250 



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



This result of the inquiry not only adds a new importance to the 

 observations of spot and storm phenomena, but it suggests the precise 

 work which should be done, both in the observatory and laboratory. 

 Not only must special prominence be given to the brightening and 

 thickening of these basic lines in spots and storms, but the existence 

 or non-existence of them in other substances besides those indicated by 

 Thalen, should be inquired into. This latter branch of work has indeed 

 already been begun, since I have pointed out (in the " Proceedings," 

 No. 194, 1879), in a table showing basic lines, that some lines in the 

 blue and green seen many times by Young in storms, are common to 

 many substances, the spectra of which were observed with a Ruther- 

 ford's grating (second order, 17,000 lines). 



In this work it will be well to include those lines which only differ 

 by a tenth of Thalen's unit, although they have been rigorously re- 

 jected in the present discussion and tables. Young, indeed, included 

 such lines, among his coincidences, the line at 5269 "5 being a case in 

 point which is widened in spots, and has been seen 50 times in storms. 



Attention must also be directed to those lines which, like those 

 shown in the following table, although seen both in spots and storms, 

 have not yet been detected in the spectrum of any chemical substance. 



List of lines seen more than ten times by Young in the storms, but 

 which do not appear in Thalen's list or maps. 



Wave-length. 



Frequency. 



Brightness. 



Whether seen 

 by Vogel in 

 spots. 



Whether seen 

 in spots by 

 Young. 



Widening. 



6515-5 



15 



4 



Yes 







6453 -8 



10 



6 



Yes 







6429 -9 



20 



4 



Yes 







6346 -1 



10 



4 



Yes 



Yes Eu. Ir * 



2 



5990 -0 



10 



4 



Yes 







D 3 5874 -9 



100 



90 



Yes 



Yes 



2f 



5275-0 



30 



15 





Yes 



2 



5197 -0 



15 



10 









* Ruthenium and iridium lines are not given in Thalen's list ; the line in ques- 

 tion is marked in the map without any remarks. In Angstrom's map it is entered 

 and marked as a line coincident with a line given by Ru, Ir. 



t But sometimes reversed. 



