Hacxert— The Photometry of N-Rays. 131 
sensitiveness, taking the sensitiveness of the fovea as 100. They are got from 
the last observation mentioned. Though these numbers are only rough 
estimations, yet they are precise enough to indicate a marked difference in the 
retinas of the two observers. The variations in fig. 1 are much larger than 
those for the same curve in fig. 2. This great difference seemed so extraordinary 
that the eyes were tested again and again in various ways with similar results. 
IMG Il 
Fra. 2. 
This greater variation in sensitiveness, combined with the greater distance of 
observation in Mr. Quinlan’s case, enabled observations of his eyes to be taken 
very easily. 
Mr. Quinlan’s sight is normal, and his distance of observation ranged from 
