On the spectrum of neutral helium II

Abstract

A rejoinder to Dr. Silberstein's reply.—The two points raised by Dr. Silberstein in reply to the criticisms of his combination formula are answered. The figures have been recalculated, taking tbe maximum limit ot the quantum numbers to be that proposed by Dr. Silberstein himself, and the number of fortuitous coincidences to be expected between the observed lines of the helium, spectrum, and those given by the formula is calculated and found to agree fairly well with the actual number. The view that the coincidences noticed are due to mere chance is maintained.