4 Mayer — Phenomena of Simultaneous Contrast-Color, 



Calling the intensity of the orange 100, we have 100x29-71 1, 

 which gives for I (the intensity of the cyan-blue), only 40*8 

 per cent of that of the orange. 



The orange yellow of the side of the ring 

 ^^-<> L facing the lamp and of the side of the trans- 

 M**"*" lucent paper facing the daylight is comple- 



mentary to the cyan-blue of the side of the 

 ring facing the daylight and of the side of the 



-S translucent paper facing the lamp. 



In fig. 4, L is the lamp ; S, the screen which 

 in this experiment is deprived of the border of 

 translucent paper ; W, the window ; M, a sil- 

 vered mirror which reflects the back of the 

 ^ cs screen to the eye which looks through an 



achromatized double refracting calc spar prism 

 at C.S., and sees two images of the side of the 

 screen reflected from the mirror and two 

 images of the side of the screen facing the 

 window. By suitably inclining and rotating 

 fig.4. the calc spar prism these images may be 



brought into the positions shown in fig. 5, in 

 which A represents one of the images of the side of the screen 

 facing the window ; B, the other image of the same ; C, is 

 one of the images of the side of the screen facing the lamp 

 and seen by reflection from the mirror. 



The overlapping of 

 these images, when the 

 illumination is properly 

 adjusted, gives the fol- 

 lowing results, as shown 

 by the letters in fig. 5, 

 where B stands for cyan- 

 blue, Y for orange yel- 

 low, and W for white. 

 The translucent paper Y 

 of B overlaps the ring 

 of A and gives white, and the blue of the ring of B over- 

 laps Y of the translucent paper of A and gives white. In 

 the same manner the orange yellow of the cardboard ring of 

 C overlaps the blue of the ring of A and gives white. Where 

 the ring of C overlaps the translucent paper of A there is a 

 more intense orange, and when the blue of the translucent 

 paper of C overlaps the blue of the ring of A we have a more 

 intense blue. On bringing B of the translucent paper of C 

 over Y of the translucent paper of A we have white. 



Experiments on the complementary colors of gratings. — Out 

 of thin cardboard, such as is used for thin visiting cards, I cut 



