OR COLOUR BLINDNESS. 167 
“The colours between which I have the most difficulty in di- 
stinguishing the difference are, in the first place, those reds 
which approach nearest to scarlet, and the yellower greens, such 
as the leaves of the lime-tree, the birch, the elm, &c. When 
blue is added to scarlet, even in a minute proportion, I perceive 
the original scarlet is changed; but when the same proportion 
of blue is added to the tint of green with which I am apt to con- 
found scarlet, 1 am unable to distinguish the difference between 
this bluer green and the scarlet to which blue has been added. 
“JT am also apt to confound dark or rather deep green and 
black, and the deeper shades of brown; .... as also gray with 
pale green, or pale red of the same depth of tint....It has been 
suggested to me that this seeming defect of vision was ideal, and 
that it arose from a carelessness in naming colours on my part ; 
but this certainly is not the case, for I have made many trials 
on the subject, which with me were quite decisive. Thus, I can- 
not perceive a bit of red sealing-wax if thrown down upon the 
grass, nor a piece of scarlet cloth hung upon a hedge, which I 
was told was to be seen a mile off. I once gathered some lichen, 
as a great curiosity, from the roof of a friend’s fishing-house; I 
thought it was of a bright scarlet, from its seeming to be of the 
same colour as the tiles; in reality it was of a bright green..... 
Upon another occasion I perceived no difference in the com- 
plexion of a foreign lady who had purposely substituted Prussian 
blue for her rouge...... Nothing in my sight contrasts more 
with black than the azure hue of the atmosphere. I also see 
much better far off than near, owing to the interposition of a 
wider stratum of air. So much is this the case with me, when 
viewing a distant object, as to overcome the effect of perspec- 
tive; and the shading in the form and garments of persons at a 
distance is often so predominant as to overcome the effect of 
diminution of size ; and although I see the object most distinctly, 
I am unable to tell whether it be a child near me or a grown 
person at a distance, &c. By candle-light all yellows appear to 
me white; crimson seems scarlet; pale green, blue; orange of 
a dirty red. I am not aware that any of my relations have the 
least peculiarity of vision.” 
The other case is that of an orchardist in Clydesdale, aged about 
fifty years. His eye is perfectly formed; the iris is a bluish- 
gray, and the pupil is surrounded with a narrow dark yellow 
circle. He discovered his imperfection by the inability to di- 
stinguish certain fruits as they hung on the tree. His first trade 
