I 



SOML COXIl-MI'OK.Ih-) . //>/ "./A ( / s /.V /7/).s/(.V // l(,l 



Tlu'so tlistiiu-tly-sopar.iti-tl arts show ili.it llii- rmiri;iiii; i-U-ilr(jii.-. fall 

 into several distinct groups, each cliaracterized 1)\ a particular spc-eci. 

 Ill l"ig. 4 wo sec the traio of the electnui^ nii films laid normalK' In 



X- V 



» wm 



Fig. 4 



tlie plane of the paper, along the top of the block marked "VU" in 

 Fig. 1. The appearance of the films at once suggests a line-spectrum. 

 The lines, indeed, are the signatures of special electron-speeds instead 

 of special radiation-frequencies; hut these two f]uantities, being 

 interconvertible, are not so profoundly different in their nature as 



