APPENDIX. 



Table 322 (concluded from page 2J5). 

 SPECTRUM SERIES. 



441 



The following table gives the series types due to the neutral (arc) and ionized (spark) elements 

 of the various groups. The question marks indicate merely that the series relations have not 

 been disentangled from the maze of spectrum lines. 



To a first approximation the equations leading to the numerical values of the various lines of a 

 series may be expressed in the following form : 



V =N/(i-|-S) 2— N/(m-|-P) ^, for instance, for the principal series. In abbreviated notation 

 these series take the following forms (Fowler), m generally takes for its lowest value, the first 

 value which makes the expression positive. The abbreviated notation expresses the laws above 

 stated. 



Principal series = (i,S) — (m,P) 



I St subordinate (diffuse) = (i,P) — (m,D) (Singlet, doublet and triplet series are distinguished 

 2nd " (sharp) = (i,P) — (m,S) by capital, Greek and small letters.) 



Fundamental (Bergmann ) = (i,D) — (m,F) 



Paschen notation is frequently used especially by writers on ionization and radiating potentials; 

 the following table indicates in part the differences for corresponding formulae: 



Other minor differences exist; Paschen values fit the Ritz formula whereas Fowler uses the 

 Hicks formula. The variable terms of the two series may take the following forms respectively: 

 N/{m+a+acN/m2}2 and N/ {m+3.'a'/m}\ 



_ For further information see Foote and Mohler's Origin of Spectra, 1922 (From which con- 

 siderable of the above is taken) and Fowler's Report of Series in Line Spectra, 1922, 

 Smithsonian Tables. 



