166 Mr. J* X. Lockyer on Recent 



the shells being due not to the outside substance existing only 

 outside, but to the outside substance extending to the bottom 

 of the sun's atmosphere, and finding in it at a certain height 

 another shell, which again formed another shell inside it, and so 

 on ; so that the composition of the solar atmosphere as one 

 went down into it, got more and more complex : nothing was 

 left behind ; but a great many things were added. 



The recent work, so far as I am acquainted with it, has not 

 in any way upset that notion ; but what it has done has been 

 to add a considerable number of new elements to this reversing 

 layer. Instead of consisting of 14 elements, as it was then 

 found to do, it may be, I think, pretty definitely accepted now 

 to consist of about thirty. 



The metals considered to be solar as the result of the 



o 



labours of Kirchhoff, Angstrom, and Thalen together with 

 the considerations brought forward regarding the length of the 

 lines, were as follows: — 



Na Fe Ca Mg Ni 



Ba Cu Zn Cr Co 



H Mn Ti Al 



Those more recently added, with the evidence by which 

 their existence in the solar atmosphere is rendered probable, 

 are as follows (in the Tables, pp. 167-169). 



It is important to bear in mind that the lines recorded in 

 these Tables are in most cases the very longest visible 

 in the photographic region of the respective spectra ; in some 

 cases they are limited to the region 39-40, which I hare more 

 especially studied ; so that the fact of their being reversed 

 in the solar spectrum must be considered the strongest evi- 

 dence obtainable in favour of the existence in the sun of the 

 metals to which they belong, pending the complete investiga- 

 tion of their spectra. 



Where, however, there is only one line, as with Li, Rb, &c, 

 the presence of these metals in the sun's reversing layer can, 

 for the present, only be said to be probable. Neither must it 

 be forgotten that, in addition to the long lines which a spec- 

 trum may contain in the red, yellow, or orange, long lines 

 may exist in the hitherto unexplored ultra-violet region ; so 

 that the necessity for waiting for further evidence before de- 

 ciding finally upon the presence or absence of such metals in 

 the sun will be rendered obvious. 



It will be thought remarkable that, if the long lines of such 

 metals as lithium and rubidium are found in the photographic 

 region of the spectrum, the long lines Li W.L. 6705, Rb 

 W.L. 6205 and 6296 should have escaped detection. 



