an Electric Source, and Line Spectra. 803- 



from 2 = 48, as far down as i = 4. The deviation swells up 

 to — 1*36 A.U. for z = 10 (which difference can be reduced a 

 little by slightly retouching the two constants), but then 

 decreases down to *08 A.U., for e = 4. One can hardly fail 

 to perceive from this Table that the simplest typical dispersion 



bX 2 



k = 



7 2 (* 2 -Y 2 ) 



2\ 5 



and the corresponding series (47) do express some very 

 essential property of the observed series, and therefore of 

 the sodium atom. 



It may be worth mentioning that there is still a certain 

 kind of qualitative agreement between the proposed theory 

 and observation. In fact, the atomic source has, according' 

 to the form of the present dispersion law, properly but one 

 free or " natural " period, e. g. that corresponding to the 

 wave-length X x =y itself (none of the remaining X/s having 

 anything essential about it). Thus one would be led to 

 expect that at or just behind the convergence-point y of 

 the series there should be strong absorption. Now, in the 

 second of his papers, just quoted, Prof. Wood points out 

 with particular emphasis that there is "a general absorption 

 beginning at the head of the series and stretching to the end 

 of the spectrum " *. It would be interesting to verify by 

 experiments whether anything of the kind happens with the 

 series of other elements. 



3. The Principal Series of Lithium. — In this case the 

 agreement of (47) with observation is equally if not more 

 satisfactory than in the preceding example. The second 

 column of Table VT1J. contains the wave-lengths calculated 

 by the formula 



V = '052S550+~' 1 *' ;7 ',. . . (47, Li) 

 "i 



and the third column those measured by Bevan (z = 41 to S) 

 and by Kayser and Runge (7 = 7 to 4; t- Bevan uses, for 

 the Moggendorff-Hicks formula, a convergence frequency 

 corresponding to the wave-length X^ =0*229975/*, "but 

 points out that his latest measurements indicate a higher 

 frequency/' /'. e. a smaller X^. The value we have adopted 

 in the above formula is X^ =y= 0*229902, and would, 

 therefore, not be far fiom the truth. 



* Translating literally from Prof. Wood's paper in Phys. Zeitschr., 

 and italicizing me few words of special interest. 



t I take the figures for A olig> as quoted by Dr. Watts, loc. cit. p. 782. 



