Q-ORE — On Known Variable Stars. 



197 



motion to account for the difference of position since 1670. "Prom 

 the fixity of position during eight years it may be inferred that the 

 Grreenwich variable is distinct fi^om Anth elm's." 



153. S YxTLVEcvjjJE. — This star follows the preceding. Elements 

 derived by Schonfeld from 63 periods show deviations up to 12 days ; 

 but these deviations follow a regular course, and indicate a shortening 

 of the period. Baxendell suspects a neighbouring fainter star to be 

 also variable. 



154. X Ctgni. — A remarkable variable, Bayer's x Cygui, some- 

 times confused with 17 (Fl.) Cygni, to which Flamsteed affixed the 

 letter ^ by mistake, the variable — which is the true x — having been 

 faint at the date of Flamsteed's observation. According to Schonfeld, 

 the observations cannot be represented by a uniform period. The 

 Elements given in the Catalogue give the maxima in 1687-1738, and 

 since 1863 too early, and in 1747-1758 and 1821-1862 too late; but 

 on the whole the observations seem to show a small lengthening of 

 the period. Erom the observations of late years the minimum occurs 

 approximately 185 days before the maximum. At some maxima the 

 star is barely visible to the naked eye. There are numerous faint 

 stars in the vicinity. The following are dates of observed maxima 

 since 1862:— 



Year. 



Date 



of 



Maximum. 



Brightness. 



Authority. 



Remarks. 



1862. 



June 25 





Schmidt. 



Ast. Nach., 1376. 



1865. 



Nov. 19 \ 

 Nov. 23 j 





Schonfeld. 

 Sclimidt. 



A. N., 1628. 



1867. 

 1869. 

 1870. 



Jan. 22 



April 22 

 June 4 



■ ' 



5-2 m. 



5-2 



Heis. 

 SclLonfeld. \ 



Visible to naked eye for about 

 21 months. A. N., 1642. 



Both good. A. N., 1857. 



=. 



June 5 



• . 



Schmidt. 





1871. 



July 13-2 \ 



• . 



j> 



A. N., 1871. 



1872. 



July 15 ) 

 Aug. 24 \ 



4-6 

 5-1 



Schonfeld. 



A. N., 1907. About = <p 



Cygni. 

 A. N., 1992. 



>> 



Aug. 26 ) 



•• 



Schmidt. 



A. N., 1969. 



R. I. A. PROC, SEK. 11., VOL. IV.— SCIENCE. 



2B 



