-I'M 



Capi. W. de W. Abney. Examination for [May 14, 



placed in juxtaposition to the colour, and the results were slightly 

 different. The table (p. 493) gives his luminosity measures. Col. I 

 is the empyric scale nnmber, II is the wave-length.nl the luminosity 

 of the colour to the normal eye, IV the luminosity to C, and V the 

 ratios of III to IV . 



In the diagram, his luminosity curve X is shown, its area being 

 1400 against 1650 for the normal eye. As will be shown, his per- 

 ception of light is only two-thirds of that of the normal eye ; hence 



