On the effect of electric and magnetic fields on spectral lines

THE LONDON, EDINBURGH, AND DUBLIN
PHILOSOPHICAL MAGAZINE AND JOURNAL OF SCIENCE.
VOL. XXVII—SIXTH SERIES.
JANUARY-JUNE 1914.
The theory put forward by the writer to explain the emission of a line-spectrum may be summarized as follows:—
The principal assumption of Planck’s theory is that the energy of a system of vibrating electrified particles cannot be transferred into radiation, and vice versa , in the continuous way assumed in the ordinary electrodynamics, but only in finite quanta of the amount
, where
is a universal constant and
corresponds to a radiation emitted during the transition of an elementary system from a state in which its energy is
to one in which it is
, we have
According to Balmer, Rydberg, and Ritz the frequency of the lines in the line-spectrum of an element can be expressed by the formula