The Line Spectra of the Elements

Abstract

IN Prof. Runge's article on the spectra of the elements in last week's issue of NATURE (p. 607) he refers to my explanation of double lines in the spectra of gases (“Cause of Double Lines in Spectra,” Trans. of the Roy.Dublin Soc.,vol. iv. 1891, p.563); and says:—“I do not understand the decomposition of the arbitrary curve” [rather, of the actual motion of the electric charge within the molecules of the gas] “in a series of superposed ellipses” [rather, into a series of pendulous motions in ellipses]. “For the movement is supposed not to be periodical” [rather, is not known to be periodical], “and Fourier's theorem then would not apply, at least the periods of the superposed ellipses would not be definite, as long as there are no data except the arbitrary curve itself” [rather, no data except those furnished by the positions and intensities of the spectral lines].