On the Chemical Constitution of the Stars. 209 



various conditions I Lave to thank Messrs. Baxandall, Shackleton, 

 Butler, and Watson. Mr. Baxandall is responsible for the wave- 

 lengths and intensities of most of the metallic and stellar lines given 

 in the paper, and he has also made the maps which deal more espe- 

 cially with the metallic lines. The maps showing the occurrence of 

 the gaseous lines in stellar spectra have been made by Dr. W. J. S. 

 Lockyer, who has also contributed the part relating to series of lines 

 in spectra. To Mr. Fowler I am indebted for help in the general 

 supervision of the various branches of the research, and for assist- 

 ance in the preparation of the paper. 



Note by Professor Schuster, F.R.S., " On the Chemical 

 Constitution of the Stars." 



I could have wished that the classification of star spectra had been 

 the only question submitted to us for discussion. The subject is 

 important and difficult enough in itself ; there are many points on 

 which opinions might have been profitably exchanged, and I think we 

 might have arrived at some general consensus of opinion which would 

 have left us more fit to form a sound judgment on the fundamental 

 questions brought forward in the second portion of Professor Lock- 

 yer's paper, in which we are directly challenged to accept the disso- 

 ciation theory in its full generality. Had Mr. Lockyer confined 

 himself to bringing forward his hypothesis as one which is legitimate, 

 consistent, and deserving of attention, many of us would, I think, 

 have agreed that he has made out a good case. But he claims his 

 theory as the only one that can explain the facts, and dismisses as 

 unphilosophical the only alternative which he discusses. I think 

 that in this he has gone too far, and to bring matters to an issue I 

 will put the case for the other side ; but before doing so I should 

 like to express my concurrence in the general system of classification 

 adopted in the paper. No classification is likely to prove successful 

 which does not constantly appeal to laboratory experiments, and I do 

 not think Professor Lockyer will have much difficulty in convincing 

 the scientific world that he has made a very material advance by 

 his investigations of the "high temperature " or " enhanced" lines 

 of the metals. 



"The only change," according to Professor Lockyer, "which we 

 can imagine on the usual hypothesis as resulting from an increase of 

 temperature, is that with the increase in volume there will be a 

 reduction in density, and all the lines will be equally enfeebled." 

 With this remark I cannot agree. The main fact to be explained is 

 the gradual displacement of hydrogen, which is predominant in the 

 hottest stars, by calcium, iron, and other metals. There are in my 



