Southeast of Cygnus, near the eastern shore of the starry river, is Aquila, the “Eagle.” Its chief star, Altair, “Eagle,” recalls Antares, not by its color, for it is not red but white, but by the singular arrangement of two small stars standing one on either side of it. Here, too, the Milky Way is very splendid, attaining astonishing brightness lower down, in Scutum Sobieskii, “Sobieski’s Shield.” The naming of this constellation was a posthumous reward to the heroic king, John Sobieski, for saving Europe by the defeat of the Turks under the walls of Vienna, after their victorious advance from Constantinople, emphasized in the public mind by the appearance of Halley’s Comet, had seemed to threaten a Moslem conquest. Twice Halley’s Comet had alarmed Europe in connection with the Turks, first in 1456, after they had taken Constantinople, and again in 1682 when they swept upon Vienna, so that it was a natural thought to associate Sobieski’s victory with some “sign in the sky,” and a more appropriate one could hardly have been found than the “shield,” bossed with star-clusters, which Hevelius selected for the purpose. The southern part of the constellation Aquila is sometimes called Antinous. For the beautiful Oriental legend of the Spinning Damsel and the Magpie Bridge connected with Aquila and Lyra, see _Astronomy with the Naked Eye_. Newcomb gives Altair ten times the luminosity of the sun. The constellations Delphinus and Anser et Vulpecula will be dealt with in the next chapter. In the mean time let us turn to the western half of the sky. Just west of the meridian, near the zenith, gleams the glorious Northern Crown, Corona Borealis. The head of Serpens is right underneath it. It is, perhaps, the most charming of all asterisms. It could hardly be called anything else than a crown or a wreath. The perfection of the figure is surprising. If its stars were larger it would be the cynosure of the sky, but small as they are they produce an effect of ensemble that could not have been exceeded if human hands had arranged them there. The superior brightness of one of them, Alpha “Gemma,” or “The Pearl,” adds greatly to the effectiveness of the combination. It is the work of a master jeweller! Yet, as I have elsewhere shown, this curious assemblage of stars is but a passing phenomenon, for they are travelling in various directions, with various speeds, and in the course of time the Northern Crown will dissolve like a figure in the clouds. In Greek mythology it was generally called the Crown of Ariadne. Just under the star Epsilon (ε) is a wonderful variable, which in 1866 suddenly blazed up to the second magnitude, and was for a time regarded as a new star. Nothing is known of its periods of change. It is not now visible to the naked eye.