256 O.N. Rood on Combination of Light of different tints. 
chart. In addition discs of a golden yellow, being some of the 
same paper I had previously used in the stereoscopic imitation 
of the luster of gold—its tint was 102-7; and finally purple discs 
were made by the mixture of ultramarine and crimson lake, 
Comparison of the results obtained by the binocular and actual combina- # 
tion of different tints. 
1. When one-half of the disc was covered with vermilion, the - ; 
the green was such that after a portion of it had been neutral- 
ized by the red, enough remained to give a strong green color — 
will be p 
thus avoided, as it was impossible to know beforehand ae the : 
result would be, when the rotation experiment was trl 
equal surfaces of the colored papers. In several cases the tints — 
en equal portions of some of the discs nearly exactly bala 
each other, so that the resultant tint by rotation appro 
to a white or neutral gray. 
2. Vermilion and ultramarine gave with some ease the same — 
tint by the two methods of combination; viz., a red purple: the 
tint was however rather more red by rotation than would have — 
tint com 
been expected from the binocular combination. 
3. Vermilion and yellow (107-7) gave by rotation @ 
taining much more yellow than would have been ex 
the binocular examination. : yidy 
4. Vermilion and purple gave the same tint in both cases 
a red purple. 
5. Vermilion and black gave approximately the same 
in the two cases; the disc was however less red by binocular a 
in both case 
vision than by rotation. 
6. Vermilion and white gave the same result 
2 . | : roximation 
7. Orange, (red lead,) and purple hp cegadage red bY 
to the same result in the two cases; the 
rotation than was expected. 
