DR. W. M. PUCKS: A CRITICAL STUDY OF SPECTRAL SERIES. 
71 
more correct measures, which at the same time estal^lished Kydbejig’s selection of tlie 
tirst five. 
Some doulit may be felt about the lines adopted for GaS. In his memoir 1 Iyi)J 3ERG 
used certain regularities he had noticed amongst other series to deduce what the 
Ga series ought to be—adopting the doublet 4172, 4033 for S^ and S 2 . He calculated 
2747 and 2436 for the two next lines in Sj and 2966, 2505 for the I) lines. Since 
then Exner and Haschek have published their spark and arc measurements. 
Kayser in his ‘ Spectroscopie ’—no doubt guided l:)y Rydberg’s calculations, as there 
w'as nothing else to go upon—allotted E. and H.’s spark line 2780'28 to Rydberg’s 
supposed 2747, with 271976 (arc) as the second of the doublet {p = 800 instead 
of 826). Ramage gives (‘Roy. Soc. Proc.,’ 70, 1901) 2780, 2718, in place of 
E. and H.’s 2780’28, 271976. It might appear, therefore, that 2718 is really a 
distinct line which, with the former, gives v = 823'65 (within errors of 826), whilst 
2719"28 is the first of another doublet with v = 826'68. He gave also 294377, 
2874'35 for D in correspondence with Rydberg’s supposed 2966 and 2894. In the 
foregoing paper I adopted the same allocation for S (l, 2), and with it have taken 
E. and H.’s spark line 2481 as (3). For this it may be said that the corresponding 
lines come well in order as lying between the corresponding ones of A1 and In, and 
the resulting formulre constants also fit in well as between those of A1 and In. On 
the other hand, they do not occur in the arc spectrum, where they ought to be 
stronger. Moreover, in E. and H.’s list, lines occur with the proper doublet separation 
and of corresponding nature and order of intensity, which certainly look as if they 
belong to the series; hut, unfortunately, there are not sufficient to settle the question. 
The lines in question are given in wave-numbers as follows :—• 
m = 1 < 
(5r) 33954-36 
6-00 
(lOr) 33960-35 
D Series. 
826-07 (lOr) 34780-43 
on = 2 
( 39975 - 17 ) (826-00) (2r) 40801-17 
(2r) 39983-85 
[ 39975 , suggested for Dj 2 ( 2 ), has not been observed.] 
S Series. 
on — 1 (30r) 23961-41 826-00 (30r) 24787-44 (in both arrangements). 
001 = 2 (3) 36757-27 826-68 (2) 37583-95. 
As against this allocation is the fact that they do not lie in corresponding positions 
