0. N. Rood on Combination of Light of different tints. 255 
Helmholtz’s method, or how far it is in point of fact possible to 
_ predict, by the binocular method, what the result of the true 
_ mixture of different tints willl be, is a question which, so far as 
_ Iknow, has never been studied. 
__ The following set of experiments was undertaken for the ex- 
_ amination of this matter. 
q The first method pursued was as follows: Light of different 
tints, complementary or not, was presented to the right and left 
eye, and the resultant tint gained by binocular vision was noted : 
mixed and presented to a single retina. In many cases the re- 
exact resultant by rotation would be; it sometimes being of 
was not at all present to the eye or mind during the 
ion. 
. 4pparatus to which was attached a circular card-board 
With its two halves painted in different colors. The dise 
‘Temaining at rest, the dividing line of the colors being vertical, 
ght of different colors entered the two apertures in the card- 
OR, and after their binocular union had been effected, the re- 
stant Was noted: the disc was then set in rotation, the stereo- 
vie Temaining in its position, and a true mixture of the two 
_» Was obtained and compared with the first result. 
. Heliaholtz has shown that vermilion represents the red of the 
pectrum up to the line C, that red lead answers to a por- 
tween C and D, but not reaching up to D; also, that the 
"8s that of 113-2. more of the latter color, with gamboge, 
Steenish-blue disc. Red dises, slightly purplish, 
80 discs colored with emerald green, 170° in the 
