96 | “|! ASTRONOMY? 
e 
N. decl. 22° 17’), in the shape of a large oval nebulous spot (jig. 18), whose 
major axis is to its minor as 4 to 3. In the two foci are found two circular 
nebule, much darker, and equally illuminated in all parts. Fig. 19 repre- 
sents a curious nebulous figure found in the head of the northern Canis 
Venaticus. It is a round, bright, central spot, surrounded by a nebulous 
ring split on one side. further improvements in the telescope will proba- 
bly exhibit more clearly the true character of these wonderful objects. The 
Magellanic Clouds, observed in the southern hemisphere and invisible to us 
(fig. 20), are in like manner highly remarkable appearances of the starry 
heavens, consisting of isolated clear spots, like separated portions of the 
Milky Way. According to Horner, who has communicated some ob- 
servations on these Magellanic Clouds, the greater of them is about as 
bright as the Milky Way in its brightest part, as near Cygnus, while 
La Caille was not able to find a single star in them with his 14-foot 
telescope. 
Multiple, Variable, and New Stars. 
17. In conclusion, it remains to state that, besides the double stars, there 
are threefold and fourfold, or multiple stars, as also changeable and new 
stars. Threefold stars are found, for example, in Orion, under 724° rt. asc., 
and 141° N. decl.,in ¢ Cancer, ¢ Libra, 7 Taurus, ¥ Cassiopeit, + Monoceros, 
¥ Libra, as also in Lynx, under 973° rt. asc.eand 592° N. declination. Of 
the fourfold stars © Orion is perhaps the most distinguished ; it stands very 
near the darkest part of the great nebula in Orion; « Lyra is also a fourfold 
star. Among multiple stars, Orion is known as the most remarkable ; it 
was known by Schroter as a 12-fold, but by Struve as a 16-fold star. The 
variable stars are also remarkable, that is, those stars whose apparent 
magnitude does not remain the same. ‘These stars shine within a certain 
period with various degrees of brilliancy, and it is said that they have a 
certain period, as, for instance, Algol in Perseus, « Hercules, 8 Lyra, 
y Antinous, 6 Cepheus, &c. Nevertheless the periods of several variable 
stars appear subject to many irregularities. Other stars often yanish 
entirely, and reappear at a later period, as Mira in Cetus, X Cygni, and 
seven stars in Leo, Virgo, Hydra, Corona, and Aquarius. 
In addition to all these, stars have sometimes appeared suddenly in 
regions of the heavens tolerably free from stars, which could not have been 
there before ; such appeared in Aquila in 389, between Cepheus and Cassio- 
peia in 945, again near the same place in 1264, in Cassiopeia (Tycho’s star) 
in 1572 and 1573, in Ophiuchus, 1604 and 1605, and in Cygnus (Anthelm’s 
star), 1670. Astronomers have not yet been able to frame a satisfactory 
hypothesis to explain the phenomena which the variable and new stars 
exhibit in so remarkable a manner. 
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