AND ITS APPLICATION TO THE DETERMINATION OF COLOUK SENSATIONS. 345 



The areas of the curves given by Columns XIII., XVI., and XVII. are equal, and 

 represent equal stimuli of all three sensations. A mixture of the three colours, 

 each being represented by ordinates of the same height, makes white. The points 

 where the red and green curves cut the blue curve are the points in the spectrum 

 which the green-blind and the red-blind match with white. 



5 10 15 ^0 Z5 30 35 40 45 50 55 60 



Fig. 2. Sensation curves having equal areas (equal ordinates at any poin*-- make white). 



^**. 



5?. 



SSr 



100 

 90 



ao 



60 



so 



40 

 30 

 20 

 JO 



35 40 



Of f/tlSMATtC 



45 



50 



60 



Fig. 3. Percentage composition in luminosities of red, green, and blue sensations of the spectrum colours. 

 VOL. CCV. A. 2 Y 



