Luby, Thomas (1800–70), mathematician, was born in Clonmel, Co. Tipperary, the son of Thomas Luby, architect, and Eleanor Luby (née Fogarty), whose family were from Castle Fogarty, Ballycahill, Co. Tipperary. The Luby family was descended from Huguenots who fled from France in 1685 and settled in Canterbury. Luby attended TCD as a sizar in 1817 (sizars were students of limited means who succeeded at a special entrance examination in classics). Awarded a scholarship (1819), he graduated BA (1821) and MA (1825).
Luby was elected to junior fellowship at TCD in 1831, was awarded the degree of DD in 1840, and co-opted a senior fellow on 6 November 1847. Election to fellowship was the normal mode of entry to an academic career, and candidates had to pass a difficult examination with a prescribed course of study weighted heavily towards mathematics but including classics, ethics, logic, and natural philosophy. They also had to be celibate. Luby maintained his contributions to mathematics after his appointment. While in the college he held various positions – chaplain, censor and junior dean, bursar, senior dean, senior lecturer, Donegal lecturer (1832–47), and professor of Greek (1852–5). He was also the examiner in mathematics for the school of civil engineers which he had called to be established in 1841, and for which he, Humphrey Lloyd (qv), and James MacCullagh (qv) had proposed the curriculum.
Though he later broadened his interests to classics, Luby made serious contributions to mathematics and was a popular tutor. He also contributed to the literary character of the university. A shrewd businessman with good diplomatic skills, he represented TCD interests at Westminster (1850) when a bill relating to the college's rights as a landlord was under consideration. A pragmatist, he was one of the members of the board, the governing body of the college, who supported the removal of religious tests (1873). On the occasion of his election as a life member of the RIA (25 February 1833) he presented the academy with the autograph of Charles Wolfe's (qv) patriotic poem ‘The burial of Sir John Moore’.
Luby published The elements of plane trigonometry (1825, 1852) and An introductory treatise on physical astronomy (1828), the latter for use by the junior classes at Trinity. He also edited Brinkley's Elements of astronomy (1836) and was co-author of several publications with Sir W. R. Hamilton (qv). He died 12 June 1870 in Dublin at 43 Leeson Street and was buried at Aberystwyth.
Luby was married twice, first to Mary Anne Wetherall and then to Jane Rathborne of Dunsina, and had six sons and four daughters. His daughter Florence, widow of Henry White, married, secondly, Sir George Ferguson Bowen (1821–99), who served as governor of Queensland, New Zealand, Victoria, Mauritius, and Hong Kong. Two of his sons-in-law were the barristers Henry Tudor Parnell and Thomas Sadleir Stoney (1822–99), and he was the uncle of the Fenian Thomas Clarke Luby (qv).