Read the following paragraph and answer the question.

1Poe really was the inventor of the detective story, which he called the "ratiocinative" tale. 2Here believing the effect intended was "to perplex the reader and whet his desire for elucidation," he originated two devices useful to this day. 3One might be called "the device of the baffled friend": He gave his brilliant detective a companion not good at solutions and had him tell the story. 4Viewing the happenings through this narrator's eyes, the reader shares his growing puzzlement. 5Poe used his second device at the tale's end: He had the detective disclose his surprising solution and then "elucidate" step by step the reasoning which led to it. 6"The Purloined Letter" demonstrated Poe's use of these two devices in a detective story.

(From: United States in Literature by Walter Blair, Paul Farmer, Theodore Hornberger, and Margaret Wasson. C. 1963 by Scott, Foresman and Company. Reprinted by permission.)

On the basis of the context clue, what is the meaning of the ratiocinative tale?