348 



Mr. J. N. Lockyer. On the 



[May 6, 



most nearly approach the first one in widening are recorded, and so 

 on till the positions of six lines have been noted, the wave-lengths 

 being given from Angstrom's map, for each region. 



It is to be observed that these observations are made without any 

 reference whatever to the origin of the lines ; that is to saj, it is no 

 part of the observer's work to see whether there are metallic coinci- 

 dences or not ; this point has only been enquired into in the present 

 reductions, that is, seven months after the last observations now dis- 

 cussed were made. In this way perfect absence of all bias is 

 secured. 



It may further be remarked that the number of lines widened 

 throughout a sun-spot period is about the same, so that the conditions 

 of observation vary very little from month to month, and from year 

 to year. 



It may be further remarked that the absolute uniformity of the 

 results obtained in the case of each of the chemical elements in- 

 vestigated indicates, I think, that the observations have been 

 thoroughly well made; and, as a matter of fact, they are not 

 difficult. 



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

 elements taken — iron, nickel, and titanium — the number of lines seen 

 in the aggregate in each hundred observations is reduced from 

 minimum to maximum, and that this result holds good for both 

 regions of the spectrum. 



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

 the lines recorded as most widened near the maximum have not been 

 recorded 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. 



