Let us next turn to the third star of the equilateral triangle mentioned above—­viz. to the star [zeta] Lyrae.  This is a splendid but easy double.  It is figured in Plate 3, but it must be noticed that the figure of [zeta] and the other nine small figures are not drawn on the same scale as [epsilon] Lyrae.  The actual distance between the components of [zeta] Lyra is 44”, or about one-fourth of the distance separating [epsilon]^{1} from [epsilon]^{2}.  The components of [zeta] are very nearly equal in magnitude, in colour topaz and green, the topaz component being estimated as of the fifth magnitude, the green component intermediate between the fifth and sixth magnitudes.

We may now turn to a star not figured in the map, but readily found.  It will be noticed that the stars [epsilon], [alpha], [beta], and [gamma] form, with two small stars towards the left, a somewhat regular hexagonal figure—­a hexagon, in fact, having three equal long sides and three nearly equal short sides alternating with the others.  The star [eta] Lyrae forms the angle next to [epsilon].  It is a wide and unequal double, as figured in Plate 3.  The larger component is azure blue; the smaller is violet, and, being only of the ninth magnitude, is somewhat difficult to catch with apertures under 3 inches.

The star [delta]^{2} Lyrae is orange, [delta]^{1} blue.  In the same field with these are seen many other stars.

The stars [gamma]^{1} and [gamma]^{2} may also be seen in a single field, the distance between them being about half the moon’s mean diameter.  The former is quadruple, the components being yellow, bluish, pale blue, and blue.

Turn next to the stars [beta] and [gamma] Lyrae, the former a multiple, the latter an unequal double star.  It is not, however, in these respects that these stars are chiefly interesting, but for their variability.  The variability of [gamma] has not indeed been fully established, though it is certain that, having once been less bright, [gamma] is now considerably brighter than [beta].  The change, however, may be due to the variation of [beta] alone.  This star is one of the most remarkable variables known.  Its period is 12d. 21h. 53m. 10s.  In this time it passes from a maximum brilliancy—­that of a star of the 3.4 magnitude—­to a minimum lustre equal to that of a star of the 4.3 magnitude, thence to the same maximum brilliancy as before, thence to another minimum of lustre—­that of a star of the 4.5 magnitude—­and so to its maximum lustre again, when the cycle of changes recommences.  These remarkable changes seem to point to the existence of two unequal dark satellites, whose dimensions bear a much greater proportion to those of the bright components of [beta] Lyrae than the dimensions of the members of the Solar System bear to those of the sun.  In this case, at any rate, the conjecture hazarded about Algol, that the star revolves around a dark central orb, would be insufficient to account for the observed variation.