has noticed such a peculiarity; but it is certainly not a pure yellow star at present (at any rate as seen in our latitude).  Owing probably to the difference of colour between Vega, Capella and Arcturus, photometricians have not been perfectly agreed as to the relative brilliancy of these objects.  Some consider Vega the most brilliant star in the northern heavens, while others assign the superiority to Capella.  The majority, however, consider Arcturus the leading northern brilliant, and in the whole heavens place three only before him, viz., Sirius, Canopus, and [alpha] Centauri.  Arcturus is remarkable in other respects.  His proper motion is very considerable, so great in fact that since the time of Ptolemy the southerly motion (alone) of Arcturus has carried him over a space nearly half as great again as the moon’s apparent diameter.  One might expect that so brilliant a star, apparently travelling at a rate so great compared with the average proper motions of the stars, must be comparatively near to us.  This, however, has not been found to be the case.  Arcturus is, indeed, one of the stars whose distance it has been found possible to estimate roughly.  But he is found to be some three times as far from us as the small star 61 Cygni, and more than seven times as far from us as [alpha] Centauri.

The star [delta] Bootis is a wide and unequal double, the smaller component being only of the ninth magnitude.

Above Alkaid the last star in the tail of the Greater Bear, there will be noticed three small stars.  These are [theta], [iota], and [kappa] Bootis, and are usually placed in star-maps near the upraised hand of the Herdsman.  The two which lie next to Alkaid, [iota] and [kappa], are interesting doubles.  The former is a wide double (see Plate 5), the magnitudes of components 4 and 8, their colours yellow and white.  The larger star of this pair is itself double.  The star [kappa] Bootis is not so wide a double (see Plate 5), the magnitudes of the components 5 and 8, their colours white and faint blue—­a beautiful object.

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.