Among the affections of the eye which not only deceive the person who is subject to them, but those also who witness their operation, may be enumerated the insensibility of the eye to particular colours. This defect is not accompanied with any imperfection of vision, or connected with any disease either of a local or a general nature, and it has hitherto been observed in persons who possess a strong and a sharp sight. Mr. Huddart 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 did not understand why they gave it that denomination, as he himself thought it completely described by being called a stocking. The circumstance, however, remained in his memory, and, with other subsequent 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 he 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. Huddart examined, constantly mistook _light green_ for _yellow_, and _orange_ for _grass green_.