There were so many crazy proposals for solving the longitude problem that 'longitude lunatic' became popular slang for anyone who was deluded. This engraving, part of William Hogarth's series of prints entitled 'The Rake's Progress', depicts the inhabitants of Bedlam, London's notorious insane asylum. One man has a telescope (perhaps for measuring lunar distances); another is shown staring fixedly at a drawing he has scratched on to the wall of a globe marked with lines of longitude and latitude, a ship, the Moon, some geometrical diagrams and a cannon firing a flare.
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Longitude Lunatics' from 'The Rake's Progress appears in: