The semi-weekly messenger. [volume] (Wilmington, N.C.) 1897-1908, 1900-06-12
THE SKIES IN JUNE.
The Suns Motion in Right Ascension.
The Equation of Time-What II
Means and How it is Calculated
The Planets-The Consultations

This is the month in which the sea-
son changes from that of the balmv
life-inspiring days of spring to those
of the more oppressive and scorching
heat of summer.
The first of the month the suns de-
clination was % degrees, 4 minutes and
on the last will be % degrees. min
utes, thus ranging during the month
over an arc of only l degree and min
utes, while for the previous month it
ranged over an arc of degrees, so
minutes. This shows how much slower
the suns motion in declination be-
comes the closer it approaches the SOL
Suces. The sun enters the sign
Cancer on the Goth of this month. This
is the summer Solstice, and the first
day of summer in the astronomical
year. This is the longest day in the
year in the northern hemisphere The
North pole is now at it's greatest in
clination to the sun and enjoys a con-
tinual day during this complete revo-
luton of the earth on it's axis While
the unequal rate of the suns motion
in ndeclination-that is, north and south
of the equtor-is great, it is not more
so than its apparent motion in right
ascension, which is also due to the
same cause-viz., the earth's orbital
motion.
Therefore, measuring time by it
proves unsatisfactory both for practi-
cal and scientific purposes, and hence
mean solar time has been selected.
Just imagine a fictitious sun moving
at a uniform rate in a line of the equa-
tor, and making a complete circuit in
the same time as the real sun performs
its circuit. Sometimes this fictitious
sun will be ahead Of the real sun and
sometimes behind it. The difference
between these two times Is called the
equation of time, amounting at most
to about 16 minutes, and from that
down to o. The time denoted by this
fictitious sun is known as mean solar
time While the real sun gives what
Is known as apparent solar time.
Mean solar and apparent solar time
coincide four times a year-viz.: April
18th, June 14th, September 1st, and
December 23rd; while the greatest diff
ference between the two occurs on Feb
ruary 10th, May 14th, July 26th, and
November End. To find the time of
day by means of the suns dial, we
have to correct the latter by means
of the equation OF time, which Is Civ
en- for every day in the year in many
or the almanacs now published Some
times this equation of time Is to be ad-
ded, and at other times to be substrac-
ted.
Thus on August 1st. when the SUNS
dial idicates apparent noon, the mean
solar time will be about minutes
past, for on that day the equation Of
time is 6 minutes and is to be added.
Thus, for another example, when the
suns dial indicates apparent noon on
October 1st, the equation Of time for
that day, which is about 10 minutes.
will have to be subtracted in order to
find mean time.
The suns apparent motion in right
ascension and declination, especially
the latter, is of the highest impor-
tance to science, as the very seasons
depend on it. The suns motion in
declination also shows why the points
of the suns rising and setting on the
horizon vary so greatly. II we wish
to find the exact point on the horizon
where the sun rises or sets for any
particular day We Will have to know
the suns declination for that day and