DR. W. M. HICKS; A CRITICAL STUDY OF SI'ECTRAL SERIPIS. 
385 
the corresponding terms of the F and F lines the ,/are different, then the value 
calculated from their sum shows a change from the normal limit. The effect shows 
itself at once and the interpretation is less certain. It is possible that where such an 
affect appears it may not be real, hut due to the existence (d‘ the two close lines 
just referred to, of which one in each set is too faint to have Ijeen observed. Tims 
if the displacements are instead of finding B— /+a:i, B— Z+x,, H+f—x^, 
B+/—the 2nd and 3rd, or the 1st and 4th may not have l)een oljserved and we 
should be led to a wrong conclusion by taking, say, the 1st and 4th as corresponding 
lines. There are cases of this kind and also where one only is absent— i.e., we find one 
close doublet for one of the F or F lines. 
The lines composing the series are given in the table below. The limit calculated 
from the first three Fj lines was found to be 30724'28 +1’80, the uncertainty being 
due to supposed maximum observation errors of ±'05A in each line. The later 
discussion of the |-{F + F) rule will show that the limit should be very close to 
30725'26 with an error probably <’3. The formula was recalculated with this limit 
by supposing the three standard lines to be in error by —'02, +‘02, —‘02, be., by half 
their supposed maximum possible errors. The formulae for the Fj and Fj series then 
become 
n = 30725-26 + N//n+r022746- 
■028705/ 
m 
7 
List of F and F Lines. 
In each order the first line of numbers gives the F set, the second the F set. 
Between these are entered the mean values of the F and F which give tlie corre¬ 
sponding limits. When the values are deduced by methods explained in the notes 
they are enclosed in ( ), when calculated and not observed in [ ]. 
m = 1 < 
(.3010-.35) 
30725-77 
1864-64 
(4875-09) 
32590-35 
830 
(5705-00) 
33420-35 
(.58441-20) 
1864-50 
(60305-70) 
830 
(61135-70) 
m = 2 < 
(8) 18607-79 
30726-05 
(4) 31102-16.e.'y* 
1862- 96 
1863- 17 
(6) 20470-75 
32589-09 
(<1) 32965-33.e.r 
829-46 
(<1) 21300-21 
m = 3 < 
r (10)2.3910-72 
30725-15 
1863-92 
(8) 25779-64 
32589-28 
829-69 
(1) 26609-33 
33418-35 
(2) .37534-.58 
1864-35 
(Sj) (2) 39404-36 
828-44 
(1) 40227-37 
m = 4 < 
(.5) 26365-19 
30724-58 
1864-61 
32362-981 
32589-96 
829-67 
(29059-47) 
33420-07 
1 
(35083-.97) 
1866-16 
(36950-13) 
831-54 
(37781-67) 
m = 5 < 
(5) 27696-15 
30725-48 
1865-51 
(1) 29561-66’ 
32589-38 
828-72 
(1) 26257-20.(4 
33419-32 
(1) .3.37.54-81 
1862-29 
(<1) 35617-10 
831-17 
(-8d (!«,) 36442-62 
* Mare prohably F;^ (16). 
t 0rF2(21). 
3 G 2 
