C. Auguste Dupin prefect "G", who appears in all three stories seeking his counsel. In "The Murders in the Rue Morgue", Dupin investigates the murder of a mother and daughter in Paris. He investigates another murder in "The Mystery of Marie Rogêt". This story was based on the true story of Mary Rogers, a saleswoman at a cigar store in Manhattan whose body was found floating in the Hudson River in 1841. Dupin's final appearance, in "The Purloined Letter", features an investigation of a letter stolen from the French queen. Poe called this story "perhaps, the best of my tales of ratiocination". Throughout
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