ASTRONOMY WITH AN' OPERA-GLASS. 521 



resented too large in the i^icture. It requires a sharp eye to see Ple- 

 ione without a glass, while Atlas is plainly visible to the unaided 

 vision, and is always counted among the naked-eye Pleiades, although 

 it does not bear the name of one of the mythological sisters, but that 

 of their father. The bright star below and to the right of Alcyone is 

 Merope ; the one near the right-hand edge of the picture, about on a 

 level with Alcyone, is Electi-a. Above, or to the north of Electra, are 

 two bright stars lying in a line pointing toward Alcyone ; the upper 

 one of these, or the one farthest from Alcyone, is Taygeta, and the 

 other is Maia. Above Taygeta and Maia, and forming a little tri- 

 angle with them, is a pair of stars which bears the name of Asterope. 

 Aboiit half-w\ay between Taygeta and Electra, and directly above the 

 latter is Celfeno. 



The naked-eye observer will probably find it difficult to decide 

 which he can detect the more easily, Celaeno or Pleione, while he will 

 discover that Asterope, although composed of two stars, as seen with 

 a glass, is so faint as to be much more difficult than either Celaeno or 

 Pleione. Unless, as is not improbable, the names have become inter- 

 changed in the course of centuries, the brightness of these stars would 

 seem to have undergone remarkable changes. The star of Merope, it 

 will be remembered, was fabled to have become faint, or disappeared, 

 because she married a mortal. At present Merope is one of those that 

 can be plainly seen with the naked eye, while the star of Asterope, who 

 was said to have had the god Mars for her spouse, has faded away 

 until only a glass can show it. It would appear, then, that notwith- 

 standing an occasional temporary eclipse, it is, in the long run, better 

 to marry a plain mortal than a god — or a lord. Electra, too, who hid 

 her fair eyes at the sight of burning Troy, seems to have recovered 

 from her fright, and at present is, next to Alcyone, the brightest star 

 in the cluster. But however we may regard those changes in the 

 brightness of the Pleiades which are based upon tradition, there is 

 no doubt that well-attested changes have taken place in the compara- 

 tive brilliancy of stars in this cluster since astronomy has become an 

 exact science. 



Observations of the proper motions of the Pleiades have shown 

 that there is an actual phj'sical connection between them ; that they 

 are, literally speaking, a flight of suns. Their common motion is to- 

 ward the southwest under the impulse of forces that remain as yet 

 beyond the grasp of human knowledge. Alcyone was selected by 

 Madler as the central sun around which the whole starry system re- 

 volved, but later investigations have shown that his speculation was 

 not -well founded, and that, so far as we can determine, the proper 

 motions of the stars are not such as to indicate the existence of any 

 common center. They appear to be flying with different velocities 

 in every direction, although — as in the case of the Pleiades — we often 

 find groups of them associated together in a common direction of flight. 



