The phenomenon of colour-blindness, or the insensibility of the eye to certain colours, has been for many years past a puzzle both to the physiologist and the philosopher. Perhaps the most remarkable case of the sort is that mentioned first by Huddart, and quoted by Sir David Brewster, of a shoemaker named Harris, living at Maryport, in Cumberland, who was utterly incapable of distinguishing any colour at all, and saw everything white, grey or black. The first time that Harris noticed this defect, was when he was about four years old; having found the stocking of a playmate in the street, he returned it to him at his cottage, and noticed that every one said it was a red stocking, but he could not understand why they should call this particular stocking red, as it seemed to him to be like every other. This circumstance remained in his mind, and a few more similar observations confirmed his suspicions that he had some defect of sight that prevented him from seeing as others did. He also observed that other children pretended to distinguish cherries from their leaves by what they called their colour, whilst he could see no difference between them, except those of shape and size. He also noticed that by means of the difference of colour, others could distinguish cherries on a tree at a much greater distance than he could; whilst he, on the contrary, could see other things at greater distances than his companions. Harris had two brothers, whose eyes were similarly defective; one of these, that Huddart examined, mistook green for yellow constantly, and orange for light green.