376 Double Stars. 



A continuation of these rough sketches must be deferred 

 to another occasion. 



DOUBLE STAES. 



Before the constellation Lyra sinks too far towards the set- 

 ting sun, we may point out some objects in it deserving of a 

 search. The search itself, in a transparent sky, will sufficiently 

 repay our trouble, for truly beautiful are the fields which, even 

 with a small aperture, pass under review in sweeping over this 

 district. We have long ago (Int. Obs. ii., 299, etseqq.) specified 

 the principal double stars ; we shall now add — 



162. (£ 2372). If we draw a line from 7 through /3, bend it 

 slightly — about 25° — to the 1ST, and carry it on fully 2°, it will 

 strike upon this fine open pair. 2 makes them 6*7 and 8'2-; 

 white and bluish — I thought the latter pale purple. His other 

 data are, 25"-147, 84°-23 (1829). Dawes's recent measures, 

 24 //, 75, 83°*57, very obligingly communicated to me, prove that 

 the vicinity is merely optical. His acute vision detects a most 

 minute point (12 mag. of 2's scale) at a short distance. 



A line carried the reverse way from /3 through 7, and 

 similarly bent a little N, if carried a shorter distance than that 

 between those stars, will fall upon— 



163. 17 Lyrce (2 2461). 3"'6. 329°-9. 6 and 11. Light 

 yellow and cerulean blue. This is called by Smyth very 

 beautiful and delicate ; and will be found a trying object for a 

 small aperture. The companion is a minute point even with 

 5^ inches. 



If we make the line joining Wega and 7 one side of an 

 equilateral triangle, the opposite angle will fall near two 5 

 mag. stars, 77, n, and 6, s. Something more than 1° p the 

 latter, a little s, is a 6 mag. star, 19 Lyrce; closely p which, 

 a little ii } lies a little quadruple group, of which the leading 



164. P. xix. 13 Lyrce (2 2472, 2473.) 18""5, 74"-8 ; the 

 two nearest 5". 337°, 350°; the same two 294°. 8, 11, 9±, 

 12. Bright yellow, pale grey, greenish, and dusky. The object 

 is a singular and beautiful one, but its chief interest is the 

 probability of variation in one of the two closer stars, which 

 Sra. has recorded as very unequal, 1835" 73, but which have 

 been noticed by several modern observers as much less so, if 

 at all. I remarked no difference, 1865' 72. There is also a 

 very minute star between the pairs not mentioned by him, 

 though quite within reach of his instrument. The lucida 

 seemed white to me. 



If we make the line from /3 to 7 the hypotenuse of a right- 

 angled triangle, of which another side is directed from 7 

 towards Wega, the right angle will fall nearly on a 



