Close by Mizar a fairly good eye has no difficulty in seeing a small star which is named Alcor (signification uncertain). The Arabs are said to have called these two stars the “Horse and his Rider,” and to have regarded it as a test of good vision to be able to see them both. It is certainly not a severe test at present. Mizar itself is telescopically double, presenting a beautiful sight in a small telescope, the distance asunder being about 14″. The smaller star is like an emerald in hue, and the color is usually remarked at once by the beginner in telescopic observation. The larger star is one of those strange objects called “spectroscopic binaries”--two suns locked in the embrace of gravitation and spinning round a centre so near to each other that to anything less penetrating than the magic eye of the spectroscope they appear as a single body. Merak and Dubhe are the celebrated “Pointers,” so called because a line drawn from the former to the latter, and continued toward the pole, passes close to Polaris, the Pole-star, of which we shall presently speak. The distance between these stars is about five degrees, so that they serve as a rough measuring-stick for estimating distances in the sky. Immediately west of the meridian will be seen a curving row of stars which indicate the head of the Bear. Three of his feet, or claws, are represented by as many pairs of stars between the Great Dipper and the Sickle of Leo, one of the pairs being east of the meridian, one west of it, and one nearly upon it. Below the outer end of the handle of the Dipper, in the direction of Denebola, a fairly bright star, Cor Caroli, which English loyalty named for the heart of the unfortunate King Charles I., shines on the collar of one of the “Hunting Dogs,” Canes Venatici, which Boötes is represented as holding in a leash as he chases Ursa Major round the pole. This, too, is a beautiful double, the contrasted colors of whose widely separated stars are finely shown by a small telescope.