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



367 



group with a limit (-2^) D(oo) O r with a limit ( + 4^) D(>), decreasing by S the 

 mantissa} of the sequents and requiring 



which again are easily satisfied within observation errors. With regard, however, 

 to (2), (3), it is not common to find two satellites so close together, and as they both 

 belong to doublet sets we should suspect that they belong to different groups, and 

 in fact the condition is satisfied by regarding the limit of 2087 5 as displaced by <?, 

 on that of 20871. 



We shall consider the conditions more fully later in connection with the more 

 accurate determination of the oun. The preceding results are sufficient to show 

 that (l), (4), (5) are a definite normal D satellite on the basis of A 2 = 4G80 . That 

 (7) (8) belong to a series probably based on A' 3 = 4243 1, and 2, 3, 6 to a parallel 

 system based on the limit ( 2^) D ( oo) or (S) D ( oo). 



I omit details about the satellite e. u, v links, but the following points are interesting. 

 The line 19116 affords an example of the two displaced D 2 lines analogous to that 

 given in 3(a) as explaining the source of the abnormal i>, separations. In addition 

 the linked line.2e + D 18 shows the same effect with two lines (2) 25380'26, (l) 25382'58. 



D 



16 , 



are curious as showing successive abnormal u links. 



D 



Thus 



(1) 18780 1888-61 (2) 20669 1888-37 (4) 22557 



Da, 



(1) 19881 1885-31 (3) 21766 1885-71 (3) 23652'29 



1889-40 (3) 23655-98 

 (1) 23659-29 



3-69 



3-31 



The two lines D 12 , D 13 which have been shown to have a relative displacement 

 of 2$i show u, v links to a mid-line displaced <^ from each. Thus (3) 22815"84 is 

 1942'15 or v-- '29 below their mean; whilst (l) 19778'52 is 1883'69 or ?t-'34 below 

 the mean of D 22 and D 23 . 



The satellites for m = 2 are more doubtful on account of the large changes in the 

 mantissse produced by observation errors. The line 38531 has a mantissa difference 

 from that of d n of 12%S, exactly the same as in D 13 (l). It should, however, be one of 

 a doublet with the second line stronger. The others show mantissse differences of 

 28cS, 103(5, 124(J, 224f(5, which, allowing for the usual changes in the second order, 

 clearly point to the sets as indicated in the table. There appears, however, no 

 analogue in m = 1 for 38324. In this case it is important to notice that the v a 



VOL. ccxx. A. 3 E 



