Imperfection of SIGHT with regard to Colours. Under the article COLOURS, is given an instance of a strange deficiency of sight in some people, who could not distinguish between the different colours. In the Phil. Trans. vol. lxviii. p. 611. we have an account of a gentleman who could not distinguish a claret colour from black. These imperfections are totally unaccountable from any thing we yet know concerning the nature of this sense.