ASTRONOMY: ADAMS AND PEASE 
393 
Although no common origin has been established for these lines this 
peculiarity in behavior might be compared to the disappearance of D2 
in the sodium spectrum, while Di persisted in reduced intensity. 
Another photograph of the spectrum of the star was obtained in April 
1915. This showed that all of the characteristic nebular lines had dis- 
appeared, the line X 4686 which is common to the spectra both of neb- 
ulae and Wolf-Rayet stars, and the hydrogen lines alone remaining. 
There are, however, traces of some of the Wolf-Rayet bands and the 
continuous spectrum is very strong. 
In a communication pubHshed by us in 1914^ we compared the spec- 
trum as then observed of Nova Geminorum No. 2 with that of three of 
the temporary stars discovered in previous years. Two of these. Nova 
Aurigae (1891) and Nova Persei (1901), were found to have strong 
continuous spectra on which the hydrogen lines appeared as bright 
bands of moderate intensity. No characteristic nebular lines were 
present in their spectra, but X 4686 was very prominent in Nova Persei, 
and present, though much less bright, in Nova Aurigae. The close 
agreement of these spectra and especially that of Nova Persei with 
the spectrum of some of the Wolf-Rayet stars was referred to in the course 
of the comparison. The interesting result now appears that the spec- 
trum of Nova Geminorum No. 2 has also developed into that of a Wolf- 
Rayet star, being essentially identical with that of Nova Persei, although 
the hydrogen lines are somewhat weaker. Measurements of the nega- 
tives of Nova Persei and Nova Geminorum show the presence of the 
following Wolf-Rayet bands in addition to X 4686 and the hydrogen lines : 
Nova Persei 4021 4200 448 4514 454 461 4634 
Nova Geminorum 402 4199 444 4512 461 469 
In Plate I are shown direct enlargements of three spectra of Nova 
Geminorum No. 2 and one spectrum of Nova Persei. The enlargement 
is about 17 fold. The dates of the photographs are as follows: 
Dale Exposure time 
Nova Geminorum (a) 1914, Feb. 22 2 hours 
Nova Geminorum (b) 1914, Nov. 16 2 " 
Nova Geminorum (c) 1915, Apr. 10-12 8 " 
Nova Persei (d) 1913, Nov. 27 8 " 
The photograph of April 10-12 was taken under very poor observing 
conditions. 
The especial feature of interest attaching to these results is the fact 
that a continuous series of observations in the case of Nova Geminorum 
No. 2 has shown the development of the spectrum of this star through 
