agine our sun to have a companion sun, a half or a third as
large as itself, and situated within what may be called planetary
distance, circling with it around their center of gravity; while a third
sun, smaller than the second and several times as far away, and
accompanied by a _black_ or non-luminous orb, swings with the first two
around another center of motion. There you would have an entertaining
complication for the inhabitants of a system of planets!

Other objects in Cancer are: Sigma 1223, double star, magnitudes six and
six and a half, distance 5", p. 214 deg.; Sigma 1291, double, magnitudes
both six, distance 1.3", p. 328 deg.--four-inch should split it; iota,
double, magnitudes four and a half and six and a half, distance 30", p.
308 deg.; 66, double magnitudes six and nine, distance 4.8", p. 136 deg.; Sigma
1311, double, magnitudes both about the seventh, distance 7", p. 200 deg.;
1712, star cluster, very beautiful with the five-inch glass.

[Illustration: MAP NO. 5.]

The constellation of Auriga may next command our attention (map No. 5).
The calm beauty of its leading star Capella awakens an admiration that
is not diminished by the rivalry of Orion's brilliants glittering to the
south of it. Although Capella must be an enormously greater sun than
ours, its spectrum bears so much resemblance to the solar spectrum that
a further likeness of condition is suggested. No close telescopic
companion to Capella has been discovered. A ninth-magnitude companion,
distant 159", p. 146 deg., and two others, one of twelfth magnitude at 78",
p. 317 deg., the other of thirteenth magnitude at 126", p. 183 deg., may be
distant satellites of the great star, but not planets in the ordinary
sense, since it is evident that they are self-luminous. It is a
significant fact that most of the first-magnitude stars have faint
companions which are not so distant as altogether to preclude the idea
of physical relationship.

But while Capella has no visible companion, Campbell, of the Lick
Observatory, has lately discovered that it is a conspicuous example of a
peculiar class of binary stars only detected within the closing decade
of the nineteenth century. The nature of these stars, called
spectroscopic binaries, may perhaps best be described while we turn our
attention from Capella to the second star in Auriga beta (Menkalina),
which not only belongs to the same class, but was the first to be
discovered. Neither our telescopes, nor