C. Auguste Dupin with artistic imagination. As an observer, he pays special attention to what is unintended, such as hesitation, eagerness or a casual or inadvertent word. Dupin's method also emphasizes the importance of reading and writing: many of his clues come from newspapers or written reports from the Prefect. This device also engages the readers, who follow along by reading the clues themselves. Poe may have gotten the last name "Dupin" from a character in a series of stories first published "Burton's Gentleman's Magazine" in 1828 called "Unpublished passages in the Life of Vidocq, the French Minister of Police". The name also
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