234 
PROF. A. FOWLER ON SERIES LINES IN SPARK SPECTRA. 
Calcium — 
Wide doublets. 
Narrow doublets . 
Strontium —• 
Wide doublets. 
Narrow doublets . 
< 
D (m) 
S (m) 
F ( m ) 
D (m) 
_ S (m) 
F (m) 
70,117 \ 
423,416 
70,340 J 
(m-0‘69117) 2 ’ 
70,117 \ 
421,559 
70,340 J 
(?n + 0'617844) 2 
81,820'0"1 
430,959 
81,880-8 J 
(m-0’039796) 2 
64,154 T 
410,836 
64,954 J 
(m-0-59254) 2 ’ 
64,154 T 
415,157 
64,954 J 
(w + 0-684636) 2 
73,833*5 T 
430,554 
74,113*2 _J 
(m-0’056189) 2 
The numeration of the members is shown in Tables III. and IV. (Lor. = Lorenser ; 
Fow. = Fowler). 
The negative terms corresponding to m = 3 in the D series, and to m = 1‘5 in the 
S series (the latter giving the first P doublet), are given very erroneously by the 
formulae, as is so often the case in the more familiar series. Nevertheless, 
Lorenser has fully established the connection of the F with the D series, 
through the usual relations, to which reference has already been made. There 
is sufficient evidence that the lines in question are to be regarded as enhanced 
lines, and, though Lorenser does not appear to have recognised this fact, his 
work proved that enhanced lines may form groups of related series which are 
generally similar to those occurring in arc spectra, but require modifications of the 
usual formulae. 
It will be observed that in Lorenser’s formulae the numerator is of the order of 
4N as in those already found for the Mg “ 4481 ” series, and the question arises 
whether 4N may not be the universal constant for enhanced lines, as N is universal 
for series of lines produced under less violent excitation. The series are not long 
enough to give a very satisfactory comparison of the relative accuracy of different 
formulae, but, so far as it goes, the evidence is distinctly in favour of the Hicks 
formula with 4N for the numerator. For the F series the formula may take the 
simpler Rydberg form with sufficient accuracy. 
The formulae for the above series are then as follows, the wave-numbers being on 
Rowland’s scale to facilitate comparison with Lorenser’s figures :— 
