But this heat, which is sufficient to evaporate the waters, would have formed a thick ring of cloud, which would have modified that excessive temperature; hence the compensation between the cold of the aphelion and the heat of the perihelion."

"At how many degrees," asked Nicholl, "is the temperature of the planetary spaces estimated?"

"Formerly," replied Barbicane, "it was greatly exagerated; but now, after the calculations of Fourier, of the French Academy of Science, it is not supposed to exceed 60@ Centigrade below zero."

"Pooh!" said Michel, "that's nothing!"

"It is very much," replied Barbicane; "the temperature which was observed in the polar regions, at Melville Island and Fort Reliance, that is 76@ Fahrenheit below zero."

"If I mistake not," said Nicholl, "M. Pouillet, another savant, estimates the temperature of space at 250@ Fahrenheit below zero. We shall, however, be able to verify these calculations for ourselves."

"Not at present; because the solar rays, beating directly upon our thermometer, would give, on the contrary, a very high temperature. But, when we arrive in the moon, during its fifteen days of night at either face, we shall have leisure to make the experiment, for our satellite lies in a vacuum."

"What do you mean by a vacuum?" asked Michel. "Is it perfectly such?"

"It is absolutely void of air."

"And is the air replaced by nothing whatever?"

"By the ether only," replied Barbicane.

"And pray what is the ether?"

"The ether, my friend, is an agglomeration of imponderable atoms, which, relatively to their dimensions, are as far removed from each other as the celestial bodies are in space. It is these atoms which, by their vibratory motion, produce both light and heat in the universe."

They now proceeded to the burial of Satellite. They had merely to drop him into space, in the same way that sailors drop a body into the sea; but, as President Barbicane suggested, they must act quickly, so as to lose as little as possible of that air whose elasticity would rapidly have spread it into space. The bolts of the right scuttle, the opening of which measured about twelve inches across, were carefully drawn, while Michel, quite grieved, prepared to launch his dog into space. The glass, raised by a powerful lever, which enabled it to overcome the pressure of the inside air on the walls of the projectile, turned rapidly on its hinges, and Satellite was thrown out. Scarcely a particle of air could have escaped, and the operation was so successful that later on Barbicane did not fear to dispose of the rubbish which encumbered the car.

CHAPTER VI

QUESTION AND ANSWER

On the 4th of December, when the travelers awoke after fifty-four hours' journey, the chronometer marked five o'clock of the terrestrial morning. In time it was just over five hours and forty minutes, half of that assigned to their sojourn in the projectile; but they had already accomplished nearly seven-tenths of the way. This peculiarity was due to their regularly decreasing speed.

Now when they observed the earth through the lower window, it looked like nothing more than a dark spot, drowned in the solar rays. No more crescent, no more cloudy light! The next day, at midnight, the earth would be new, at the very moment when the moon would be full. Above, the orb of night was nearing the line followed by the projectile, so as to meet it at the given hour. All around the black vault was studded with brilliant points, which seemed to move slowly; but, at the great distance they were from them, their relative size did not seem to change. The sun and stars appeared exactly as they do to us upon earth. As to the moon, she was considerably larger; but the travelers' glasses, not very powerful, did not allow them as yet to make any useful observations upon her surface, or reconnoiter her topographically or geologically.

Thus the time passed in never-ending conversations all about the moon. Each one brought forward his own contingent of particular facts; Barbicane and Nicholl always serious, Michel Ardan always enthusiastic.