230 Royal Astronomical Society. 



Eclipses of the sun visible at Athens, occurred Nov. 4, 426 a.c. 

 and Oct. 25, 417 a.c. 



The lunar eclipses visible at Athens during the war are, 



A.C. A.C. A.C. 



428 June 17 421 Feb. 2 413 Aug. 27 



425 April 15 421 July 28 407 Oct. 21 



425 Oct. 9 418 Nov. 21 406 April 15 



On the Diminution of Brightness in |S Ursa Minoris. 



Extract of a letter from Sir J. F. W. Herschel to the Presi- 

 dent : — 



Allow me to call your attention to the remarkable diminution 

 which has taken place in the apparent brightness of /3 UrsBe Mino- 

 ris since 1840 and 1841. In the course of a series of observations 

 which I earned on in those years, on the comparative brightness of 

 the stars, the star in question was always ranked above Polaris, and 

 far above /3 Ursse Majoris and a Coronse. To the last-named star it 

 is still superior, and perhaps a little (but very little) to the former ; 

 but with Polaris it will bear no comparison. That the change is in 

 /3, and not in Polaris, is evident. The latter retains its rank ; it re- 

 mains (as I have always observed it) much inferior to a, f, and 

 ij Ursa? Majoris ; but when compared with £, there is some doubt. 

 I incline to place it a little higher in the scale than that star ; and I 

 find on consulting my lists, that on the 30th April, 1840, it was 

 judged then also superior to £, but that on the next night this order 

 was reversed ; proving that then, as now, a difficulty existed in de- 

 ciding the relative claims of the two stars to superiority. 



/3 Ursae Minoris must therefore clearly claim a place among the 

 slowly variable stars, a class of especial interest ; and I hope this 

 notice may suffice to induce some of our astronomical fraternity to 

 keep an eye on its future progress. 



On the Double Stars, #Cygni, yLeonis, &c. By J. R. Hind, 

 Esq. 



In 1783 Sir W. Herschel estimated the distance of the stars of 

 SCygni to be nearly 2" # 5 ; in 1802 and 1804 he could not see the 

 companion at all. It was rediscovered in 1826 by M. Struve, who 

 found the distance to be nearly 2", whence he conjectured the pe- 

 riodic time was about 40 years. This guess was, however, contra- 

 dicted by subsequent observations ; and M. Struve now accounts for 

 the anomalous disappearance by supposing the light of the smaller 

 star to be variable. Mr*. Hind has computed two orbits which sa- 

 tisfy the observations pretty well, and which nearly agree, except in 

 the node and inclination. The method of calculation is that de- 

 scribed by Sir J. F. W. Herschel in the Memoirs of the Astronomi- 

 cal Society, vol. v. p. 171, &c. Though these elements are only 

 approximate, yet they give a general idea of the form of the orbit. 

 The periodic time is about 180 years. 



By the same mode of calculation, Mr. Hind has obtained a first 

 approximation to the orbit of y Leonis, with a periodic time of nearly 



