Henry Perigal
| Henry Perigal | |
|---|---|
Henry Perigal
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| Born | 1 April 1801 |
| Died | 6 June 1898 (aged 97) |
| Nationality | British |
| Fields | Mathematics, Astronomy |
| Known for | pythagorean theorem |
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.
Perigal descended from a Huguenot family who emigrated to England in the late 17th century, and was the oldest of six siblings. After working as a clerk for the Privy Council, he became a bookkeeper in a London stockbrokerage in the 1840s. He remained a lifelong bachelor.
Perigal was a member of 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. 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.
In his booklet (London: Bell & Sons, 1891) Perigal provided a proof of the Pythagorean theorem based on the idea of dissecting two smaller squares into a larger square. The five-piece dissection that he found may be generated by overlaying a regular square tiling whose prototile is the larger square with a Pythagorean tiling generated by the two smaller squares. Perigal had the same dissection printed on his business cards, and it also appears on his tombstone.
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