The “Mare Imbrium” lay before the eyes
of the travellers like an immense depression of which
the details were not very distinct. Near them
on the left rose Mount Lambert, the altitude of which
is estimated at 1,813 metres, and farther on, upon
the borders of the Ocean of Tempests, in north lat.
23 deg. and east long. 29 deg., rose the shining mountain
of Euler. This mountain, which rises only 1,815
metres above the lunar surface, has been the object
of an interesting work by the astronomer Schroeter.
This savant, trying to find out the origin of
the lunar mountains, asked himself whether the volume
of the crater always looked equal to the volume of
the ramparts that formed it. Now this he found
to be generally the case, and he hence concluded that
a single eruption of volcanic matter had sufficed
to form these ramparts, for successive eruptions would
have destroyed the connection. Mount Euler alone
was an exception to this general law, and it must
have taken several successive eruptions to form it,
for the volume of its cavity is double that of its
inclosure.
All these hypotheses were allowable to terrestrial
observers whose instruments were incomplete; but Barbicane
was no longer contented to accept them, and seeing
that his projectile drew regularly nearer the lunar
disc he did not despair of ultimately reaching it,
or at least of finding out the secrets of its formation.
CHAPTER XIII.
LUNAR LANDSCAPES.
At half-past two in the morning the bullet was over
the 30th lunar parallel at an effective distance of
1,000 kilometres, reduced by the optical instruments
to ten. It still seemed impossible that it could
reach any point on the disc. Its movement of translation,
relatively slow, was inexplicable to President Barbicane.
At that distance from the moon it ought to have been
fast in order to maintain it against the power of
attraction. The reason of that phenomenon was
also inexplicable; besides, time was wanting to seek
for the cause. The reliefs on the lunar surface
flew beneath their eyes, and they did not want to
lose a single detail.
The disc appeared through the telescopes at a distance
of two and a half leagues. If an aeronaut were
taken up that distance from the earth, what would
he distinguish upon its surface? No one can tell,
as the highest ascensions have not exceeded 8,000
metres.
The following, however, is an exact description of
what Barbicane and his companions saw from that height:—
Large patches of different colours appeared on the
disc. Selenographers do not agree about their
nature. They are quite distinct from each other.
Julius Schmidt is of opinion that if the terrestrial
oceans were dried up, a Selenite observer could only
tell the difference between the terrestrial oceans
and continental plains by patches of colour as distinctly
varied as those which a terrestrial observer sees upon
the moon. According to him, the colour common
to the vast plains, known under the name of “seas,”
is dark grey, intermingled with green and brown.
Some of the large craters are coloured in the same
way.
