Carl Theodore Heisel (1852–1937) was a mathematical

crank Crank may refer to: Mechanisms * Crank (mechanism), in mechanical engineering, a bent portion of an axle or shaft, or an arm keyed at right angles to the end of a shaft, by which motion is imparted to or received from it * Crankset, the compone ...

who wrote several books in the 1930s challenging accepted mathematical truths. Among his claims is that he found a way to

square the circle Squaring the circle is a problem in geometry first proposed in Greek mathematics. It is the challenge of constructing a square with the area of a circle by using only a finite number of steps with a compass and straightedge. The difficulty ...

. He is credited with 24 works in 62 publications. Heisel did not charge money for his books; he gave thousands of them away for free. Because of this, they are available at many libraries and universities. Heisel's books have historic and monetary value. Paul Halmos referred to one of Heisel's works as a "classic crank book." �
How to Write Mathematics
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Selected works

References

{{DEFAULTSORT:Heisel, Carl Theodore Pseudomathematics 1852 births 1937 deaths