Perfons who could not dijlinguifh Colours. 263 
in general he often miftook for black, but never ima- 
gined white to be a dark colour, nor a dark to be a white 
colour. 
He was an intelligent man, and very defirous of un- 
derftanding the nature of light and colours, for which 
end he had attended a courfe of lectures in natural phi- 
lofophy. 
He had two brothers in the fame circumftances as to 
light ; and two other brothers and lifters who, as well as 
their parents, had nothing of this defeat. 
One of the firft mentioned brothers, who is now liv- 
ing, is mafter of a trading veflel belonging to Mary- 
port. I met with him in December 1776, at Dublin, 
and took the opportunity of converting with him. I 
wilhecl to try his capacity to diftinguifh the colours 
in a prifm,, but not having one by me, I afked him, 
Whether he had ever feen a rain-bow ? He replied, He 
had often, and could diftinguifh the different colours ; 
meaning only, that it was compofed of different colours, 
for he could not tell what they were. 
I then procured and Ihewed him a piece of ribbon : 
he immediately, without any difficulty,, pronounced it a 
ftrlped and not a plain ribbon. He then attempted to 
name the different ftripes: the feveral ftripes of white 
he uniformly, and without hefitation, called white : the 
four black ftripes he was deceived in, for three of them 
he 
