The Board of Trade lantern was designed for testing colour vision, specifically seamen's ability to distinguish different coloured navigational and hazard lights at sea. Developed as a result of the Parliamentary Committee which reported in 1912, it aimed to reproduce typical ships' lights at specificed distance. The subject being tested viewed the lantern in a darkened room sitting six metres away. The lantern was superceded in 1970 (see ZBA4463) but the arrangement and dimensions of its two half millimetre 'point sources' persists. The light source was an oil lamp, so there is a chimney inside the lamp to allow gases to escape.