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 cyclide 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 are themselves examples of Dupin cyclides. They were discovered by (and named after) Charles Dupin in his 1803 dissertation under Gaspard Monge. The key property of a Dupin cyclide is that it is a channel surface (envelope of a one-parameter family of spheres) in two different ways. This property means that Dupin cyclides are natural objects in Lie sphere geometry. Dupin cyclides are often simply known as "cyclides", but the latter term is