Girard Desargues

Girard Desargues , alias S.G.D.L. (the Sieur Girard Desargues Lyonnois as it signs itself its writings) is a geometrician and Architecte French born with Lyon the March 2nd 1591 and deceased in Lyon in October 1661, considered as founder of the projective Géométrie: he gave his name to the Configuration of Desargues and the Théorème of Desargues.

Youth

One has only scattered documents on the life of Desargues, and the former years with 1630 are badly known. Desargues was apparently the third of six children: Jean and Christophe, his two older brothers, lawyers at the Parliament of Paris, then Antoine, Francoise and Catherine. In 1621, he is silk trader in Lyon, but in 1626, he accomplished already a voyage in Flandres, and applies for the town of Paris a patent for the construction and the exploitation of fountains. In 1628, its two elder has just died, he goes extremely to inherit the family goods. The participation of Desargues in the Siège of the La Rochelle (1627-1628) plausible, but is supported forever by documentary sources.

Installation in Paris

Desargues settles in Paris about 1630. In 1634, the father Mersenne evokes in his letters a treaty of prospect that Desargues is writing, but its first treaties go back to 1636. Transmitted to the members of the Academy of Mersenne, these works are appreciated of Fermat and Descartes in particular, but the same does not apply for from there Brouillon project of an attack to the evenemens of the meetings of the cone with a plan, written in a language borrowed from the " language of bois" companions carpenters, i.e. signs of marking of the structural members, directing them towards the building site. This small treaty, exploiting constructions of the conical Prospect to study the properties of the Conical S (ellipse, parabola, hyperbole) introduced for the first time the concepts of duality point-right-hand side and Not ad infinitum. Descartes considers the methods geometrical of Desargues but judge the style of the booklet unnecessarily obscure and provocant, because the priority must be the clarity of the expression. However, Descartes disparages as the Essay for Conical the of the young person Blaise Pascal, by saying as this last especially benefitted from the lessons of Desargues.

Quarrel with Beaugrand

In 1636, the Secretary of King Jean de Beaugrand had published a treaty entitled Geostatice on the form of the law of gravitation, treaty whose demonstrations were disputed inter alia by Descartes, Guy of the Brush, and Desargues. Beaugrand in its turn criticized the draft-project of Desargues by disputing the originality of the proposals of the treaty, borrowed from the Coniques of Apollonius. The quarrel envenima until the death of Beaugrand in 1642.

Application to arts

As from 1639, Girard Desargues opens a course deprived to teach with the craftsmen (stone masons, carpenters, engravers, manufacturer of instruments) the applications of his technique of linear prospect, which implicitly introduces (by the fact that the reducing parallels contribute ad infinitum) and for the first time the idea of a point ad infinitum. The engraver Abraham Bump, inter alia, attends this institution as from 1641, and consequently becomes the most faithful propagandist of the method of the Lyons geometrician. On the other hand, the architects and the painters dispute its methods. Actually a conflict whose amplitude escapes to us is engaged, that it is necessary to parallel with the combat that Abraham Bosse against the Academy delivers. Désargues is wounded with the throat after an attempted murder of a companion of the duty, at one moment when the trade-guild is divided between Protestants and catholics, and that Désargues takes clearly party for the recognition of the knowledge of the art of the feature transmitted by the trade-guild, and against the monopolization of sciences by the clerks. The polemic continues well after the death of Désargues where its theorems are fought by the Jesuits until the XVIII° century, after which they will not be even known any more.

Return to Lyon

The disorders of the Sling encourage Desargues to regain Lyon in 1648. It is undoubtedly at that time that it takes part in the construction of certain buildings, like the frontage of the Town hall. In 1651, it builds the Hotel Olivier de Senozan , located at number 1 of the Place Bellecour. This hotel, today hotel of Europe placed since most of the sovereigns of passage to Lyon.

A letter of Huygens gives to understand that in 1660, Desargues however had regained Paris because it took part in the Mylon academy.

Works of Desargues

Example of the one in the universal ways of the SGDL concerning the practique one of the prospect without emploier no tierce point… (1636), Paris, 12 p.+ 1 pl.
Draft-project of an attack to the evenemens of the meetings of the cone with a plan (1639), Paris, 30 p.
Draft-project of example in a universal way concerning the practique one of the traict to evidence for the cut of the stones (1640), Paris, 4 p.+ 5 pl.
Draft-project of the SGDL concerning a universal manner to pose the style and to trace the lines of Quadran to the rays of the sun… (1640), leaflet

References

Rene Taton the mathematical work of Girard Desargues (1951, rééd. 1988 by Inst. Interdisc. of And. Épist.), ED. VRIN, Paris, ISBN 2-7116-0694-5
Dhombres, Sakharovitch and Al Desargues in its time (1994), ED. Albert Blanchard, Paris, ISBN 2-853-67188-7

See too

Internal bond

Mathematical in Europe at the XVIIe century
Theorem of Arguesian Desargues
Geometry

External bonds

Biography in French
Biography in English

Random links: