366 SCIENTIFIC RECORD FOR 1885. 



I think, became much brighter, though statcmeuts were made early in 

 September that it was of the 2d or 3d juagnitude 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 [February, 

 1886]. - - - 



'' 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 dis- 

 covery it was some time before it could be generally corrected. - - - 

 The assumption of any intimate physical connection of the new star with 

 the nebula has been given up by Vogel, of Potsdam, and Hasselberg, of 

 Pulkowa, who have examined its spectrum. Within the limits of this 

 nebula there can be counted from fifteen hundred to two thousand tele- 

 scopic stars, and one of these has proved to belong to the class of tempo- 

 rary 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 firstsaw the new star on September 6, when its magnitude seemed 

 to me 7 J, 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 7 of the 

 present year, and probably the star will be visible in the 26-inch refract- 

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

 visibility in our telescope, or of nearly the 16th magnitude. The passage 

 from the 7th magnitude to the 16th 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-iuch telescope. Several hypotheses were pro- 

 loosed to account for this wonderful star, and one that seemed to me quite 

 ingenious is that of Mr. Monck, of Ireland, who assumed that this star is 

 one of the swiftly-moving ones that in rushing through the nebula had 

 been set on fire, like a meteor in our atmosphere. Led by some such 

 suggestion, and also by that of Professor Peters that it would be inter- 

 esting to test the parallax of such a star, on September 29 I began some 

 measures of the new star by referring it by means of polar co-ordinates 

 to a known star of the 11th magnitude, distant from it a little less than 

 2'. - - - I do not think my measures show any proof of a parallax, 

 though they indicate, perhaps, a diminution of the distance, and even 

 this may be sufficiently accounted for by variations in the light and 

 color of the new star, since such variations would be likely to affect the 

 measures. - - - 



"The great nebula of Andromeda is easily visible to the naked eye, 

 and doubtless it was known to the astronomers of very ancient times. 

 Those astronomers watched the heavens with unaided vision much 

 more carefully than do modern astronomers, and they were far better 

 acquainted with the constellations. The old astronomers had a theory 

 that this nebula was variable both in form and brightness. They kad 

 X^oor means of judging of its form, but it is possible that their esti- 



