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Gaspard Monge

French mathematician who invented descriptive geometry and co-founded École Polytechnique.

Gaspard Monge

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Gaspard Monge, Comte de Péluse (9 May 1746 – 28 July 1818), was a French mathematician credited with inventing descriptive geometry—the mathematical foundation of technical drawing—and regarded as a founder of differential geometry. Alongside chemist Claude Louis Berthollet, chemist-physician Jean-Antoine Chaptal, and polymath Pierre-Simon Laplace, he helped establish Arts et Métiers ParisTech. During the French Revolution, he served as Minister of the Marine and played a key role in reforming French education, co-founding the École Polytechnique, France's top engineering school, with Lamblardie and Lazare Carnot.

Monge was born in Beaune, Côte-d'Or, to a merchant. He studied at the Oratorian college in Beaune, then in 1762 entered the Collège de la Trinité in Lyon, where, just a year after starting his studies, he became a physics teacher at seventeen. After finishing his education in 1764, he returned to Beaune and created a large-scale plan of the town, devising observation methods and building the necessary instruments; the plan, still held in the town library, was presented to the town. An engineer officer who saw it wrote to the commandant of the École Royale du Génie at Mézières, recommending Monge, who then obtained a draftsman job. Engineer and historian L. T. C. Rolt credited Monge with the birth of engineering drawing. While at the Royal School, he joined Freemasonry, initiated into the "L’Union parfaite" lodge.

Because the officer school admitted only aristocrats, Monge could not enroll. His manual skill was valued, but his mathematical abilities went unused. Still, he developed his ideas in his spare time and met Charles Bossut, the mathematics professor at the École Royale du Génie. Monge later recalled being tempted to tear up his drawings in frustration at being valued only for that skill. After a year, he was asked to produce a défilement plan for a fortification to optimize its defensive layout. Défilement in military terms means aligning fortification summits in a vertical plane to avoid gunfire from higher ground outside. A fort must shield defenders so that from any outside point, there is no direct line of sight into defensive positions. This safe area, the defilade, can be imagined by placing a lamp at each attacker's possible firing position; the shadow cast by the walls is the defilade. Défilement is a type of defilade where attackers may be elevated above ground, protecting defenders from artillery on raised siege platforms. Enfilade fire—where an attacker shoots along a straight wall segment, hitting all defenders on it—is especially dangerous. Computing défilement was complex because European forts, like star forts, had increasingly intricate geometry to counter artillery. Military engineer Vauban had proposed a slow manual method: soldiers at critical outside positions measured the polygonal line formed by the curtain wall's top edge, creating a sequence of triangles forming a polygonal dome; the space under it was the safe defilade. An established calculation method took a week, but Monge devised a drawing-based solution that took only two days. Initially rejected, his work was later recognized for its value. His method involved graphically constructing visibility cones—for a hemisphere H with a raised point p on the wall, the visibility cone at p is tangent to H with apex at p. This work launched descriptive geometry, kept as a French military secret for years. When Bossut left the École Royale du Génie, Monge replaced him in January 1769, and in 1770 he also became instructor in experimental physics.

In 1777, Monge married Cathérine Huart, who owned a forge, sparking his interest in metallurgy. In 1780 he joined the French Academy of Sciences and began his friendship with chemist C. L. Berthollet. In 1783, after leaving Mézières, he was appointed examiner of naval candidates following the death of É. Bézout. Though pressed by the minister to write a complete mathematics course, he refused to deprive Mme Bézout of her only income from her late husband's textbooks. In 1786 he published his *Traité élémentaire de la statique*.

The French Revolution transformed Monge's career. A strong supporter, in 1792, after the Legislative Assembly created...

born
9 May 1746, Beaune, Côte-d'Or, France
died
28 July 1818
field
Mathematics, engineering
nationality
French
known_for
Inventor of descriptive geometry, father of differential geometry, co-founder of

Verified Timeline

1806181818491992

Lore & Background

Monge was born at Beaune, the son of a merchant. He was educated at the college of the Oratorians at Beaune, then went to the Collège de la Trinité at Lyon, where one year after beginning studies he was made a teacher of physics at age seventeen. After finishing his education in 1764 he returned to Beaune, where he made a large-scale plan of the town, inventing methods of observation and constructing necessary instruments. An officer of engineers who saw it recommended him to the commandant of the École Royale du Génie at Mézières, and he was given a job as a draftsman. Because those studying at the officer school were exclusively drawn from the aristocracy, he was not allowed admission. His manual skill was highly regarded, but his mathematical skills were not made use of. At this time he came into contact with Charles Bossut, the professor of mathematics at the École Royale du Génie. 'I was a thousand times tempted,' he said long afterwards, 'to tear up my drawings in disgust at the esteem in which they were held, as if I had been good for nothing better.'

