DR. W. M. HICKS: A CRITICAL STUDY OF SPECTRAL SERIES. 405 
c?\=+-02, whilst 38203 corresponds to 30f(5 with riX ='Ol. They should form 
portions of doublets with lines at 39977-48, 39995-58. None have been observed, but 
it must be remembered tbat these are close to the end of the observed region where only 
^ oundin,.^ with (e + u) we find lines (l) 28530-91, 
(3) 28548 26 respectively, e + u—71 and e + u+'04 behind the expected lines 
showing no lines at ahead, which should be visible if they existed. We may, 
therefore, conclude the two lines in question belong to a doublet set. With regard to 
the suspected Djg line (38111) we find in this neighbourhood 
(1) 38134-61 1780-23 [39915-84] 815-20 (in) 40731-04 
(1) 38129-37 1778-21 (l) 39907-58 810-36 (l) 40717-94 
(In) 38108-60 
Calculation shows that the first lines of these sets give with Du (2) separations 
depending on displacements 43^(i (d\ = O), 44|-,i(c^A-= -Ol), 48^(5 (d\ = --03). All 
that can be said is that these lines may be the required satellite sets. As, however, 
a displacement of only produces a change of about -05 in X it is not possible to get 
any certainty. It is further possible that some of the set may belong to parallel 
series. For instance 38108 = (2,^0 38129. The first two are,' however, so close 
d\ = 00 and -01 that they are entered as Djg lines. 
For the second group 20305 is a IAS displacement from 20581. We should expect 
the corresponding m = 2 line about the same displacement from 38366. This is 
satisfied by the line (l) 38292-32 giving 148 with d\ = --01. There is also a doublet 
(l) 38285-86, 1778-08, (l) 40063-94 with normal separation and displaced 15^S with 
dX = -00. The first D (l) is displaced 122^8 from its D„ line 20305 and the second 
by an extra 73^^. If the Dij2) line is taken as 38285 the calculated line with 
122^8 IS 37611-59. There is no line here, but there is a doublet, which with this line 
may be written 
(2) 37606-15 1780-83] 
X (1) 39386-98 
[37611-59] 1775-39 J 
The mean of these two separations is 1778-11 or the normal We have here a 
parallel inequality due to 2<5i displacement in' 39386 and an extra 2^^ in 37606 or 
37606 is 123^,5 ahead of D„. 
Again calculating the 73|-^ displacement on 30706 the line should be 37174-40. It 
is not observed but there is a triplet close to it showing a similar inequality to the 
former. It is 
1774-38 
(l) 37159-39 
(Di) 37166-43 
1781-42 
(1) 38940-81 
813-67 (<1) 39754-48 
