Note 22 — § 4. Double Spectral Lines.

The lines of the ordinary hydrogen spectrum from a vacuum-tube also appear as close doublets with high dispersion. Considering, however, the want of sharpness of the lines and the discrepancies between the distance of components found by different observers, it seems probable that the lines are not true doublets, but are due to an effect of the electric field in the discharge. This is also indicated by the fact that the distance between the components observed increases with the number of the line, contrary to the behaviour of ordinary double lines. The distance between the components observed by Paschen and Back (loc. cit.) was cm. and cm. for and respectively. According to Stark’s experiments on this corresponds to a resolution produced by an electric force of about 900 volt per cm. The ratio between an electric resolution of and should, according to the calculations of section 2, be 0.76; the ratio between the components observed is or 0.83.