720 Messrs. H. E. Ives and E. F. Kingsbury on the 



The values of fig. 7 are plotted in fig. 8 on the same 

 scheme as the experimental values o£ fig. 2. It will be seen 

 that there is practically complete similarity. 



Fig. 8. 





# 



" Log Scale, 



Calculated relationship between " slit widths " for various colours 

 compared with a "white " standard as the illumination is varied. (To 

 be compared with the previously obtained experimental data shown in 

 fig. 2.) 



5. Discussion of some Consequences of Theory. 



A few points call for brief discussion. In drawing the 

 straight lines of figs. 1 and 7 as crossing at a certain point, 

 it has been assumed that at the condition of equal brightness 



