The New York herald. [volume] (New York [N.Y.]) 1840-1920, 1851-07-28

sal gravtation was ultimately developed. Sir w.
Her-chell, and other astronomers have followed up
Ms researches and reasonings, and have made over
wheiming discoveries rs to the bOundless extent OF
the stellar universe. from which it appears that the
sun itself Is but fixed star, and that all the fxei
stars are SO many suns, with their planets revolving
around them
The earth is planet revolving around the SUM-
The moon is a satellite Of the earth, revolving
around it In the space Of twenty. seven DAYS eisht
hours, while at the same time it accompanies the
earth in its annual revolution around the sum The
moon always presents the face to US, by which
it is evident that she turns bus upon her axis
while she performs revolution around the EARTH so
that her inhabitants have but one night and one day
in the course Of lunar month. When the moon is
nearly in right line between the and the earth,
we do not see her. because her dark side is turned
towards us AS she advances in her orbit, we see
Der under the form of moon, and from one
degree to another till the whole Of the enlightened
side appears to us. and the is fall. She then
proceeds in her orbit till she is gbbous and by de-
grees disappears; after which she becomes new
moon again.
When the moon is at full she is said to be in
opposition; when a new moon, to be in conjunction
with the sun. AT each Of these times the sun, the
moon and the earth are in the same light line; but
in the FIRST ease, the earth IL between The and
the moon; in the second. the moon is between tho
sun and the Garth. When the moon passes be-
tween the and the earth she interceps his rays,
or Ia other words casts a shadow upon the earth;
then the sun is collapsed, and the daylight gives
place to darkness while the moons shadow u pass.
ing over When, on the contrary, the earth is
between the AMI the moon, it is the earth that
intercepts the SUMS rays and casts shadow the
moon. She then disappears from our vie Y And is
eclipsed, for she can only be by the light of
the sUn reelected from her surface
Why, then, II will be asked by person ignorant
OF astronomy, have We not u solar and a lunar
eclipse every month! The reason is that the planes
Of tie orbits Of the earth and moon do not exactly
coincide, but ntersect each other; and the
noon generally passes either one side the
other when she is in conjunction with or in oppos-
ton to the sun, and therefore does not intercept
the suns rays, or produce an eclpse-for this can
only take place when the earth and moon are in
con jul ction those parts of their orbits which
cros ntersect each other, because it Is then only
that they are both in the same plane aud in right
line with the sun. These points Of intersection
called the nodes Of their orbits The orbit of any
hea, eny body i the circle it describes in revolving
around its centre Of gravtation. partial eclipse
OF the moon takes place when, IN passing by the
earth, she does not entirely escape her shadow.
When the eclipse happens precisely at the nodes,
it is not only total but lasts some length Of time.
When the sun is ecpsed, the total darkness is
fined TO one particular part OF the EARTH the moons
SHADOW not being large enough to cover IL all.
The lunar ecipses, on the contrary, visible fro
every part Of the earth where the moon is above
the horizon the shadow Of the earth being so large
to completely cover it, As the sun is larger than
the earth. the shadow of the earth is conical and
il gradually dminishes, and is much smaller than
the earth, where the moon passes through 1t yet,
We bpd the not only to be totally ecpsed, but
ing ouly by reflected light, disappears absolutely
when the light Of the sun is intercepted fcom her.
be does not, therefore, like the sun, become in
visible only from particular spots ON thu earths
surfa &C, but abs olutely and universally until the
light Of the sun begins to shine on her again. The
length OF eclipse depends on the respective dis
tsLees and magnitudes OF the sun, earth an 4 moon
The diameter OF the is about three eleveuths
that OF the eaIth OF the Who'll bulk OF tho earth
~ times greater than that of the moon. The dis
tsnce OF the moon il about 2.O0OO miles from the
earth; that If The sun 9ta millions of miles The
dsmeier OF the sun, compared with that Of the
earth, is in the proportion Of II to aud its bulk
in the proportion OF 300, 900 to 1. When the
moon eclrses the to us, to-day. the earth is
eciipsed to the for, II the moon intercepts
the suns ", and casts a sh idow us, We must
necessarily disappear to the moon; but only par
tially-a black spot will appear to pass over the
earb leaving the other parts, which not covered
by he shadow, illuminated.
Ecupses are calculated with unerring certainty.
Four nave been set down for the present year, and
that which takes pla, 80 to-day, the last of thcm-
two OF the and two Of the moon-two visible ia
Europe, and two in America. The first eclipse Of
this year . partial eclipse Of the moon Janu-
AIRY 18th, invisible in the United States. Second,
abhular eclipse Of the sun, invisible ia the nj
ted States Third, partial eclipse of the moon,
IoIk ID began about six minutes before o'clock,
A. NJ, ara ended at 3 hours, 10 min A. NJ. The
fourth eclipse, which takes place this morning, IL
total eclipse OF the sup, partially visible in thS
United States. The following table will show Mt
what time it viii commerce. and obtain its greatest
observation at the different obseryatories Of the
1 nif.d