DE. W. M. HICKS; A CRITICAL STUDY OF SPECTRAL SERIES. 
429 
In No. I the sounded line is on the verge of the observed region. In No. 2 the 
sounded is about 4 too large, and there appears a displacement on the last. The 
u, V links themselves are too short to reach. 
m = 3. [37650-6 from Calculated F, 37717 from Observed ( 5 (^i) F.] 
(3) 23973-69.U (O) 15944 (W.).2u (2) 18739 (C.E.).2^ + 4p 
37654-29 + dy 5651+dv 43305-2 + 2du 2795+4p 46100-2 + 2dt) 
Here the reproduced line refers to the normal line calculated from the formula. 
The V link is too short for the second and third lines, 2v reaches it, hut 2v on the 
first would require a reference line in the ultra-red. Also 15944 is possibly 
F,(2). 
m = 4. [34779-80.] 
(3) 23584 (C.K.). 
u 
{Sy) ( 0 ) 23598-2 (W.).n 
34776-0 5655-2+ de-du 
{-2S,){3) 16725-1 (W.).e 
40431-2 
Again note a C.K. copper line supported by a W. and R.E. displaced line 
m = 5. [33259-17.] 
(2) 25213-7 (W.).u (O) 18024 (W.).e 
33259-05 5635-25 + dv 38894-3 2808-0 + de —dv 41702-3 
Here appears the frequent 5635. It is 5649-14, that is, there is a limit 
displacement of in the second line and an extra one in the third, making the 
second separation 2816. 
m = 6. 
'The same links cannot serve as sounders for all three lines. 
For Fj is ( 2 ) 211725-4 (W.).^^ = 32364-34 + dw as against calculated 32362-14. 
For Fg is v.{2) 16816-5 (W.).e.w = S8004:'S+de + du-dv. 
For F 3 (4) 18448 (C.E.).2n = 40831-6+ 2dw. 
These give separations 5640-5, 2826-8, where the sum has the normal value. In 
( — ^ 1 ) ( 3 ) 23973-69 (W.).n = 35178-45 which is 2816-2 ahead of Fj we have the 
completion of a mesh with the other three lines. 
The foregoing discussion has shown : (l) that this F set belongs to the 1864 type 
discovered in X ; (2) that the usual displacements are present and that the calculated 
value per oun—13-96—satisfies all the numerical relations formed; and (3) that the 
lines observed with copper electrodes by Cameeon and Eamsay seem to belong 
specially to parallel series to this set. We could feel complete confidence in the 
allocation of the lines were it not that the a constant in the formula is positive, and 
that the line m = 6 is not reproduced more closely. The absence of direct 
