Q-ORE — On Knoion Variable Stars. 199 



159. Y SAGiTTAEn. — Entered in Chacornac's Chart, 1852-3, but 

 not seen by Peters on the following dates: — 1868, June 24 ; 1870, 

 June 6; 1873, June 24; 1875, July 1 and 2, and August 9; 1877, 

 June 17 and July 4; 1878, June 30; 1879, June 23 and July 12. 

 He found it, however, visible on tbe following dates, and compared 

 its brightness with that of neighbouring small stars : — 1868, July 12 ; 

 1871, June 20; 1872, June 29; 1876, July 15 and 19; 1877, July 6 

 ("sehr schone Luft, gerade sichtbar"); and 1880, June 18. 



160. R Sagitt^. — This star has a double minimum. From Schon- 

 feld's observations, the intervals of the phases about the chief mini- 

 mum (at the mean 10 m.) are as follows : — 



Pirst Max. 



. 8-6 m. . 



. 14-4 days 



Second Min. . 



. 9-0 



. 34-5 „ 



Second Max. . 



. 8-8 



. 45-3 „ 



with marked irregularities of brightness, especially near the first 

 minimum. The period seems to have decreased up to 1870-71, and 

 since then become greater. Schonfeld finds that the following for- 

 mula would reduce the deviations of all the epochs under 2-9 days : — 



Min Ep. E = 1868-4-25-968 + 70"i-467 E - 2^-463 sin (4° 30' E). 



161. E Delphini. — Observed by Hencke, August 6, 1851, as 9 m., 

 and considered to be a new planet ; and not firrther observed until 

 July, 1859, when it was found to be a variable by Schonfeld. The 

 Elements represent 5 good maxima since 1865 within 7 days, and all 

 the earlier observations. Schonfeld has not succeeded ia observing a 

 minimum. A 12 m. star s.p. 



162. P (34) Ctgni. — The so-called Nova of 1600, which was re- 

 markably variable (up to about 3 mag.) in the begirming of the 17th 

 century; but since about 1677, it has been almost always recorded in 

 transit observations of 5 m. or 5i. The only notable exception is an 

 observation by Bessel, 1825, September 14, when it was rated 6-7. 

 It is marked in Bayer's Maps with the letter P. Kepler's observa- 

 tions of the star in 1602 agree closely with the place of 34 Cygni, 

 according to modern observations. According to Kepler, it remained 

 of the third magnitude for many years, and then disappeared. It 

 was again observed by Dominique Cassini in 1655, and gradually 

 brightened during 5 years, until it reached the 3rd magnitude, and 

 afterwards diminished. In 1677, 1682, and 1715, it is recorded of 

 the 6th magnitude ; and there is no further record of any marked 

 increase of brightness. Pigott assumed a period of about 18 years, 

 but this seems very doubtful. 



2B2 



