Person: Perigal, Henry
Henry Perigal was a clerk, stockbroker, amateur mathematician and astronomer. He is known for his mechanical production of geometric curves, for his dissection proof of Pythagoras' theorem and for his unorthodox ideas on astronomy.
Mathematical Profile (Excerpt):
- Henry Perigal Sn became Assistant Secretary to the Victualling Board working in the Admiralty Office.
- Sigurd the Dane, who in 908 made a successful raid on Normandy, assumed the name of Perigal, and settled in France.
- Henry Perigal belongs to the tenth generation of their descendants.
- Henry Perigal Sr was friendly with John Holt Ibbetson, who was an inventor who published works such as Specimens of Eccentric Circular Turning, with Practical Illustrations for producing Corresponding Pieces in that Art (1817) and A Brief Account of Ibbetson's Geometric Chuck, manufactured by Holtzapffel & Co., with a selection of 32 Specimens, illustrative of some of its powers (1833).
- Perigal, who was known by the nickname "Cyclops" (in fact Cyclops, in brackets, is carved on his tomb), seems to have had a variety of jobs over the first forty years of his life but the main one was as a clerk in the Privy Council Office.
- From the 1840s he worked as a bookkeeper for his friend Henry Tudor who was a stockbroker operating from an office at 29 Threadneedle Street, London.
- Perigal continued working for Henry Tudor & Son, Stockbrokers, and only retired from the firm when he was 87 years old.
- On a paper Perigal wrote in 1869 he gives the address 57 Warren Street, Fitzroy Square.
- From the time he was young, Perigal was interested in curve tracing using Ibbetson's geometric chuck, a tool used in ornamental wood turning.
- We are indebted for them to the kindness of Mr Henry Perigal, of Smith Street, Chelsea, a gentleman whose pursuits are scientific, and who practices the higher branches of turning as an amateur, and has devoted much time and money to the investigation of the effects of combined motions, as shown in the curves, resulting from them.
- Before looking in more detail at Perigal's ideas and inventions, we should make it clear that although he did some nice geometric work, most of his ideas relating to astronomy were incorrect.
- The reader might well ask: "Why is he being included in this archive if many of his ideas were incorrect?" Perigal was an eccentric man but also clever.
- His friends included George Biddell Airy, William Henry Mahoney Christie (1845-1922) (an Astronomer Royal), Lord Kelvin, Lord Rayleigh, George Gabriel Stokes, Silvanus Phillips Thompson (1851-1916), James Whitbread Lee Glaisher and James Joseph Sylvester.
- Perigal was a regular at Saturday evening soirées of the Marquess of Northampton, and he exhibited various instruments at these events.
- Perigal's incorrect views on astronomy did not prevent him being elected a fellow of the Royal Astronomical Society (he was elected on 8 February 1850).
- Perigal's completely false idea that the Moon did not rotate seems to have become one of the main obsessions in his life.
- There must have been a debate about it at the Astronomical Club in January 1865 when John Couch Adams argued the case for the moon to rotate and Perigal the case for non-rotation.
- Others were motivated by Perigal's curves.
- Mr Perigal had obtained the solution, in a considerable variety of cases by the method of trial, aided by mechanical appliances, and has exhibited them in his beautiful series of machine-engraved epicycloids.
- Another example is Perigal's offer, in 1868, of a prize of £10 if somebody could identify a curve he had discovered with his 'two circles machine'.
- £10 in 1868 is the equivalent of over £1000 today.] Who found Perigal's curve and won the generous prize?
- Many of Perigal's inventions are now held by the South Kensington Museum.
- We have noted that Perigal was elected to the Royal Astronomical Society in 1850; he had been proposed by De Morgan.
- Perigal joined the Society on 4 June 1850 and he was appointed Treasurer of the Society on 24 May 1853.
Born 1 April 1801, Newington, Southwark, London, England. Died 6 June 1898, St Giles, London, England.
View full biography at MacTutor
Tags relevant for this person:
Origin England
Thank you to the contributors under CC BY-SA 4.0! 
- Github:
-
- non-Github:
- @J-J-O'Connor
- @E-F-Robertson
References
Adapted from other CC BY-SA 4.0 Sources:
- O’Connor, John J; Robertson, Edmund F: MacTutor History of Mathematics Archive
