1892.] 



On Nova Auriga?. 



489 



used the three lines of the triplet were well separated, and that we 

 sought in vain for a similar triplet in the star ; and, further, that if the 

 probable shift of the star's spectrum towards the red be taken into 

 account, the star line would fall rather more to the blue side of the 

 more refrangible pair of the triplet, we consider it probable that the 

 star line has some other origin. The stellar line is multiple, but it was 

 found difficult to observe it with a sufficiently narrow slit. A thin 

 and denned bright line was clearly seen at the blue side of the 

 rather broad stellar line, but the remaining and less bright part of 

 the line was not certainly made out, but on one occasion it was more 

 than suspected of consisting of several lines. 



We consider the evidence to be against the star line having its 

 origin in magnesium, especially as no correspondingly bright lines 

 were observed in the Nova at the positions of the other strong lines 

 of the spark spectrum of magnesium, nor in our photograph at the 

 position of the strong magnesium triplet a little more refrangible 

 than H. 



The third bright line in the green of the Nova which is nearest 

 to F, and the least brilliant of the group of lines in this region, was 

 found to have a wave-length of about X 4921. A large number of 

 bright lines were seen in the spectrum besides those which have been 

 entered on the map (Plate 4). 



The lines only of which we were able to fix the position with 

 approximate accuracy are drawn across the spectrum. The places 

 of the lines drawn partly across the map are from estimations only. 



We observed a line a little more refrangible than D, of which the 

 position when corrected for the shift of the spectrum, is at or very 

 near that of D 3 . Also a bright line below C, and others between 

 C and D. 



On February 2 and February 3 groups of numerous bright lines 

 crowded the spectrum between b and D, which were less easily seen 

 as the star waned. 



The continuous spectrum extended, when the star was brightest, 

 below C, and as far into the blue as the eye could follow it, at this 

 time to a little distance beyond Gr. 



The visible spectrum of the Nova, and especially the reversal of 

 H and K, and of the complete series of the hydrogen lines in the 

 ultra-violet, together with the probable presence of D 3 , suggest 

 strongly a state of things not unlike what we find in the erupted 

 matter at the solar surface. In a photograph of a prominence 

 taken on March 4, 1892, which I have received from M. Deslandres, 

 not only H and K and the complete series of hydrogen lines are 

 reversed, but three bright lines appear beyond, which may be more 

 refrangible members of the same series.* 



* [M. Deslandres informs me that his measures of the positions of the three lines 



