THE STRUCTURE OF THE SERIES OF LINE- AND BAND-SPECIRA. 595 
the constant n of equation (19) some evidence may be brought forward which seems to 
point to the conclusion that in the various groups n is always an integral multiple of 
one and the same number. For instance, we have seen that in the Mg-group n had 
almost exactly twice the value of that in the Zn-group. If, in the various groups, we 
assume for m (equation 19) the values 
Li-group: m=10580 
Mg-group : 6536 
Zn-group : 23772 
the following comparison will show that by assuming n=4 x 10* or 8 x 10* we can 
approximately represent the wave-frequencies of the tails of the subsidiary series : 
Comp. Comp. 
ie (n= 4 x 104) i (n= 8 x 104) 
ite: 28589 28150 Mg: 39780 39970 
Nal: 24486 24506 Ca: 33919 33752 
Ke: 21994 21826 Sry 31060 31040 
Rb: 20965 21035 
Cs: 19748 19902 | Comp. 
Ven (n= 4 x 104) 
Zn: 42925 42931 
Cd: 40766 40827 
He: 40168 40101 
Applying the relation (19) to the principal series of the alkali-group, we find for the 
two elements of lowest atomic weight Li and Na, n=2 x 10‘, but for the three others 
K, Rb and Cs, n =8 x 10%, with the corresponding values of m: 34610 and 12758. 
Veo Comp. Veo Comp. 
is: 43498 43395 1K 35030 35250 
Na: 41468 41573 Rb: 33762 33668 
Cs: 31526 31402 
Again we have to confess, however, that the materials at our disposal are too 
limited to demonstrate the alleged property of the quantity n conclusively, and hence 
that it is useless to enter upon further comment. The history of the subject here 
discussed must warn us to state such regularities with due reserve, and not to rush to 
hasty conclusions, however tempting they may be. 
I shall now discuss in a few words some interesting results with regard to the 
constant a, of the RypBreRc-TuHieLe equation. It was shown at the beginning of this 
investigation that we can write 
1 —-2 b \—-4 
V=Ve.— —(m+ map ARIIL) a, sucte, ne 
a 1) a, 1) 
an equation which assumes the form of Ryppere’s formula when b,=0. As is well 
