The star [xi] Bootis is an exceedingly interesting object. It is double, the colours of the components being orange-yellow and ruddy purple, their magnitudes 3-1/2 and 6-1/2. When this star was first observed by Herschel in 1780 the position of the components was quite different from that presented in Plate 5. They were also much closer, being separated by a distance of less than 3-1/2 seconds. Since that time the smaller component has traversed nearly a full quadrant, its distance from its primary first increasing, till in 1831 the stars were nearly 7-1/2 seconds apart, and thence slowly diminishing, so that at present the stars are less than 5 seconds apart. The period usually assigned to the revolution of this binary system is 117 years, and the period of peri-astral passage is said to be 1779. It appears to me, however, that the period should be about 108 years, the epoch of last peri-astral passage 1777 and of next peri-astral passage, therefore, 1885. The angular motion of the secondary round the primary is now rapidly increasing, and the distance between the components is rapidly diminishing, so that in a few years a powerful telescope will be required to separate the pair. Not far from [xi] is [pi] Bootis, represented in Plate 5 as a somewhat closer double, but in reality--now at any rate--a slightly wider pair, since the distance between the components of [xi] has greatly diminished of late. Both the components of [pi] are white, and their magnitudes are 3-1/2 and 6. We shall next turn to an exceedingly beautiful and delicate object, the double star [epsilon] Bootis, known also as Mirac and, on account of its extreme beauty, called Pulcherrima by Admiral Smyth. The components of this beautiful double are of the third and seventh magnitude, the primary orange, the secondary sea-green. The distance separating the components is about 3 seconds, perhaps more; it appears to have been slowly increasing during the past ten or twelve years. Smyth assigns to this system a period of revolution of 980 years, but there can be little doubt that the true period is largely in excess of this estimate. Observers in southern latitudes consider that the colours of the components are yellow and blue, not orange and green as most of our northern observers have estimated them. A little beyond the lower left-hand corner of the map is the star [delta] Serpentis, in the position shown in the Frontispiece, Map 3. This is the star which at the hour and season depicted in Map 2 formed the uppermost of a vertical row of stars, which has now assumed an almost horizontal position. The components of [delta] Serpentis are about 3-1/2 seconds apart, their magnitudes 3 and 5, both white.