Year: 1874

EDITOR REPUBLICAN,:


OF all the phenomena of the heavens,
there are none that ave moro engaged the
attention Of mankind than eclipses of the
sun and moon. and to those unacquainted
with astronomical principles, nothing ap-
pears moro extraordinary than the accuracy
with which they can be predicted. In the
early ages. when the sciences were confined
to religious monks, and the world had little
or no enlightenment. APPEARANCES Of this
kind were generally regarded as alarming
deviations from the established laws Of
nature. and were always regarded as ca
lamitous Omens, presaging the death Of
kings or some illustriOus character, and
this superstition is not unfrequently allud.
ed to at the present time. In China. where
astronomy is made eubsevient to the in.
terests of the State. they have particular
ceremonies appropriated to those days in
which eclipses are to take place, and both
the prince and the people are ecrupuIously
exact in their observance, and still later.
but few. even among philosophers them.
selves, were able to account for them. At
length, when men began to apply them
selves to observations, and the celestial
motions were better understood. these pho.
nOmena werc found to depend upon q re-.
gular cause. and to admit Of q natural aud
easy solution.


10 enter into popular explanation Of all
parts Of this doctrine. would be impractica-
BILE. with our limited space ut Land. We
shall, therefore, attempt to give general
idea Of the subject, and tn show. without
the embarrassment of calculations, the
foundation upon which it depends.


In the first place, all opaque, or dark
bodies, when they are exposed to the light
of the sun, cast q shadow in the opposite
direction. and as the earth is body Of this
kind, whose shadow extends over large
space, and to great distance, it is plain,
that if the moon, in its orbit. passes into
this shadow, it must be deprived Of light.
and euffer an eclipse.


Thus, in the eclipse of Saturday. the
twenty-fourth, the earth acting a. station.
ary. and sending forth q conical shadow,
whose base rests on our globe, and whose
vertex is beyond the lunar orbit, the moon
still remained visible, though its light was
much dimmed, the red rays predOminating.
Nor was this red light an optical delusion,
for there il generally some light dis
cernable in tho whole face of the moon,
even during its greatest obscurity-to-
tality. Its general surface presented a
bling that of the clouds after sunset
This light proceeds from the solar rays
refracted by the earth's atmosphere
and bent to such a degree as to pass into
the shadow; these rays, which are not suf-
fciently refracted to reach the surface of
the earth. where they would be absorbed,
continuing on their course. After they
have traversed the atmosphere they are
bent behind the earth. and tend, as it we're,
to the focus of q lens, and some OF them
reach the moon, even when the earth IL
directly interposed between it and the cum
go as to prevent its reception of any light
independently Of this infection of rays. Ii
the light thus tending to point behind the
earth were not in q great degree absorbed
by the atmosphere, it's effect would be very
for, if we consider one Of the
luminous points of the suns disc. this point
could only send directly q single ray to
each point of space, but the effect Of the
earth's atmosphere is the cause of q cone of
luminous rays to fall behind the earth.
The consequence is. that in most eclipses.
the obscured part of the moon is more or
less family visible. The degree in which
eraf state Of the earth's atmosphere at the
time. The red rays having the greatest
are those which principally
lind their way to the moon.


A lunar eclipse being OccasiOned by the
Of the earth between the sun
and moon, is an actual deprivation of light
to the moon. It, therefore. is for the time
really dimmed, not merely in appearance to
IL spectator at some particular place, but
absolutely and universally. We have no
occasion. therefore, TO refer to any particu.
lar point on the surface Of the earth. or to
embarrass ourselves with any cOnsidera-
tions Of difference between observations
made at different places. We have only to
when the light transmitted to the
moon from the sun actually fails.


The farther the earth is from the SIN. the
more slowly do the lines join them, or the
boundaries OF the shadow approach each
other, and the larger. therefore, is the
shadow at the moons distance; and besides
this. the nearer the moon is to the earth.
the larger. all other things continuing the
same, is the part OF the shadow through
which it pass es. On both accounts, the dura-
ton of an eclipse is greater when the moon
is at the least aud the sun at the greatest
distance from the earth.


During the whole time OF the total i'm.
merson. y faint white light was seen which
seemed to break ont from behind the moon,
and to encompass it equally on all sides. in
breadth less than onetifteenth part of the
moons diameter. This secondary appeared
q variable reddish, and its disc was very
welt defined within the whiteness. The
total immersion began about ll:40 p. NJ.
The duration of t0tality was about thirty
three minutes, when the first rays shot forth
with their luminary characters; total OBJ
passed at about $50 A. M.


Eclipses of the sun are more frequent
than those of the moon, because the suns
ecliptio limits are greater than the
Yet We have more visible eclipses
OF the moon than of the sun, because
eclipses of the moon are seen from all parts
of that hemisphere of the earth which is
next her. and are equally great to each of
these parts, but the SUMS eclipses arc
visible only to that small portion of the
next him WhereOn the moons
shadow falls.


In astronomy eclipses of the moon are Of
great use for ascertaining the periods of its
motions, especially such eclipses as are OBJ
served to be alike in all circumstances, and
The longitudes of places are found by
eclipses, but for this purpose eclipses of the
moon are more useful than those of the sun,
because they are more frequently visible,
and the same lunar eclipse ls of equal ex-
tent and duration at all places where it is
eeen. Both solar and lunar eclipses serve
to determine the time of any past event,
for there are so many particulars observ-
able in every eclipse. with respect to its
quantity, the places where it Is visible (if of
the SUM-, and the time Of the day or night,
that it is impossible there can be two solar
eclipses in the course of many ages which
are alike IN all CIRCUMSTANCES.


s.. SUMMERS. N. y.





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