Armchair detective an arm-chair, my brother would be the greatest criminal agent that ever lived." "The first example of armchair detecting can be found in the work of Edgar Allan Poe. In "The Mystery of Marie Rogêt" (1842), C. Auguste Dupin, working wholly from newspaper accounts, arrives at the correct explanation for a young woman's mysterious disappearance." Baroness Orczy's Old Man in the Corner sits in a restaurant and talks to an acquaintance about cases, almost always finishing by revealing that he has solved the crime. A more literal use of this term can be found in Rex Stout's Nero Wolfe novels
Dupin cyclide "R" are a 3-dimensional vectors, and "A" and "B" are constants. Families of cyclides give rise to various cyclidic coordinate geometries. In Maxime Bôcher's 1891 dissertation, "Ueber die Reihenentwickelungen der Potentialtheorie", it was shown that the Laplace equation in three variables can be solved using separation of variables in 17 conformally distinct quadric and cyclidic coordinate geometries. Many other cyclidic geometries can be obtained by studying R-separation of variables for the Laplace equation. 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