I)K. W. M. HICKS: A CRITICAL STUDY OF SPECTRAL SKRIKS. U67 



addition of 5, to the denominator of D(oo) produces a change 19"19, and this 

 changes the denominator of VD to those ' given in the table, and as is seen now, 

 produces a difference of 2^, tatween it and the next. Now, this alteration in D ( ) 

 diminishes the value of v by 5'65, whilst, as we have seen alx>ve, it is apparently '69 

 too much or VD a (2) is 5'65 + '69 = 6'34 below the value of VD,,(2). Now, this is 

 just the change made by deducting 2<\ from the denominator of VD,,. The exact 

 value is 6"74, which is within the limits. The way in which, witli the considerable 

 numbers involved (i$, = 377), all the different abnormalities are simultaneously made 

 to fit in with a normal scheme gives some confidence that this is the real explanation. 

 The scheme of actual lines may be represented thus : 



Actual D u (2) = ( + ,) D M (2), 

 D 13 (2) = ( + <*,) D,,(-24,M, 



Contrary to the case in other elements the successive differences are equal after the 

 first, and the limiting value of the denominator is reached at m = 7. They can all 

 from 7 to 14 be, within limits, equal; but there is an apparent rise with the high 

 orders. 



O. 



Two series one of doublets and one of triplets have been recognised in oxygen. 

 The table shows that the D lines of both sets fall into line quite naturally with 

 multiples of A, closely except in the case in the doublet sets of m = 7, 8 

 these cases the denominators are equal within limits, but much larger than those for 

 m = 6 instead of being less, and the deviation is real since the difference is more 

 than 15 times the probable error for m = 7, and T5 times that for m = 6, which 

 latter has a very considerable probable error "5 as against '07.* The divergence for 

 m = 8 can be accounted for, as it is probable that there are two close lines here due 

 to different series, viz., that for this series m = 8 and the other for a parallel 

 for which m = 5, and may therefore be stronger. As it throws some light 

 subject it may be well to say a few words about it here. RUNGE and 

 three lines at 626478, 6261'68, 6256-81, with separations 7'83, 12"43, and mtens 

 1, 3, 1, so that the centre is the strongest. There is a corresponding s 

 5408-80 5405-08, with the same separations within error limits and mtensit: 

 again with the centre strongest. The strongest lines of these two triplets forn 

 series with the observed value of D" (8). They are of a diffuse type and 



* These are not to be confounded with K.R.'s possible errors. The poible errors are probably 



larger. 



