These papers contain the business archive of the Stevensons from the late 18th century to the mid 20th century. They consist mainly of letterbooks, incoming correspondence, reports, memoranda, maps and plans, with a large number of printed pamphlets and reports by the Stevensons and others, concerning all the civil engineering works with which the family was involved. The main interest lies in the material relating to harbours and to lighthouse construction, and to the work of the Northern Lighthouse Commissioners.