"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."