186 Proceedings of the Royal Irish Academy. 



the period 373'6 days, with, a maximum on June 21, 1868. Schon- 

 feld calls its colour " intensiv rothgelb" ; Pogson, " vivid red" ; and 

 Auwers, " orange." 



91. Y YiEGiKis. — Observed by Schmidt, 1866, June 6, as a star of 

 about 4^m., and considerably brighter than the neighbouring star, 68 

 (i) Virginis. It afterwards gradually decreased in brightness. 



It was rated Q^vn. by Lalande (25086), 8 m. byPiazzi, and 6-7 m. 

 by Heis. It is 7 m. in Harding's Atlas. 



Dr. Gould says that the Cordoba estimates (5-7 to 6-3) fully con- 

 firm the variability ; and I have therefore designated the star Y Yir- 

 ginis, as suggested by him, (It is marked Z in Proctor's Atlas, 

 Map 7.) 



Schjellerup, in his translation of Al-Sufi's MS. (10th century), 

 identifies the star (and correctly I think) with one numbered 19 of 

 Yirgo by Al-Sufi, and thus described: — "La 19' est la meridional du 

 cote posterieur du quadrilatere, apres al-simdh (Spica), s'inclinant vers 

 le sud ; elle est des moindres de la cinquieme grandeur ; Ptolemee la 

 dit absolument de cinquieme, mais elle est plus pres de la sixieme. . . . 

 .... Avec al-simak et la 17^ [76 Yirginis] elle forme un triangle 

 iscoscele, cette etoile etant an sommet." 



In 1879 Burnham made the interesting discovery that the star 

 was a close double, the components of nearly equal magnitude, 6*2 

 and 6-5, at a distance of 0""48, on an angle of 80'''4 for 1879. 4. 



92. R. Centattki. — A variable discovered at Cordoba in 1871. The 

 observations show that the light curve is irregular. A Maximum, 

 6"1 m. occurred about the middle of April, 1871. It sunk to a Mini- 

 mum towards the end of that year, when it was invisible in a 4|^-inch 

 telescope, and reached a secondary Maximum of 6-7 m. about April 20, 

 1872. It then fell to a secondary Minimum of 8"7 m. about August 

 3, and rose again to 6-0 m. at the end of September, 1872. A Maxi- 

 mum of over 6"4 m. took place about August 3, 1877, and 6'1 about 

 June 28, 1878. Dr. Gould thinks the observations may be " reconciled 

 by supposing a full period of 525 days, with epoch of principal maxi- 

 mum, 1871, April 18 ; and two intermediate maxima following the 

 principal one by 197 and 378 days respectively." This does not, 

 however, agree with observations of 6J m. and 6 m., made 1874, June 

 25 and 26 ( Uranometria Argentina, p. 268, 269). 



93. T Boons.— Only seen by Baxendell, 1860, April 9, as 9f m. ; 

 April 11, 10 m. ; April 20, as 12-8 m. ; April 23, invisible, and below 

 14 m. Schonfeld failed to see it in several trials since 1865. Place, 

 according to Baxendell, 1™ 45^ preceding, and 11' 30" south of Arc- 

 turus. Schonfeld asks, "1st der Stern eine kurz vor dem Erloschen 

 aufgef undone JSTova gewesen ?" 



