Page:The evolution of worlds - Lowell.djvu/254

216 able the sensation of spreading appalling news, that the press of America, and incidentally Europe, took fire, with the result, so I have been written, that by the time the pictured catastrophe reached the Pacific "it had assumed the dimensions of a first magnitude fact."

This is the first way in which our world may come by its death. It is possible, but unlikely. For our Earth, long before that, is morally certain to perish otherwise.

The second mode is one, incident to the very constitution of our solar system. It follows as a direct outcome of that system's mechanical evolution, and may be properly designated, therefore, as due to natural causes. It might be diagnosed as death by paralysis. For such it resembles in human beings, palsy of individual movement afflicting a planet instead of a man.

Tidal friction is the slow undermining cause; a force which is constantly at work in the action of every body in the universe upon every other. As we previously explained, the pull of one mass upon another is inevitably differential. Not only is the second drawn in its entirety toward the first, falling literally as it circles round, but the nearer parts are drawn more than the centre and the centre more than those farthest away. We may liken the result to a stretched rotating rubber ball, with, however, one important difference,—that each layer is more or less free to shear over the others. The bulge, solicited by the rotation to keep up, by the