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.