1919] on Energy Distribution in Spectra 529 



of its history. It has not often been possible even to determine the 

 actual number of component radiations, in an apparent broad band 

 with a structure, emitted from such a star, at least with any real 

 certainty. A method which automatically sifts out such bands and 

 gives peaks on a photograph at all the maxima of intensity in the 

 band may well be expected to contribute greatly to the elucidation of 

 the phenomena taking place, which must in any case be totally 

 different from anything known by our terrestrial experience. 



The only other class of phenomenon depending for its elucidation 

 on precise measures of intensity in spectrum lines, to which I shall 

 refer with further illustrative slides, is the variation which takes place 

 in the spectrum from a helium tube as we recede from the cathode. 

 The slides serve to show the considerable differences which take place 

 in the distribution of the various series, which are all emitted most 

 strongly at unequal distances from the cathode. One very extra- 

 ordinary result, indicated clearly on the last slide, is the fact that 

 there exists a narrow region of the tube in which the characteristic 

 spark line X4686 is emitted simultaneously with the helium band 

 spectrum, a circumstance which necessitates some readjustment of 

 preconceived ideas. 



[J. W. N.] 



