leaked away gravitation would draw together the particles of vapor until a drop of water was formed, and so from invisible vapor our puff of steam would have become a visible liquid. Behold a miracle! Yet the explanation is simple. As the process of cooling continued, the drop of water would become a substance of yet a different order, for there would still be some heat left in the water, and this would

Fig. 1,-representing the equator of the solar atmosphere after it has abandoned a ring at the centrifugal limit, according to Laplace's theory.

continue to escape into space, until finally, when the freezing point was reached, the drop of water, through the action. of crystallization, would turn into a ball of ice. We should thus see a puff of steam change from an invisible gas to a vapor, from a vapor to a liquid, and from a liquid to a solid body, and all through the simple process of cooling.

The creation of a world is just as simple as that. Heat

and gravitation, those arch-mechanics, which without the aid of saw or hammer have builded the universe, contended for mastery in the evolution of the earth just as they did in our puff of steam. Gravitation has always prevailed in the end, because gravitation cannot leak away like heat. The earth was first a nebula - perhaps an invisible gas-then in the state of a liquid, and finally it became, as we see it, solid, cool and habitable. It is only a question of the

EQUATOR OF SOLAR ATMOSPHERE

Fig. 2,-representing the ring broken into several segments.

amount and intensity of heat. Given heat enough and it would be as easy to turn the earth into a nebulous cloud as to melt a snow-flake.

Laplace gives us one hypothesis of the origin of the solar system, which I will endeavor to illustrate. (At this point the lights in the church were extinguished, and a picture of a revolving nebula was thrown upon the screen,

which was made to throw off concentric rings of nebulous matter. These rings being thinner at some point than elsewhere, broke at the thinnest place, condensed into oblate spheroids, and, with continued rotation, into spheres. See Figures 1, 2 and 3, pages 56, 57 and 58.) The rotating nebulous mass contracts by loss of heat; and, accord

EQUATOR OF SOLAR ATMOSPHERE

Fig. 3.-representing the fragments of the ring, as shown in Fig. 2, gathered up into spherical form by the mutual attraction of their molecules. It will be seen that the spheres must naturally revolve around the solar equator in the same direction that it moves, and also rotate on their axes in the same direction. Moving in nearly the same orbit, they would next be gathered into a single sphere, moving around the sun in the same direction, but with eccentricities dependent upon the force and directions of their collisions at the time of their uniting.

ing to a well-known law, as it contracts its velocity of rotation increases. When the centrifugal and centripetal forces at the equator of the mass balance one another a ring

of matter separates off and is left suspended around the contracting nucleus. Other rings form in the same way, until a series of them surrounds the central mass which has contracted into a sphere. But these rings are not everywhere of equal thickness, and the tendency of their constituent particles to gravitate toward the thickest part causes them to separate at the thinnest point, and finally to form oblate spheroids of nebulous matter, which ultimately condense into spheres.

If

Let us illustrate this by supposing that we have a grindstone, on which, while rotating, we pour a film of water. we revolve it fast enough the water will fly off, but we may revolve it just fast enough to cause the centrifugal and centripetal forces to balance. Then if we could make the stone contract in size, the layer of water would be left suspended in the air as a ring surrounding the revolving grindstone. In the case of the revolving nebula, the contraction of the inner sphere of nebulous matter assists in the separation of

the surrounding ring. The spheres formed from the rings would in turn throw off additional rings to form satellites.

Now, if we look at the solar system, we discover in its character and movements strong confirmation of this hypothesis. We find there just what would naturally occur were this theory a correct one. Each planet revolves around the central orb at its own speed and in its own distinct orbit, and in a direction in common with the rotation of the original nebulous mass. The nebular theory constitutes therefore a conclusive and nearly satisfactory explanation of the way in which those great demiurgic forces, heat and grav

In the plan

itation, have wrought out the results we see. et Saturn we have an example, patent to any observer, of the probable truth of the nebular theory. (A representation of the planet was thrown upon the screen. See Fig. 4, page 59.) Through any telescope, even of moderate power, we may see that this planet is surrounded by rings, which, being nearly equal in density, have not been broken up into satellites by the unequal attraction of their various parts. Though these rings seem solid and uniform through the telescope, it is reasonably certain that they are composed of many small bodies, rotating in the same plane, and so presenting the appearance of a flat surface.