John Casey (12 May 1820, Kilbehenny,

County Limerick County Limerick () is a western Counties of Ireland, county in Republic of Ireland, Ireland. It is in the Provinces of Ireland, province of Munster and is located in the Mid-West Region, Ireland, Mid-West which comprises part of the Southern Reg ...

Ireland Ireland (, ; ; Ulster Scots dialect, Ulster-Scots: ) is an island in the North Atlantic Ocean, in Northwestern Europe. Geopolitically, the island is divided between the Republic of Ireland (officially Names of the Irish state, named Irelan ...

– 3 January 1891,

Dublin Dublin is the capital and largest city of Republic of Ireland, Ireland. Situated on Dublin Bay at the mouth of the River Liffey, it is in the Provinces of Ireland, province of Leinster, and is bordered on the south by the Dublin Mountains, pa ...

) was a respected Irish geometer. He is most famous for Casey's theorem on a circle that is tangent to four other circles, an extension of Ptolemy's theorem. However, he contributed several novel proofs and perspectives on

Euclidean geometry Euclidean geometry is a mathematical system attributed to ancient Greek mathematics, Greek mathematician Euclid, which he described in his textbook on geometry, ''Euclid's Elements, Elements''. Euclid's approach consists in assuming a small set ...

. He and Émile Lemoine are considered to be the co-founders of the modern geometry of the circle and the triangle.

Biography

He was born at Kilbehenny in Limerick, Ireland and educated locally at Mitchelstown, before becoming a teacher under the Board of National Education. He later became headmaster of the Central Model Schools in Kilkenny City. He subsequently entered

Trinity College Dublin Trinity College Dublin (), officially titled The College of the Holy and Undivided Trinity of Queen Elizabeth near Dublin, and legally incorporated as Trinity College, the University of Dublin (TCD), is the sole constituent college of the Unive ...

in 1858, where he was elected a Scholar in 1861 and was awarded the degree of BA in 1862. He was then Mathematics Master at Kingston School (1862–1873), Professor of Higher Mathematics and Mathematical Physics at the newly founded

Catholic University of Ireland The Catholic University of Ireland (CUI; ) was a private Catholic Church, Catholic university in Dublin, Ireland. It was founded in 1851 following the Synod of Thurles in 1850, and in response to the Queen's University of Ireland and its assoc ...

(1873–1881) and Lecturer in Mathematics at its successor, the University College Dublin (1881–1891).

Honours and awards

In 1869, the

University of Dublin The University of Dublin (), corporately named as The Chancellor, Doctors and Masters of the University of Dublin, is a research university located in Dublin, Republic of Ireland. It is the degree-awarding body for Trinity College Dublin, whi ...

awarded Casey the Honorary Degree of Doctor of Laws. He was elected a

Fellow of the Royal Society Fellowship of the Royal Society (FRS, ForMemRS and HonFRS) is an award granted by the Fellows of the Royal Society of London to individuals who have made a "substantial contribution to the improvement of natural science, natural knowledge, incl ...

in June 1875. He was elected to the

Royal Irish Academy The Royal Irish Academy (RIA; ), based in Dublin, is an academic body that promotes study in the natural sciences, arts, literature, and social sciences. It is Ireland's premier List of Irish learned societies, learned society and one of its le ...

and in 1880 became a member of its council. In 1878 the Academy conferred upon him the much coveted Cunningham Gold Medal. His work was also acknowledged by the Norwegian Government, among others. He was elected a member of the Societe Mathematique de France in 1884 and received the honorary degree of Doctor of Laws from the

Royal University of Ireland The Royal University of Ireland was a university in Ireland that existed from 1879 to 1909. It was founded in accordance with the University Education (Ireland) Act 1879 as an examining and degree-awarding university based on the model of the ...

in 1885.

Major works

* 1880
''On Cubic Transformations''
* 1881
On Cyclides and Sphero-quartics
from

Internet Archive The Internet Archive is an American 501(c)(3) organization, non-profit organization founded in 1996 by Brewster Kahle that runs a digital library website, archive.org. It provides free access to collections of digitized media including web ...

* 1882
The First Six Books of the Elements of Euclid
link from

Project Gutenberg Project Gutenberg (PG) is a volunteer effort to digitize and archive cultural works, as well as to "encourage the creation and distribution of eBooks." It was founded in 1971 by American writer Michael S. Hart and is the oldest digital li ...

* 1885
A Treatise on the Analytic Geometry of the Point, Line, Circle and Conic SectionsSecond edition, 1893
links from Internet Archive * 188
A Sequel to the First Six Books of Euclid, 4th edition
link from Internet Archive * 1886: ''A Treatise on Elementary Trigonometry'' (Dublin, 1886) * 1888
''A Treatise on Plane Trigonometry containing an account of the Hyperbolic Functions''
* 1889
''A Treatise on Spherical Geometry''
link from Internet Archive

References

Sources

* ''Irish Monthly'' (1891), XIX, 106, 152 * ''Proc. Royal Society'' (1891), XLIX, 30, p. xxiv.

External links