hey were directing their glasses towards its gloomy depths,
Barbican mentioned to his friends Kepler's strange idea regarding the
formation of these ring mountains. "They must have been constructed," he
said, "by mortal hands."

"With what object?" asked the Captain.

"A very natural one," answered Barbican. "The Selenites must have
undertaken the immense labor of digging these enormous pits at places of
refuge in which they could protect themselves against the fierce solar
rays that beat against them for 15 days in succession!"

"Not a bad idea, that of the Selenites!" exclaimed Ardan.

"An absurd idea!" cried M'Nicholl. "But probably Kepler never knew the
real dimensions of these craters. Barbican knows the trouble and time
required to dig a well in Stony Hill only nine hundred feet deep. To dig
out a single lunar crater would take hundreds and hundreds of years, and
even then they should be giants who would attempt it!"

"Why so?" asked Ardan. "In the Moon, where gravity is six times less
than on the Earth, the labor of the Selenites can't be compared with
that of men like us."

"But suppose a Selenite to be six times smaller than a man like us!"
urged M'Nicholl.

"And suppose a Selenite never had an existence at all!" interposed
Barbican with his usual success in putting an end to the argument. "But
never mind the Selenites now. Observe _Eratosthenes_ as long as you have
the opportunity."

"Which will not be very long," said M'Nicholl. "He is already sinking
out of view too far to the right to be carefully observed."

"What are those peaks beyond him?" asked Ardan.

"The _Apennines_," answered Barbican; "and those on the left are the
_Carpathians_."

"I have seen very few mountain chains or ranges in the Moon," remarked
Ardan, after some minutes' observation.

"Mountains chains are not numerous in the Moon," replied Barbican, "and
in that respect her oreographic system presents a decided contrast with
that of the Earth. With us the ranges are many, the craters few; in the
Moon the ranges are few and the craters innumerable."

Barbican might have spoken of another curious feature regarding the
mountain ranges: namely, that they are chiefly confined to the northern
hemisphere, where the craters are fewest and the "seas" the most
extensive.

For the benefit of those interested, and to be done at once with this
part of the subject, we give in the following little table a list of the
chief lunar mountai