Person: Casey, John
John Casey was an Irish geometer best kown for his work on the geometry of the circle.
Mathematical Profile (Excerpt):
- While resident in Kilkenny, Casey was introduced to advanced mathematics by a former student of Trinity College, Dublin, who proposed that Casey should study a theorem of Poncelet, concerning polygons inscribed in a circle of a coaxial system.
- Casey's short proof of Poncelet's theorem was communicated to Richard Townsend, Fellow of Trinity College, in 1858, and was published in the Quarterly Journal of Mathematics 5 (1862), 43-53.
- Casey thereafter corresponded with Townsend and George Salmon on geometric problems, and they persuaded him to enter Trinity College as pensioner in 1858 to undertake a degree course; he was elected a non-foundation scholar in 1861 and graduated in 1862.
- Casey applied unsuccessfully in 1867 for the vacant professorship of mathematics at Queen's College, Cork.
- In a letter to Townsend dated 5 November 1873, he declined this position, and Townsend explained in a letter to the Registrar of Trinity College, written the following day, that Casey felt obliged to accept the professorship at the Catholic University.
- As the Catholic University had virtually no students and could not pay regular salaries, Casey supported himself by giving grinds.
- Following the establishment of the Royal University in 1880 and the reconstitution of the Catholic University premises at St Stephen's Green as University College, Casey was elected to a fellowship of the Royal University in 1882, at a yearly salary of £400.
- Casey wrote over 25 research papers but his mathematical reputation rests on the six textbooks he wrote: A sequel to the first six books of the Elements of Euclid (1881; 8th ed.
- 1902) which is remarkable for its large store of exercises, collected and devised by himself and Richard Townsend, which occasioned the publication of a separate Key to the exercises of Casey's Elements of Euclid (1885) by Casey's son, Joseph.
- It was in his Sequel to Euclid that Casey presented for the first time in a textbook those extensions of the theorems of Euclid that became known as the newer geometry of the triangle; indeed, he and the French mathematician Émile Lemoine (1840-1912) are held to be the founders of the so-called Modern Geometry of the circle and triangle.
- Casey's work was much appreciated in Belgium and France, and Professor Joseph Neuberg of Liège made substantial additions to later editions of Sequel to Euclid.
- Casey was a member of the Royal Irish Academy (1866) and fellow of the Royal Society (1875), and held honorary doctorates in laws from Trinity College Dublin (1869) and the Royal University of Ireland (1885).
- From 1874 or 1875 onwards, Casey lived at 86 Iona Terrace, which is part of the South Circular Road in Dublin and close to Casey's place of work at St Stephen's Green.
- Casey died of bronchitis on 3 January 1891 and was buried at Glasnevin Cemetery.
Born 12 May 1820, Coolattin, Kilbehenny, Co. Limerick, Ireland. Died 3 January 1891, Dublin, Ireland.
View full biography at MacTutor
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Origin Ireland
Thank you to the contributors under CC BY-SA 4.0! 
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- @Roderick-Gow
References
Adapted from other CC BY-SA 4.0 Sources:
- O’Connor, John J; Robertson, Edmund F: MacTutor History of Mathematics Archive
