380 On the Bright Lines in the Spectrum of the Chromosphere. 



Kirchhoff, which renders the coordination of the two scales some- 

 times difficulty and makes the atlas of KirchhofF far superior to 

 the other for use in the observatory. 



The numbers in the fourth column are intended to denote the 

 percentage of frequency with which the corresponding lines are 

 visible in my instrument. They are to be regarded as only 

 roughly approximative; it would; of course, require a much 

 longer period of observation to furnish results of this kind 

 worthy of much confidence. 



In the fifth column the numbers denote the relative brilliance 

 of the lines on a scale where 100 is the brightest and 1 the faint- 

 est. These numbers also, like those in the preceding column, 

 are entitled to very little weight. 



The sixth column contains the symbols of the chemical sub- 

 stances to which, according to the maps above referred to, the 

 lines owe their origin. 



There are no disagreements between the two authorities ; in 

 the majority of cases, however, Angstrom alone indicates the 

 element ; and there are several instances where the lines of more 

 than one substance coincide with each other and with a line of 

 the solar spectrum so closely as to make it impossible to decide 

 between them. 



In the seventh and last column the letters J., L., and R. de- 

 note that, to my knowledge, the line indicated has been observed 

 and its place published by Janssen, Lockyer, or Rayet. It is 

 altogether probable that a large portion of the other lines con- 

 tained in the catalogue have before this been seen and located by 

 one or the other of these keen and active observers; but if so, I 

 have as yet seen no account of such determinations. 



I would call especial attention to the lines numbered 1 and 

 82 in the catalogue ; they are very persistently present, though 

 faint, and can be distinctly seen in the spectroscope to belong to 

 the chromosphere as such, not being due, like most of the other 

 lines, to the exceptional elevation of matter to heights where it 

 does not properly belong. It would seem very probable that 

 both these lines are due to the same substance which causes the 

 D 3 line. 



I do not not know that the presence of titanium vapour in 

 the prominences and chromosphere has before been ascertained. 

 It comes out very clearly from the catalogue, as no less than 20 

 of the whole 103 lines are due to this metal. 

 Hanover, N. H., September 13, 187L 



