Henry Perigal

Henry Perigal, Jr. FRAS MRI (1 April 1801 – 6 June 1898) was a British stockbroker and amateur mathematician, known for his dissection-based proof of the Pythagorean theorem and for his unorthodox belief that the moon does not rotate.

Biography Perigal descended from a Huguenot family who emigrated to England in the late 17th century, He was an original member of the British Astronomical Association in 1890; he would be oldest member of the BAA if all the members were gathered together. Although Perigal was long-lived, his father lived even longer, becoming a centenarian. Perigal had the same dissection printed on his business cards, and it also appears on his tombstone,

In the same book, Perigal expressed the hope that dissection based methods would also solve the 1925 Tarski's problem of circle-squaring by dissection. That problem had been shown to be impossible to solve in a constructive way in 1963. Nevertheless, a non-constructive solution has been proposed by Miklós Laczkovich in 1990.

Perigal also proposed the first 6-pieces solution to the square trisection problem.

As well as being interested in mathematics, Perigal was an accomplished lathe worker, and made models of mathematical curves for Augustus De Morgan. He falsely believed that the moon does not rotate with respect to the fixed stars, and used his knowledge of curvilinear motion in an attempt to demonstrate this belief to others.