English watercolour painter who studied for a while under Varley (1804) and first exhibited at the Royal Academy in 1805. He lived by teaching and published several books, of which the best-known is the Treatise on Landscape Painting and Effect in Watercolours (1813-14, reprinted 1922). His favourite painting ground was North Wales, but he visited Holland and Belgium in 1826 and France in 1829 and 1832. His effects are extremely broad, with a vigour of handling that sometimes appears forced, as if for exhibition. In 1836 he discovered accidentally a kind of cheap wrapping paper made in Dundee, which exactly suited his style, since the rough, slightly tinted paper absorbed the washes quickly. A similar kind of paper is now sold as 'Cox Paper'. In 1840 he took lessons in oil painting from Muller, but his watercolours have always been more prized. The best collection of his work is in his native Birmingham. His son David (1809-1885) was also a painter. //