The length of this republic, from Atlas and Pleione to Celæno, is 4'/23" of time, or 1°6' of arc; the breadth, from Merope to Asterope, is 36'.[8]
In the quadrilateral, the length from Alcyone to Electra is 36', and the breadth from Merope to Maia 25'. To us it appears as though, if the Full Moon were placed in front of this group of nine stars, she would cover it entirely, for to the naked eye she appears much larger than all the Pleiades together. But this is not so. She only measures 31', less than half the distance from Atlas to Celæno; she is hardly broader than the distance from Alcyone to Atlas, and could pass between Merope and Taygeta without touching either of these stars. This is a perennial and very curious optical illusion. When the Moon passes in front of the Pleiades, and occults them successively, it is hard to believe one's eyes. The fact occurred, _e.g._, on July 23, 1897, during a fine occultation observed at the author's laboratory of Juvisy (Fig. 26).
[Illustration: FIG. 26.--Occultation of the Pleiades by the Moon.]
Photography here discovers to us, not 6, 9, 12, 15, or 20 stars, but hundreds and millions.
These are the most brilliant flowers of the celestial garden.
[Illustration: FIG. 27.--Stellar dial of the double star [gamma] of the Virgin.]
We, alas, can but glance at them rapidly. In contemplating them we are transported into immensities both of space and time, for the stellar periods measured by these distant universes often overpower in their magnitude the rapid years in which our terrestrial days are estimated. For instance, one of the double stars we spoke of above, [gamma] of the Virgin, sees its two components, translucent diamonds, revolve around their common center of gravity, in one hundred and eighty years. How many events took place in France, let us say, in a single year of this star!--The Regency, Louis XV, Louis XVI, the Revolution, Napoleon, Louis XVIII, Louis Philippe, the Second Republic, Napoleon III, the Franco-German War, the Third Republic.... What revolutions here, during a single year of this radiant pair! (Fig. 27.)
But the pageant of the Heavens is too vast, too overwhelming. We must end our survey.
Our Milky Way, with its millions of stars, represents for us only a portion of the Creation. The illimitable abysses of Infinitude are peopled by other universes as vast, as imposing, as our own, which are renewed in all directions through the depths of Space to endless distance. Where is our little Earth? Where our Solar System? We are fain to fold our wings, and return from the Immense and Infinite to our floating island.