Professor Hoffmann's Best Math and Logic Puzzles

You invite a gentleman to stand in the middle of the room. Taking a piece of chalk, you undertake to draw round him a circle which he cannot jump out of. How is it to be done?
This riddle, "The Charmed Circle," is but one of dozens of antique treats from a classic collection of brainteasers. Professor Hoffmann published his great treasury of old and new puzzles in 1893. Since then, puzzle aficionados have reveled in the Victorian charm of the professor's challenges. This compilation features some of the most pleasantly perplexing highlights from the original edition — 158 puzzles in all, with complete solutions.
Four different kinds of puzzles include those involving arithmetic, a selection of word and letter puzzles, puzzles with counters, and "quibble" or "catch" puzzles, which rely upon a double meaning or a clever interpretation of the question — such as "The Charmed Circle," above, in which the triumphant puzzle-solver draws a chalk line around the subject's waist.