230 PROCEEDINGS OF THE AMERICAN ACADEMY 



At first, I took red and green strips. At a distance of 12 meters I 

 could tell the difference between the strips because the red was darker 

 than the green, but I could not distinguish the colors at that distance. 

 I could distinguish the colors at about 9 meters. I could tell the 

 direction of the strips at about 16 meters. 



I next took green and yellow strips. I could perceive that there 

 was a difference between the colors at 10.5 meters, because the yellow 

 almost blended with the white background, while the green did not 

 look so faint. I could make out the green color at 8 meters, the yel- 

 low at 7.5 meters. The direction of the strips could be seen at 14 

 meters ; but no difference could be detected in the colors. 



With red and yellow I could perceive that there was a difference at 

 12 meters, since the red appeared darkest on the white background. 

 I could make out the red color at 9 meters, the yellow at 7.5, and 

 tell the direction of the strips at 1 6 meters. 



All the above were on a white background. I then took a black 

 background. 



Yellow and Green {narrow strips). 



Could distinguish the colors at 13 meters. Could tell the direction 

 of the strips at 20 meters. 



Red and Yellow (narrow). 



The yellow is visible at 20 meters, but cannot make out the color at 

 that distance. I can make out the color at 13 meters. Red color is 

 just visible at 8 meters. I can see that there is a strip where the red 

 is, but cannot make out the color at 10 meters. 



Red and Green ((narrow strips). 



The green can be seen in contrast to the black at 20 meters. The 

 green color can be detected at 13.5 meters. I can make out the red 

 color at 8 meters. The red blends with the black background at 10 

 meters. 



Yellow and Green (strips ttvice as wide as those vsed above). 



I could distinguish a difference of tint at 20 meters; but could make 

 out the colors at 18 meters. 



Red and Yellow (double width). 



The red color can be made out at 13 meters; but the red strip be- 

 comes invisible at 15 meters. 



