A plaque on Brougham (or Broom) Bridge, where Broombridge Street crosses the Royal Canal, commemorates William Rowan Hamiltons invention of quaternions on the spot on 16 Oct 1843. The plaque is under the bridge, on the towpath, and was unveiled by the Taoiseach, Eamon De Valera, on 13 Nov 1958. The Irish Post Office issued two stamps with Hamilton's portrait on the day.


Hamilton (1805-1865) was President of the Royal Irish Academy in 1837-1847 and the Academy has a portrait of him and the only known complete example of his Icosian Game, inscribed to his friend J. T. Graves, the inventor of 'octaves' or octonions. (Hamilton neglected to publish this and so the credit went to Cayley a year later. In early 1996, a second example of the Icosian Game, but of the board only, came to light.)

Hamilton was born in Dominick Street and was baptised in St. Mary's Church, Mary Street. He entered Trinity College in 1823 and was elected as Andrews Professor and Astronomer Royal before completing his BA. He was Astronomer Royal of Ireland in 1827-1865 and hence lived in Dunsink Observatory, Dunsink Lane, to the northwest of the city, north of Phoenix Park, from 1827 until his death. (The Observatory and the Andrews Professorship were abandoned in 1921, but the Observatory was taken over by the Dublin Institute for Advanced Studies during World War 2.) On 15 Aug 1835, on the occasion of a dinner for the BAAS meeting, the Viceroy of Ireland knighted Hamilton in the Long Room of Trinity Library, the first Irish scientist to be knighted. He is buried in Mount Jerome Cemetery, Harold's Cross Road, just south of the Grand Canal from the city centre. The 1992 Science and Engineering Library building at Trinity College is named for him.

Trinity College Dublin (TCD often called Dublin University in older literature), was approved by the City Council in 1590, was given a Royal Charter in 1592 and opened in 1594. Archbishop Laud was Chancellor of the College in 1637. The first professor of mathematics was Miles Symner, an ex-student and a former major in the Parliamentary army who had assisted William Petty in surveying, who was appointed in 1652. After the Restoration, there was some confusion about positions. The Earl of Donegall endoweda Lectureship which was incorporated with the professorship and Symner was appointed to this post.

The Governors of the Erasmus Smith Schools established Erasmus Smith's Professorships of Natural Philosophy (1724) and of Mathematics (1762). Notable Erasmus Smith's Professors of Natural Philosophy have been: Bartholomew Lloyd (1822-1831); Humphrey Lloyd (1831-1843); James McCullagh (1843-1847); George Francis Fitzgerald (1881-1901, of the contraction). Notable Erasmus Smith's Professors of Mathematics have been: Bartholomew Lloyd (1813-1822); James McCullagh (1835-1843); Charles Graves (1843-1862); William Snow Burnside (1879-1914); Heini Halberstam (1962-1964); Gabriel Andrew Dirac (1964-1966).

The will of Provost Francis Andrews established the Andrews Professorship of Astronomy in 1774, including funds for an observatory, which was built at Dunsink. The first Andrews Professor was Henry Ussher, from 1783 until his death in 1790, supposed due to prolonged exposure to the cold night air. He was succeeded by John Brinkley, a Cambridge graduate who had worked at the Royal Observatory in Greenwich. From 1792 until 1921, the Andrews Professor was also Astronomer Royal of Ireland. Brinkley received the Copley medal of the Royal Society in 1824 and was President of the Royal Astronomical Society in 1831. Later notable holders have been: William Rowan Hamilton (1827-1865); Robert Stawell Ball (1874-1892); Charles Jasper Joly (1897-1906, who edited Hamilton's Elements of Quaternions); Edmund Taylor Whittaker (1906-1912). Presumably these all resided at Dunsink? The Andrews Chair was left vacant in 1921, but re-established as an honorary chair in 1984.

A University Professorship in Natural Philosophy was established in 1847. Notable holders have been: John Leighton Synge (1925-1930); Albert Joseph McConnell (1930-1952, who became Provost in 1952).

The Old Library was built in 1712-1732. Its upper floor, the Long Room, was long the largest library room in the world, even before its heightening in c1860. The c800 Book of Kells is now displayed on the ground floor. The library includes Usshers collection. The Long Room has a collection of portrait busts, including Aristotle, Locke, Newton, Plato, Socrates, Ussher (see below). In 1992 a William Rowan Hamilton Building opened, containing the Science and Engineering Library and five lecture halls.

James Ussher (1581-1656) was born at 3 Fishamble Street (demolished in 1944). He was a student at TCD from 1593 and was later a fellow. He went into the Church, becoming Archbishop of Armagh. In 1650 he published his famous assertion that Creation had taken place 'upon the entrance of the night preceding' Sunday 23 October, 4004 BC.
William Molyneux was a student in 1671-1674 . His Dioptrica Nova of 1692 includes the first publication of Halley's equation for thin lenses. His son Samuel was also a student here, but went to London.

St. George Ashe (late 17C) was Symner's successor as Donegall Lecturer and was later Provost. He published on Euclid in the Phil. Trans. of the Royal Society of London.

Narcissus Marsh (late 17C) was another Provost. He published on acoustics in the Phil. Trans. He was later Archbishop of Dublin and his library is preserved as Marsh's Library, St. Patrick's Close, built in 1705. It contains some 17C mathematical works. It is perhaps the best example of what a medieval library was like. It still has reader's cages in which readers could be locked in! There is a shelf of books in the original chained style, though the books no longer have their chains.

