114 LETTERS ON NATURAL MAGIC. 



accompanied with any imperfection of vision, or connected 

 with any disease cither of a local or a general nature, and it 

 has hitherto been observed in persons who possess a strong 

 and a sharp sight. Mr. Hudclart has described the case of 

 one Harris, a shoemaker, at Maryport, in Cumberland, 

 who was subject to this defect in a very remarkable 

 degree. He seems to have been insensible to every 

 colour, and to have been capable of recognizing only the 

 two opposite tints of black and white. " His first suspicion 

 of this defect arose when he was about four years old. 

 Having by accident found in the street a child's stocking, 

 he carried it to a neighbouring house to inquire for the 

 owner : he observed the people call it a red stocking , 

 though he di'd not understand why they gave it that 

 denomination, as he himself thought it completely de- 

 scribed by being called a stocking. The circumstance, 

 however, remained in his memory, and, with other subse- 

 quent observations, led him to the knowledge of his defect. 

 He observed also that, when young, other children could 

 discern cherries on a tree by some pretended difference 

 of colour, though he could only distinguish them from 

 the leaves by their difference of size and shape. He 

 observed also that, by means of this difference of colour, 

 they could see the cherries at a greater distance than ho 

 could, though he could see other objects at as great a 

 distance as they, that is, where the sight was not assisted 

 by the colour." Harris had two brothers whose perception 

 of colours was nearly as defective as his own. One of 

 these, whom Mr. Hudclart examined, constantly mistook 

 light green for yellow, and orange for grass green. 



Mr. Scott has described in the Philosophical Transac- 

 tions his own defect in perceiving colours. He states 

 that he does not know any green in the world ; that a pink 

 colour and a pale blue are perfectly alike; that he has 

 often thought a full red and a full green a good match ; 



