248 Mr. J. N. Lockyer. On the [June 19, 



Number of lines affected in spots 108 



Number of lines bright in storms 122 



Number of lines common to spots and storms ...... 68 



Number of lines seen in neither spots nor storms ... 183 



So muck for the list of lines as a whole : the following list shows the 

 number of lines assigned to each metal, the number of lines which 

 occur in both spots and storms, or only in one or the other, and the 

 number of lines unaffected. 







Number 



Number of lines due 





Metal. 



Number 

 of lines. 



of lines 

 common 



to 



Unaffected. 







to spots 



Spots. 











and storms. 



Storms. 







8 



4 



6 



6 







Magnesium 



4 



3 



4 



3 









23 



1 



3 



7 



14 





25 



7 



15 



10 



7 





18 















18 





12 



1 



3 



2 



8 





19 



3 



3 



3 



16 





16 



2 



3 



6 



9 





15 















15 



Chromium... .... . 



14 



3 



3 



5 



9 





87 



11 



18 



18 



62 





104 



33 



50 



62 



25 





345 



68 



108 



122 



183 



It will be seen that the ratio^ between the affected and unaffected 

 lines is very variable. 



What strikes one indeed in regard to all these substances is the won- 

 derful irregularity in the behaviour of the various lines ; there is no 

 relation for instance between the widening of the lines in the spots 

 and their appearances in the prominences. As I have before shown, 

 there is no relationship between the intensities of the lines and their 

 appearances in the spots and storms. 



Amongst the substances shown in the table I have included stron- 

 tium, in order that the difference in its behaviour in comparison with 

 calcium and barium may be seen. 



But all these, however, are matters for subsequent discussion ; 

 what does come out in the strongest way is the following very re- 

 markable fact. 



Among the 345 lines given by Thalen are 18 with identical read- 

 ings in two spectra. I have before given reasons to show that these 

 are not due to mutual impurities, they therefore are the exact equiva- 

 lents of those lines which I have termed basic in my communication of 

 last December to the Royal Society. 