George Berkeley (1685-1753) entered Trinity College in 1700, age 15; BA, 1704; Junior Fellow, 1707; An Essay Towards a New Theory of Vision, 1709; Librarian for some time, including the planning of the 'Old Library' with its famous Long Room; Junior Dean. Ordained in the Church of Ireland, 1709. From about 1713, he was on travelling leave, returning in 1721, when he was Senior Fellow, received BD and DD degrees and was appointed Lecturer in Divinity. In 1724, he became Dean of (London)Derry and resigned from the College.

Bartholomew Lloyd ( 1772-1837) was a student, then Erasmus Smith's Professor of Mathematics in 1813-1822, then of Natural Philosophy in 1822-1831, then Provost from 1831. He introduced modern degree courses in mathematics and physics and wrote several standard texts. In Aug 1835, he presided over the first Dublin meeting of the BAAS.

Humphrey Lloyd (1800-1881), son of the above, graduated with a gold medal in science in 1819. He succeeded his father as Erasmus Smith's Professor of Natural Philosophy in 1831-1843 and was Provost from 1867. His work was in optics and magnetism: he found conical refraction according to Hamilton's prediction and established a magnetic observatory, moved to University College Dublin's Belfield campus in the 1970s.

James McCullagh (1809-1847) was Erasmus Smith's Professor of Mathematics in 1835-1843, then of Natural Philosophy in 1845-1847. He was the proponent of the best(?) theory of the ether. He was known to have a great deal of work in manuscript form, but he apparently destroyed it before committing suicide.

There is a statue of George Salmon (1819-1904) in Front Square. His Treatise on Conic Sections of 1848 and Treatise on the Analytic Geometry of Three Dimensions of 1862 were standard works well into the 20C. He became professor of divinity in 1866 and Provost from 1888.


John Joly (1857-1933) was professor of geology, but a noted polymath. FRS in 1892 for work on the specific heat of gases at constant volume. Gave an explanation for the rise of sap in plants. Estimated the age of the earth from the salinity of the oceans, getting 85,000,000 years. Devised a system of colour photography. The Joly Memorial Lectureships were inaugurated in 1935 by Rutherford.

J J Sylvester received his first degree here as an honorary award because English universities would not give degrees to non-Anglicans until 1871. Dionysius Lardner was a student. A. W. Panton was here. John Leighton Synge (1897?-1995) was a student, graduating in 1919, but went to Toronto for 1920-1925. He returned in 1925 and was elected Fellow and University Professor of Natural Philosophy, until 1930 when he went to Toronto again and then the USA. He returned to the Dublin Institute for Advanced Studies in 1948 until his retirement in 1972. He was the nephew of the playwright J. M. Synge. Ernest Thomas Sinton Walton (1903-1995) (born in Dungarven, County Waterford) was a student and continued with research, but soon went to Cambridge. He returned to the Trinity Physics Department in 1934 and was Erasmus Smith Professor from 1946. Nobel Prize in Physics, with Cockcroft, in 1951.

William Parsons, later third Earl of Rosse, was a student at Trinity College from 1819 and Chancellor from 1862. In 1867, he went to a seaside house in Monkstown, in the south of Dublin, for his health, but died there. Laurence Parsons, later fourth Earl of Rosse, was a student at Trinity to 1864 and Chancellor.

In Oct 1683, William Molyneux (1656-1698) and St. George Ashe organised The Dublin Society for the Improving of Natural Knowledge, Mathematicks and Mechanicks, soon renamed The Dublin Philosophical Society. The first president was Sir William Petty, with Molyneux as secretary and treasurer. Narcissus Marsh was an early member. The Society only ran until 1687 but it was revived briefly in 1693 and in 1707. In 1731, the Royal Dublin Society was founded as the continuation of the Philosophical Society. The Royal Irish Academy was founded in 1785. It is located at 19 Dawson Street.

George Stokes was a student at a school run by a Rev. R. H. Wahl from c1832 to 1835.

William Sealey Gossett (Student) (1876-1937) worked at Guinnesss St. James Gate Brewery from 1899-1935 . It is in Thomas Street, west of the city centre. His application of statistical methods to brewing was so valuable that Guinness required him to use a pseudonym for his publications.

Eamon de Valera (1882-1975) studied mathematics at Blackrock College, then University College, then Trinity College. He taught mathematics at school, college and university levels before going into politics. He participated in the Easter Rising of 1916, and was sentenced to life imprisonment. Released in the General Amnesty of Jun 1917, he was re-arrested in May 1918 and escaped from Lincoln Gaol in Feb 1919. He retained a lifelong interest in mathematics, founding the Dublin Institute for Advanced Studies, and was Chancellor of the National University (an umbrella organization of all the universities in Ireland). He was President of Ireland from 1959 until 1973. He lived at Talbot Lodge, Linden, Blackrock.

Erwin Schrödinger lived at 65 Merrion Square.


William Wilkins, a notable example of a mathematician turned architect, designed Nelson's Pillar, erected in O'Connell Street at the intersection north of the General Post Office, but blown up (or down??) by extremists in 1966, leaving just some fragments.


The National Museum, Kildare Street, has the Hollywood Stone, the British Isles' largest (about 3 ft by 3 ft 9 in) carved stone labyrinth, discovered at Hollywood, Co. Wicklow, in 1908. It was beside St. Kevin's Road, an ancient pilgrim track from Hollywood to Glendalough. Dating ranges from -200 to +500. Sadly it was removed to storage in Apr 1994 about a week before my visit to examine it!


In this museum is the splendid 12C Cross of Cong, which James McCullagh purchased and donated.


There is also a 10C game board comprising a 7 × 7 pattern of holes.

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An extract from The Mathematical Gazetteer of the British Isles created by David Singmaster