690 PROGRESS OF ASTRONOMY FOR 1891 AND 1892. 



l)eiio(l of about 130 years. The size of this orbit around the common 

 center of gravity is about equal to that of Uranus around the sun. 

 Tlie phiiie of the orbit is inclined about 1*0° to our line of vision. 



Several interesting cases of variability have been detected in the 

 examination of the photographs of stellar specti-a ;it the Harvard Ob- 

 servatory all sliowing the bright hydrogen lines; the change in bright- 

 ness exceeding two magnirudes. The director of the Harvard Obser- 

 vatory has called for the cooperation of astronomers i)rovided withtele- 

 scojjesof moderate i)ower and not otherwise engaged, for the observa- 

 tion of a list of seventeen circnmpolar variables of long period. The 

 methods to be followed are set forth in a circular issued by the observa- 

 tory, and accessible to all who are interested. 



Nova Auriga' — One of the most remarkable outbursts of "new stars" 

 or "7?o/Yf'" that lias ever been recorded, occurred during the year 1892 — 

 a. phenomenon of double interest in that it afforded an opportunity of 

 study under improved astronomical api)aratus. 



On February 1, 1892, an anonymous j)ostal card was received at the 

 Royal Observatory, I']diid)urgb, announcing the presence of a new star 

 in the constellation Auriga. It subsequently turned out that the dis- 

 coverer was Dr. Thomas S. Anderson, an amateur astronomer living in 

 Edinburgh, that the discovery had been uuide by the help of a star-atlas 

 and a snuill pocket telescope, and that the star had been seen by him 

 for some days previous to February 1 ; it was of about the fifth magnitude. 

 Ill the first observations at Edinburgh it was found to be of a yellow 

 tint and about the sixth magnitude, its position for 1892 being right 

 ascension 5'' 25'" 3-^; declination -(-30o 21'. Very fortunately system- 

 atic photographs of this region had been made for some time by Prof. 

 Pickering at the Harvard Observatory, and the Nova was in factfinind 

 to have been i)hotographed on thirteen plates taken between December 

 10, 1891, and January 20, 1892; while it does not appear upon a plate 

 taken at Heidelberg on December 8, which shows stars down to the 

 ]iinth magnitude. The outburst, at least above the ninth magnitude 

 seems, therefore, to be ])retty well fixed between December 8 and 10, 

 1892. 



The iSTova remained of the fourth or fifth magnitude till the end of 

 February, then diminished somewhat rapidly, and by the end of March 

 it was of the twelfth to fourteenth magnitude. 



In August it was again easily visible. At the Lick observatory it 

 was found to be of 10.5 magnitude on August 17, and 9.8 on August 

 19, and further fiuctnations in brightness have occurred. 



The spectrum was of the greatest interest. The chief characteristic 

 was a brilliant array of l)right. broad lines, attended by dark compan- 

 ions on the more refrangible sides. Numerous finer details were then 

 added, dark lines crossing the broad, bright bands, and bright lines 

 marking the dark companions. 



