Phoebe Sarah Hertha Ayrton (28 April 1854 – 23 August 1923), née Phoebe Sarah Marks and known in adult life as Hertha Ayrton, was a British engineer, mathematician, physicist, and inventor. She was awarded the Hughes Medal by the Royal Society for her work on electric arcs and ripples in sand and water.
Phoebe Sarah Marks was born in Portsea, England in 1854. She changed her first name to Hertha when she was a teenager. After passing the Cambridge University Examination for Women with honors in English and mathematics, she attended Girton College at Cambridge University, the first residential college for women in England. Charlotte Scott also attended Girton at this time, and she and Marks helped form a mathematics club to “find problems for the club to solve and ‘discuss any mathematical question that may arise'” . Marks passed the Mathematical Tripos in 1880, although with a disappointing Third Class performance. Because Cambridge did not confer degrees to women at this time, just certificates, she successfully completed an external examination and received a B.Sc. degree from the University of London.
From 1881 to 1883, Marks worked as a private mathematics tutor, as well as tutoring other subjects. In 1884 she invented a draftsman’s device that could be used for dividing up a line into equal parts as well as for enlarging and reducing figures. She was also active in devising and solving mathematical problems, many of which were published in the Mathematical Questions and Their Solutions from the “Educational Times”. Tattersall and McMurran write that “Her many solutions indicate without a doubt that she possessed remarkable geometric insight and was quite a clever student of mathematics.”
Marks began her scientific studies by attending evening classes in physics at Finsbury Technical College given by Professor William Ayrton, whom she married in 1885. She assisted her husband with his experiments in physics and electricity, becoming an acknowledged expert on the subject of the electric arc. She published several papers from her own research in electric arcs in the Proceedings of the Royal Society of London and The Electrician, and published the book The Electric Arc in 1902. According to Tattersall and McMurran,
The text included descriptions and many illustrations of her experiments, succinct chapter reviews, a comprehensive index, an extensive bibliography, and a chapter devoted to tracing the history of the electric arc. Her historical account provided detailed explanations of previous experiments and results involving the arc and concluded with the most recent research of the author and her colleagues…The book was widely accepted as tour de force on the electrical arc and received favorable reviews on the continent where a German journal enthusiastically praised if for its clear exposition and relevant conclusions.
Hertha Ayrton had been elected the first female member of the Institution of Electrical Engineers in 1899. In 1902 she became the first woman nominated a Fellow of the Royal Society of London. Because she was married, however, legal counsel advised that the charter of the Royal Society did not allow the Society to elect her to this distinction (this advice was reversed in 1923, but the first woman was still not admitted to the Royal Society until twenty years later.) However, in 1904 Ayrton did become the first woman to read her own paper before the Royal Society. This paper was on “The origin and growth of ripple-mark” and was later published in the Proceedings of the Royal Society. In 1906 Ayrton received the Royal Society’s Hughes Medal for her experimental investigations on the electric arc, and also on sand ripples. She was the fifth recipient of this prize, award annually since 1902 in recognition of an original discovery in the physical sciences, particularly electricity and magnetism or their applications, and as of 2011, one of only two women so honored. (The award is now given for original discovery in the physical sciences, particularly as applied to the generation, storage and use of energy.)
After her husband’s death in 1908, Ayrton continued her research. One set of experiments validated Lord Rayleigh’s mathematical theory of vortices. She also invented a fan that could create spiral vortices to repel gas attacks. These became known as Ayrton fans, but were never widely used.
Ayrton was an active member of the Woman’s Social and Political Union and participated in many suffrage rallies between 1906 and 1913. She was a founding member of the International Federation of University Women and the National Union of Scientific Workers. She served as vice-president of the British Federation of University Women and vice-president of the National Union of Women’s Suffrages Societies. Two years after her death in 1923, her lifelong friend Ottilie Hancock endowed the Hertha Ayrton Research Fellowship at Girton College.