The Murders in the Rue Morgue C. Auguste Dupin and the Paris setting. Dupin reappeared in "The Purloined Letter", which Poe called "perhaps the best of my tales of ratiocination" in a letter to James Russell Lowell in July 1844. The original manuscript of "The Murders in the Rue Morgue" which was used for its first printing in "Graham's Magazine" was discarded in a wastebasket. An apprentice at the office, J. M. Johnston, retrieved it and left it with his father for safekeeping. It was left in a music book, where it survived three house fires before being bought by George William Childs. In 1891, Childs
Dupin cyclide that the class of Dupin cyclides is invariant under Möbius (or conformal) transformations. In complex space formula_2 these three latter varieties can be mapped to one another by inversion, so Dupin cyclides can be defined as inversions of the torus (or the cylinder, or the double cone). Since a standard torus is the orbit of a point under a two dimensional abelian subgroup of the Möbius group, it follows that the cyclides also are, and this provides a second way to define them. A third property which characterizes Dupin cyclides is that their curvature lines are all circles (possibly through