THE SPECTRUM OF NOVA PERSEI AND THE STRUCTURE OF ITS BANDS. 287 
( a y i) 
U FT (Ho) 
F (uo) can be eliminated by f(). I apply formula (2) to (%, So, Mo, £) and (2%, 8, #’o, ¢), 
. ts 
which can be replaced by (2, 8, #0 = ), then 
0 
8 _ Slo) 
So F (0) 
1 
I _ ist Fu) 
1, 4S F (p45) 
(14) 
(15) 
Since the sensitiveness is constant for the same wave-length, I/I, suttices for our 
purpose. It appears in Table XVII., where it is referred to the intensity of the radiation 
mm, = 5007. 
Compared with the March-April spectrum all the bright bands except the three H- 
bands, and perhaps the bands A, = 4634-6 and 4611°9, have come into existence, or have 
grown much in intensity. The radiation at \,=4363'7 is twice as intense as that of 
the three H-bands, which in the spring were the most prominent bands of the spectrum. 
The other bands observed in the spring have almost entirely disappeared. None of the 
radiations faded at a slower rate than the nebular radiation \= 5007. Several radiations 
began to decrease already in October, and others started in November. The decline of 
the bands \ = 4363°7 and 4725 in the two months 1901 November 13 to 1902 January 
12 is further remarkable. Four radiations faded at the same rate, H;, 4612, 4959, 5007, 
and perhaps H,, while H, certainly decreased at a much greater rate in October. I may 
mention that I calculated s,/s by (14) from estimates of degrees of blackness made on a 
photograph of the sky spectrum. The values 7/2, calculated by (15) show that, with the 
only exception of the radiation at \,=3869, that at \=5007 was the most intense 
already in August 1901. 
In October and November 1902 the relative intensities agree better with those of the 
nebular spectrum than before. It must of course be borne in mind that the spectrum 
on the last plates was extremely ditficult to see, the intensity of the maximum of the 
band A,=5007 being only of degree 1, and that the figures belonging to that period 
are only a rough approximation. The trend of the table is certainly to show that the 
intensities are approaching those of the average nebular state. 
16. The Faint Bands.—One may conclude by analogy that the faint bands would 
be reduced to lines under ordinary conditions. In that case, on account of their 
breadth, several must be due to multiple lines. On a whole they agree fairly 
well with the maxima of the intensity curve observed in March and April. Considering 
the uncertainty of the wave-lengths of these faint bands, about 5 t.m., a convincing 
proof as to their origin cannot be brought, though it is probable that they are the 
remnants of the bright spectrum in the first months. It may be mentioned that the 
hydrogen lines given under B in Table VII. also explain them, provided seven of them 
be: excluded. 
