334 



LIGHT AND WEBER-FECHNER LAW 



of a differential equation according to which dS = c. , in which S 



= the magnitude of sensation, / is the intensity of the exciting cause, 

 and c is the constant of the series. Integrating, this equation becomes 

 S = c.\ogeI-\-K. This means that the sensation is proportional 



o 



S 7 e 9 10 



Rate 



Fig. 1. The small circles show the experimental points in which Rate = 

 ; the line is drawn through the points calculated for the 

 logj + K 



100 



Reaction time in seconds 



rate by means of the equation, Rate = 



