came too close and left its mark as it
flew past."

"Fanciful exclamations, dear friends," observed Barbican; "but I'm not
surprised at your excitement. Yonder is the famous _Valley of the Alps_,
a standing enigma to all selenographers. How it could have been formed,
no one can tell. Even wilder guesses than yours, Ardan, have been
hazarded on the subject. All we can state positively at present
regarding this wonderful formation, is what I have just recorded in my
note-book: the _Valley of the Alps_ is about 5 mile wide and 70 or 80
long: it is remarkably flat and free from _debris_, though the mountains
on each side rise like walls to the height of at least 10,000
feet.--Over the whole surface of our Earth I know of no natural
phenomenon that can be at all compared with it."

"Another wonder almost in front of us!" cried Ardan. "I see a vast lake
black as pitch and round as a crater; it is surrounded by such lofty
mountains that their shadows reach clear across, rendering the interior
quite invisible!"

"That's _Plato_;" said M'Nicholl; "I know it well; it's the darkest spot
on the Moon: many a night I gazed at it from my little observatory in
Broad Street, Philadelphia."

"Right, Captain," said Barbican; "the crater _Plato_, is, indeed,
generally considered the blackest spot on the Moon, but I am inclined to
consider the spots _Grimaldi_ and _Riccioli_ on the extreme eastern edge
to be somewhat darker. If you take my glass, Ardan, which is of somewhat
greater power than yours, you will distinctly see the bottom of the
crater. The reflective power of its plateau probably proceeds from the
exceedingly great number of small craters that you can detect there."

"I think I see something like them now," said Ardan. "But I am sorry the
Projectile's course will not give us a vertical view."

"Can't be helped!" said Barbican; "we must go where it takes us. The day
may come when man can steer the projectile or the balloon in which he is
shut up, in any way he pleases, but that day has not come yet!"

Towards five in the morning, the northern limit of _Mare Imbrium_ was
finally passed, and _Mare Frigoris_ spread its frost-colored plains
far to the right and left. On the east the travellers could easily see
the ring-mountain _Condamine_, about 4000 feet high, while a little
ahead on the right they could plainly distinguish _Fontenelle_ with an
altitude nearly twice as great. _Mare Frigoris_ was soon passed, and the
whole