[allen] 



PHENOMENA OF THE PERSISTENCE OF VISION 



205 



was another hjue of blue, , the wave length of wliich was -440 /i. This 

 figure is taken from the paper previously referred to. Assuming that 

 the curve for X = .474 fi, would be practically the same as that for 

 À = . 440 n, an assumption which is almost certainly correct, it is 

 seen that fatiguing ;thej eye with blue produces two elevations in the 



Fig, 8. 

 TABLE 6. 



