ole Star itself is of the second magnitude, but
its companion is only of the ninth, and on account of its minuteness is
regarded as a good test for telescopes of small aperture. Mizar, in the
constellation Ursa Major, is a beautiful double star. The components are
wide apart, and can be easily observed with a small instrument.

There is a remarkable star in the constellation of the Lyre (Epsilon
Lyrae), described as a double double. This object can just be
distinguished by a person with keen eyesight as consisting of two stars;
when observed with a telescope they appear widely separated, and each
star is seen to have a companion, the entire system forming two binary
pairs in active revolution. The pair which first cross the meridian
complete a revolution in about 2,000 years; the second pair have a more
rapid motion, and accomplish it in half that time. The two pairs are
believed to be physically connected, and revolve round their common
centre of gravity in a period of time not much under one million years.

Cor Caroli, in Canes Venatici, is a pleasing double star, the components
being of a pale white and lilac colour.

Albireo, in the constellation of the Swan, is one of the loveliest of
double stars. The larger component is of the third magnitude, and of a
golden yellow colour; the smaller of the sixth magnitude, and of a
sapphire blue.

Epsilon Booetis, known also as Mirac, and called by Admiral Smyth
'Pulcherrima,' on account of its surpassing beauty, is a delicate object
of charming appearance. The components of this lovely star are of the
third and seventh magnitudes: the primary orange, the secondary
sea-green.

The late Mr. R. A. Proctor, in describing a binary star system, writes
as follows: 'If we regard a pair of stars as forming a double sun, round
which--or, rather, round the common centre of which--other orbs revolve
as planets, we are struck by the difference between such a scheme and
our own solar system; but we find the difference yet more surprising
when we consider the possibility that in some such schemes each
component sun may have its own distinct system of dependent worlds. In
the former case the ordinary state of things would probably be such that
both suns would be above the horizon at the same time, and then,
probably, their distinctive peculiarities would only be recognisable
when one chanced to pass over the disc of the other, as our Moon passes
over the Sun's disc in eclipses. For shor