Omega

the universe. Doubtless, our logic is radically incomplete, puerile even, in comparison with the real and eternal Truth, and might be justly compared with that of two ants talking together about the history of France. But, confessing the modesty which befits the finite in presence of the infinite, and acknowledging our nothingness as compared with the universe, we cannot avoid the necessity of appearing logical to ourselves; we cannot assume that the abdication of reason is a better proof of wisdom than the use of it. We believe that an intelligent order presides over the universe and controls the destiny of worlds and their inhabitants; that the larger members of the solar system must last longer than the lesser ones, and, consequently, that the life of each planet is not equally dependent upon the Sun, and cannot, therefore, continue indefinitely, any more than the Sun itself. Moreover, direct observation confirms this general conception of the universe. The Earth, an extinct sun, has cooled more rapidly than the Sun. Jupiter, so immense, is still in its youth. The Moon, smaller than Mars, has reached the more advanced stages of astral life, perhaps even has reached its end. Mars, smaller than the Earth, is more advanced than the Earth and less so than the Moon. Our planet, in its turn, must die before Jupiter, and this, also, must take place before the Sun becomes extinct.

Consider, in fact, the relative sizes of the Earth and the other planets. The diameter of Jupiter is eleven times that of the Earth, and the diameter of the Sun about ten times that of Jupiter. The diameter of Saturn is nine times that of the Earth. It seems to us, therefore, natural to believe that Jupiter and Saturn will endure longer than our planet, Venus, Mars or Mercury, those pigmies of the system!

Events justified these deductions of science. Dangers lay in wait for us in the immensity of space; a thousand accidents might have befallen us, in the form of comets, extinct or flaming suns, nebulae, etc. But the planet did not perish by an accident. Old age awaited the Earth, as it waits for all other things, and it grew old faster than the Sun. It lost the conditions necessary for life more rapidly than the central luminary lost its heat and its light.

During the long periods of its vital splendor, when, leading the chorus of the worlds, it bore on its surface an intelligent race, victors over the blind forces of nature, a protecting atmosphere, beneath which went on all the play of life and happiness, guarded its flourishing empires. An essential element of nature, water, regulated terrestrial life; from the very beginning this element had entered into the composition of every substance, vegetable, animal and human. It formed the active principle of atmospheric circulation; it was the chief agent in the changes of climate and seasons; it was the sovereign of the terrestrial state.

From century to century the quantity of water in the sea, the rivers and the atmosphere diminished. A portion of the rain water was absorbed by the Earth, and did not return to the sea; for, instead of flowing into the sea over impermeable strata, and so forming either springs or subterranean and submarine watercourses, it had filtered deeper within the surface, insensibly filling every void, every fissure, and saturating the rocks to a great depth. So long as the internal heat of the globe was sufficient to prevent the indefinite descent of this water, and to convert it into vapor, a considerable quantity remained upon the surface; but the time came when the internal heat of the globe was entirely dispersed in space and offered no obstacle to infiltration. Then the surface water gradually diminished; it united with the rocks, in the form of hydrates, and thus disappeared from circulation.

Indeed, were the loss of the surface water of the globe to amount only to a few tenths of a millimeter yearly, in ten million years none would remain.

This vapor of water in the atmosphere had made warmth and life possible; with its disappearance came cold and death. If at present the aqueous vapor of the atmosphere should disappear, the heat of the sun would be incapable of maintaining animal and vegetable life; life which, moreover, could not exist, inasmuch as vegetables and animals are chiefly composed of water.5

The invisible vapor of water, distributed through the atmosphere, exercises the greatest possible influence on temperature. In quantity this vapor seems almost negligible, since oxygen and nitrogen alone form ninety-nine and one-half percent of the air we breathe; and the remaining one-half of one percent contains, besides the vapor of water, carbonic acid, ammonia and other substances. There is scarcely more than a quarter of one percent of aqueous vapor. If we consider the constituent atoms of the atmosphere, the physicist tells us that for two hundred atoms of oxygen and nitrogen there is scarcely one of water-vapor; but this one atom has eighty times more absorptive energy than the two hundred others.

The radiant heat of the Sun, after traversing the atmosphere, warms the surface of the Earth. The heat waves reflected from the warmed earth are not lost in space. The aqueous vapor atoms, acting like a barrier, turn them back and preserve them for our benefit.

This is one of the most brilliant and the most fruitful discoveries of modern physics. The oxygen and nitrogen molecules of dry air do not oppose the radiation of heat; but, as we have just said, one molecule of water-vapor possesses eighty times the absorptive energy of the other two hundred molecules of dry air, and consequently such a molecule is sixteen thousand times more efficacious in so far as the conservation of heat is concerned. So that it is the vapor of water and not the air, properly speaking, which regulates the conditions of life upon the Earth.

If one should remove this vapor from the surrounding atmosphere, a loss of heat