290 THE SPECTRUM OF NOVA PERSEL AND THE STRUCTURE OF ITS BANDS. 
20. Results. —1. The spectrum consists of a line spectrum in which each line is_ 
broadened into a band, the broadening being proportional to the wave-length of the 
line and independent of the element. Tables V. and XIV. give the common structure 
of the bands. 
The position of the maxima and of the minima or reversals remains unchanged 
during the whole period 1901 March to 1902 November. (See Table XVIII. and 
Plate IT.) 
2. The intensity curve of the spectrum in March and April is satisfied by the 
hydrogen and helium lines, some of which vary in intensity during this period. (See 
Table VIL B, and Plates I. and II.) It is probable that the spectrum is due to 
hydrogen and helium. 
3. From August 1 1901 to the end of 1902 the bands belong to the lines of the 
spectrum of planetary nebule, and their relative intensities converge towards those of 
the average nebular spectrum. (See Table XVII. and Plate II.) Probably the March- 
April spectrum is also faintly present during the whole period. 
I wish to acknowledge the help I have received from my Assistant, Mr James 
CoNNELL, who attended to the guiding of the telescope and plotted the curves given 
in the plates accompanying this paper. 
