Public ledger. [volume] (Memphis, Tenn.) 1865-1893, 1876-08-30
Some Of the Favorit- Lunar studie'

and the great Talma.
Some OF the FavOrit- Lunar studies
There are two lunar spots which
the selenographer regards with
special favor, because Of the evil
dence they seem to give of change.
One is a crater lying on the So
called sea of serenity, which some
popular observers regard as the left
eve of the "man in the moon"
Here there was once a deep crater
nearly seven miles across, a very
distinct and obvious feature even
with the small telescope Qess than
four inches in aperture) used by
Beer and Nader in forming their
celebrated chart. But, ten years
ago, the skillful astronomer
Scmidt, a selenographer Of sele-
nographers, who has, in fact, given
the best energies Of his life to
moor-gazing, found this crater
missing. When he announced the
fact to the scientific world, armed
with very powerful instruments,
looked for the crater which had
BEEN so clearly seen with Madler's
small telescope; but though they
found a crater, it was nothing like
the crater described by Nader.
The present crater is scarcely two
miles in diameter, and only Just
visible with powerful telescopes; all
around it there is a shallow depr6s-
sion, occupying a region about as
large as the whole crater had
been before. 1t seems impos-
sible to doubt that great change
has taken place here, and the ques
ton arises whether the change hai
been produced by volcanic activity
or otherwise. Sir John Hcrsche
pronounced somewhat confidently
in favor of the former hypothesis
"The most plausible conjecture,
said he, "as to the cause Of thi
disappearance seems to be the fillin9
up Of the crater from beneath b,
an efusion of viscous lava, which
overhowing the rim on all sides
may have so flowed down the out
side slope as to efface its ruggedness
and convert it into a gradual de
clivity, casting no stray shadows,
J But how tremendous the volcani
energy required to fill with lava
crater nearly seven miles in diane
J ter and more than half a mile deeI
The volcanic hypothesis seems o
this account utterly incredible, TO
if such energy resided in the moon
interior we should find her Who'll
surface continually changing. Fa
4 more probable seems the idea tina
] the wall Of this crater has simpl
5 fallen in, scattering its fragment
| over what had been the floor Q
the crater. The forces at wor
, on the moon are quite competen
= to throw down steep crater VAL
S like those which seem formerl
: to have girt about this dee
g cavity. Under the tremendou
= and long-lasting heat Of the luna
5 midday sun, the rock substance 9
4 the moons surface must expant
e while during the intense cold of tn
i lunar night a corresponding con
t traction must take place. Unde
e the influence of this alternate eS
/, pansion and contraction the strong
e est of the lunar crater-walls mus
I be tending to their downfall. Thel
+ substance must be gradually crum
bling away. From time to tim
S large masses must topple over an
e occasionally long ranges OF crater
G wall must be brought to the grounC
u 1t seems conceivable enough, cel
5 tainly far more probable than an
!. other Interpretation which has bee
7 offered, that the crater-wall iiri
d missed by Schmidt was destroye
in this way. The other fayprlt
e region of selenographerS is a niue
l. larger one--the great-walled plal
Is called Plato, and by the older a
tronomers the greater black lake
is sixty miles in diameter, end su
ct rounded by mountains, some
j which rise nearly two thousand fly
d hundred yards above the level Z
ie the floor.
id How n Rfrd Files.