452 
DR. W. xM. HICKS: A CRITICAL STUDY OF SPECTRAL SERIES. 
There can be little doubt about these lines forming a series, but there is so far no 
independent evidence that it is of the F type beyond its analogous position in the 
spectrum to that of the other rare gases. If it is of this type we should expect to 
find a nnmber of parallel series as well as of the associated F type. It is then 
necessary to test for these conditions. 
A considerable number of parallel series can be arranged all weak for m = 3 as in. 
the original series. Some of these are given in the following list in which the 
numbers in clarendon below the wave-numbers give the separations from the corre¬ 
sponding F lines. Those to the right of the vertical line are added. The others are 
deducted. 
2-67(0)...71 
(1) 16768<^ 
(8) 16816 
(2)16831 
(2) 16845 
(4) 16889 
312-73 [5-56(0). 
.71 265-36 
'249-59 
235-84 
191-63 
23623 
__ 
(0) 23798 
(1) 23812 
(2) 23854 
315-2±3 
246-69 
232-58 
191-29 
26695 
2671^5 
26766 
(1) 26776 
26816 
314-6±3 
264 ±3 
244±3 
233-33 
193 ±6 
w.(9) 28396 
(1) 28302 
28216.% 
_ 
262-83 
250-28 
228 ±6 
(3) 29196t 
_ 
— 
29257 
261-7 
200 ±9 
(5)16925 
(1) 16948 
(5) 16996 
(5) 17222-^ 
(7) 17342 
155-86 
113-00 
85-23 
141-51 
261-22 
_ 
_ 
_ 
2Jkl83 
24312 
138 ±6 
267 ±6 
26860 
(26892)* 
(2) 26922 
(4) 27148^ 
27285 
150 ±6 
117 ± 
87-10 
138-83 
275 ±6 
(9) 28396 
(5) 28438 
(4) 28474 
e. (5) 28888 
(28819)1 
156-33 
113-61 
87-57 
138-68 
267 ±6 
(3) 29196.Mt 
293J^3 
29369 
(1) 29592 
29727 
155-0 
115 ±9 
89 ±9 
134-15 
268 ±9 
30175 
30194.U 
139 ±9 
265 ±9 
The wave-numbers in italics are by L.D. and subject to probable errors dX = -5 and possible dX = 1. 
For values of links see below. 
* u.26997-6 = 26891-0; 2669J^8.e = 26891-8. 
t U.28927 = 28820-3; 28711.U = 28817-7, mean taken. 
I One at least must be a coincidence, or the two series can simply be linked by w or v. 
