The daily Cairo bulletin. (Cairo, Ill.) 1878-1???, 1880-12-26
The Star Sirius.
Dr DAVID TRowpnmor, waterbury, N. Y

On n clear night when the atmos-
phere is free from smoke and haze, as we
sometimes have it in winter, we have
presented to rs the most sublime spec
taclc that nature has TO offer for our
contemplation. Turn the eyes in any
direction above the horizon, and we
sec stars innumerable, from those Of
the first magnitude to Others so small
that we catch only q glimpse of them
by means Of a side view, the stars dis
appearing when we turn the eyes and
the attention directly on them.
Those stars which we distinctly see
on any night, leaving the planets out
of consideration, appear to occupy the
same relative positions with respect to
one another night after night and year
after year. We sec them all appear to
move toward the west each night, aud
we notice after suitable lapse of time
that they seta little earlier each night,
SO that at the end of q year they all
como back to the place Of starting.
When we reflect that all these stars
are as free to move as the earth or the
moon. how wonderful it is that they
thus appear to retain their relative
positions 50 exactly, even for centur-
les. We must conclude that their
real motions are very slow, or the stars
arc very fur from us. We are now
sure (but the ancient astronomer was
uoD that in many instances the stars
are in rapid motion.
But we did not commence to write
about all the stars, but only one OF
them, Sirius, or the Dog-Star; this
star shines during our winter evenings
and it may be easily recognized by its
great briliancy, and its magnitude
which is greater than that of any other
fixed star. 1t has received the name
of Dog star, from the constellation,
or collection Of stars which it occu-
pies. For convenience of recognition
and reference the ancient astronomers
divided the starry heavens into con-
stellations, each one having some
what definite outline which could be
traced by means of the stars. The
name CaaiS MVor, or the Greater
Dog, was given to that one which coil
tains the star Sirius; and since this is
the principal star i'll the constellation,
it is often called the Dog-Star. This
star, has played somewhat important
part in the history of mankind. 1t
was to certain extent the almanac OF
the Ancient Egyptians.
The present position of Sirius is in
right ascension 50 deg. 50 min. 80 Sec,
anu in south declination IL deg. 30
min. % sec. This position is subject
both to an apparent and real var
iation. The apparent variation is due
to a gyratory motion OF the earth,
which causes the poles OF the heavens
| (the north pole is now near the north
star to revolve around the poles of
the eclipuc, or the vanishing points
of a straight line drawn through the
centre OF tie earth, and perpendicular
to the plane Of the suns apparent or
bit. This revolution is completed in
about 10000 years, aud it gives rise to
the procession of tie eq1enoreS. Since
the stars right ascension is reckoned
from the spring, or vernal equinox,
the procession causes it to increase at
slow rate. The declination will also
vary from the same cause.
The real variation of the position of
Sirius is due to its proper motion, as
it is called. Though the stars are call
ed fred stars, yet they really are not
SO, but each one has an independent
motion of its own, by which it is car
ried through space with greater or
less rapidity. This motion of the
stars is owing to the attractive influ-
encc which they exert OH one another.
The whole proper motion, however,
is not real, but II part of 1t is apparent
and due to the real, or proper motion
of the sun, carrying with him tho
planetary system. Theproper motion
Of Sirius is subject to some irrcgularity,
but the matter has been pretty thor
oughly discussed by DR.. Auwers, SO
that il is now very well understood.