158 
an all-including notation. This necessity already appears on a cursory 
examination of the notations used by PascHeN (Rrrz's notation), 
Hicks (a modified RypBerG notation), and Mocrnporrr (in the: cited 
communication), while, as we saw above all three entertain 
about the same idea about the differential action. Let us now try 
‘to bring unity in this by considering the thought they have all in 
common, viz. that in accordance with Rrrz’s theory *) on the magnetic 
atomic fields, every spectral line is brought about by the difference 
of TWO actions. 
So in the notation of every spectral line it should be expressed, 
with what member of what two series (sequences) it is related. For 
the designation of these series the nomenclature introduced by Hicks ”*) 
is the most convenient, because the notations mp, ms ete. exist al- 
ready also with Rivz’s formula. 
So we distinguish : 
1. Principal series or Pe (aS? Bed 
2. Sharp series or Stas 
3. Diffuse series or Daer AN yD) 
4. Fundamental series or Fr w=1.2.38..) 
The form of these series is somewhat different for the different 
spectral formulae, but yet there is close agreement. The numerators 
are the same for all three, (Ritz, Mocrnporrr-Hicks, and mine), 
viz. the universal constant 109675,0. The roots from the denomina- 
tors are threeterms. The first term of it is the parameter (m or 2), 
the second a constant (a, p,s,d or u), the coefficient of the third 
term being denoted by (6,2, 0,9 or y). Let us now also bring 
agreement in this, and in imitation of Rrrz introduce different, but 
corresponding symbols for the different series, so for the constant 
terms resp. p,s,d, and f, and for the last coefficients resp. =, 0, d, 
and gp. 
Then the meaning of Pz, Sx ete. will be according to the formulae 
of Ritz, (R), of Mocrnporrr-Hicks (MH), and according to my 
formula (L): (see table p. 159). 
X may be put here: 1.2.3... The notation, as Rrrz introduced 
it for the 2"¢ subordinate series (1,5; 2,5; 3,5;...) should be dis- 
carded. It makes the matter difficult to survey. Though for some 
metals we do get the impression that we have to do with x + 0,5 + 
a certain fraction, this is by no means the case for all, and I 
entirely concur with the conclusion of Hicks‘), who has inquired 
into this matter more closely : 
