“It is a small, black hole in the sky. It is round and sharply defined. Its measured diameter on the negative is 2′.6. On account of its sharpness and smallness and its isolation, this is perhaps the most remarkable of all the black holes with which I am acquainted. It lies in an ordinary part of the Milky Way, and is not due to the presence or absence of stars, but seems really to be a marking on the sky itself” (_Astrophysical Journal_, January, 1910). These things really transcend explanation (see _Curiosities of the Sky_). Above Ophiuchus and his Serpent, almost exactly overhead in the latitude of 40° N., we see the quadrilateral figure marked out by four of the principal stars of the constellation Hercules. The head of Draco, described in Chapter I, is beyond it toward the north-northeast. Hercules stands feet upward in the sky, his head, indicated by the star Alpha, or Ras Algethi, the “Kneeler’s Head,” being situated a few degrees west-northwest of Ras Alhague. Thus the two giants have their heads together. But while the occupation of Ophiuchus is plain, nobody, not even in ancient times, when the constellation received its name, has ever been able to say what Hercules is laboring at. When he was on the earth everybody followed his deeds and understood, if they could not emulate, them. He was as comprehensible as a modern pugilist. Now, however, that he has been translated to the stars, his labors are of a more mysterious nature, and, judging from his attitude, he finds them harder than any he undertook for the benefit of mankind here below. One is tempted to think that the powers he offended, when he boldly entered the land of shades and snatched the wife of his friend, King Admetus, from the hand of Death himself, are now taking an ample vengeance. Ras Algethi is a very beautiful double star, one red, the other green or blue, and both, strangely enough, are variable in brightness. Their distance apart is 4″.7. Their spectrum indicates that they are advanced toward extinction many stages beyond our sun. The star Zeta (ζ), one of those in the quadrilateral, is a closer double, distance about 1″, and is binary, the period of revolution being about thirty-five years.