e.

With the naked eye we see on the moon a considerable variation in the
light of different parts of its surface; we discern that the darker
patches appear to be rudely circular, and that they run together on
their margins. Seeing this little, the ancients fancied that our
satellite had seas and lands like the earth. The first telescopes did
not dispel their fancies; even down to the early part of this century
there were astronomers who believed the moon to be habitable; indeed,
they thought to find evidence that it was the dwelling place of
intelligent beings who built cities, and who tried to signal their
intellectual kindred of this planet. When, however, strong glasses
were applied to the exploration, these pleasing fancies were rudely
dispelled.

Seen with a telescope of the better sort, the moon reveals itself to
be in large part made up of circular depressions, each surrounded by a
ringlike wall, with nearly level but rough places between. The
largest of these walled areas is some four hundred miles in diameter;
thence they grade down to the smallest pits which the glass can
disclose, which are probably not over as many feet across. The writer,
from a careful study of these pits, has come to the conclusion that
the wider are the older and the smaller the last formed. The rude
elevations about these pits--some of which rise to the height of ten
thousand feet or more--constitute the principal topographic reliefs of
the lunar surface. Besides the pits above mentioned, there are
numerous fractures in the surface of the plains and ringlike ridges;
on the most of these the walls have separated, forming trenches not
unlike what we find in the case of some terrestrial breaks such as
have been noted about volcanoes and elsewhere. It may be that the
so-called canals of Mars are of the same nature.

[Illustration: Fig. 23.--Lunar mountains near the Gulf of Iris.]

The most curious feature on the moon's surface are the bands of
lighter colour, which, radiating from certain of the volcanolike
pits--those of lesser size and probably of latest origin--extend in
some cases for five hundred miles or more across the surface. These
light bands have never been adequately explained. It seems most likely
that they are stains along the sides of cracks, such as are sometimes
observed about volcanoes.

The eminent peculiarity of the moon is that it is destitute of any
kind of gaseous or aqueous envelope. That there is no distinct