Foremost amongst the great clusters with which we are acquainted stands the Milky Way, which has pre-eminently occupied the attention of philosophers from the earliest ages of antiquity.

The course of the Milky Way amongst the constellations is thus sketched by Sir J. Herschel, whose description we shall quote with a few verbal alterations.

Neglecting occasional deviations, and following the line of its greatest brightness, as well as its varying breadth and intensity will permit, its course conforms nearly to that of a great circle inclined at an angle of about 63° to the equinoctial, and cutting that circle in E.A. 0h. 47m., and 12h. 47m.; so that its northern and southern poles respectively are situated in E.A. 12h. 47m., Decl. N. 27° and E.A. 0h. 47m., Decl. S. 27°. Throughout the region where it is so remarkably subdivided, this great circle holds an intermediate situation between the 2 great streams; with a nearer approximation, however, to the brighter and continuous stream, than to the fainter and interrupted one. If we trace its course in order of right ascension, we find it traversing the constellation Cassiopeia, its brighter part passing about 2° north of the star δ of that constellation, i. e. in about 62° of north declination. Passing thence between γ and ε Cassiopeia?, it sends off a branch to the south preceding side, towards α Persei, very conspicuous as far as that star, prolonged faintly towards e of the same constellation, and possibly traceable towards the Hyades and Pleiades as remote outliers.