PROF. A. FOWLER ON SERIES LINES IN SPARK SPECTRA. 
253 
Table XIII.—Magnesium Combination Series B (3 f—mf). 
Limit, 3/ = 27,469’3. 
m. 
a(I.A.) 
(Fowler). 
n 
(observed). 
n 
(calculated). 
O-C, 
An. 
Remarks. 
5 
6545-80 
15,272-8 
15,262-7 
+ 10-1 
Tnrt • f A 6546*77 (Row.). 
Lor. gives 1 A 6545.66 
6 
5401-05 
18,509-9 
18,501-9 
+ 8-0 
„ „ A 5401-2 
7 
4851-10 
20,608-2 
20,603-9 
+ 4-3 
8 
4534-26 
22,048-2 
22,045-3 
+ 2-9 
9 
4331-93 
23,078-1 
23,076-0 
+ 2-1 
10 
4193-44 
23,840-2 
23,838-5 
+ 1-7 
11 
4093-90 
24,419-8 
24,418-5 
+ 1-3 
It will be observed that in each case there is a systematic difference between 
observation and calculation. In Series A, however, the differences are very slight, and 
possibly negligible ; but in Series B they are too large to be attributed to faulty 
observations. The terms mf have been derived from observations of a high order of 
accuracy, and in the case of Series B, the calculated wave-numbers would not be 
affected by any error in the adopted value of the limit of the f series. It is scarcely 
probable that Series B, with its limit so near to 3/, is independent of the “ F.P.” 
system, and it would therefore appear that the combination principle is not exact in 
every case, except probably as regards the values of the limits. 
Calculations of formulae for the two series from the observed lines themselves confirm 
the values of the limits given by the combination terms. These formulse are as 
follows:— 
A (m) = 27,956-48- 
4 x 109679-3 
m + 0-993807 + 
0-008967V 
m 
7 
B (rn) = 27,468-38 
4 x 109679-3 
m + 0"994863 + 
0-014621 
m 
The residuals (O —C) left by the formulse on the observed wave-numbers are— 
m = 5 
O-C 
Series A = 0‘0 # 
„ B = 0-0* 
6 
+ 0-3 
+ B8 
7 
O'O* 
0 ' 0 # 
8 
9 
10 
11 
+ 0-1 
0-0 
- 0-3 
0 ' 0 # 
+ 0-1 
0-0 
o-o 
0 " 0 # 
A general view of the enhanced line series of magnesium now identified is given in 
