1879.] 



Mr. J. N. Lockyer. On Basic Lines. 



247 



XXVI. " Report to the Committee on Solar Physics on the Basic 

 Lines common to Spots and Prominences." By J. NORMAN 

 Lockyek, F.R.S. Communicated at the request of the 

 Committee. Received June 19, 1879. 



I have now for some time past been making efforts to bring together 

 the varions observations which have been recorded of the lines visible 

 in solar disturbances at the sun's limb, and those observed to be 

 widened, brightened or otherwise modified in the spectra of solar 

 spots. 



The result which stares us in the face when we examine the lists of 

 the lines given by Young as representing his Sherman work is so 

 striking, both with regard to the conclusions which we are justified in 

 drawing from the old work, and the suggestions for future opera- 

 tions, that I have thought it desirable to call attention to it without 

 waiting until the Italian observations have been discussed. 



Although Young's observations of the cbromospheric lines extend 

 over the whole visible spectrum, the list of lines in the solar spots is 

 limited to the region between B and b, I have therefore limited the 

 discussion to this region. 



As a basis for the discussion, I have used the lines given in Thalen's 

 admirable tables, comparing these lists with the lines shown in 

 Angstrom's and Thalen's map, and indicating the intensities of the 

 lines which are given in the tables, and which particular line occurs 

 in the map only. 



Further, as a discussion of the coincident lines shown in some sheets 

 of Angstrom's map, which I communicated to the Royal Society last 

 March, had convinced me that the lines shown to be common to two or 

 more substances by Thalen were not due to impurities (" Proceedings 

 of the Royal Society," No. 194, 1879), I have shown these co- 

 incidences, where they occur, in a special column. 



Having then Thalen's list for a basis, other columns showing us 

 whether each line is seen in spots and prominences, and how it is 

 affected, give us in one view, for each metallic substance, exactly what 

 happens to the lines of that substance. We see at once, for instance, 

 which lines are not touched, those again which are visibly affected 

 both in spots and storms, or those recorded in one table and not in the 

 other. 



Taking all the lines included in the discussion, the following 

 statistics will show how they are distributed : — 



Total number of lines in Thalen's list and map included 



in the discussion 345 



s 2 



