On the Vision of Colours. 37 
My idea of brown I obtain from a piece of white 
paper heated almost to ignition. This colour by 
day-light seems to have a great affinity to green, as 
may be imagined from what I have said of greens. 
Browns seem to me very diversified; some I should 
call red:—dark brown woollen cloth I should call 
black. 
The light of the rising or setting sun has no par- 
ticular. effect; neither has a strong or weak light. 
Pink appears rather duller, all other circumstances 
alike, in a cloudy day. ° 
All common combustible substances exhibit co- 
lours to mein the same light; namely, ¢allow, oil, 
wax, pit-coal. 
_ My vision has always been.as it is now. 
IJ], AN ACCOUNT OF OTHERS WHOSE VISION 
HAS BEEN FOUND SIMILAR TO MINE, 
It has been already observed that my brother per- 
ceived the change in the colour of the geranium such 
as myself. Since that time having made a great 
number of observations on colours, by comparing 
their similarities, &c. by day-light and candle-light, 
in conjunction with him, I find that we see as near- 
ly alike as any other persons do. He is shorter 
sighted than myself. 
As soon as these facts were ascertained, I con- 
ceived the design of laying our case of vision before 
