462 Prof. W. M. Hicks on 



The next two calculated lines are 60543, 60917. There 

 are strong lines at 60536-36*6dX and 609087-37d\,. 

 but they are too strong and moreover show evidence of being 

 summation lines (see later, p. 473). The formulae reproduc- 

 tions combined with the observed combinations would then 

 seem to support the allocations given as at least one of the 

 frayed out fragments of the system. The whole region round 

 the observed combinations is full of lines of the same nature 

 (2n) and may possibly be combinations for some of the 

 other P fragments. The combinations considered above are 

 collected in Table III. at the end. 



The establishment of the hypothesis of the break-up of a 

 normal series into a large number of displaced, and linked or 

 otherwise shifted lines is of fundamental importance. The' 

 laws regulating this break-up can only be discussed when a 

 large mass of material for comparison has been collected. 

 As a contribution to this some instances are considered in an 

 appendix. 



Spectral constants. — With the establishment of the S limit 

 as 31523*48 + fit becomes possible to apply the same methods- 

 as were employed in the discussion of the spectra of Ag and 

 Au to determine the value of v more accurately and to 

 deduce therefrom the value of the onn and of the various 

 links. There are no interferential measures giving v directly 

 but, as in Ag, Au, Fabry and Perot give such for Dn(2) and 

 D 22 (2). K. R.'s values are very accurate and give definitely 

 that A = 50 8 and that the satellite separation for D(2) is 

 due to 236V The separation of D n , 1) 2 2 given by F. P/s 

 measures, \\ 5153*251 4- -001.^, 5218*202 + *001^ in LA.,, 

 is 241-4632- -00376 # 2 + "00367 a?!. The calculation carried 

 out on the same lines as in the case of Ag and Au gives 

 in R.A. 



v = 248-44402 - -0038 fa - a*), 

 A = 7307-087--3310f--113ff 2 + \L10a? 1 , 

 8 = 146-1419 -•00662f-'0022 < z/ where y-x 2 -x 1 . 



From these and s(l) = 31523*48 + f-P 1 (l) = 62306*25 + f 

 the calculated links are 



a = 245-54 c = 251*39 



b = 248-44 d = 254-39 



e — 999*77 



u = 680*68 v = 692*02. 



With ambiguities of f == zb'l and y of 1, the spectral 



