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



385 



the corresponding terms of the F and F lines the f 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, but due to the existence of the two close lines 

 just referred to, of which one in each set is too faint to have been observed. Thus 

 if the displacements are x l} .JC 2 instead of finding B /+ B /+, ~B+fx t , 

 B+fx. 2 , the 2nd and 3rd, or the 1st and 4th may not have been observed 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 F, 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, i.e., by half 

 their supposed maximum possible errors. The formulae for the F L and F, series then 

 become 



n = 30725 '26 + N/JW + 1 '022746- - 



/ I 



m 



LtST 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 the 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 = 



m 2 



in = 4 



(3010-35) 



30725-77 



(58441-20) 



(8) 18607-79 

 30726-05 



(4) 31102 -16.e.t>* 



(10) 23915-72 



30725 15 



(2) 37534-58 



(5) 26365-19 

 30724-58 



(35083-97) 



(5)27696-15 



30725-48 



(1) 33754-81 



830 (5705-00) 



33420-35 



830 (6 11. '55 -70) 



829-46 (<1) 21300-21 



829-69 (1)26609-33 

 33418-35 



828-44 (1)40227-37 



829 ' 67 (29059 47) 



33420-07 

 831-54 (37781-67) 



828-72 (l)26257-20.w 



33419 * 32 

 831-17 (-8J (In) 36442 -62 



