They are both well worthy of study, the former being a very bright globular cluster, the latter a bright and large round nebula.

The spectra of these, as of the great cluster, resemble the solar spectrum, being continuous, though, of course, very much fainter.
The star [delta] Herculis (seen at the bottom of the map) is a wide and easy double--a beautiful object.

The components, situated as shown in Plate 3, are of the fourth and eighth magnitude, and coloured respectively greenish-white and grape-red.
The star [kappa] Herculis is not shown in the map, but may be very readily found, lying between the two gammas, [gamma] Herculis and [gamma] Serpentis (_see_ Frontispiece, Map 2), rather nearer the latter.
It is a wide double, the components of fifth and seventh magnitude, the larger yellowish-white, the smaller ruddy yellow.[5] Ras Algethi, or [alpha] Herculis, is also beyond the limits of the map, but may be easily found by means of Map 2, Frontispiece.

It is, properly speaking, a multiple star.

Considered as a double, the arrangement of the components is that shown in Plate 3.