Further Observations on Nova Persei. 



231 



the Nova decreased very suddenly, dropping from 4*2 to 5*5 in twenty- 

 four hours, and becoming only just visible as a naked-eye star. 



The following gives a summary of the eye estimates made by 

 (1) Dr. Lockyer, (2) Mr. Fowler, and (3) Mr. Butler:— 







(2.) 



(3.) 



March 5 . . . . 



2-7 



2-7 



— 



6.... 



. 2-9 



— 



— 



9 



— 



3-5 



3-5 



10 .. 



3-7 







11 







<4'0 



12 





3-8 





21 





4-0 



4-2 



22 









23 



4-2 



4-2 



4-5 



24 .. 



. 4-2 



4-2 



4-5 



25 



5-5 



5-5 



5-5 



Colour. 



The colour of the Nova has undergone some distinct changes since 

 the observation on March 5th last, when it was shining with a clarety- 

 red hue. On the 9th and 10th it was observed to be much redder, due 

 probably to the great development of the red C line of hydrogen. 



On the 23rd and 24th, the star was noted as yellowish-red, while on 

 the 25th (after the sudden drop in magnitude) it was very red, with, 

 perhaps, a yellow tinge. 



The Visual Spectrum. 



Since March 5th the spectrum from C to F has become very much 

 fainter, the bright lines of hydrogen being relatively more prominent 

 than they were before ; indeed, C and F throughout this period have 

 been the most conspicuous lines, especially the former, while the bright 

 lines AA, 5169, 5018, and 4924, and the line in the yellow near D, were 

 the most prominent of the others. 



All these lines have been gradually becoming weaker, but there is an 

 indication that A. 5018* has been brightening relatively to A 5169. 



Accompanying the great diminution in the light of the Nova 

 observed on the evening of the 25th, the spectrum was found to have 

 undergone a great change : the continuous spectrum had practically 

 disappeared, and a line near D (probably helium, D 3 ) became more 

 distinct. The other lines were hardly visible. 



# The line near this wave-length in later observations is probably the chief 

 nebular line 5007, which accounts for the apparent brightening of 6018. 



