Lastly, the observer may turn to the pair Mizar and Alcor, the former the middle star in the Great Bear’s tail, the latter 15’ off. It seems quite clear, by the way, that Alcor has increased in brilliancy of late, since among the Arabians it was considered an evidence of very good eyesight to detect Alcor, whereas this star may now be easily seen even in nearly full moonlight. Mizar is a double star, and a fourth star is seen in the same field of view with the others (see Plate 5). The distance between Mizar and its companion is 14".4; the magnitude of Mizar 3, of the companion 5; their colours white and pale green, respectively.
A HALF-HOUR WITH ANDROMEDA, CYGNUS, ETC.
Our last half-hour with the double stars, &c., must be a short one, as we have already nearly filled the space allotted to these objects. The observations now to be made are supposed to take place during the fourth quarter of the year,—at ten o’clock on October 23rd; or at nine on November 7th; or at eight on November 22nd; or at seven on December 6th; or at hours intermediate to these on intermediate days.
We look first, as in former cases, for the Great Bear, now lying low down towards the north. Towards the north-east, a few degrees easterly, are the twin-stars Castor and Pollux, in a vertical position, Castor uppermost. Above these, a little towards the right, we see the brilliant Capella; and between Capella and the zenith is seen the festoon of Perseus. Cassiopeia lies near the zenith, towards the north, and the Milky Way extends from the eastern horizon across the zenith to the western horizon. Low down in the east is Orion, half risen above horizon. Turning to the south, we see high up above the horizon the square of Pegasus. Low down towards the south-south-west is Fomalhaut, pointed to by [beta] and [alpha] Pegasi. Towards the west, about half-way between the zenith and the horizon, is the noble cross in Cygnus; below which, towards the left, we see Altair, and his companions [beta] and [gamma] Aquilae: while towards the right we see the brilliant Vega.
During this half-hour we shall not confine ourselves to any particular region of the heavens, but sweep the most conveniently situated constellations.
[Illustration: PLATE V.]
First, however, we should recommend the observer to try and get a good view of the great nebula in Andromeda, which is not conveniently situated for observation, but is so high that after a little trouble the observer may expect a more distinct view than in the previous quarter. He will see [beta] Andromedae towards the south-east, about 18 deg. from the zenith, [mu] and [nu] nearly in a line towards the zenith, and the nebula about half-way between [beta] and the zenith.
With a similar object it will be well to take another view of the great cluster in Perseus, about 18 deg. from the zenith towards the east-north-east (see the pointers [gamma] and [delta] Cassiopeiae in Map 4, Frontispiece), the cluster being between [delta] Cassiopeiae and [alpha] Persei.