How do you make that out?" asked his companions, surprised.
"Because we make their skins into drum heads!" replied Ardan, with an air, as if answering a conundrum.
Barbican and M'Nicholl could hardly help laughing at the absurd reply of their lively companion, but their hilarity was soon stopped by the expression his face assumed as he bent over Satellite's body, where it lay stretched on the sofa.
"What's the matter now?" asked Barbican.
"Satellite's attack is over," replied Ardan.
"Good!" said M'Nicholl, misunderstanding him.
"Yes, I suppose it is good for the poor fellow," observed Ardan, in melancholy accents. "Life with one's skull broken is hardly an enviable possession. Our grand acclimatization project is knocked sky high, in more senses than one!"
There was no doubt of the poor dog's death. The expression of Ardan's countenance, as he looked at his friends, was of a very rueful order.
"Well," said the practical Barbican, "there's no help for that now; the next thing to be done is to get rid of the body. We can't keep it here with us forty-eight hours longer."
"Of course not," replied the Captain, "nor need we; our lights, being provided with hinges, can be lifted back. What is to prevent us from opening one of them, and flinging the body out through it!"
The President of the Gun Club reflected a few minutes; then he spoke:
"Yes, it can be done; but we must take the most careful precautions."
"Why so?" asked Ardan.
"For two simple reasons;" replied Barbican; "the first refers to the air enclosed in the Projectile, and of which we must be very careful to lose only the least possible quantity."
"But as we manufacture air ourselves!" objected Ardan.
"We manufacture air only partly, friend Michael," replied Barbican. "We manufacture only oxygen; we can't supply nitrogen—By the bye, Ardan, won't you watch the apparatus carefully every now and then to see that the oxygen is not generated too freely. Very serious consequences would attend an immoderate supply of oxygen—No, we can't manufacture nitrogen, which is so absolutely necessary for our air and which might escape readily through the open windows."
"What! the few seconds we should require for flinging out poor Satellite?"
"A very few seconds indeed they should be," said Barbican, very gravely.
"Your second reason?" asked Ardan.
"The second reason is, that we must not allow the external cold, which must be exceedingly great, to penetrate into our Projectile and freeze us alive."
"But the Sun, you know—"
"Yes, the Sun heats our Projectile, but it does not heat the vacuum through which we are now floating. Where there is no air there can neither be heat nor light; just as wherever the rays of the Sun do not arrive directly, it must be both cold and dark. The temperature around us, if there be anything that can be called temperature, is produced solely by stellar radiation. I need not say how low that is in the scale, or that it would be the temperature to which our Earth should fall, if the Sun were suddenly extinguished."
"Little fear of that for a few more million years," said M'Nicholl.
"Who can tell?" asked Ardan. "Besides, even admitting that the Sun will not soon be extinguished, what is to prevent the Earth from shooting away from him?"
"Let friend Michael speak," said Barbican, with a smile, to the Captain; "we may learn something."
"Certainly you may," continued the Frenchman, "if you have room for anything new. Were we not struck by a comet's tail in 1861?"
"So it was said, anyhow," observed the Captain. "I well remember what nonsense there was in the papers about the 'phosphorescent auroral glare.'"
"Well," continued the Frenchman, "suppose the comet of 1861 influenced the Earth by an attraction superior to the Sun's. What would be the consequence? Would not the Earth follow the attracting body, become its satellite, and thus at last be dragged off to such a distance that the Sun's rays could no longer excite heat on her surface?"
"Well, that might possibly occur," said Barbican slowly, "but even then I question if the consequences would be so terrible as you seem to apprehend."
"Why not?"
"Because the cold and the heat might still manage to be nearly equalized on our globe. It has been calculated that, had the Earth been carried off by the comet of '61, when arrived at her greatest distance, she would have experienced a temperature hardly sixteen times greater than the heat we receive from the Moon, which, as everybody knows, produces no appreciable effect, even when concentrated to a focus by the most powerful lenses."
"Well then," exclaimed Ardan, "at such a temperature—"
"Wait a moment," replied Barbican. "Have you never heard of the principle of compensation? Listen to another calculation. Had the Earth been dragged along with the comet, it has been calculated that at her perihelion, or nearest point to the Sun, she would have to endure a heat 28,000 times greater than our mean summer temperature. But this heat, fully capable of turning the rocks into glass and the oceans into vapor, before proceeding to such extremity, must have first formed a thick interposing ring of clouds, and thus considerably modified the excessive temperature. Therefore, between the extreme cold of the aphelion and the excessive heat of the perihelion, by the great law of compensation, it is probable that the mean temperature would be tolerably endurable."
"At how many degrees is the temperature of the interplanetary space estimated?" asked M'Nicholl.
"Some time ago," replied Barbican, "this temperature was considered to be very low indeed—millions and millions of degrees below zero. But Fourrier of Auxerre, a distinguished member of the Académie des Sciences, whose Mémoires on the temperature of the Planetary spaces appeared about 1827, reduced these figures to considerably diminished proportions. According to his careful estimation, the temperature of space is not much lower than 70 or 80 degrees Fahr. below zero."
"No more?" asked Ardan.
"No more," answered Barbican, "though I must acknowledge we have only his word for it, as the Mémoire in which he had recorded all the elements of that important determination, has been lost somewhere, and is no longer to be found."
"I don't attach the slightest importance to his, or to any man's words, unless they are sustained by reliable evidence," exclaimed M'Nicholl. "Besides, if I'm not very much mistaken, Pouillet—another countryman of yours, Ardan, and an Academician as well as Fourrier—esteems the temperature of interplanetary spaces to be at least 256° Fahr. below zero. This we can easily verify for ourselves this moment by actual experiment."
"Not just now exactly," observed Barbican, "for the solar rays, striking our Projectile directly, would give us a very elevated instead of a very low temperature. But once arrived at the Moon, during those nights fifteen days long, which each of her faces experiences alternately, we shall have plenty of time to make an experiment with every condition in our favor. To be sure, our Satellite is at present moving in a vacuum."
"A vacuum?" asked Ardan; "a perfect vacuum?"
"Well,
