DR. W. M. HICKS: A CKITICAL STUDY OF SPECTRAL SERIES. 
387 
in series 381530, 3813'7"8, 381274, the last in a mesh. They are probably real. The 
next link, 1134U38, is clearly a true u link. Of the two next + 3192'59-5635'63 to 
D 21 (2) the second is a very close d, and it would appear, therefore, that the spurious 
link is 3192'59, which is about as far as possible from a modified a link. There is 
also a long chain stretching from 21558 in map (ii. b. 4) to D n , which will be considered 
later. 
The linkage is now taken up from 21558 (i. b. 3) with a chain of a large number 
of links requiring few modifications. Nos. 14, 15, 16, are parts of two meshes, 
equivalent to parallel sets of three lines at a distance 31977. The second mesh is the 
case taken as an example on p. 367 to illustrate the reality of displacements. The 
opposite sides of the mesh are exactly equal, so that it is highly improbable that 
errors of observation enter to any extent. The values of the four a links are as far 
as possible from modified ones, and the displacements must arise in some other way, 
the lines 41325, 41320 being displaced in opposite directions from 4132274. The 
formula is given for this and the two displacements entered under d\. There is an 
analogous mesh at the bottom of col. f attached to 25813, but involving two different 
links. The sides 319979+ 4603'92 = 780372 whilst a + c = 7802'91. This region is 
a maze of links which have a look of reality, even modified links constantly repeat 
themselves in similar arrangements, for instance 11345, 14935, 17250. The formulae 
are continued from 38127 (i. e. 6) by a chain through them from which the formulae 
for the other lines can be easily written down. The chain from 18985 (i.f l) in the 
annexe is parallel to one from 18577 (i. a. 1). From the X n line, 19113, only a 
short chain extends with a problematical link at the end. It depends of course on 
d\ instead of d' 2 - 
At No. 25 the X 12 satellite is taken up. At 17410 on the diagram the chain passes 
from (a. 3) to (f. 2) for convenience of spacing. The part from 17410 to 41866 
appears also in the P map, and the P formulae for 17410, 28755 are Nos. 20, 21. In 
this chain it should be noted that a line—an enhanced one—is connected to 36991 by 
a link 1134 5 '09. The Zeeman pattern, as found from Hartmann’s measures, is 0/6|-, 
viz., that of a D n line. It is connected by the links e — u to a D 12 line for which the 
typical pattern is 5/10. This relationship is certainly not to be expected, and throws 
some doubt on the link 11345'09. Formulae are given as far as 18985. The 
representation of the slightly abnormal u, v links looks artificial. The abnormality is 
clearly real, as they so frequently appear and in similar positions. It is possible they 
are due to displacements in the YD with a kind of satellite displacement, but if so 
they are too small to be accounted for by displacements. From 19738 another 
chain starts—drawn in the lower part of the map—containing again a number of the 
same abnormal u, v links. Nos. 25, 26, which are separated by a very exact e link, 
have the equal abnormal links attached symmetrically, viz., 11345'52 to No. 25 and 
—11345'09 to No. 26. The symmetry is striking, but the first leads to a connection 
with the S (3) linkage and the second is that on which the Zeeman effect has thrown 
3 H 2 
