The Exploits of Chevalier Dupin the introduction by Ellery Queen, and the non-fiction piece on Dupin by Harrison. "The Exploits of Chevalier Dupin" contains the following tales: The Exploits of Chevalier Dupin The Exploits of Chevalier Dupin is a collection of detective short stories by author Michael Harrison. It was released in 1968 by Mycroft & Moran in an edition of 1,917 copies. The stories are pastiches of the C. Auguste Dupin stories of Edgar Allan Poe. The stories were first published in Ellery Queen's Mystery Magazine. There is an expanded UK edition by a different publisher which adds a further five stories This appeared
Dupin cyclide of Dupin cyclides is invariant under the larger group of all Lie sphere transformations; any two Dupin cyclides are Lie-equivalent. They form (in some sense) the simplest class of Lie-invariant surfaces after the spheres, and are therefore particularly significant in Lie sphere geometry. The definition also means that a Dupin cyclide is the envelope of the one-parameter family of spheres tangent to three given mutually tangent spheres. It follows that it is tangent to infinitely many Soddy's hexlet configurations of spheres. A further special property of a cyclide is: An elliptic cyclide can be represented parametrically by the following formulas