DE. W. M. HICKS: A CRITICAL STUDY OF SPECTRAL SERIES. 441 



C.E. lines. Behind this is .a line (2) 22079'34 W. (d\ = '05) corresponding to the -S r 

 displacement in the sequent i.e., the modified D separation. With S(oo) Jtg 

 mantissa = 804161 -2677- 2677di/, + 



= 25 



If this be combined with the mantissa of 29964 = 913105 = 51 1,1 giving 

 A 2 = 32166-27 -1-116^, there results the equation 



This can be satisfied by f = 0, dv l = 0, and p a fraction. It does not therefore help to 

 a closer determination. With good measures it should be practicable to find dv^ 

 within '05 and p a small fraction. This equation would then give the small correction 

 for and so increase considerably the degree of accuracy of A., and 8. The particular 

 point however gained is that here is found one of the fundamental d sequences 

 depending on pure multiples of A 2 . 



(4) They all show 5640 links when this link lands in the observed region except 

 22868. Where the measures are reliable they congregate round a value 5G33 + . The 

 22079 of the last paragraph is 563373 above the 16445. This is a further justifica- 

 tion of 22079 belonging to a S l displaced sequent. 



With 20438 as J) 1 (l), RYDBERG'S table gives D (2) as in the neighbourhood 37486 

 100. A u sounder gives the region 23806. There is a line (10) 2378375 (W.) 

 which if linked in this way gives D n (2) = 3746375. The two lines 'in = 1, 2, and 

 S ( oo ) give the formula 



n= 50403-N/JW-K909G01 + _ 003564 1' 

 / ( m } 



with D(3) = 43242'02. The e-sounder requires 19563. The only line in the neigh- 

 bourhood is A = 5105 by RAMSAY, who says his measurement is very rough. If we 

 allow d\ = 5A, the wave-number is 19583 20, and it may be the line sought for. 

 There seem also other D n groups as in X. One instance is adduced in the next 

 paragraph. 



I end the discussion of the RaEm spectrum by a consideration of the source 

 of the 564.0 separation. In X we found the conditions satisfied by oun displace- 

 ments on the F (oo) of 5 A 2 S lt and 2A 2 + 6^. But here the values of the separations 

 themselves seem very indeterminate. The values as arranged on p. 431 would seem 

 to point to 5633, 5649 with v 2 about 2800 and 2820. The limit of the particular 

 F series on which our whole discussion of RaEm is based is 29964'20. As a fact, how- 

 ever, this limit can only generate in the proper neighbourhood separations of 5646, 

 2806, and the displacements are 5A 2 6^, 2A 2 +2^. The dependence on these 



3 o 2 



