After all, we may deceive ourselves in thinking, as we are apt to do, that explosive energies lock themselves up only in small masses of matter. There are many causes producing explosions in nature, every volcanic eruption manifests the activity of some of them. Think of the giant power of confined steam; if enough steam could be suddenly generated in the center of the earth by a downpour of all the waters of the oceans, what might not the consequences be for our globe? In a smaller globe, and it has never been estimated that the original asteroid was even as large as the moon, such a catastrophe would, perhaps, be more easily conceivable; but since we are compelled in this case to assume that there was a series of successive explosions, steam would hardly answer the purpose; it would be more reasonable to suppose that the cause of the explosion was some kind of chemical reaction, or something affecting the atoms composing the exploding body. Here Dr Gustav Le Bon comes to our aid with a most startling suggestion, based on his theory of the dissipation of intra-atomic energy. It will be best to quote him at some length from his book on _The Evolution of Forces._ “It does not seem at first sight,” says Doctor Le Bon, very comprehensible that worlds which appear more and more stable as they cool could become so unstable as to afterward dissociate entirely. To explain this phenomenon, we will inquire whether astronomical observations do not allow us to witness this dissociation. We know that the stability of a body in motion, such as a top or a bicycle, ceases to be possible when its velocity of rotation descends below a certain limit. Once this limit is reached it loses its stability and falls to the ground. Prof. J. J. Thomson even interprets radio-activity in this manner, and points out that when the speed of the elements composing the atoms descends below a certain limit they become unstable and tend to lose their equilibria. There would result from this a commencement of dissociation, with diminution of their potential energy and a corresponding increase of their kinetic energy sufficient to launch into space the products of intra-atomic disintegration. It must not be forgotten that the atom being an enormous reservoir of energy is by this very fact comparable with explosive bodies. These last remain inert so long as their internal equilibria are undisturbed. So soon as some cause or other modifies these, they explode and smash everything around them after being themselves broken to pieces.