. "As the interior fires became
extinguished the incandescent matter was concentrated and the lunar disc
became cool. By degrees the consequences of this phenomenon came
about--the disappearance of organic beings and the disappearance of
vegetation. Soon the atmosphere became rarefied, and was probably drawn
away by terrestrial attraction; the breathable air disappeared, and so
did water by evaporation. At that epoch the moon became uninhabitable,
and was no longer inhabited. It was a dead world like it is to-day."

"And you say that the like fate is reserved for the earth?"

"Very probably."

"But when?"

"When the cooling of its crust will have made it uninhabitable."

"Has the time it will take our unfortunate globe to melt been
calculated?"

"Certainly."

"And you know the reason?"

"Perfectly."

"Then tell us, sulky _savant_--you make me boil with impatience."

"Well, my worthy Michel," answered Barbicane tranquilly, "it is well
known what diminution of temperature the earth suffers in the lapse of a
century. Now, according to certain calculations, that average
temperature will be brought down to zero after a period of 400,000
years!"

"Four hundred thousand years!" exclaimed Michel. "Ah! I breathe again! I
was really frightened. I imagined from listening to you that we had only
fifty thousand years to live!"

Barbicane and Nicholl could not help laughing at their companion's
uneasiness. Then Nicholl, who wanted to have done with it, reminded them
of the second question to be settled.

"Has the moon been inhabited?" he asked.

The answer was unanimously in the affirmative.

During this discussion, fruitful in somewhat hazardous theories,
although it resumed the general ideas of science on the subject, the
projectile had run rapidly towards the lunar equator, at the same time
that it went farther away from the lunar disc. It had passed the circle
of Willem, and the 40th parallel, at a distance of 400 miles. Then
leaving Pitatus to the right, on the 30th degree, it went along the
south of the Sea of Clouds, of which it had already approached the
north. Different amphitheatres appeared confusedly under the white light
of the full moon--Bouillaud, Purbach, almost square with a central
crater, then Arzachel, whose interior mountain shone with indefinable
brilliancy.

At last, as the projectile went farther and farther away, the details
faded from the travellers' eyes, the mountains were confounded