THE NE W STAR WHICH FADED fNTO STAR MIST. 1 2 1 



The observers at Paris did their best to observe the 

 spectrum of the star and the all-important changes in the 

 spectrum. But they had unfavourable weather. It was not 

 till December 2 that the star was observed at Paris, by which 

 time the colour, which had been very yellow on November 

 24, had become "greenish, almost blue." The star had also 

 then sunk from the third to far below the fourth magnitude. 

 It is seldom that science has to regret a more important loss 

 of opportunity than this. What we want specially to know 

 is the nature of the spectrum given by this star when its 

 light was yellow ; and this we can now never know. Nor 

 are the outbursts of new stars so common that we may 

 quickly expect another similar opportunity, even if any 

 number of other new stars should present the same series of 

 phenomena as the star in Cygnus. 



On December 2, the spectrum, as observed by M. 

 Cornu, consisted almost entirely of bright lines. On De- 

 cember 5, he determined the position of these lines, though 

 clouds still greatly interfered with his labours. He found 

 three bright lines of hydrogen, the strong double sodium 

 line in the orange-yellow, the triple magnesium line in the 

 yellow-green, and two other lines one of which seemed to 

 agree exactly in position with a bright line belonging to the 

 solar corona. All these lines were shining upon the rainbow- 

 tinted background of the spectrum, which was relatively faint. 

 He drew the conclusion that in chemical constitution the 

 atmosphere of the new star was constituted exactly like the 

 solar sierra. 



Herr Vogel's observations commenced on December 5, 

 and were continued at intervals until March 10, when the 

 star had sunk to below the eighth magnitude. 



Vogel's earlier observations agreed well with Cornu's. 

 He remarks, however, that Cornu's opinion as to the exact 

 resemblance of the chemical constitution of the star's atmo- 

 sphere with that of the sierra is not just, for both Cornu 

 and himself noticed one line which did not correspond 

 with any line belonging to the solar sierra; and this line 



