236 



THE ROYAL SOCIETY OF CANADA 



•1170 of total intensity to produce a change in the sensation that was 

 just percei)til)le. This portion of light reduced to the intensity of the 

 standartl of brightness at the polariser was found to be represented 



Intensity 



by -58 as shown in the table, which gives us the least perceptible in- 

 crement with an intensity at the polariser equal to the intensity of 

 the standard. Now, as already stated, the intensity of the light under 



