Evening star., 1899-04-01

In the west Orion, followed by his two
dogs, Procyon and Sirius, is about to set.
Between west and northwest Taurus, the
Bull, is already partly below the horizon.
his golden horns now pointing directly
upward. In midheavens in the northwest
is Auriga, the Wagner, carrying upon his
left shoulder the She Goat, marked by the
brilliant star Capella, and in his lap her
three Kids.
Midway from the horizon to the zenith,
in the west, are the Twins, Castor and Pol
lux, and close beside them Is the planet
Mars.
Facing the south at the hour named we
shall have directly before us-well up to-
ward the zenith-the old cons tellation Leo,
the Lion. The star Regulus, the Lions
Heart (Cor Leonis) and the jewel in the
handle of the Sickle, which forms thu
Lions head and shoulders, is very nearly
on the meridian.
The Water Snake.
Between Leo and the southern horizon the
Hydra or Water Snake, stretches its enor-
nous length of over 100 degrees. The re-
gion traversed by this immense constella-
ton is chiefly remarkable for it's poverty IN
stars. 1t contains but one which rises to
the second magnitude This is Cor Hydrae,
five degrees a little west of south from
Regulus. Its Arabic name, Alphard, signi-
f1es the solitary one. The head of the Hy
dra Is formed by little group of stars
of which the brightest, the eye, is of the
third magnitude, situated very nearly mid
way between Regulus and Procyon. 1t is
very pretty object for the opera glass,
which shows a dozen or more stars here.
The tail Of the Hydra now touches the hori-
zon directly beneath the star Spica. The
Hydra Is not a particularly striking con-
stellation. Still, 1t can be traced with the
aid of a chart.
Standing the back of the Hydra are
two small consultations. the Crater.
Cup, and Corvus, the Crow, which, though
they contain between them but one star
that attains to the full third magnitude,
are both very pretty asterisms, particularly
when scanned with an opera glass. With
the aid Of the Planisphere they can be
found easily. Note that the Cup is about
equally distant from Regulus and Spica.
The Grow, though less like" as a constel-
lation than the Cup is the more conspicu-
Gus object of the two. Its brightest star
at the lower left-hand corner, in the
Crows feet-bearS the Arabic name AL
chIba, which means tent and was prob
ably applied originally to the whole con-
stellation, which certainly resembles tent
quite as closely as 1t does bird.
Is Sirius a Giant SUM-
Prof T. ]. ]. See has lately investigated
the "law of temperature for gaseous celes-
tial bodies,' and among other conclusions
at which he has arrived is one of great in
terest respecting the star Sirius. Prof. Sees
law" deduced from a mathematical treat
ment of the subject, Is that condensing
gaseous mass grows hotter in the exact
ratio it's diameter becomes less. For ex-
ample, the temperature of the sun is now,
according to the most recent determination
of it, about 5000 degrees centigrade. The
sun Is undoubtedly contracting its dimen-
sions and this, as was first pointed out by
Helmholtz, is what keeps 1t from cooling
off. Professor See now declares that the
contraction of the sun generates heat suf1i-
cient, not merely to keep up its tempera-
ture, but also to make it hotter. Should
the sun, In the course of future ages con-
tract to one-half of its present diameter,
its temperature would then be double what
it now is, or 5000 degrees centigrade. AS
the sun. or any other luminous body, grows
hotter Its light becomes whittier, until, when
the highest known temperature is reached,
it becomes blue-white. The sun may be
expected eventually, therefore, to shine
with the blue-white light of Sirius, instead
of. as now, with yellow light which
causes it to be classed with such stars as
Arcturus and Capella.
If this conclusion is well grounded, then
the opinion which has heretofore prevailed
among astronomers that the blue-white
stars-the so-called "Sirian starS'-which
are undoubtedly the hottest of the heavenly
host. are suns in the earliest stage of their
existence, Juvenile worlds" must be aban-
doned. They are, on the contrary, suns in
which the heating process has been going
on the longest, and therefore they are not
younger, but are older. than the yellow
solar" stars.
Merely a Guess.
Still another conclusion respecting Sirius
has been drawn by Prof. See from his law
one which Is equally in conflict with the
generally received opinion regarding this
star We have been. taught that Sirius is
probably giant sun" much larger than
our own sun. though how much larger no
one has ventured to say. This view Is
based upon the fact that since we have
known the distance of Sirius from us
100000 times that of the sun-it has been
possible to calculate that to shine as
brightly as It does it must be actually
about fifty times as brilliant as the sun.
The sun in its place would shine as a star
OF the second magnitude. Il 1t be assumed