458 DE. W. M. HICKS : A CRITICAL STUDY OF SPECTKAL SERIES. 



limit and that the present pair run parallel to one 26S above the old D 13 . If this existed 

 it should be 21142'64, 21191'98, 21211'69. There are lines for the last two but none 

 for the first. They are 



[2114274] [49-24] (0) 21190'61 20'10 (6) 2121071. 



There is thus considerable evidence for the existence of parallel S groups as well as 

 of parallel D ones. Each set has its corresponding i/,, ^ separations, but with the 

 same oun multiples for A 1; A 2 . We should consequently expect to find the presence 

 of corresponding a ... e links. With the S limit 52112 the e link is found to be 191 '49. 

 Now the occurrency curve for e gives a maximum between 195 '6 and 196 pointing 

 to a S limit as basis about 650 less than 53081 or, say, 52430. This makes e = 195 '63, 

 ,/ ( = 48 '9. Do we find evidence for S and D sets about this amount less in wave- 

 number than the old ? For the S we are landed in a region which forms a gap in B.'s, 

 or W.'s observations but which contains a number of lines by L.D. Amongst these 

 we find 



Si. S 2 . 



1429 -\ 



1957 i-279644 47 280114 

 105-9 J 



213 

 281774 40 282174 



The suggested S 1( S 2 fall into the proper positions, the link 1429 is one of WATSON'S 

 constants, 195 "7 is the a link proper to the limit, 105 "9 is u or v, and 213 is 2u or 2v. 

 For the D sets we find amongst W.'s lines 



(0) 20551-35 49-62 (2) 20600'97 

 157-51 



00 20708-86 



The 20551 is 601 below D, : , = 21156, which when the variability of the satellites is 

 considered may be taken as the analogue of 610 for the S set. If it is corrected* by 

 dn = "7 (d\ = --'17) the v 1 becomes the correct value 48'9, and it is then also separated 

 from 20708 as a D n line by 156'8, which at once suggests the origin of the 156 

 parallel F and F sets previously brought to light. If this relation be real, the old 

 F(oo) 31851 is a d satellite sequent, belonging to 2055T35 or ...2'0 and the limit is 

 20552-0 + 31851'13 = 52403'13. Not only is the 156 separation found, but there are a 

 large number of lines in the neighbourhood which give, possibly within the error limits, 

 the other separations indicated by the traces of parallel F series adduced at the 

 beginning. Also as indicating a D region we find large repetitions of e and b links 



* Not necessarily error, probably the usual D displacement on sequent. 



