Delaware gazette and state journal. (Wilmington, Del.) 1883-1902, 1900-04-05
The SKIES IN APRIL.

quarter on the 9th, full on the 1ith,
last quarter on the s2d, and new on
the 29th. On the 18th she will he in I
apogee aud on the 9th in perigee !
Willis on, the LIST of the month the sun
was 4 degrees 2s minutes II seconds I
north of the equator, it will in the I
course of 1t traverse large arc and at |
its termination be nearly ii degrees |
farther north.
We have repeatedly had occasion to
mention the solar time as distinct from
the mean time, the former on account
of irregularities net being adapted for
civ proposes, while the latter obviates
this difficulty and Is enc now in uni
versai use, though it is but little more
than a hundred years since apparent
solar time was discarded in favor OF
mean time Apparent time is the time
shown by the sun dial, and mean time
the one indicated by an imagined
fictitious sun. which moves uniformly
and in the celestial equator, completing
its annual course in exactly the same
time MS that in which the actual sun
malSes the circuit of the ecliptic The
difference between moan and apparent
timc is called the equation of time.
As AN example let US take the LIST of
April. The equation of time for this
date was 4 minutes 2 seconds, to be
added. The mean time of the southing
OF the sun for the LIST of April was,
therefore, IL hours 4 minutes and 2
seconds. If the calculations are mado
according TO Eastern standard time We
must add for the latitude of Baltimore
6 minutes 20 seconds, since the lonRi-
tude of Baltimore from Greenwich is 8
hours 6 minutes and 26 seconds. Con-
sequently at Baltimore the sim southed
at 10 hours 10 minutes and 2S seconds
on the LIST Of April. The Nautical
Administrators mentions when the
equation of time is to be added or to
be subtracted. Four times in the year
apparent time and mean time agree,
or, in other words the equation Of time
reduces to zero. These four dates are
April 10th, Juno 18TH, September LIST
and December Gath.
The planet Mercury at the beginning
OF the month will be in Aquarius, but
during the greater part in Pisces.
Almost Immediately after sunset and
long before the glimmer Of the evening
twilight has vanished from the sky the
may be seen high up, shining with a
luster that is her own and renders it
well-nighl impossible to take her for
any other planet. During the month
she will reach her greatest eastern
elongation, when she will be about AZ
degrees distant from the sun. Venus
will not Get unit half-past 10 o'clock
in the evening. At the time when she
is on the point Of disappearing beneath
the western horizon her only rival in
briliancy is Just about rising in the
east, SO that for a brief time both
Venus and Jupiter may be seen on
Numerically opposite points OF the
horizon. The foime will then be in
Taurus and the latter in Scorpio. 1t is
in place here to remind the reader
again that the boundary lines Of the
consultations are not SO clearly ano
definitely marked as those of countrie:
in our biographies. In the case Of
Jupiter, for instance, it is not easy t.
tell whether he lie in Scorpio Oh
Sagittarius, which are two contiguous
CONSULTATIONS. Mars is morning star
rising little before o'clock, wher
the morning twilight is illuminating
the eastern portion of the sky, render
ing the appearance of the planet some
what faint. Mars is in the constel
lation Pisces. Saturn, being il
Sagittarius, will rise about half al
hour after midnight.
The Importance of that peculia
illumination OF the heavens some tim
before the sun has actually risen ant
after it has actually set is so evider
that few remarks concerning it can
not be regarded as out Of place il
articles that are devoted to the interest
sky. We're it not for the twilight th
daylight would at once change into th
darkness of the night. and vice versa
To twilight it is owing that the Ion
nights OF the Arctic regions Of th
earth arc considerably relieved of thei
dreary darkness. Twilight is cause
by the reflection of light from tn
upper regions of the atmosphere Of th
earth. II is most probably due to n
Election from foreign matter III the a
and also to the fact that air, under th
ordinary conditions, possesses in 4
slight degree the power OF reflection
SO that as long as any air exposed {
the sun rays il visible to the observe
it will send him more or less light an
appear illuminated. The dun alton
twilight depends upon the latitude
the place and varies with the seasoi
of the year and Is consequently d
pendent upon the declination OF Il
I sun. 1t also depends upon the elevate
above the surface of the earth, since
high elevations the amount of air abo
the observers head is less, renderiI
the duration of twilight very Erie
Twilight lasts until the sun has SUI
IL degrees below the horizon. at Il
equator, where the circles of dai
rotation are perpendicular to the hoi
zon, when the sun is in tine celesti
equator, it descends through is degre
in an hour and IL minutes; that
twilight lasts l hour and IL minute
When the sun is not in the equator /
duration Of twilight is somewhat j
creased. At the North Pole there
night as long as the sun is south OF t
equator, hut whenever it is not me
than is degrees south the sun is ney
more than IS degrees below the horizo
About the close OF September the S
sinks below the horizon and there
continual twilight until the 18th
November, when it attains distar
of IS degrees from the equator. Fro
this date there is no twilight until [
end Of January, from which time tn,
is continual twilight until about |
middle of March, when the sun ri
aboye the horizon and continues abe
the horizon uninterruptedly for
months. At intermediate points Of [
earth the duration of twilight may Y;
form the minimum of ] hour and
minutes TO several weeks. In our o
latitude during the months OF MAJ
and September twilight lasts about
hour and a half, while in midsummer
last little over two hours. In latiti