DR. W. M. HICKS: A CRITICAL STUDY OF SPECTRAL SERIES. 
389 
(1) 28311-62 4425-90 
(4) 28047-34 4131-62 
(2) 18466-47 
7313-17 
Fj 1863-92 Fg 829-69 F3 4426 43 (2) 31035-76 
1975-86 1974-70 1970-10 
(4) 25891-58 1862-76 (2) 27754-34 825-09 (4) 28579-43 1864-94^ 
Here F^, 25891, 27754 form a series inequality with c7 + 2 , ; F^ forms a parallel 
inequality with 28341 and 28047 with u-2, v-2 ; 18466, F„ 27754 a series inequality 
with d, e ; and Fg a parallel inequality with v-2, d-2. 
As a rule in the list only displaced lines are dealt with and only occasionally linked 
ones. The evidence is strong for the existence of possible series with limits 30725 
{±xSi) especially x = 2 and that for each order most of the energy goes to a line 
with one of these limits, not necessarily the same for different orders nor for the same 
triplet set, nor for the same F or F type. 
Notes.—A displacement produces 4-97 on Fi(oo), 5-43 on FA 00 ), and 5-65 on 
~ 1- The shortest sounder to reach from the calculated F (l) to the oliserved 
region is 2 e, giving values in the neighliourhood of 17700. In this neighliourhood'we 
find a triplet (No. 2 of the sets on p. 383) ^ 
( 6 ) 17638-55 1864-64 (3) 19503-29 829-93 (l) 20333-22, ‘ 
which m separation and order of intensity corresponds precisely to the values required. 
With the normal value of e they indicate lines vvdth wave-numbers at 3010-35, 
4875 09, 5705 02 . In connection with the question of satellite effect it may be worth 
noting that lines in the neighbourhood of the above may be arranged with them thus 
( 6 ) 17638 1864-64 (3) 19503 829-93 (l) 20333 
12-52 
. (3) 19515-81 
25-53 
(5) 17664-07 
To complete the set there should be a line at 17651-31, but it was not observed 
by Baly. a sequence displacement in/(l) of 3 (ii produces a change of 12-76 and 
of 6(^1 of 25 53. These are practically exact and correspond to the diffuse satellite 
arrangement with this difference, that the triplet appears as a main set in which the 
fiist line is strongest. They depend on 3()i, 6 ^^ displacements, so that the mantissa 
of the doublet set, that of 19515, is exceedingly close to 9 OA 2 , viz., 90 x 10997-17. 
With Fi(l) = 3010 should go Fj(l) = 58440-17. This is outside the observed 
legion on the other side, in the ultra-violet, and requires even larger sounders than 
F(l). The treble link 3c = 21942-30 requires a line at 36497-87. There is no line 
