66 



Prof. F. Allen on Four Transition Points in the 



Table VI. 



'toDfji. 



•690 



■647 



•593 



•553 



•535 



Normal 

 Persistence. 

 •0337 sec. 

 •0221 

 •0167 

 •0137 

 •0141 



Eye fatigued 

 with X "540 [x. 



•0318 sec. 



•0218 



•0161 



•0138 



•0161 



■0171 



. Normal Eye fatigued 



Persistence, with X -540 /u 



•522 u -0164 sec. -0190 sec. 



•495 

 •453 

 •423 

 •410 



•0209 

 •0360 

 •0538 

 •0620 



•0209 

 •0378 

 •0538 

 •0602 



Since the persistency curve for the wave-length A,*577yu,, 

 fig. 11, had previously been determined to be of the double 



Fio-. 11. 



red and green elevation type, it was evident that the transition 

 point must be near A, '570//,. This hue was then used as the 







Table VII. 



X. 



Normal 



Eye fatigued 



A. 



Persistence. 



with X *570 fi. 



735 [x 



•0337 sec. 



•0320 sec. 



•522 / 



690 



•0221 



•0224 



•495 



647 



•0167 



•0168 



•453 



593 



•0137 



•0137 



•423 



553 

 535 



•0141 



•0146 

 0153 



•410 



Normal Eye fatigued 



Persistence, with X "570 ft. 

 •0164 sec. -0163 sec. 



•0209 -0205 



•0360 -0365 



•0538 -0554 

 •0620 



