Girard Desargues (; 21 February 1591 – September 1661) was a French

mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change. History On ...

and engineer, who is considered one of the founders of

projective geometry In mathematics, projective geometry is the study of geometric properties that are invariant with respect to projective transformations. This means that, compared to elementary Euclidean geometry, projective geometry has a different setting, ...

. Desargues' theorem, the Desargues graph, and the crater Desargues on the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

are named in his honour. Bosse - Pratique du trait a preuves, 1643 - 1219339

Born in

Lyon Lyon,, ; Occitan language, Occitan: ''Lion'', hist. ''Lionés'' also spelled in English as Lyons, is the List of communes in France with over 20,000 inhabitants, third-largest city and Urban area (France), second-largest metropolitan area of F ...

, Desargues came from a family devoted to service to the French crown. His father was a royal

notary A notary is a person authorised to perform acts in legal affairs, in particular witnessing signatures on documents. The form that the notarial profession takes varies with local legal systems. A notary, while a legal professional, is disti ...

, an investigating commissioner of the Seneschal's court in Lyon (1574), the collector of the

tithe A tithe (; from Old English: ''teogoþa'' "tenth") is a one-tenth part of something, paid as a contribution to a religious organization or compulsory tax to government. Today, tithes are normally voluntary and paid in cash or cheques or more ...

s on ecclesiastical revenues for the city of Lyon (1583) and for the

diocese of Lyon The Archdiocese of Lyon (Latin: ''Archidiœcesis Lugdunensis''; French: ''Archidiocèse de Lyon''), formerly the Archdiocese of Lyon–Vienne–Embrun, is a Latin Church metropolitan archdiocese of the Catholic Church in France. The Archbishop ...

. Girard Desargues worked as an

architect An architect is a person who plans, designs and oversees the construction of buildings. To practice architecture means to provide services in connection with the design of buildings and the space within the site surrounding the buildings that h ...

from 1645. Prior to that, he had worked as a tutor and may have served as an engineer and technical consultant in the entourage of Richelieu. As an architect, Desargues planned several private and public buildings in Paris and Lyon. As an engineer, he designed a system for raising water that he installed near Paris. It was based on the use of the

epicycloid In geometry, an epicycloid is a plane curve produced by tracing the path of a chosen point on the circumference of a circle—called an ''epicycle''—which rolls without slipping around a fixed circle. It is a particular kind of roulette. Equati ...

al wheel, the principle of which was unrecognized at the time. His research on perspective and geometrical projections can be seen as a culmination of centuries of scientific inquiry across the classical epoch in optics that stretched from al-Hasan

Ibn al-Haytham Ḥasan Ibn al-Haytham, Latinized as Alhazen (; full name ; ), was a medieval mathematician, astronomer, and physicist of the Islamic Golden Age from present-day Iraq.For the description of his main fields, see e.g. ("He is one of the pri ...

( Alhazen) to Johannes

Kepler Johannes Kepler (; ; 27 December 1571 – 15 November 1630) was a German astronomer, mathematician, astrologer, natural philosopher and writer on music. He is a key figure in the 17th-century Scientific Revolution, best known for his laws o ...

, and going beyond a mere synthesis of these traditions with Renaissance perspective theories and practices. His work was rediscovered and republished in 1864. A collection of his works was published in 1951, and the 1864 compilation remains in print. One notable work, often cited by others in mathematics, is "Rough draft for an essay on the results of taking plane sections of a cone" (1639). Late in his life, Desargues published a paper with the cryptic title of ''DALG''. The most common theory about what this stands for is ''Des Argues, Lyonnais, Géometre'' (proposed by

Henri Brocard Pierre René Jean Baptiste Henri Brocard (12 May 1845 – 16 January 1922) was a French meteorologist and mathematician, in particular a geometer. His best-known achievement is the invention and discovery of the properties of the Brocard point ...

). He died in Lyon.

References

* J. V. Field & J. J. Gray (1987) ''The Geometrical Work of Girard Desargues'',

Springer-Verlag Springer Science+Business Media, commonly known as Springer, is a German multinational publishing company of books, e-books and peer-reviewed journals in science, humanities, technical and medical (STM) publishing. Originally founded in 1842 ...

, . *

René Taton René Taton (4 April 1915 – 9 August 2004) was a French author, historian of science The history of science covers the development of science from ancient times to the present. It encompasses all three major branches of science: natura ...

(1962
Sur la naissance de Girard Desargues.
''Revue d'histoire des sciences et de leurs applications'' Tome 15 n°2. pp. 165–166.

External links

*
Gerard Desargues, Brouillon Project d'une Atteinte aux Evenemens des Rencontres du Cone avec un Plan
{{DEFAULTSORT:Desargues, Girard 1591 births 1661 deaths 17th-century French mathematicians 17th-century French architects French engineers French geometers Architects from Lyon

See also

References

External links