"This thesis considers the eighteenth-century search for the longitude through Plate 8 of William Hogarths's A Rake's Progress, where a 'longitude lunatic' seeks to solve the problem on the wall of his cell in Bedlam. In doing so, it addresses two linked issues: first how the longitude problem was discussed by the wider British community, and how this affected the actors directly involved in seeking the solution; and second, what was so iconic about this problem that made Hogarth place it at the centre of his modern moral series about a young man ruing by London society. This thesis combines considerations of longitude from plays, poems, religious tracts, novels, prints, paintings and correspondence, alongside the archices and instruments that recorded the search by the Board of Longitude. Useful parallels emerge between the Board's most famous applicant, John Harrison, and William Hogarth's career."--Provided by the author.