lit Mr. .1. Norman Lockyer. On the Causes [Apr. M, 



The investigation has shown that there is a close relation between 

 the spectra of comets and the spectra of new stars, but whereas in 

 comets only one swarm has to be considered, in new stars there air 

 two s warms which may or may not be equally dense or of c|iutl 

 dimensions. The spectrum of a new star is therefore a compound 

 one. We have, in fact, a mixed radiation and absorption spectra 

 similar to that presented by a variable like Mira Ceti when at it.-, 

 maximum brilliancy. In another paper I have shown that variables 

 of the Mira type are really double swarms, and hence the conclusion 

 that the difference between this class of variables and new stars is 

 only a difference in the orbits of the subsidiary swarms. 



Omitting Nova (U) Orionis, which proved to be only a long period 

 variable, ouly three new stars have been spectroscopically observed ; 

 namely, Nova Corona) (1866), Nova Cygni (1876-77), and No 

 Andromeda (1885). 



In Nova Coronae, when first observed, a spectrum of bright lines 

 was superposed upon one of dark Hues. The absorption phenomena 

 were similar to those characteristic of stars like * Orionis, and the 

 chief radiation was that of hydrogen. A discussion of the observa- 

 tions suggests that two of the ill-defined lines in the blue may have 

 been due to carbon. In the discussion of cometary phenomena which 

 I have previously communicated to the Society, I pointed out that 

 in many cases the blue band appeared to have two maxima, one at 

 A, 468 and one at X 473, and it is more than probable that the two 

 lines of the Nova were identical with those of comets.* 



In comets, the blue band, whether single or double, is generally 

 admitted to be due to carbon, from its association with the undoubted 

 carbon band in the green, and the same origin is therefore probable 

 in the case of the Nova. Whatever the origin of the two lines in 

 Nova Coronoe, the fact of their being common to comets and a new 

 star is the point I am anxious to bring out. The F line was 

 recorded throughout the whole period of observation, and another 

 bright line, apparently coincident with the chief nebula line, w 

 recorded by Messrs. Stone and Carpenter. 



The suggestion that a new star is produced by the collision of two 

 meteor-swarms or streams is fully borne out by the discussion of the 

 observations of Nova Coronae. The mixed phenomena of absorption 

 and radiation which were obsei-ved are simply and sufficiently ex- 

 plained on this supposition. An attempt is made in the paper i 



* Note, April 4. The band in question is also probably identical with the one 

 seen in some of the stars of the \Volf-Ra\et type. Dr. and Mrs. Uuggins ha>r 

 recently made observations of some of these stars which have led them to conch 

 that the oand is not due to carbon (' Roy. Soc. Proc.,' vol. 49, p. 3d). I am not 

 convinced on this point, but I shall take another opportunity of replying to their 

 remarks. 



