Sea mills is about halfway between bristol and the mouth of the avon. The river trym joins the avon here and it was once the site of a roman port and an unsuccessful eighteenth-century dock. Object Type: painting. Date: 1844. Dimensions: height: 66 cm (25.9 in); width: 91.4 cm (35.9 in). Medium: oil on canvas. Collection: Bristol City Museum and Art Gallery. Joseph Walter - Sea Mills, Bristol