Hartley & Ramage — Wave-lengths of Principal Lines in Spectrum of Gallium, 



the intensities of the solai- lines over a wide scale, extending from 1, a line just 

 clearly visible on the map, to 1000, for the H and K lines ; and it is remarked that 

 this is hardly enough for the enormous differences in intensity. Below 1, the 

 lines, in the order of faintness, proceed from to 0000, indicating lines more and 

 more difficult to see. The lines in his table which lie near to the two measured 

 lines in the arc spectrum of gallium are the following ; — 



Solar Lines,* 



4171-854, Cr, La, Mn, N 

 4172-066, Ti, Fe, . 

 4172-211, Al(?), . 

 4172-296, Fe, 



,Fe, 



Intensity. 



3 

 2 

 1 

 2 



4032-610, Fe, .... 2 



4032-789, Fe, .... 4 



4032-985, ..... 000 



4033-112, 00 



4033-224, Fe, Mn, S., . . . 7d. 



We find that the lines in the solar spectrum most nearly coincident with the 

 gallium lines, according to our determinations of their wave-lengths, are the 

 following : — 



Solar Lines. Intensity. Gallium Lines. Intensity. 



4172-211, Al,t . 1 4172-214 1 



4033-112, . . 00 4033-125 00 



We believe these numbers to be quite accurate to the second decimal place. 

 Our micrometer measures to the ten-thousandth of an inch, and an error of this 

 magnitude makes a difference of 0-0033 in the wave-length. We used lines in the 

 arc spectrum as fiducial lines, which correspond with the following solar lines : — 



* Astrophysical Journal, vol. i. 1895. 



f Corrected by Rowland, and definitely assigned to aluminium. See the Astrophysical Journal, 

 December, 1897. 



1 Astrojihysical Journal, vol. i., February and March, 1895, and vol, vi., December, 1897. 



