We may suitably remark in this place, with Arago, that no precise drawing of the ancient constellations has come down to us. We only know their forms by written descriptions, and these often very short and meagre. A verbal description can never take the place of a drawing, especially if it is a complex figure, so that there is a certain amount of doubt as to the true form, position, and arrangement of the figures of men, beasts, and inanimate objects which composed the star-groups of the Grecian astronomers--so that unexpected difficulties attend the attempt to reproduce them on our modern spheres. Add to this that alterations have been avowedly introduced by the ancient astronomers themselves, among others by Ptolemy, especially in those given by Hipparchus. Ptolemy says he determined to make these changes because it was necessary to give a better proportion to the figures, and to adapt them better to the real positions of the stars. Thus in the constellation of the Virgin, as drawn by Hipparchus, certain stars corresponded to the shoulders; but Ptolemy placed them in the sides, so as to make the figure a more beautiful one. The result is that modern designers give scope to their imagination rather than consult the descriptions of the Greeks. _Cassiopeia_, _Cepheus_, _Andromeda_, and _Perseus_ holding in his hand the _Head of Medusa_, appear to have been established at the same epoch, no doubt subsequently to the Great Bear. They form one family, placed together in one part of the heavens, and associated in one drama; the ardent Perseus delivering the unfortunate Andromeda, daughter of Cepheus and Cassiopeia. We can never be sure, however, whether the constellations suggested the fable, or the fable the constellations: the former may only mean that Perseus, rising before Andromeda, seems to deliver it from the Night and from the constellation of the Whale. The Head of Medusa, a celebrated woman, that Perseus cut off and holds in his hand, is said by Volney to be only the head of the constellation Virgo, which passes beneath the horizon precisely as the Perseus rises, and the serpents which surround it are Ophiucus and the polar Dragon, which then occupies the zenith.