Still keeping within the boundary of our map, we may next turn to the fine cluster 2 H (vii.) in Monoceros. This cluster is visible to the naked eye, and will be easily found. The nebula 2 H (iv.) is a remarkable one with a powerful telescope.
The star 11 Monocerotis is a fine triple star described by the elder Herschel as one of the finest sights in the heavens. Our observer, however, will see it as a double (see Plate [3]). δ Monocerotis is an easy double, yellow and lavender.
We may now leave the region covered by the map and take a survey of the heavens for some objects well seen at this season.
Towards the south-east, high up above the horizon, we see the twin-stars Castor and Pollux. The upper is Castor, the finest double star visible in the northern heavens. The components are nearly equal and rather more than 5" apart (see Plate [3]). Both are white according to the best observers, but the smaller is thought by some to be slightly greenish.
Pollux is a coarse but fine triple star (in large instruments multiple). The components orange, grey, and lilac.
There are many other fine objects in Gemini, but we pass to Cancer.
The fine cluster Præsepe in Cancer may easily be found as it is distinctly visible to the naked eye in the position shown in Plate [1], Map I. In the telescope it is seen as shown in Plate [3].
The star ι Cancri is a wide double, the colours orange and blue.
Procyon, the first-magnitude star between Præsepe and Sirius, is finely coloured—yellow with a distant orange companion, which appears to be variable.
Below the Twins, almost in a line with them, is the star α Hydræ, called Al Fard, or "the Solitary One." It is a 2nd magnitude variable. I mention it, however, not on its own account, but as a guide to the fine double ε Hydræ. This star is the middle one of a group of three, lying between Pollux and Al Fard rather nearer the latter. The components of ε Hydræ are separated by about 3½" (see Plate [3]). The primary is of the fourth, the companion of the eighth magnitude; the former is yellow, the latter a ruddy purple. The period of ε Hydræ is about 450 years.