existence of your humanity in the Moon, the Chair would respectfully ask
how it has all so completely disappeared?"

"It disappeared completely thousands, perhaps millions, of years ago,"
replied the unabashed Captain. "It perished from the physical
impossibility of living any longer in a world where the atmosphere had
become by degrees too rare to be able to perform its functions as the
great resuscitating medium of dependent existences. What took place on
the Moon is only what is to take place some day or other on the Earth,
when it is sufficiently cooled off."

"Cooled off?"

"Yes," replied the Captain as confidently and with as little hesitation
as if he was explaining some of the details of his great machine-shop in
Philadelphia; "You see, according as the internal fire near the surface
was extinguished or was withdrawn towards the centre, the lunar shell
naturally cooled off. The logical consequences, of course, then
gradually took place: extinction of organized beings; and then
extinction of vegetation. The atmosphere, in the meantime, became
thinner and thinner--partly drawn off with the water evaporated by the
terrestrial attraction, and partly sinking with the solid water into the
crust-cracks caused by cooling. With the disappearance of air capable of
respiration, and of water capable of motion, the Moon, of course, became
uninhabitable. From that day it became the abode of death, as completely
as it is at the present moment."

"That is the fate in store for our Earth?"

"In all probability."

"And when is it to befall us?"

"Just as soon as the crust becomes cold enough to be uninhabitable."

"Perhaps your philosophership has taken the trouble to calculate how
many years it will take our unfortunate _Terra Mater_ to cool off?"

"Well; I have."

"And you can rely on your figures?"

"Implicitly."

"Why not tell it at once then to a fellow that's dying of impatience to
know all about it? Captain, the Chair considers you one of the most
tantalizing creatures in existence!"

"If you only listen, you will hear," replied M'Nicholl quietly. "By
careful observations, extended through a series of many years, men have
been able to discover the average loss of temperature endured by the
Earth in a century. Taking this as the ground work of their
calculations, they have ascertained that our Earth shall become an
uninhabitable planet in about--"

"Don't cut her life too short! Be merciful!" cried Ardan