Double Stars. — Occultations. 303 



51. 7} Lyrce. 28"-3. 84°*8. 5 and 9. Sky-blue and violet 

 (1834-74). I found the large star yellow, 1849*76 and 1850-77, 

 with 8f inches; and 1849-93, with Mr. Bishop's 7-inch 

 achromatic in the Regent's Park: pale yellow, 18 62 "7 7, with 

 many powers of 5^ inches. On the other hand, Struve makes 

 it ccerulea during 5 years, about 1830. It lies in a beautiful 

 field, containing a pretty open 8 mag. pair s p, and a smaller 

 open pair, 10 and 11 mag. fa, little n. To find it let a line 

 joining Wega and 7 be taken as one side of an equilateral tri- 

 angle — the opposite angle to the left will fall near two small 

 stars, the uppermost of which is r\ • or 77 is about one-third of 

 the distance from Wega to 7 Cygni — 



The two stars /3 and 7 Lyrce point at some distance s f } on 

 to the left, a little above a glorious object. 



52. (3 Cygni. ATbireo, in the beak of the swan. 34"*4. 55°*6. 



3 and 7 (perhaps, Smyth says, underrated). Golden-yellow 

 and smalt-blue ; merely, as it seems, in optical juxtaposition, 

 though one of the most splendid and beautiful as well as best- 

 known pairs in the heavens. Any telescope, fit to be turned 

 upon the stars at all, will show it, though of course it will gain 

 greatly with increase of light and power. 



We will now examine some interesting objects in the head 

 of the long winding constellation Draco, many folds of which 

 lie between Wega and the further part of Ursa Major. 



A line from (3 Lyrce through Wega falls at some little dis- 

 tance upon a 2nd mag. star in the Dragon's head, 7 Draconis, 

 or Has al Tannin, worth looking at for its fine deep yellow 

 hue, but more remarkable as passing almost exactly through 

 the zenith of Greenwich, in consequence of which Bradley, in 

 observing it vainly for a parallax which his instrument could 

 not detect, was led, in 1728, to the discovery of the aberration 

 of light. A similar line from 7 Lyrce through Wega falls upon 

 another 2nd mag. star in the head, ft Draconis, or Altvaicl, 

 almost exactly n of which, at a short distance, lies — 



53. v l and jf Draconis. 61"*9. 311°*8. Both 5, and pale 

 grey. A bright pair, suitable for a small telescope, which 

 seems to have a proper common motion. 



As far from v, p, as /3 is from 7, we get our next object — 



54. fj, Draconis. 3""6. 206°-7 (1830-79). 3"'3. 200-3 (1839-53). 



4 and 4^. White and pale white. This beautiful double star 

 is undoubtedly binary, with a period, Smyth thinks, of about 

 600 years. Two inches of aperture, he found, would show it. 

 Secchi's measures give, for 1857 - 5, 2"*746 and 188°'37, so that 

 its progressive motion is striking. 



Two lines, through 7 and /3, and through v and fi, converge 

 a little beyond — 



55. 17 Draconis. S"'3, 115°*7. 6 and Qh Pale yellow and 





