40 On ihe Vision of Colours. 
vision, except as to colours, is as clear and distinct 
as that of other persons. Only two or three are 
short sighted. It is remarkable that I have not 
heard of one female subject to this peculiarity. 
From a great variety of observations made with 
many of the abovementioned persons, it does not 
appear to me that we differ more from one another 
than persons in general do. We certainly agree in 
the principal facts which characterize our vision, and 
which I have attempted to point out below. It is 
but justice to observe here, that several of the re- 
semblances and comparisons mentioned in the pre- 
ceding part of this paper were first suggested to me 
by one or other of the parties, and found to accord 
with my own ideas.. 
CHARACTERISTIC FACTS OF OUR VISION, 
i. In the solar spectrum three colours appear, 
yellow, blue, and purple. The two former make a 
contrast; the two latter seem to differ more in de- 
gree than in kind. 
2. Pink appears, by day-light, to be sky-blue 
a little faded; by candle-light it assumes an orange 
or yellowish appearance, which forms a strong con- 
trast to blue. , 
_ 3. Crimson appears a muddy blue by day; and 
crimson woollen yarn is much the same as dark 
blue. 
4. Red and Scarlet have a more vivid and fla- 
ming appearance by candle-light than by day-ligh 
