tear. The earth's superficies, although much
more recent, has been worn and ground down in
all directions by the continual action of wind
and water. The moon is the object in which to
study plutonian action, or the effects of heat in
all their purity, and deserves more attention than
she has hitherto received from competent
observers. Her singular marshes, gulfs, and seas;
her circular valleys; her gigantic star-shaped
formations; her isolated mountains, standing
on level ground, without any apparent rise of
the surrounding strata; her rectilinear fissures,
which look like canals dug by an intelligent
hand; her innumerable variety of oblong hills,
lying nearly in the same direction with, but a
slight deviation from, the meridian lines; the
different shades of her soil, from the stellar
brightness of certain peaks, up to sombre grey
and steel blue; all these diverse appearances
make a strong appeal to natural history and
geology.

But this study is rendered more difficult by
the preconceived ideas which we entertain.
Thus, there is a top striking analogy between
her principal formations and earthly volcanoes.
In these latter, however, you have to climb to
a considerable height from the solid ground
before you reach the circular rampart, and you
have to descend only a little way to get to the
bottom of the upheaved crater. In the moon
it is exactly the reverse. It is a general rule,
to which there is no known exception, that the
bottom of all the circuses is profoundly
depressed below the surrounding soil. If you are
looking at a rampart which rises five hundred
yards above the ground outside it, be sure that
its top will be from one thousand to fifteen
hundred yards, sometimes three thousand yards,
above the level of the bottom of the crater.
And yet this bottom does not look in any
respect like an excavation whose contents have
been hollowed out by throwing them up; for,
in the most extensive circuses, this bottom
follows the general curvature of the moon, and
appears simply to form part of a smaller inner
sphere with a shorter radius. Add to this, the
absence of any real chain of mountains; those
so called are, in all probability, nothing but the
remains of ancient broken-up circuses. We
may, therefore, admit that the formation of the
lunar mountains is due to causes completely
different to those which have fashioned our own
terrestrial crust.

Although the moon does not, like the earth,
exhibit a surface partly covered with land and
partly with water, but appears to be entirely
coated with solid substances, still her different
parts present as varied an aspect as the earth
would do to a dweller in the moon; without,
however, there being the slightest resemblance
between the planet and the satellite. The moon
has only regions of plain and regions of mountain,
and the difference between flat and hilly
ground suffices to produce the strange contrasts
which we observe; the former appears dull and
sombre, whilst the other is bright and luminous.

Observers are not agreed about the colour of
the lunar plains. Some say that no tint but
grey is to be seen; Humboldt asserts that the
Sea of Crises is grey mixed with dark green,
and that the Seas of Serenity and of Humours
are likewise green. A reddish tinge prevails in
the Marsh of Sleep. The circular plains whose
centre is not occupied by mountains, are mostly
grey approaching to blue, resembling polishecl
steel. But Julius Schmidt holds that the plains
of the moon are not really coloured with green,
but that it depends on the state of our
atmosphere, and still more on the way in which we
make use of a telescope. If he could prove that
there was no green in the moon, it would be a
serious objection to the belief that her plains
are covered with rich vegetation analogous to
that of our tropical countries. But whatever
doubt there may be respecting the hues of red
and green, there can be none about the great
contrasts of light and darkness. Grimaldi,
Plato, and Endymion are circuses, each enclosing
a very black crater. The most brilliant point,
shining like a lighthouse, is the summit of
Aristarchus, between the Ocean of Tempest's and the
Sea of Rain.

At full moon, as before stated, the sun's
rays fall directly on the visible hemisphere of
our satellite; every shadow disappears, and
its rugged mountains exhibit no relief whatever.
If, at that time, we examine it with
a telescope of some power, our eye is
immediately attracted by certain mountains which
are resplendent with light, and which are
surrounded by a sort of glory whose rays dart to
great distances in all directions. These
radiating mountains offer a miniature resemblance
to vulgar pictures of the rising sun. The rays
convert the annular mountains, their focuses,
into so many radiating systems; they exhibit the
appearance of luminous trains which attain a
breadth of from twelve to five and twenty miles;
their length is considerable, occasionally exceeding
five hundred, and even seven hundred and
fifty miles. These luminous projections cast no
shadow: hence, they cannot be spurs or
buttresses of the mountain. They stretch with
equal intensity of light over plain and mountain
up to heights of more than nine thousand feet,
and that without effacing the outline of the
irregularities of the ground over which they
pass.

Many opinions have been hazarded as to the
nature of these luminous trains. Sir J. Herschel
thought they might be formed by ancient streams
of lava; but there is no evidence to confirm the
supposition. Those illustrious selenographs
Lohrmaun and Maedler exerted every means in their
power to obtain a knowledge of these mysterious
ribbons of light, but they have failed to give
any satisfactory explanation. Humboldt believed
that there is no guessing what changes in the
soil could determine the presence of luminous
rays around certain annular mountains. It is
singular that they should not become visible to
us until the sun's direct rays efface every shadow
in the moon, and that they should disappear as
soon as the light again falls obliquely and the