418 Scientific Intelligence. 
. On some illusions, and other phenomena, attendant on vision through 
~ colored media ; by Siton Newcoms.—(1.) Let one put a red glass over 
the right eye, pressing it in so. closely that little or no light can get to 
the eye except through the glass, hold a green or blue one over the left 
eye in the same manner, and thus look at surrounding objects in general 
for a few minutes. On removing the glass he will find that white objects 
will appear greenish when observed with the right eye alone, and reddish, 
or tinged with orange, when viewed with the left eye alone. 
Evidently this illusion must be one of sensation, and not one merely of 
judgment ; the term illusion (or error) of sensation, being applied to the 
case in which the impression actually conveyed to the mind is different 
sation transmitted by one eye that it would respecting a similar sensation 
t i may be held so that it will be 
impossible for the observer to say which eye is covered by the red glass 
and which by the green one; yet on removing the glasses he can speed- 
ily solve the question by shutting the eyes alternately,” 
This phenomenon may be accounted for on the general principle that 
the increase of sensibility of the eye when placed for some time in dark- 
ness takes place independently with respect to the several colors of light ; 
so that an eye from which all the red light is excluded will become sen- 
sitive to red light with equal rapidity whether light of other colors is 
admitted or excluded : 
[This is analogous to the experiment of Count Schoffgotsch. His 
diploscope consists of a rotating disc painted half green, half red, and is 
observed through two tubes held before the two eyes. One eye becomes 
fatigued by the green light, the other by the red; if now the disc is set in 
tion, the first eye sees only red, the other only green light. (See Eisen- 
lohr, Physik, p. 327.)] 
2. The two following experiments illustrate very finely the doctrine of 
corresponding retina points, and the inability of the eye to distinguish the 
a y which observed sensation is conveyed 
white paper, having on it two s ts, f teary ay Ue 
other of a very brigh pots, one of a very bright red, a 
®ppear so nearly of the general color of the paper as to be scarecly visi 
8d will mot present theTafntnSndieaton of being vod he dh 
be closed the red spot will seem black, and the green spot will appear 
