The Purloined Letter The Purloined Letter "The Purloined Letter" is a short story by American author Edgar Allan Poe. It is the third of his three detective stories featuring the fictional C. Auguste Dupin, the other two being "The Murders in the Rue Morgue" and "The Mystery of Marie Rogêt". These stories are considered to be important early forerunners of the modern detective story. It first appeared in the literary annual "The Gift for 1845" (1844) and was soon reprinted in numerous journals and newspapers. The unnamed narrator is discussing with the famous Parisian amateur detective C. Auguste Dupin some of his most
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