Prof Henry John Stephen Smith FRS FRSE FRAS LLD (2 November 1826 – 9 February 1883) was an Irish mathematician and amateur astronomer remembered for his work in elementary divisors, quadratic forms, and Smith–Minkowski–Siegel mass formula in number theory. In matrix theory he is visible today in having his name on the Smith normal form of a matrix. Smith was also first to discover the Cantor set. Life Smith was born in Dublin, Ireland, the fourth child of John Smith (1792–1828), a barrister, who died when Henry was two. His mother, Mary Murphy (d.1857) from Bantry Bay, very soon afterwards moved the family to England. He had thirteen siblings, including Eleanor Smith, who became a prominent educational activist. He lived in several places in England as a boy. His mother did not send him to school but educated him herself until age 11, at which point she hired private tutors. At age 15 Smith was admitted in 1841 to Rugby School in Warwickshire, where Thomas Arnold was the school's headmaster. This came about because his tutor Henry Highton took up a housemaster position there. At 19 he won an entrance scholarship to Balliol College, Oxford. He graduated in 1849 with high honours in both mathematics and classics. Smith was fluent in French having spent holidays in France, and he took classes in mathematics at the Sorbonne in Paris during the 1846–7 academic year. He was unmarried and lived with his mother until her death in 1857. He then brought his sister, Eleanor Smith, to live with him as housekeeper at St Giles. Smith remained at Balliol College as a mathematics tutor following his graduation in 1849 and was soon promoted to Fellow status. In 1861, he was promoted to the Savilian Chair of Geometry at Oxford. In 1873, he was made the beneficiary of a fellowship at Corpus Christi College, Oxford, and gave up teaching at Balliol. In 1874 he became Keeper of the University Museum and moved (with his sister) to the Keeper's House on South Parks Road in Oxford. On account of his ability as a man of affairs, Smith was in demand for academic administrative and committee work: he was Keeper of the Oxford University Museum; a Mathematical Examiner for the University of London; a member of a Royal Commission to review scientific education practice; a member of the commission to reform University of Oxford governance; chairman