DR. W. M. HICKS: A CRITICAL STUDY OF SPECTRAL SERIP:S. 
357 
not far from that shown by S(l) is indicated by the fact that there are several 
accurate separations of about 179'5, e.gr., 
(6) 20621 179-31 (8) 20800 179-61 (4) 20980 
(3) 26893 179-35 (l) 27072 
(1) 31359 179-62 (4) 31538 
of which the first is part of a linkage. With the limit 51731-05 + f and 
j'l = 179 - 50 + V 2 = 75-60 + cZi/^, the values of Aj, Ag are 
Ai = 2519--073^+14dj.i = 43|(57-59 +-32 -0016^), 
A 2 = 1057--030^+14^1/2 = 18|-(57-91 + -77 di/2--0016^), 
or 
A = A 1 + A 2 = 62 X 57 - 70 . 
The oun is thus given by 4(5j = (5 = 57-7 with some uncertainty owing to inexactness 
in the observed triplet separations. Its value calculated direct from the atomic 
weight 39-9 should be ^ = 361-8 x (-399)^ = 57-6 +-14, the uncertainty being due to the 
uncertainty +-05 in the atomic weight. The value ofs(l)=_p(l)-S(l) = 94373-10, 
from which the u, v links may be calculated. The e, u, v links are found to be 
e = 719-7l + 4di/i, 
u = 439-47 + 2-43^1/1, 
V = 442-67 + 2-47 di/i. 
The examination of the spectrum gives the occurrency curve shown in Plate 2, 
fig. 4. It shows a very distinct maximum in the region around 720 but little to 
show the exact position. The values appear somewhat irregular. If, e.g., the ordinate 
for 719-6 be drawn, it would be the same as for those at 720-5 and 721. It may be 
noted that if the maximum is taken at 720-4, i/j is -18 larger = 179-68 and the oun 
calculated from Ai becomes the same as from A. But this is rarely the case in 
triplets. As, moreover, the link 719-7 when applied to the observed S{1, 2, 3) lines 
gives better agreement than a link 720-4 we shall use it for the purpose of sounding. 
The results of sounding 
follow : — 
are exhibited in diagram 
S(l). 
form in Plate 3. The 
details 
42642-10 
42462-67 
42387-07 
-e [41922-39] 
-e[41742-96] 
-e(3) 41666 
- -06 
(-78i)(2) 41474 
-e-i;(4) 41299 -02 
(-78i)(2) 41218 
— e — u 81-86 - 06 
- e-v 
- -03 
( 681 ) (1) 41488 
-2e(2) 41023 --02 
( 681 ) (2) 41231 
e( - 681 ) (1) 43355 -00 
-2e + M(4) 41460 -11 
- 2e - li (2) 40585 --10 
+ e (3) 43183 --06 
-2e(l) 40949 
- -10 
We find in the three sets clear indications of displacements producing separations of 12 or 13. As they 
appear in different orders such displacements can only arise in the limit. Two cases occur in m = 1, viz., 
