188 



Mr. J. Norman Lockyer. 



In the same year I also studied the changes in the line spectra in 

 relation to the changes observed when known compounds were dis- 

 sociated, and after discussing certain objections I submitted the con- 

 clusion that the known facts with regard to the changes in line 

 spectra " are easily grouped together, and a perfect continuity of 

 phenomena established on the hypothesis of successive dissociations 

 analogous to those observed in the cases of undoubted compounds."* 



Special Reference to Solar Work. 



Neglecting the flutings in the extreme red, which are due to our 

 own atmosphere, the only fluting known to exist in the solar spec- 

 trum is one which I ascribed to carbon in 1878. f 



Hence the solar work has had mainly to do with line spectra. 

 With regard to these, the following anomalies on the ordinary view- 

 are given as specimens of the many which have been recorded. 



1. Judging by the lines seen in their spectra, the order in which 

 the elements thin out as the cooler parts of the sun's atmosphere are 

 reached has no relation to their atomic weights, either old or new.. 

 This order is 



Ca 



H 



He 



Sr 



Mg 



Fe" 



Ti 



Mn 



2. Inversion of intensity of lines seen under different circum- 

 stances.:]: 



I showed in 1879 that there was no connexion whatever between 

 the spectra of calcium, barium, iron, and manganese and the chromo- 

 sphere spectrum beyond certain coincidences of wave-length. The 

 long lines seen in laboratory experiments are suppressed, and the 

 feeble lines exalted in the spectrum of the chromosphere. In the 

 Fraunhofer spectrum, the relative intensities of the lines are quite 

 different from those of coincident lines in the chromosphere. 



3. The simplification of the spectrum of a substance at the tem- 

 perature of the chromosphere. To take an example, in the visible 

 region of the spectrum, iron is represented by nearly a thousand 

 Fraunhofer lines ; in the chromosphere it has only two representa- 

 tives. 



* < Roy. Soc. Proc.,' vol. 28, p. 179. 

 f Ibid., vol. 27, p. 308. 

 t Ibid., vol. 28, p. 428. 



