“The director of the observatory has announced that he does not believe in the first two, and that in his opinion a collision with the comet will have only insignificant results. I agree with him in every respect, and I now wish to add, after listening attentively to the learned addresses of my distinguished colleagues, that I do not believe in the other three either.
“Ladies,” continued the Columbian astronomer, “you know as well as we do that nothing is eternal. In the bosom of nature all is change. The buds of the spring burst into flowers, the flowers in their turn become fruit, the generations succeed each other, and life accomplishes its mission. So the world which we inhabit will have its end as it has had its beginning, but neither the comet, nor water, nor the lack of water are to cause its death agony. To my mind the whole question hangs upon a single word in the closing sentence of the very remarkable address which has just been made by our gracious colleague, the president of the physical society.
“The Sun! Yes, here is the key to the whole problem.
“Terrestrial life depends upon its rays. I say depends upon them—life is a form of solar energy. It is the Sun which maintains water in a liquid state, and the atmosphere in a gaseous one; without it all would be solid and lifeless; it is the Sun which draws water from the sea, the lakes, the rivers, the moist soil; which forms the clouds and sets the air in motion; which produces rain and controls the fruitful circulation of the water; thanks to the solar light and heat, the plants assimilate the carbon contained in the carbonic acid of the atmosphere, and in separating the oxygen from the carbon and appropriating the latter the plant performs a great work; to this conversion of solar into vital energy, as well as to the shade of the thick-leaved trees, is due the freshness of the forests; the wood which blazes on our hearthstones does but render up to us its store of solar heat, and when we consume gas or coal today, we are only setting free the rays imprisoned millions of years ago in the forests of the primary age. Electricity itself is but a form of energy whose original source is the Sun. It is, then, the Sun which murmurs in the brook, which whispers in the wind, which moans in the tempest, which blossoms in the rose, which trills in the throat of the nightingale, which gleams in the lightning, which thunders in the storm, which sings or wails in the vast symphony of nature.
“Thus the solar heat is changed into air or water currents, into the expansive force of gases and vapors, into electricity, into woods, flowers, fruits and muscular energy. So long as this brilliant star supplies us with sufficient heat the continuance of the world and of life is assured.
“The probable cause of the heat of the Sun is the condensation of the nebula in which this central body of our system had its origin. This conversion of mechanical energy must have produced 28,000,000 degrees centigrade. You know gentlemen, that a kilogram of coal, falling from an infinite distance to the Sun, would produce, by its impact, six thousand times more heat than by its combustion. At the present rate of radiation, this supply of heat accounts for the emission of thermal energy for a period of 22,000,000 years, and it is probable that the Sun has been burning far longer, for there is nothing to prove that the elements of the nebula were absolutely cold; on the contrary they themselves were originally a source of heat. The temperature of this great daystar does not seem to have fallen any; for its condensation is still going on, and it may make good the loss by radiation. Nevertheless, everything has an end. If at some future stage of condensation the Sun’s density should equal that of the Earth, this condensation would yield a fresh amount of heat sufficient to maintain for 17,000,000 years the same temperature which now sustains terrestrial life, and this period may be prolonged if we admit a diminution in the rate of radiation, a fall of meteorites, or a further condensation resulting in a density greater than that of the Earth. But, however far we put off the end, it must come at last. The suns which are extinguished in the heavens, offer so many examples of the fate reserved for our own luminary; and in certain years such tokens of death are numerous.
“But in that long period of seventeen or twenty million years, or more, who can say what the marvellous power of adaptation, which physiology and paleontology have revealed in every variety of animal and vegetable life, may not do for humanity, leading it, step by step, to a state of physical and intellectual perfection as far above ours, as ours is above that of the iguanodon, the stegosaurus and the compsognathus? Who can say that our fossil remains will not appear to our successors as monstrous as those of the dinosaurus? Perhaps the stability of temperature of that future time may make it seem doubtful whether any really intelligent race could have existed in an epoch subjected, as ours is, to such erratic variations of temperature, to the
