Sherlock Holmes primarily relies on abduction: inferring an explanation for observed details. "From a drop of water", he writes, "a logician could infer the possibility of an Atlantic or a Niagara without having seen or heard of one or the other". In "A Scandal in Bohemia", Holmes infers that Watson had got wet lately and had "a most clumsy and careless servant girl". When Watson asks how Holmes knows this, the detective answers: In the first Holmes story, "A Study in Scarlet", Dr. Watson compares Holmes to C. Auguste Dupin, Edgar Allan Poe's fictional detective, who employed a similar methodology. Alluding to
Charles Dupin Charles Dupin Baron Pierre Charles François Dupin (6 October 1784, Varzy, Nièvre – 18 January 1873, Paris, France) was a French Catholic mathematician, engineer, economist and politician, particularly known for work in the field of mathematics, where the Dupin cyclide and Dupin indicatrix are named after him; and for his work in the field of statistical and thematic mapping, In 1826 he created the earliest known choropleth map. He was born in Varzy in France, the son of Charles Andre Dupin, a lawyer, and Catherine Agnes Dupin. He studied geometry with Monge at the École Polytechnique and then became a