Year: 1874

SOME IDEAS ABOUT THE MOON.


THOUGH poets, perhaps, may not like it,
the veil of mystery is torn from the moon.
1t is at length disclosed to us to be a great
barren waste of rugged mountains and
extinct volcanoes, the whole devoid of
air, water, vegetation, or animal life-a
rocky solitude going without intermis-
sion drearily round the earth-for the
eArth's, not for its own, advantage -4~


The mean distance at which the moon
makes these circuits is, as formerly men,
toned, 237, 600 miles. Observed by pow
erful telescopes, its apparent distance is
brought within two or three hundred miles,
which distance affords a good outline of
objects, but nothing can be distinguished
smaller than what will measure hun
dred and fifty yards across. Among
astronomers there are hopes that, by en-
larged telescope powers, we may bring
the moon as clearly before us as we can
see Mont Blanc from Geneva with the
naked eye. AS everyone knows, the
moon is visible by means of the light
which is thrown upon it by the sun.
Moonlight may, therefore, be called SUM-
light at secondhand


The moon, however, may sometimes be
seen by the SUMS light being reflected
upon it from the earth. This earth-light
on the moon is seen in particular condi-
tions of the atmosphere, within day or
two after new moon At such time the
old moon, as people please to call it, is
said to lie in the new moons arms-an
evil omen, as was once supposed; the
light shining dimly on the body lying
within the bright crescent being nothing
else than earth shine, and no omen either
good or bad.


BY receiving and rejecting the SUMS
rays, the moon is obviously an opaque
sphere, which by best computation is
2,160 miles in diameter, or about afourth
of that OF the earth. Rotating on its
axis it revolves round the earth in the
same measure of time, that is, twenty
seven days and aquarter. In other words,
its rotary motion is twenty-seven and
half times slower than that of the earth.
In consequence of the rotary motion on
its axis and its revolution round the
earth coinciding, the moon always pre-
sents the same side to us. The sun, how
ever, lights it up on both sides. At times,
we are able to see a little more than one
side-as much as ur-sevenths of its sur





to the earth letting us, as it were, look
which was traced by Galileo to It's true
cause, is explained as follows by the writ
ers before us: "The center of motion of
the moon being the center of the earth, it
is clear that an observer, on the surface of
the latter, looks down upon the rising
moon as from an eminence, and thus he
is enabled to see more or less over or
around her. AS the moon increases in
altitude the line of sight gradually be-
comes parallel to the line joining the OBJ
server and the center of the earth, and at
length he looks her full in the face; he
loses the full view and catches another
sideface view as she nearS the horizon in
setting" These changes in the point of
views have greatly facilitated the taking
of pictorial photographs of the moons
surface.


These photographs can, of course, be
executed only in calm and clear atmos-
phere when the moon is at the full, and
to wait for such opportunities great
patience is required. If all other circum-
stances be favorable, the atmosphere is
partly cleared by the action of the moon,
for its rays, though ordinarily described
as cold" the cold, chaste moon"-par-
take in small degree of the heat OF SUM-
shine, and accordingly exert dispersive
influence on the clouds. A succession of
clear moonlight nights is known to farm
ers to have a ripening effect on grain.


Looked at even with the naked
eye, the moon is not a uniformly clear
body. 1t has dusky and light spots, sig
nifying that it has an irregular surface.
The dusky portions, which collectively
oh txxyr = srIc nf 46a
at one time considered the seas, and such
they are sometimes still called. Close
examination by powerful telescopes shows
that these sea-like spaces are only plains,
on which there are comparatively few
prominences to reflect the SUMS light.
The features of the moons disc which
rivet attention are prominences mostly in
the shape of circular craters of volcanoes,
some of vast dimensions, and many of a
small size. Besides these circular mark
ings, which, so to speak, give pock.
pitted appearance to the whole surface.
there are stretches of rugged and pictur
esque mountains of great altitude, all
seemingly of volcanic origin. The circu-
lar -crater-form markings are diverse in
character. In some cases they appear as
if crowning mountain heaps of ashes and
cinders, in the manner of Etna and Vesu
vius; in other instances, where the edges
of the craters do not rise high above the
plains, the volcanoes resemble prodigious
hollows, miles in breadth and depth
That the whole have at one time been ir
volcanic action is obvious from the fac
that at the bottom of the craters are seer
tue remains of the small, tapering cones
whence the lava and ashes were pro
jected


The picture map of the moon contained
IN the work before us presents the outlines
OF 2So craters, and, as these are only OF
one side, we may conclude that there il
fully as great number on the other-sa,
upward OF 500 in ALL The bulk of thos
which are visible are near what we woult
call the upper part Of the moon, from