AYRTON, Hertha, née Marks, British physicist, 1854-1923. In 1902, her book ‘The Electric Arc’ made her work in this area prominent. Hertha invented a sphygmograph (called a pulsemeter then) and a drafting dividing line device for engineers/draftsmen, worked on searchlights for the Admiralty (1905-10), and in WW1 devised the Ayrton Anti-Gas Fan for dispersal of poisonous gases from gun emplacements or in trench warfare (used in 1916). In 1898 she had been the only woman member of the Institute of Electrical Engineers. Hertha was honoured with an FRS in 1902 (when there was no mechanism for women in the Society), and in 1906 she became the first woman to get a medal from the Royal Society. In 1920, she was a founder member of the National Union of Scientific Workers. Her husband William Ayrton was a pioneer of electrical engineering and education on electricity. From 1905-8 they worked as a team on searchlights, but Hertha was already famous for her work on electric arcs. These electric arc lights were for movie-projection (cinematography), Hertha redesigned the housing and the lights.