Gentleman detective He lives in Paris with his close friend, the anonymous narrator of the stories. Like the much later Lord Peter Wimsey (see below), Dupin is a bibliophile, and met his narrator friend while both were searching for "the same rare and very remarkable volume" in an obscure library. For hobbies, Dupin is "fond" of enigmas, conundrums, and hieroglyphics. Dupin also bears the French title "Chevalier", meaning that he is a knight in the Légion d'honneur. The classic British gentleman detective appears soon after Poe's Dupin. A gentleman amateur is the ultimate hero of "The Moonstone" (1868), a famous epistolary novel
Dupin indicatrix Dupin indicatrix In differential geometry, the Dupin indicatrix is a method for characterising the local shape of a surface. Draw a plane parallel to the tangent plane and a small distance away from it. Consider the intersection of the surface with this plane. The shape of the intersection is related to the Gaussian curvature. The Dupin indicatrix is the result of the limiting process as the plane approaches the tangent plane. The indicatrix was invented by Charles Dupin. For elliptical points where the Gaussian curvature is positive the intersection will either be empty or form a closed curve. In the