xiii.] SPOTS AND FLAMES. 175 



great advance had been made in the localization of solar pheno- 

 mena ; in short, there was now another kind of work a newer 

 kind of work going on. Observers began to give attention to 

 the bright lines of solar prominences, and the lines thickened 

 in solar spots. I shall here limit myself to the general state- 

 ment that the divergence between the spectra of the different 

 substances as observed in the sun and in our laboratories was 

 very much intensified as facts were accumulated from these new 

 regions. Very many of the lines observed in prominences were 

 lines with no terrestrial equivalents, and the spot-spectrum 

 often contained lines much thickened which were either not 

 represented at all, or only feebly, among the Eraunhofer lines. 



As the work of tabulating the lines went on, and the more 

 complex outpourings of vapours from the sun's interior were 

 studied, it was found that the prominence lines coincident with 

 those seen in the spectra of iron, calcium, and so forth, were by 

 no means the brightest lines by no means the most important 

 or most prominent lin.es in the known spectra of those sub- 

 stances, but lines which really we had very great difficulty in 

 recognising as characteristic of any particular spectrum. There* 

 they certainly were, however, mapped as very fine lines by the 

 most industrious observers. Similarly with the spots, there 

 was an absolute inversion of the thicknesses of the lines of any 

 one substance. 



6. Motions indicated ~by Different Lines in Spots and Flames. 



Closely allied to these results we had another extraordinary 

 fact. We could quite understand why in a spot the change 

 of refrangibility of the magnesium lines when there was a 

 storm going on in the sun should be different from the change 

 of refrangibility of, say, the iron lines. The natural explanation 

 was, of course, that the magnesium gas was going at one rate, and 



