XVJIL] THE PREDICTION VERIFIED. 249 



these lines vary from the positions of lines in the solar spectrum. 

 "The spectra of these stars," Dr. Huggins continues, "may 

 therefore be arranged in a continuous series, in which first we 

 find this line to be absent. Then it appears as an exceedingly 

 thin line. We then pass to another stage in which it is distinct 

 and defined at the edges ; in the solar spectrum it becomes 

 broad and winged, and lastly in Arcturus there is further pro- 

 gress in the same direction, and the line, now a broad band, 

 exceeds in intensity H." Absolute continuity we see is the story 

 which Dr. Huggins brings us with reference to this concrete 

 case of H and K in the details and in the general. Well might 

 Dr. Huggins ask after this : " Do these modifications not repre- 

 sent some of the stages through which our sun has passed ? " 

 In another part of his paper he uses the term " life changes." 

 Now the life of a star is its temperature, and all these changes 

 must have been produced by the running down of temperature, 

 and I think the simplest view to take, limiting ourselves to the 

 concrete case of H and K, is that the substance which pro- 

 duces K has been formed at the expense of the substance which 

 produces H, and the reason that we see these two lines in 

 calcium when a high temperature is employed is that we reveal 

 the presence of these true root-forms. There may be very many 

 more difficult explanations, but that I think is the simplest one 

 to which one is driven by the logic of facts. 



The appeal to the stars, then, I think, amply justifies the 

 prediction which I based upon the comparison of solar with 

 terrestrial phenomena; and, therefore, tends to show that the 

 basis on which those predictions were founded had at all events 

 some little glimmering of truth about it. I think also that it 

 increases the number of dissociation stages through which we 

 must assume the vapours of our so-called elements to pass 

 when higher temperatures are employed in succession. 



How rigid a test we have been able to apply to these views 

 by means of Dr. Huggins' remarkably beautiful researches the 



