DR. W. M. HICKS: A CRITICAL STUDY OF SPECTRAL SERIES. 



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.g., 



(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 + and 

 v l = 179'50 + c^!, v 2 = 75'60 + dv 2 , the values of Aj, A 2 are 



A! = 2519- '073+ Ud Vl = 43f (57-59 + '32 c^-' 



A 2 = 

 or 



A = 



2 = 18j(57'91 + 77 e^-' 

 A 2 = 62x57'70. 



The oun is thus given by 4(^ = S = 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 S = 361'8 x ('399) 2 = 57'6 '14, the uncertainty being due to the 

 uncertainty '05 in the atomic weight. The value of s(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 = 71971 + 4 c^ 1; 

 u = 439-47 + 2'43 di/,, 

 v = 442-67 + 2-47^. 



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/ a is "18 larger = 179"68 and the oun 

 calculated from A! becomes the same as from A. But this is rarely the case in 

 triplets. As, moreover, the link 7197 when applied to the observed S(l, 2, 3) lines 

 gives better agreement than a link 720"4 we shall use it for the purpose of sounding. 



The results of sounding are exhibited in diagram form in Plate 3. The details 



follow : 



8(1). 



42462-67 



-e[41742-96] 

 --(4) 41299 



42642-10 



-e[41922-39] 

 (-780(2)41474 

 -e-u 81-86 



(680(1)41488 

 e (- 680 (1) 43355 



-06 



-00 



-2e(2) 41023 



- 2e + w(4) 41460 



-2e-u(2) 40585 



+ e(3)43183 



-02 



'02 

 "11 

 -10 

 -06 



42387-07 



-e (3) 41666 

 (-780(2)41218 



--06 



-e-v 



(680(2)41231 

 -2e(l) 40949 



-'03 



--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., 



