THE PLEIADES.
The Pleiades prove that, several thousand years ago even as now, stars of the seventh magnitude were invisible to the naked eye of average visual power. The group consists of seven stars, of which six only, of the third, fourth, and fifth magnitudes, could be readily distinguished. Of these Ovid says (Fast. iv. 170):
“Quæ septem dici, sex tamen esse solent.”
Aratus states there were only six stars visible in the Pleiades.
One of the daughters of Atlas, Merope, the only one who was wedded to a mortal, was said to have veiled herself for very shame and to have disappeared. This is probably the star of the seventh magnitude, which we call Celæne; for Hipparchus, in his commentary on Aratus, observes that on clear moonless nights seven stars may actually be seen.
The Pleiades were doubtless known to the rudest nations from the earliest times; they are also called the mariner’s stars. The name is from πλεῖν (plein), ‘to sail.’ The navigation of the Mediterranean lasted from May to the beginning of November, from the early rising to the early setting of the Pleiades. In how many beautiful effusions of poetry and sentiment has “the Lost Pleiad” been deplored!—and, to descend to more familiar illustration of this group, the “Seven Stars,” the sailors’ favourites, and a frequent river-side public-house sign, may be traced to the Pleiades.