Daily gazette and comet. (Baton Rouge, La.) 1856-186?, 1860-07-03


dinary interest is now being taken
by all astronomers in the question
OF the secular acceleration of the
moons mean motion" In the
French Academic for months past
the question has been holly discus
sed, and English and German as
tronomers, we see, are engaging
eagerly in the controversy. As tho
interest in this subject is not con-
fined TO technical astronomy, but
extends to other matters of very
wide range, it may be worthy Of
brief illustration. From the time
of Newton it had been known that
the motions of the moon are dis
turbed by the attraction of the sun
aud that great part of the effect
is the following kind.
When the moon is between the
sun and the earth the sun attracts
the moon away from the earth, and
when the earth is between the sun
and the moon the sun attracts the
earth away from the moon thus,
in both cases, it tends to separate
the earth and the moon, diminish
ing the attraction of the moon to
the earth. IL this diminution were
always the same in amount, the
periodic time of the moon passing
round the earth would always be
the same. In order to reconcile
the eclipses of the moon recorded
by Ptolemy with modern observa-
tons of the moon, it was necessa-
ny to suppose that in every success
sive century the moon moves n lit
tie quicker than in the preceding
century, in a degree which is near
ly represented by supposing that
at each successive lunation tho
moon approaches nearer to the
earth by one inch
The principal cause of this was
discovered by Laplace. Sometime
after, However, Mr.. Adams announ-
ced his discovery, that a part Of
the suns disturbing force had been
omitted by Laplace. The sun pulls
the moon in the direction in which
she is going $50 as to accelerate
herr in some parts of her orbit, aud
in the opposite direction $50 as
to retard her( in other parts. La
place and others supposed that
these accelerations and retarda-
tons exactly balance. Mr.. Adams
gave reasons for supposing that
they do not balance. In this he
was subsequently supported by NJ.
Delaunay, "a very eminent French
mathematician, who, making bis
calculations in different way, ar
rived at the very same figures.
But he is opposed by Baron Planta
by the Count de Pontecoulant and
by Prof. Hansen, who all maintain
that Laplace's investigations are
J sensibly correct.
: And in this state the controversy
, stands at present. 1t is to be re-
7 marked that observations can here
, give no assistance. The question
is purely weether certain algebra
cal Investigations are right or
J wrong. And it shows that what is
commonly called mathematical
} evidence" is not so certain as many
persons imagine; and that it ulti-
mately depends on moral evidence.
The effect of Mr.. Adams alteration
is to diminish Laplace's change of
the periodic time by more than one
; third part. The computations Of
, the ancient eclipses are very sensi.
bly, affected by this. Indeed, the
general question Of the theory Of
the moons acceleration may pro-
, perly be indicated as the most i'm
, portant of astronomical specala-
J tions at the present time.
-
Bag Thackery, we are told, is
about to publish bis famous lectures
on the Georges in the CornhiII Maya
zine, which he edits. He proposed
at one time, coming to this country
r in the Great Eastern, but was com
g PEELED to give up his intention, in
consequence of the additional labor
forced upon him in preparing notes
and supplements to the lectures
p. ,rsons who heard them in this
coun. Try will be glad to get them in
print.