128 



Sir Norman Lockyer. 



important difference between the two groups, as I pointed out in the 

 Bakerian Lecture. In the Antarian stars we have to deal with con- 

 densing swarms of meteorites in which the temperature is increasing, 

 whereas in the Piscian stars we have an advanced stage in the cooling 

 of masses of meteoritic vapours. In the case of Antarian stars we have 

 mixed radiation and absorption flutings, and I suggested a way in 

 which the stars of the group might be divided into fifteen distinct 

 species, representing successive stages in condensation. We have now 

 to consider a similar classification of the Piscian stars, of which I stated 

 in the Bakerian Lecture (p. 26) : — " The species of which it will 

 ultimately be composed are already apparently shadowed forth in the 

 map which accompanies Duner's volume, and they will evidently be 

 subsequently differentiated by the gradual addition of other absorptions 

 to that of carbon, while at the same time the absorption of carbon 

 gets less and less distinct." 



In considering the stars of this group, it is most important to bear in 

 mind that there are indications of carbon absorption in the spectrum 

 of the sun. I first obtained evidence of the existence of carbon vapour 

 in the solar atmosphere in 1874, and in 1878 I communicated a paper 

 to the Eoyal Society on that subject."^ Angstrom had already shown 

 that the true carbon /mes were not reversed in the solar spectrum, but 

 I demonstrated by photographic comparisons that there was a perfect 

 correspondence between the individual members of the brightest part 

 of the fluting in the ultra violet (commencing at A 3883*55), and a 

 series of fine dark lines in the solar spectrum. I pointed out that this 

 carbon vapour existed in a more complicated molecular condition (as 

 is evidenced by the flutings) than the metallic vapours in the sun's 

 atmosphere.! 



There can therefore be no doubt that in the sun carbon absorption 

 is ju«t commencing, and that, as I stated in a former paper, J "the 

 indications of carbon will go on increasing in intensity slowly, until a 

 stage is reached when, owing to reduction of temperature of the most 

 effective absorbing layer, the chief absorption will be that of carbon — 

 a stage in which we now find the stars of Class III& of Yogel's 

 classification." 



* ' Eoy. Soc. Proc.,' vol. 27, p. 308. 



t Note {added 1899). — Professor Rowland has since identified a considerable 

 number of faint lines in the solar spectrum, on the more refrangible side of h, with 

 the constituents of the green carbon fluting ('Prelim. Table of Solar Spectrum 

 Wave-lengths/ p. 90), and we thus have direct evidence of the presence in the 

 solar spectrum of the band which is perhaps the most characteristic feature of the 

 Piscian stars. 



X ' Eoy. Soc. Proc.,' vol. 43 (1887), p. 155. 



