130 



Mr. J. N. Lockyer. 



[Nov. 17, 



It is fair to myself to say that I was not aware of these observa- 

 tions when I began to write this paper. The fact of the line at 500 

 remaining alone in Nova Cygni made it clear that if my views were 

 correct, the same thing should happen with comets. It now turns 

 out that the crucial observation which I intended to make was made 

 twenty years ago. 



In Comets b, 1881, and c, 1882, the only lines recorded were mag- 

 nesium b ; but, as before, the apparent absence of other lines might 

 be due to continuous spectrum. 



Of the five bands shown in Huggins's photograph of the spectrum 

 of Comet Wells, taken with a wide slit, no less than three agree fairly 

 in position with three lines seen in the spectra of meteorites. The 

 wave-lengths of these are 4253, 4412, and 4769, and it is interesting 

 to note that, so far, the origin of these lines is undetermined. The 

 two remaining bands are at wave-lengths 4507 and 4634. 



It is seen, then, that the spectra of comets — when their internal 

 motions are relatively either slow or fast, and when therefore the 

 number of collisions, and with it the heat of the stones in collision, 

 will vary extremely — resemble the spectra of meteorites seen in glow 

 tubes. 



7. " Stars " with Flutings which have been observed in the Laboratory 

 and in Luminous Meteors and Comets. 



The most prominent bright flutings of carbon are not only 

 observed in luminous meteors and comets, but in stars of Class Ilia, 

 and in some " Novas," notably Nova Orionis. So far, then, these 

 bodies may in a certain measure be classed with luminous meteors 

 and comets. But there is an important difference in the phenomena, 

 for we have absorption as well as radiation. The discussion shows 

 that the dark (or absorbing) flutings in these bodies are partly due 

 to the absorption of light by the most prominent flutings of Mn and 

 Zn, seen at low temperatures. This inquiry is being continued. 



We have, then, in these bodies a spectrum integrating the radiation 

 of carbon and the absorption of Mn and Zn vapour. 



The law of parsimony compels us to ascribe the bright fluting of 

 carbon in these stars to the same cause as that at work in comets, 

 where we know it is produced by the vapours between the individual 

 meteorites or repelled from them. 



Hence we are led to conclude that the absorption phenomena are 



1867. The spectra of these objects, as far as their feeble light permitted them to 

 be observed, appeared to be very similar. In the case of each of these comets the 

 spectrum of the minute nucleus appeared to consist of a bright line between b and 

 F, about the position of the double line of the spectrum of nitrogen, while the nebu- 

 losity surrounding the nucleus and forming the coma gave a spectrum which was 

 apparently continuous" (Huggins, *Roy. Soc. Proc.,' vol. 16, p. 387). 