After a year at the École Royale, Monge was asked to produce a défilement plan for a fortification. The established method took a week, but Monge devised a way of solving the problems by using drawings that took only two days. At first his solution was not accepted, but upon examination the value of the work was recognised. The essence of his method was to graphically construct visibility cones. Continuing his researches, Monge began the subject of descriptive geometry, which was kept as a French military secret for years. After Bossut left the École Royale du Génie, Monge took his place in January 1769, and in 1770 he was also appointed instructor in experimental physics. In 1777, Monge married Cathérine Huart, who owned a forge, leading him to develop an interest in metallurgy. In 1780 he became a member of the French Academy of Sciences; his friendship with chemist C. L. Berthollet began at this time. In 1783, after leaving Mézières, he was appointed examiner of naval candidates. In 1786 he wrote and published his Traité élémentaire de la statique. During the French Revolution, Monge was a strong supporter. In 1792, on the creation by the Legislative Assembly of an executive council, Monge accepted the office of Minister of the Navy, and held this office from 10 August 1792 to 10 April 1793, when he resigned. When the Committee of Public Safety made an appeal to the academics to assist in the defence of the republic, he applied himself wholly, writing the Description de l'art de fabriquer les canons and Avis aux ouvriers en fer sur la fabrication de l'acier. He took a very active part in the measures for the establishment of the École Normale (which existed only during the first four months of the year 1795) and of the school for public works, afterwards the École Polytechnique, and was at each of them professor for descriptive geometry. From May 1796 to October 1797 Monge was in Italy with C.L. Berthollet and some artists to select the paintings and sculptures being levied from the Italians. While there he became friendly with Napoleon. Upon his return to France, he was appointed as the Director of the École Polytechnique, but early in 1798 he was sent to Italy on a mission that ended in the establishment of the short-lived Roman Republic. From there Monge joined Napoleon's expedition to Egypt, taking part with Berthollet in the scientific work of the Institut d'Égypte. They returned with him in 1799 to France. On the formation of the Sénat conservateur he was appointed a member of that body, with the title of count of Pelusium (Comte de Péluse), and he became the Senate conservateur's president during 1806–7. Then on the fall of Napoleon he had all of his honours taken away, and he was even excluded from the list of members of the reconstituted Institute. Napoleon Bonaparte stated Monge was an atheist. His remains were first interred in a mausoleum in Le Père Lachaise Cemetery in Paris and later transferred to the Panthéon in Paris. A statue portraying him was erected in Beaune in 1849. Monge's name is one of the 72 names inscribed on the base of the Eiffel Tower. Since 4 November 1992 the Marine Nationale operate the MRIS Monge, named after him.

Reader's Guide

Gaspard Monge's significance lies in his foundational contributions to geometry and engineering education. He is commonly presented as the inventor of descriptive geometry, which became the mathematical basis of technical drawing, and as the father of differential geometry. His method for solving fortification défilement problems using graphical constructions—rather than the established method's week of calculations—led to the development of descriptive geometry, a subject initially kept as a French military secret for years. Monge's work in reforming the French educational system was pivotal: he helped found, with Lamblardie and Lazare Carnot, the École Polytechnique, France's most prestigious engineering school, and taught descriptive geometry there. His lectures were published as Géométrie descriptive in 1799 from transcriptions of his lectures given in 1795. He also contributed to the establishment of Arts et Métiers ParisTech alongside Berthollet, Chaptal, and Laplace. During the French Revolution, he served as Minister of the Navy from 10 August 1792 to 10 April 1793 and applied his skills to the defence of the republic, writing on cannon manufacture and steel production. His later association with Napoleon brought him honours, including the title of count of Pelusium, and he became president of the Sénat conservateur during 1806–7. After Napoleon's fall he was stripped of all honours and excluded from the reconstituted Institute. His name is one of the 72 inscribed on the base of the Eiffel Tower, and a statue of him was erected in Beaune in 1849.

Did You Know?

Frequently Asked Questions

Who is Gaspard Monge?

Gaspard Monge (1746–1818) was a French mathematician and engineer widely credited as the creator of descriptive geometry and a foundational figure in differential geometry. He also held the noble title Comte de Péluse and was a key co-founder of École Polytechnique.

What did Gaspard Monge invent?

He is credited with devising descriptive geometry, the mathematical framework that underpins technical drawing and engineering design. His broader geometric work also laid early groundwork for what later developed into differential geometry.

What role did Gaspard Monge play during the French Revolution?

He served as Minister of the Marine and took an active part in restructuring France's educational institutions. Alongside Laplace, Berthollet, and Chaptal, he helped establish Arts et Métiers ParisTech as part of the revolutionary push to modernize technical training.

How did Gaspard Monge shape French higher education?

He was instrumental in founding École Polytechnique and in redesigning the French system of scientific and engineering instruction. His systematic teaching approach to geometry became a lasting model for technical pedagogy.

Where was Gaspard Monge born and when did he die?

He was born on 9 May 1746 in Beaune, in the Côte-d'Or region of France, and died on 28 July 1818. His life spanned the late eighteenth and early nineteenth centuries, encompassing both the Revolution and the Napoleonic era.

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