The Wheeling daily intelligencer. [volume] (Wheeling, W. Va.) 1865-1903, 1891-11-12

hAt tNlNSANAhB hOhb. " hNh
thus situated, tho earth, sun aud moon
arc nearly in straight line with each
othcr-tho earth being between the
other two--and these conditions
the moon, ut her full, mist
pass through tho carth's shadow md
he cclipacd, either totally or partially.
II the moon, ut the time OF her oppo-
sition, be exactly in her node, she will
pass through the center OF tho eartll's
shadow, and be totally oclipscd. II, ut
the time OF opposition, the moon comes
within six degrees Of her node, she will
still pass through the carth's shadow,
though not centrally, and be totally
cclipsed; but ii she be twelve degrees
from her node, she will only Just grazc
the earth's shadow, and pNss BY IL
without being cClipsed at all, which
occurrence is called, and known TO
astronomers as M "appulsc."
The length OF the enrths shadow Ia
nearly four times the distance from the
earth othc moon which is about 2i0,-
00Omilos and the moon, when cclipsCd,
passes through the broader part OF it,
the breadth OF the shadow where the
moon crosses 1t being two and two.thirds
times the breadth OF the moon. The
duration OF lunar eclipse depends,
therefore, upon tho difference between
the diameter OF the moon and that Sec
ton OF the carth's shadow through
which size passes. 1t is not necessary
for the moon 10 pass through the centre
OF the carli's shadow in order to pro-
dUcc total eclipse, but when tho moon
passes through tho centre Of the shadow
the eclipse Is both total and central, ut
which time its duration is the longest
possible. When all eclipse OF tho moon
is both total and central, the total phase
may last nearly two hours, and the par
tial portions OF the eclipse three or four
hours, but the duration OF all cclipses
not central varies with the moons dis
tancc from her node. As tho moon over
takes the cartha shadow from the west
lunar eclipse always begins on the
east side OF the moon, rs her eastern
Limb first enters the shadow, and the
in this respect from an eclipse OF the
sun, which begins on the western and
ends Oh the eastern side oil the suns
disk.
The first and most obvious fact
learned from al eclipse OF tho moon is
that the earth is round. ms its shadow
when seen on the moons disk is always
circular, whether the eclipse be great or
small, and whatever side the earth pre-
sents to the mood ut the time. AS this
takes place always, in whatever position
the earth may be, and while the earth
is revolving rapidly upon its axis, it
follows that the earth must either be
an exact globe, or go little different
from globe that its deviation from the
figure is imperccptiblc in its shadow on
the moon. Nothing but Il spherical oO-
jeCi will cast 4 circular shadow. in
Whatever position it is placed, and it is
said that Columbus was first led to
believe that the earth is round by obscrv-
ing its shadow on the moon during IN
eclipse, for up to his time the earth had
not been circumnaEigatcd, and he did
not have the positive proof OF its
rotundity that VIC now possess. 1t is I
TACT not generally known that the
,carth's shadow, which obscurcs the
moons disk, may be frequently OBJ
served and its circular form clearly
recognized in 4 peculiar phenomenon OF
daily occurrence, known 10 mctcorolo-
gists rs the Twilight Curve, which is
visible every clear evening after sunset,
but has probably been noticed by COM
paratively few persons.
AT THE SAME MOMENT EVERYWHERE.
The phases will occur at exactly the
same instant in I'LL places where they
are visible, though the time by the