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Girard Desargues (; 21 February 1591 – September 1661) was a French 
Born in
Sur la naissance de Girard Desargues.
''Revue d'histoire des sciences et de leurs applications'' Tome 15 n°2. pp. 165–166.
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
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, pro ...
. Desargues' theorem
In projective geometry, Desargues's theorem, named after Girard Desargues, states:
:Two triangles are in perspective ''axially'' if and only if they are in perspective ''centrally''.
Denote the three vertices of one triangle by and , and tho ...
, the Desargues graph
In the mathematical field of graph theory, the Desargues graph is a distance-transitive, cubic graph with 20 vertices and 30 edges. It is named after Girard Desargues, arises from several different combinatorial constructions, has a high level ...
, 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.
Born in Lyon
Lyon,, ; Occitan: ''Lion'', hist. ''Lionés'' also spelled in English as Lyons, is the third-largest city and second-largest metropolitan area of France. It is located at the confluence of the rivers Rhône and Saône, to the northwest of t ...
, 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 r ...
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 prin ...
(Alhazen
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 prin ...
) 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.
See also
*Desarguesian plane
In mathematics, a projective plane is a geometric structure that extends the concept of a plane. In the ordinary Euclidean plane, two lines typically intersect in a single point, but there are some pairs of lines (namely, parallel lines) that d ...
, non-Desarguesian plane
In mathematics, a non-Desarguesian plane is a projective plane that does not satisfy Desargues' theorem (named after Girard Desargues), or in other words a plane that is not a Desarguesian plane. The theorem of Desargues is true in all projective s ...
*Desargues' theorem
In projective geometry, Desargues's theorem, named after Girard Desargues, states:
:Two triangles are in perspective ''axially'' if and only if they are in perspective ''centrally''.
Denote the three vertices of one triangle by and , and tho ...
*Desargues graph
In the mathematical field of graph theory, the Desargues graph is a distance-transitive, cubic graph with 20 vertices and 30 edges. It is named after Girard Desargues, arises from several different combinatorial constructions, has a high level ...
*Desargues configuration
In geometry, the Desargues configuration is a configuration of ten points and ten lines, with three points per line and three lines per point. It is named after Girard Desargues.
The Desargues configuration can be constructed in two dimensions f ...
*Desargues (crater)
Desargues is an ancient lunar impact crater that is located near the northern limb of the Moon, on the western hemisphere. It lies nearly due south of the crater Pascal, and southeast of Brianchon. The proximity of this crater to the limb means ...
* Perspective (graphical)
Linear or point-projection perspective (from la, perspicere 'to see through') is one of two types of 3D projection, graphical projection perspective in the graphic arts; the other is parallel projection. Linear perspective is an approximate r ...
/ Perspective (visual)
Linear or point-projection perspective (from la, perspicere 'to see through') is one of two types of graphical projection perspective in the graphic arts; the other is parallel projection. Linear perspective is an approximate representation, ...
*Optics
Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviole ...
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 in ...
, .
* 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 ...
(1962Sur la naissance de Girard Desargues.
''Revue d'histoire des sciences et de leurs applications'' Tome 15 n°2. pp. 165–166.
External links
*{{DEFAULTSORT:Desargues, Girard 1591 births 1661 deaths 17th-century French mathematicians 17th-century French architects French engineers French geometers Architects from Lyon