38 



Mr. J. N. Lockyer. On the 



[Jan. 20, 



minimum period, the vapours of terrestrial elements can exist then at 

 the sun-spot level and give some of their characteristic absorption lines ; 

 while at the more intensely heated and much disturbed maximum 

 sun-spot period the vapours of terrestrial elements are dissociated, 

 at the spot level, and give vapours which have no terrestrial equiva- 

 lents. 



Since last May the reduction of the observations of the most 

 widened lines in the region b to D has been continued, and the results 

 are given in the present communication. They strikingly confirm 

 those previously obtained. The conclusions drawn in the previous 

 paper are therefore much strengthened by the evidence obtained from 

 this new region. 



The observations referred to in the former paper were given in a 

 series of tables ; corresponding tables are given in the present com- 

 munication ; so that a clear comparison can be made. Tables A and B 

 show that for each of the elements taken — iron and titanium — the 

 number of lines seen in the aggregate in each hundred observations 

 decreases from the minimum to the maximum period. 



Nickel was given in the previous paper, but in this region, b to D, 

 Thalen only gives five lines due to nickel, and only one of these is 

 found amongst the most widened lines, and that only once in the fifth 

 hundred. 



Table C gives the lines recorded as most widened, but not included 

 as metallic lines by Angstrom or Thalen, and it will be noticed these 

 are recorded as most numerous at the maximum period. 



In the curves given in Fig. 1, it is seen that there is the same 

 rapid rise in the unknown lines to the third hundred, the same gradual 

 rise from this to the sixth hundred, and then the commencement of the 

 fall, just as in the previous paper for the other region of the spectrum 

 under observation. The curve due to iron exhibits an almost exact 

 coincidence with the one previously published for the other region, 

 with the difference that in this part of the spectrum the number of 

 iron lines is not so great. 



The titanium curve shows a sudden rise in the fifth hundred. One 

 line (5226) was amongst the most widened no less than twenty-two 

 times, and it is a singular fact that this line was only recorded as 

 most widened on one other occasion (in the fourth hundred) in the 

 whole 700 observations. Although at first sight this seems to be a 

 result contrary to that obtained in the case of iron, it should be 

 remarked that this line is one seen in the spectrum of the spark and 

 may be considered to be due to high temperature, therefore its 

 appearance in the maximum period was fully in accordance with the 

 other facts adduced. 



The reductions have been made and the tables prepared by Messrs. 

 Mills, Spencer, and Taylor. 



