Double Stars. 373 



will help to identify it ; it is much fainter than those stars, but 

 still steadily visible to a good eye. Its data are as follows : 



61. 61 Gygni. 15"'6. 90°*5. (1830-81). 16-3. 96°*3 

 (1839'69). 51 and 6. Yellow and deeper yellow. Period 

 more than 540 years, according to Bessel, who thinks that their 

 joint mass may be about half the mass of our sun. Their orbit 

 may possibly be 50 times as large as that of the earth. Secchi's 

 measures, 1855*997, — 17"*946 and 105°*93, — show its con- 

 tinued motion, contrary to W. Struve's opinion. 



Our next object is at the tip of the Swan's E. wing. A 

 line from y to e Gygni, prolonged as far again, but bent rather 

 upwards, catches \ Gygni, 3 mag. ; if carried still onwards to 

 the E. and a little to the S., somewhat further from £than £is 

 from e, it falls upon icPegasi, a 4 mag. star, a little N. of which 

 is the following, of similar brightness : — 



62. fi Gygni. 5"*4. 114°*3. 5 and 6. White and pale 

 blue (1839-62, 1850-6). So W. Struve, 1831-63. Sestini made 

 them yellow and more yellow, 1844*5. Dembowski gave 

 "jamie rougeatre" and " olivatre," 1853, 1854; <e blanc jaune 

 clair " and "jaune cendre," 1855. I found the larger star 

 yellow, 1850-69, 1851*81, while the other showed the curious 

 effect, already mentioned in No. 29 of our list, of an undecided 

 and changeable hue, blue and tawny. At present I see the 

 principal star yellow. A third blue 1\ mag. star, at 3' 36"*8, 

 completes this beautiful group. Secchi, whose colours are here 

 uncertain and variable, found, for the close pair, 1857*559, 

 4"*364 and 116°* 10, and hence, and from the large value of its 

 common proper motion, he considers that its physical connec- 

 tion is unquestionable. 



A little E. of the galaxy, and nf AUair, lies a lozenge-shaped 

 group of four moderate-sized stars, the lowermost with a com- 

 panion close on its right, and another as a pendant to the whole. 

 This is Delphinus ; more appropriately named than is usually the 

 case with these strangely devised configurations. The nf, or 

 uppermost star of the lozenge is — ■ 



63. yDelphini. 11"*8. 273°'3. 4 and 7. Golden yellow 

 and flushed grey, 1850*7. Smyth had made the smaller star light 

 emerald in 1839, corresponding more with Struve's viridicoe- 

 rulea. Sir W. Herschel called them both white ; whence, as 

 he had a known bias for red tints, Struve infers the possibility 

 of change. This, though without the interest, so far as we 

 know, of physical connection, is a beautiful object, and within 

 the reach of very small telescopes. Smyth commanded it with 

 an aperture of two inches. 



In tracing the galaxy from Cassiopea towards the NE. hori- 

 zon, we soon come to a fine 2 mag. star involved in a lucid glow 

 arising from the presence of a number of minute attendants. 



