This is the nebular theory of system-building. We see that in it three things are pre-supposed, or taken for granted; first, matter in a state of slowly rotating glowing vapor; second, a law of gravitation; third, a law of tangental motion. In the one hundred years since this hypothesis was first developed by Laplace, no one has ever seen the glowing vapor consolidating to suns. These processes are far too long to have been within any human observation, but long and careful study has enabled man to learn some of the wonderful laws by which the universe is governed. Let us see if this explanation of Laplace fits anything which we find in our solar system. Has any great globe rings wheeling about it? Yes; the huge planet Saturn has a triple ring. Besides this ring, Saturn has eight moons, as if some other ring had broken up, and its parts had come together into satellites. The planet Jupiter has four satellites, Mars has two, Uranus has four, Neptune one, and our earth has one, called the moon. There are also in our system a number of very small planets, closely grouped, called asteroids. In the nebular hypothesis these asteroids might represent matter cast off at first in rings, breaking and finally condensing into spheres. Here we find in our solar system between the larger planets Mars and Jupiter a splendid zone of minor planets. Comets are also explained by this theory, as large masses of material, too evenly balanced among the planets to yield to the attraction of any one of them, but owning the attraction of the sun, the centre of gravity of our entire system, and wheeling about it in vast elliptical orbits. Finally it is supposed by some that the general speed of our entire system is slackening. This “slowing up” of the system is supposed to be due to the friction of ether which pervades all space, and also to a great depth of hot and expanded material more thin than air, which extends about the sun, wrapping it in a vast, fine mantle of gas, as our atmosphere surrounds our globe. But if it is true that the motion of our system is growing slower, it will be many millions of years before the change will be great enough to notice; just as, granting that the sun is losing its heat, it will be many millions of years before it ceases to shine upon and warm our globe. In fact the lessening of speed in the solar system, and the lessening of sun heat, are as yet only theories and not proved facts. The sun will shine on, and the worlds will whirl around it, through time which no human mind can calculate.