[ALLEN] PHENOMENA OF THE PERSISTENCE OF VISION 



TABLE 2— Continued. 



199 



III. It was noiticed from time to time that the persistence of colour 

 impressions was not constant over all parts of the retina. When no 

 flickering of the colour under observation was perceptible in the centre 

 of the retina, a slight movement of the eye 'in )any direction, which 



Fig. 3. 



allowed the light to fall upon tlie peripheral portions of the retina, was 

 always sufficient to destroy the apparent continuity of the light. 



To investigate this, a short piece of platinum wire, heated electri- 

 cally so as to be just plainly visible, was placed in such positions, that, 

 when viewed directly by the eye, the flickering light of the 'spectrum fell 

 at determinate positions on the outlying pants of the retina. 



