author
John Casey
1820–1891
An Irish geometer and teacher, he came to mathematics later than many of his peers and still made a lasting mark. He is best remembered for Casey’s theorem and for lively, elegant work on Euclidean geometry.
1 Audiobook
The First Six Books of the Elements of Euclid
by Euclid, John Casey
About the author
Born in County Limerick in 1820, John Casey grew up in modest circumstances and worked first as a teacher. He later studied at Trinity College Dublin as a mature student, earning high honors in mathematics and going on to build a strong reputation as both an educator and a scholar.
Casey wrote widely on geometry, especially the geometry of circles and triangles. His best-known result is Casey’s theorem, and his books helped make advanced geometry more accessible to students and readers who enjoyed clear, rigorous mathematical writing.
He spent much of his career connected with education in Ireland, including work as a schoolmaster, and he was elected a Fellow of the Royal Society. He died in Dublin in 1891, remembered as a gifted geometer who brought freshness and precision to classical mathematics.