PLEASURES OF THE TELESCOPE. 511 



until its recent discovery in a rare Norwegian mineral, was not 

 known to exist on the earth) are bright, but they vary in visibil- 

 ity. Moreover, dark lines due to hydrogen also appear in its spec- 

 trum simultaneously with the bright lines of that element. Then, 

 too, the bright lines are sometimes seen double. Prof. Pickering's 

 explanation is that ft Lyrse probably consists of two stars, which, 

 like the two composing ft Auriga?, are too close to be separated 

 with any telescope now existing, and that the body which gives the 

 bright lines is revolving in a circle in a period of about twelve days 

 and twenty-two hours around the body which gives the dark 

 lines. He has also suggested that the appearances could be ac- 

 counted for by supposing a body like our sun to be rotating in 

 twelve days and twenty -two hours, and having attached to it an 

 enormous protuberance extending over more than one hundred 

 and eighty degrees of longitude, so that when one end of it was 

 approaching us with the rotation of the star the other end would 

 be receding, and a splitting of the spectral lines at certain periods 

 would be the consequence. "The variation in light," he adds, 

 " may be caused by the visibility of a larger or smaller portion of 

 this protuberance." 



Unfortunate star, doomed to carry its parasitical burden of 

 hydrogen and helium, like Sindbad in the clasp of the Old Man of 

 the Sea ! Surely, the human imagination is never so wonderful 

 as when it bears an astronomer on its wings. Yet it must be ad- 

 mitted that the facts in this case are well calculated to summon 

 the genius of hypotheses. And the puzzle is hardly simplified by 

 Belopolsky's observation that the body giving dark hydrogen 

 lines shows those lines also split at certain times. It has been cal- 

 culated, from a study of the phenomena noted above, that the 

 bright-line star in ft Lyrse is situated at a distance of about fifteen 

 million miles from the center of gravity of the curiously compli- 

 cated system of which it forms a part. 



We have not yet exhausted the wonders of Lyra. On a line 

 from ft to 7, and about one third of the distance from the former 

 to the latter, is the celebrated Ring Nebula, indicated on the map 

 by the number 4447. We need all the light we can get to see this 

 object well, and so, although the three-inch will show it, we shall 

 use the five-inch. Beginning with a power of one hundred diame- 

 ters, which exhibits it as a minute elliptical ring, rather misty, 

 very soft and delicate, and yet distinct, we increase the magnifica- 

 tion first to two hundred and finally to three hundred, in order to 

 distinguish a little better some of the details of its shape. Upon 

 the whole, however, we find that the lowest power that clearly 

 brings out the ring gives the most satisfactory view. The circum- 

 ference of the ring is greater than that of the planet Jupiter. Its 

 ellipticity is conspicuous, the length of the longer axis being 78" 



