Michael Harrison (writer) Michael Harrison (writer) Michael Harrison (25 April 1907 – 13 September 1991) was the pen name of English detective fiction and fantasy author Maurice Desmond Rohan. Michael Harrison was born in Milton, Kent, England, on 25 April 1907. He attended the University of London and served briefly in the British Military Intelligence during World War II. He married Marie-Yvonne Aubertin. Harrison published seventeen novels between 1934 and 1954 when he turned to writing detective fiction. He wrote pastiches of Conan Doyle's Sherlock Holmes and Poe's C. Auguste Dupin and was a noted Sherlock Holmes scholar. His most successful work, "In
Dupin cyclide Dupin cyclide In mathematics, a Dupin cyclide or cyclide of Dupin is any geometric inversion of a standard torus, cylinder or double cone. In particular, these latter are themselves examples of Dupin cyclides. They were discovered by (and named after) Charles Dupin in his 1803 dissertation under Gaspard Monge. The key property of a Dupin cyclide is that it is a channel surface (envelope of a one-parameter family of spheres) in two different ways. This property means that Dupin cyclides are natural objects in Lie sphere geometry. Dupin cyclides are often simply known as "cyclides", but the latter term is