248 



CARNEGIE INSTITUTION OF WASHINGTON. 



1892, Nova Persei of 1901, and Nova Geminorum of 1912, is shown in 

 the accompanying table: 



Displacement at X ^500. 



Within the Hmits of error of measurement, accordingly, the dis- 

 placements in all of these stars are in the ratio 3 to 2 to 1. 



(3) The displacements of the absorption lines in the spectrum of 

 Nova Aquilae showed a rapid decrease immediately after the discovery 

 of the star and then a gradual increase of about 0.5 a each day until a 

 maximum was reached late in June 1918. After this there seems to 

 have been a slow decrease as the lines grew faint and disappeared. 

 It seems probable that a similar change occurred in the other Novae to 

 which reference has been made, so that the relationship of the dis- 

 placements referred to above held strictly for the same spectral phase. 

 Measurements of the photographs of the spectrum taken on June 8 

 and 9, 1918, immediately after the discovery of the star, show that the 

 minimum negative displacement coincided with the maximum of light. 



(4) The structure of the emission bands during the autumn of 1918 

 and the spring of 1919 appears to have been the same for both 

 hydrogen and nebulium and apparently was of a fairly stable nature. 

 The bright maxima and the absorption lines are in all cases displaced 

 from the centers of the bands by amounts which are proportional to 

 the wave-length. 



Miscellaneous Investigations. 



(1) Observations of the spectrum of the variable star RU Camelo- 

 pardalis show that it belongs to type R, but has bright hydrogen lines 

 at minimum of Hght and dark hydrogen lines at maximum. The 

 enhanced lines are strong and the character of the general spectrum is 

 very similar to that of the Cepheid variables, among which the star is 

 usually classed. The radial velocity is variable, with a range of about 

 45 km., the maximum velocity of approach coinciding with maximum 

 of light, as in the case of the Cepheids. The relative intensities of the 

 bright hydrogen lines are the reverse of those found among variables 

 of type Md. 



(2) The Cepheid variable W Serpentis has been found to have 

 bright hydrogen lines with a dark central component symmetrically 

 placed. This is the first variable of this type known to show bright 

 lines in its spectrum. 



