310 Prof. \V. M. Hicks on th 



Again the general result is, as in I), that 30644*60 is too 

 large by about two units. 



We pass now to the consideration of the F series. In 

 general we find in many-lined spectra several sets of F series 

 depending on different A multiples, and very numerous dis- 

 placements especially in the lower orders. It suggests in 

 fact that starting from the fundamental ~F L (1), F 2 (1) lines,, 

 successive lines are produced by successive additions of oun 

 multiples*, and that the intensities fluctuate as the mantissa? 

 increase. Our present object is not to discuss the normal 

 F sets in Ag — a discussion which would require considerable 

 time and space — but only so far as to obtain data to settle 

 the value of £. We have evidence above of the existence of 

 D (1) lines depending on d 2 (1) = N/(1 + 34A) 2 with satellite 

 separations of 72 and 75'2, i.e. in the neighbourhood of 

 23 h l displacements. We expect therefore to find F doublet 

 series with the limits F 2 (oo )-d 2 (l) ==28998*98 + 1*286 f,. 

 F 1 (oo)=^ 2 (l) — 72-0 or —75'2; also with /(l) depending 

 on a A multiple. There is nothing to show a p?iori what 

 this multiple may be. There may in fact be several such. 

 We will attempt to see whether we can find indications of 

 sets depending on f(l) = d 2 (l) — i.e., the same multiple as in> 

 d 2 . The mantissa is # 944, and using Rydberg's tables we 

 will search for F and F lines in the neighbourhood of de- 

 nominators 2944, 3'944, .... The result is given in the 

 following table, in which the wave-numbers entered on 

 the left beneath the ordinal numbers are those calculated 

 from the given denominators. 



The F 2 (l) lines would be zero, i. e. give no oscillation, and 

 would therefore be probably unstable. We should expect 

 in this case to find the normal line displaced, showing the 

 same phenomenon in F 2 (l) also. The lines given under 

 m = l for F indicate this. The actual F l5 F 2 lines observed 

 appear to be displaced by 21 ouns in opposite directions (the 

 asterisk effect noted above under D), the change per oun here 

 being 3*13. The calculated F(l) lines have the observed 

 linked ones shown. The value used for F : is the mean of 

 the three linked and for F 2 is the displaced 21 6\ from the 

 corresponding observed. The line 57846 is c^(l) +^(1).. 

 For m = 2 the F lines are still outside the observed region 

 for K. R.'s arc lines and only just within for Eder and 

 Valenta's spark lines. They consequently cannot be tested. 

 Also any of the e.u.v. links lands in a region in which a long 



* For the general discussion of this point see [III., V.]. 



