THE SPECTRUM OF NOVA PERSEI AND THE STRUCTURE OF ITS BANDS. 257 
TasBLE I.—continued. 
Photo-Plate No. 4, 1901 March 25. 
Angle of inclination of plate=13°; width of slit 0°020 mm. ; Imperial plate; exposure 4 hours; the 
plate is fogged and the spectrum is much fainter than on plate No. 3; the spectrum was measured 4 times 
and referred to 30 standard lines; the definition is not so good as on plates Nos. 1, 2, 3, 5. 
A | v. | Intensity. A v. | Intensity. r | ». | Intensity. A % Intensity. 
| 40415 | Ol AR 4318°7 | 0-2 to 4540 | 4 b 4851°8 | 0-9 
4049 1-4 4320:0 | 0°6 | 4559°7 | 0°3 3 | 4858-0 
Mees |o2| | |asas | 1 | a eo ee 4859-6 
4065°0 | 0°5 4328°9 | 0-4 BL 4613) 2 : ba 4863°4 | 0-7 : 
4072°6 | 0-7 : 4335°2 s 4617 | 11 ; 4 | 4865-0 \ 
4081-1 | 0-4 6 4337°8 ne 4626°6 | 0:8 i 4866°1 | 0-4 P 
4083°4.| 1:1 "i 43449 | 0-4 | ; 4648:4 | 0°7 ; 4871:0 A 
4092°5 | 1:0 4354-0 4.660 2 6 | 4872°8 
55 | 0 / 5 75 
4100°8 0-9 ; 43546 Ee 46691 | 0°6 ; 4879°9 | 0-7 
4109 16 7 4360-0 | 0:3 ’ 4682 4 ; 4882 
41156 | 1:0 i 4365°2 | 0-3 : 4691-0 | O-5 : 4884 
4119 9D : 4372 ey i 4701 3 ‘ 4885°5 | 0-7 2 
41220 | 1-0 A 4384 1:7 ea 47220 | 0:8 4 | 4894 1 ‘ 15 
4135 18 ' 4398 | 5 ’ 3 | 4729 1°8 a 3 | 4905-7 | 06 f 
4157 3 44287 | 0 4739°9 | 0-4 4912 
0 2°5 2 1-2 
4165 16 i 4434 °| 1:3 : 4750 11 ff 4929 ; 
4207 5 ’ 4454°6 | 1:0 | 4 | 4770 4 | a 1 | 4947 11 ne 
4261 16 ; 4459°3 | 0-7 , 5 | 4826-3 | 0-9 ? 4968 15 ie 
4277 7 oe 4480°5 | O-4 : 4834-4 | 1-1 | 4986'2 | 0-2 ie 
4282°8 | 0°8 me 4493 4 ; 4836°1 0 5006 6 os 
4307 7 3 45039 | 0:8 ! 4837°9 | 0-1 ie 5020 4 he 
4317-7 | 0-2 4527 3 4846:2 | 0°6 5045°8 | 0-8 
4318-7 | 0:2 0 4540 4 ny 4851:8 | 0-9 : 
bands are due to hydrogen radiations, which, under ordinary conditions, would produce 
the three hydrogen lines. Tables II., III., IV. prove the statement. 
Let A) be the wave-length of a hydrogen line, \ the observed wave-length of a 
point in the band, s the correction for the orbital motion of the earth, then 
1 
») A4S= Nyt door 
determines dp, belonging to a certain point of a band, and it must be shown that a, has 
the same value for corresponding points of all three bands. In Table II. the values of 
% are compiled. The positions of the first, third, fourth and fifth minima agree as 
