In particular he revived and gave new force to the theory of colour-vision associated with the name of Thomas Young, showing the three primary colours to be red, green and violet, and he applied the theory to the explanation of colour-blindness.
From 1855 to 1872 he published at intervals a series of valuable investigations connected with the " Perception of Colour " and " Colour-Blindness," for the earlier of which he received the Rumford medal from the Royal Society in 1860.
In 1794 he was elected a member of the Manchester Literary and Philosophical Society, and a few weeks after election he communicated his first paper on "Extraordinary facts relating to the vision of colours," in which he gave the earliest account of the optical peculiarity known as Daltonism or colour-blindness, and summed up its characteristics as observed in himself and others.
