Perigal, Henry 1801 - 1898

English; British

(1801-1898), stockbroker and amateur mathematician

Henry Perigal, born on the 1st April 1801, was a 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. Perigal worked at odd jobs for many years, but finally in his mid-forties became a book keeper for a stock broker friend of his and remained in this position until his retirement at 87. He pursued science throughout his life, but with mixed success. By his own account he came across his proof of Pythagoras' Theorem while trying to square the circle, and he held probably throughout all his life the somewhat bizarre belief that in moving around the Earth to present constantly the same face to us, the moon did not rotate relative to the stars.

Perigal was a member of many scientific societies, the London Mathematical Society from 1868 to 1897 and was treasurer of the Royal Meteorological Society for 45 years, from 1853 until his death in 1898. He was elected as a fellow of the Royal Astronomical Society in 1850. He attended the Royal Institution regularly as a visitor for many years, and finally became a member in 1895, at age 94. At one scientific meeting his portrait was exhibited with the caption, "Venerable patriarch of the London scientific societies.

Perigal died on the 6th June 1898 - almost living though the entire 19th Century. His diagram for dissection proof - of Pythagoras' Theorem is carved on his gravestone in the churchyard of the Church of St. Mary and St. Peter in Wennington, Essex.