A. Hall — Nova Andromedm. 301 



of Andromeda, says that he is confident there was no star in 

 the place of the new one which was easily visible in his tele- 

 scope on the 15th and 16th of August. This testimony is im- 

 portant, and serves to fix the time of the appearance of the 

 nova, or at least the time it became an easy object in telescopes, 

 within very narrow limits. This time must have been between 

 the 16th and 20th of August, 1S85. It is probable that the 

 star increased rapidly in brightness, since on August 31st it 

 was of the seventh magnitude. It never, I think, became much 

 brighter, though statements were made early in September that 

 it was of the second or third magnitude, and easily visible to 

 the naked eye. Its diminution of brightness began about 

 August 31, and has gone on pretty steadily until the present 

 time. There have been several attempts to show that there 

 were fluctuations in its brightness, but these are so uncertain 

 that we must wait for the complete evidence. 



At first, the position of the new star was confounded with 

 that of the bright point of the nebula, and as this mistake 

 added interest to the discovery, it was some time before it could 

 be generally corrected. The coincidence with the nucleus of 

 the nebula seemed to indicate that we had before our eyes the 

 formation of a sun from nebulous matter, and hence a strong 

 proof of the nebular hypothesis. Our popular astronomical 

 writers were not slow to improve the occasion, but in fact 

 the new star never coincided with the nucleus. The assump- 

 tion of any intimate physical connection of the new star with 

 the nebula has been given up by Yogel, of Potsdam, and 

 Hasselburg, of Pulkowa, who have examined its spectrum. 

 Within the limits of this nebula there can be counted from 

 fifteen hundred to two thousand telescopic stars, and one of 

 these has proved to belong to the class of temporary stars, 

 so-called, of which we have records of from 20 to 30. What 

 causes these stars suddenly to flame out, and then to fade 

 gradually away we do not know ; and so far as I know, there 

 is hardly a plausible theory. 



I first saw this new star on September 6, when its magni- 

 tude seemed to me 7J, and the star had a decidedly ruddy 

 tinge. This color lasted but a few weeks, and as the star 

 grew fainter it became of a white color. My observations have 

 been continued until February 7th of the present year, and 

 probably the star will be visible in the 26-inch refractor after 

 the present moon has passed. It is now very near the limit 

 of visibility in our telescope, or of nearly the sixteenth magni- 

 tude. The passage from the seventh magnitude to the six- 

 teenth corresponds to a very great change of brightness, since 

 it is the passage from the limit of visibility to the naked eye to 

 that in a 26-inch telescope. Several hypotheses were proposed 



