142 
Proceedings of the Poyal Society of Edinburgh. [Sess. 
and thus, by combining it with (17) and (18) as in § 4 of the present paper, 
we obtain the equations 
\] = hv 
2/Aao a 
i' 
N 
Since in Bohr’s Hydrogen atom we have ^ , where is Rydberg’s 
AIXiOjq '}1/q 
constant and 7i^ is the quantum number corresponding to the orbit , the 
last equation becomes 
N 
which is the well-known formula for the frequencies of the series lines of 
Hydrogen. 
It will be seen that, in this view, the underlying reason for Ritz’s 
Principle of Combination in series-spectra is that each spectral line is 
produced by the discharge of a condenser whose opposite surfaces are 
concentric spheres ; the two terms whose combination determines the 
frequency of the line depend respectively on the radii of the two spherical 
surfaces. The determination of the frequency of the oscillatory discharge 
of this condenser depends on the connection found in the present paper 
between Planck’s quantum constant and the self-induction of the atomic 
oscillator, namely, the connection expressed by equation (18). 
(Issued separately June 2, 1922.) 
