

xxiii.] EXPLANATION OF TABLES. 319 



think perhaps it may in time, and that we shall ultimately be 

 able, in the way indicated, to classify spots according to their 

 temperature. 



Although the reduction of the whole 700 observations is not 

 yet complete, some of the general results obtained from the 

 whole of the observations up to 1885 may be briefly referred to 

 in this place. 



I first give tables (A, B, C) showing that for each of the 

 chemical elements so far considered iron, nickel, and titanium 

 the number of lines seen in the aggregate in each hundred 

 observations is reduced from the sun-spot minimum to the maxi- 

 mum, and this result holds good for both regions of the 

 spectrum. 



I give another table (D) showing that during the observations 

 the lines recorded as most widened near the maximum period of 

 sun-spots have not been tabulated amongst metallic lines by either 

 Angstrom or Thalen, and that many of them are not among the 

 mapped Fraunhofer lines, though some of them may exist as 

 faint lines in the solar spectrum when the observing conditions 

 are best. 



The result of the observations of 700 spots observations 

 extending over six years along this line, may be thus briefly 

 stated. As we pass from minimum to maximum, the lines 

 of the chemical elements gradually disappear from among 

 those most widened, their places being taken by lines of which 

 at present we have no terrestrial representatives. Or, to put 

 the result another way at the minimum period of sun-spots 

 when we know the solar atmosphere is quietest and coolest, 

 vapours containing the lines of some of our terrestrial elements 

 are present in sun-spots. The vapours, however, which produce 

 the phenomena of sun-spots at the sun-spot maximum are 

 entirely unfamiliar to us. 



