The Chromosphere Line Ångström 6676.9

Abstract

WITH regard to Prof. Young's observations as to the noncoincidence of the bright chromosphere line (NATURE, November 12, p. 28) with the corresponding dark line 6676.9 of Ångström's scale, it may be interesting to note that Profs. Liveing and Dewar have observed a barium line at 6677, which is therefore slightly less refrangible than the dark solar line. In his catalogue Prof. Young also gives a barium line at 6018.0, which is identified with Kirchhoff 933.8. In the course of the observations of sun-spot spectra taken at Stonyhurst with a twelve-prism spectroscope, no dark solar line has been noted in this position except in two uncertain instances over spots. It would be an important fact should two barium lines be found in the chromosphere without corresponding dark lines.