XXIIL] GENERAL STATEMENTS. 



11. Towards the end of the first series a few lines appeared 

 among the most widened ones which are not represented, so far 

 as is known, among the lines seen in the spectra of terrestrial 

 elements. This change took place when there was a marked 

 increase in the solar activity. 



A second series was begun on 29th September, 1880, and came 

 down to October, 1881. The second series, like the first one, 

 consisted of 100 observations, these observations being either of 

 different spots or of the same spots seen on different days, and 

 therefore in different stages of development. 



The following results were obtained : 



12. The number of new lines seen amongst the most widened 

 lines steadily increased. Many of these lines are very faint in 

 the solar spectrum, and are unrecorded by Angstrom, while they 

 are wide and dark in the spot-spectrum. 



13. In the months of May and June (1881), there was a 

 great change in the spectra of the spots, the old lines dying out 

 and new lines appearing. 



14. When series of observations, consisting of ten consecutive 

 observations of the spectra of spots, taken from the commence- 

 ment of the first series in November, 1879, and from the end of 

 it on 27th September, 1880, were compared with those made 

 towards the end of the second series on 18th July, 1881, it was 

 found that the lines widened in each set were markedly distinct 

 from those in the other sets. 



To illustrate this, I give the diagram on page 316. At the top 

 are some of the principal Fraunhoferic lines in the region F to 

 D, the lengths representing the intensities. The lower part 

 of the diagram is divided into three sections by strong lines ; 

 the first of these (1 10) contains the observations made be- 

 tween November 12, 1879, and January 20, 1880, the second 

 (11 20) the observations made between September 27 and 

 October 1, 1880, and the third those made between July 18 and 

 "July 29, 1881. 



