Further Observations on Nova Persei. 



403 



The Visual Spectrum. 



In the continued observations the C and F lines of hydrogen have 

 always been recorded as " conspicuous," other prominent lines being 

 near A 447, A 465, and A 501 (the last named being sometimes as 

 bright as F or even brighter), and a line in the yellow which recent, 

 measures show to be D 3 . 



The strong lines in the green at AA4924, 5019, 5169, and 5317, 

 which occurred in the earlier photographs, and which were ascribed to 

 iron, are either absent from the later photographs or appear only as 

 very weak lines. 



It has been noted that the lines 447, 501, and D 3 appear to vary 

 with the magnitude of the star, becoming relatively more prominent 

 towards a minimum. 



The continuous spectrum has been described throughout as " weak " 

 or "very weak." 



On the evening of April 25, Messrs. Fowler and Butler made 

 comparisons of the Nova spectrum with the spectra of hydrogen, 

 helium, and that furnished by an air spark between poles of iron and 

 zinc. For this purpose a Hilger two-prism star spectroscope was 

 used with the 10-inch refractor. The hydrogen line F and the helium 

 line D 3 were found to be sensibly coincident with Nova lines. '^The 

 middle of the strong green line, previously mentioned as A 501, 

 practically coincided with the nitrogen line 5005*7, and therefore 

 there is little doubt that it is identical with the chief nebular line 

 A5007 - 6. This line was also compared with the asterium line at 

 A5015'7, but was found to be decidedly non-coincident with it,, 

 though of sufficient breadth to nearly reach it. 



Photographic Spectrum. 



In so far as the number and positions of the lines are concerned,, 

 the few photographs available for discussion were obtained in the 

 early part of the period dealt with in the present paper (March 26 to 

 May 7), and show a spectrum very similar to that of March 25, which 

 was described in detail in the last paper. The chief lines shown in 

 the photographs are H/3, Hy, HS, He, and Hf, together with 4471 

 and 4650. 



Characteristics of H/3. 



In continuation of the series of light curves of H/3 reproduced in 

 the last paper, I give those plotted by Mr. Baxanclall from the later 

 photographs. 



It will be seen that the line H/3 still shows two maxima of intensity. 

 As recorded in the previous paper, the less refrangible component gave, 



