Page:Popular Science Monthly Volume 7.djvu/224

212 On our earth its furnace is the sun, and its boiler the moist lands, the rivers, lakes, and oceans. But it is evident that its mode of operation would not be substantially affected if the heat were supplied not as in our case from an outside source, but from the original internal heat of the sun or planet itself. So, also, the essential nature of the cyclone would not be altered whatever be the kind of vapor condensed, whether it be of water, of iron, of copper, of gold, or of granite. The above derivation of the power of the cyclone is therefore applicable throughout time and space.

For the condensation of any vapor whatever would present very much the same phenomena as those with which we are familiar. Let us suppose the earth of such a temperature as to keep iron in nearly the same condition relatively as water is now; that is, partly vapor floating in the atmosphere, partly fluid gathered in oceans, lakes, and rivers, and partly like solid snow and ice as in the colder seasons and latitudes. Evaporation would go on at the surface of the fluid iron until the atmosphere became nearly saturated. As soon as condensation began an ascending current would be formed. Toward the bottom of this current the winds would rush in spirals just as they do now. As the vapor of iron rose and came to the strata of less and less pressure and temperature, it would expand, cool, and condense, and descend in molten showers of liquid metal. Or, if the temperature were low enough, or the summit of the storm high enough, a shower of iron hail, or snow, would be the result.

Nor need we stay our imagination here. The time was, when our globe had no solid or liquid nucleus, but was wholly gaseous. It was literally an atmosphere, and nothing else. All the matter of the earth then floated, a vast globular ocean of vapor. The power which kept its particles apart was heat. Before these particles could come together and the solid foundations of the world be laid, it was necessary that the heat should be got rid of. The means by which this purpose was accomplished was mainly the cyclone. Around the limits of the vaporous world radiation into empty space could go on rapidly. Not so in the interior. Conduction of heat even along a bar of iron is a very slow process. It is million-fold slower through gas. Hence, the quickest way of carrying the heat from the interior to the summit of the atmosphere, where it might escape, was, to carry up the matter itself which contained a large amount of heat, either actual or potential. This work was accomplished by the cyclone.

Let us endeavor to form some conception of the cyclone of primeval times. Let us fancy ourselves in the solar system ere yet it became separated into insulated worlds, and just as condensation is going on. Gases of different specific gravities tend to intermingle even though at first arranged in separate layers above one another. Many of the gases would also be of nearly the same specific gravity. Hence, although in general the denser gases would tend together toward the