr. J. Croll on the Origin of MebulcB* 5 



and before the mass has had sufficient time to pass completely 

 into the gaseous condition. The two bodies coming into col- 

 lision with such enormous velocities would not rebound like 

 two elastic balls, neither would they instantly be converted 

 into vapour by the encounter. The first effect of the blow 

 would be to shiver them into fragments, small indeed as com- 

 pared with the size of the bodies themselves, but still into 

 what might be called in ordinary language immense blocks. 

 Before the motion of the two bodies could be stopped, they 

 would undoubtedly interpenetrate each other; and this of course 

 would break them up into fragments. But this would only be 

 the work of a few minutes. Here, then, we should have all 

 the energy of the lost motion existing in these blocks as heat 

 (molecular motion), while they were still in the solid state; for 

 as yet they would not have had sufficient time to assume the 

 gaseous condition. It is obvious, however, that the greater 

 part of the heat would exist on the surface of the blocks (the 

 place receiving the greatest concussion), and would continue 

 there while the blocks retained their solid condition. It is 

 difficult in imagination to realize what the temperature of the 

 surfaces would be at this moment. For, supposing the heat 

 were uniformly distributed through the entire mass, each 

 pound, as we have already seen, would possess 100,000,000,000 

 foot-pounds of heat. But as the greater part of the heat would 

 at this instant be concentrated on the outer layers of the blocks, 

 these layers would be at once transformed into the gaseous 

 condition, thus enveloping the blocks and filling the inter- 

 spaces. The temperature of the incandescent gas, owing to 

 this enormous concentration of heat, would be excessive, and 

 its expansive force inconceivably great. As a consequence the 

 blocks would be separated from each other, and driven in all 

 directions -with a velocity far more than sufficient to carry 

 them to an infinite distance against the force of gravity were 

 no opposing obstacle in their way. The blocks by their mutual 

 impact would be shivered into smaller fragments, each of which 

 would consequently become enveloped in incandescent gas. 

 These smaller fragments would in a similar manner break up 

 into still smaller pieces, and so on until the whole came to 

 assume the gaseous state. The general effect of the explosion, 

 however, would be to disperse the blocks in all directions, ra- 

 diating from the centre of the mass. Those towards the outer 

 circumference of the mass, meeting with little or no obstruc- 

 tion to their onward progress, would pass outwards into space 

 to indefinite distances, leaving in this manner a free path for 

 the layers of blocks behind them to follow in their track. 

 Thus eventually a space, perhaps twice or even thrice that in- 



