CATALOGUE OF BINARY STARS. 207 



As some confusion has arisen in designating the star 

 riamsteed^s '' 51 Librae/^ I have, at the suggestion of the 

 Rev. W, R. Dawes, inserted it as "^ Scorpii" (=jP/. 51 

 Libra), as it undoubtedly belongs to Scorpio, which con- 

 stellation otherwise has no star marked ^, while Libra has 

 three stars indicated by that letter. The remarks of Mr. 

 Dawes respecting this star are interesting, and I venture 

 to quote his ovni words ; Mr. Dawes says : — " The interest 



A 4-B 

 which attaches to ^ Scorpii — ^— and C is so exceedingly 



small compared with that which belongs to A and B as a 

 binary system, that I can only account for the close and 

 rapidly revolving pair being omitted by any of the observers 

 to whose lists you refer by the very probable fact that 

 their telescopes were not competent to show it as a double 

 star. Its low situation, in these latitudes, increases the dif- 

 ficulty of observing it successfully with telescopes which 

 could divide it well.'' Respecting Dembowski's observa- 

 tions on this triple star, Mr. Dawes also remarks : — " Of 



A+B 



—I— and Che gives, 1863-14, P=70°-46, D = 7'i54, and, 



for 1 865, P = 7 1 °*02, D = 7* 1 1 2, Whatever weight may at- 

 tach to these results, they rather go to negative the sup- 

 position of C's having any orbital movement in respect of 

 A and B. Indeed, notwithstanding the regular decrease 

 of Struve's angles, I have thought the motion so doubtful 

 as to require observations at long intervals only ; and I find 

 I have not measured the star (C) since i840'56, P = 69°*45j 

 D. = 7'43. Herschel II.. obtained P = 70°-93, D = 7*07 in 

 1831-38, and at the Cape P=77°-2 in 1834-35. ThesCj 

 compared with Dembowski's more recent results, throw 

 some doubt on former deductions. But no list of binary 

 stars should be without A : B, the variation of angle having 

 amounted to nearly 160° in 40 years, and about 150° since 

 I began to observe it." 



