ns of considerable altitude," I
remarked, pointing out Mount Huygens, nearly 20,000 feet high, Mount
Hadley, 15,000 feet, and Mount Woolf, 12,000 feet in height. "This range
curves round towards the east, and finishes with a fine ring-plain
called Eratosthenes--some thirty-seven miles in diameter, with a floor
depressed 8000 feet below the lunar surface. It encloses a central
mountain, and on the east wall there is one peak which rises 16,000 feet
above the floor.

"The ranges in this part of the moon are, perhaps, more like those on
our earth than others to be found on its surface, but much more wild and
rugged.

"Eastward and northward of these ranges is the Sea of Showers, on which
there are several fine ring-mountains and walled plains--notably
Autolychus and Aristillus, two very perfect ring-mountains some 9000
feet high.

"One of the most striking, on account of its size and situation, is that
large one which is called Archimedes, and is about fifty miles in
diameter; and you will notice that a rugged mass of mountains and high
hills extends from it to a distance of over a hundred miles on the
south. The floor of this walled plain is only about 600 feet below the
general level, and the mountain walls average about 4000 feet in height;
but there is at least one peak some 7000 feet high.

"You will see a little below and westward of Archimedes the commencement
of a system of large cracks or crevasses in the lunar surface which are
known as 'rills.' Many such systems are found in various parts of the
moon; some of the cracks are comparatively shallow, but, according to
Professor Langley, others are known to be at least eight miles deep, and
may be infinitely deeper, though I cannot say I understand how these
great depths have been arrived at. The length of the cracks varies from
a few miles to over three hundred miles, and from a few hundred yards to
some miles in width. They are attributed partly to volcanic action, but
mainly to the contraction of the crust of the lunar globe as it became
cold. Being so much smaller, the moon would cool much more rapidly than
the earth, and the disruptive effects would necessarily be greater."

John here touched my arm, and pointing to some mountains on the borders
of a large elongated oval area, close to the north-western terminator
where the sun was setting, asked me what they were. I explained that the
dark area was known as the Mare Crisium, or Sea of Conflicts, and is
po