**Louis Lefébure de Fourcy** was a French mathematician who taught at the École Polytechnique. He is best known for having refused Galois entry to the school.

- Its wealth came from plantation agriculture and it was in this business that Étienne-Louis worked.
- Étienne-Louis Lefebvre died in Saint-Domingue in 1794.
- Among those who entered in the same year, we mention François Arago, Charles-Julien Brianchon and Claude-Louis Mathieu.
- The three years that Lefébure de Fourcy spent at the École Polytechnique were, of course, years during which France was in the grip of the French Revolution.
- One consequence of this was that Lefébure, as we shall name him for the remainder of this biography, dropped the aristocratic "de Fourcy" in his name.
- France had adopted the revolutionary calendar so Lefébure and his fellow students studied for eight and a half days in each 10 day week at the École Polytechnique.
- Lefébure graduated from the École Polytechnique in 1805 and enrolled in the École d'artillerie in Metz.
- Things had changed since he was a student.
- It had also moved from the buildings it had occupied when Lefébure was a student, to occupy two colleges not far from the Panthéon.
- He was awarded a doctorate in 1811 after submitting two theses.
- He dedicated these works to Sylvestre Lacroix who must have acted as an advisor.
- Around this time there were major changes in France with the defeat of Napoleon in 1814 and the restoration of the monarchy.
- He became a répétiteur in descriptive geometry in 1815 and, from 1817 to 1820, he was an examiner in descriptive geometry and the 'graphic arts'.
- In addition to his duties at the École Polytechnique, Lefébure was appointed to teach mathematics at the College Louis-le-Grand in December 1814.
- Charles Lefébure de Fourcy became Inspector General of Roads and Bridges and participated in the building of the Suez Canal.
- At Louis-le-Grand, Louis Lefébure de Fourcy was promoted to teach the special class in October 1817.
- Of the 21 students in the special class of 1817-18, one was the poet, novelist, and dramatist, Victor Hugo.
- He crossed the class in a stride, giving rapid demonstrations, streaking the table with lines.
- The Royal College of Saint-Louis was founded in 1820 and Lefébure was appointed as professor of mathematics.
- Lefébure taught at the College of Saint-Louis for five years, leaving in December 1825 when he was appointed as an assistant to Sylvestre Lacroix at the faculty of Science in Paris.
- The country was divided into four regions, and also Paris, and an examiner travelled in a region for some weeks during the summer to interview promising young boys nominated by local families or dignitaries.
- The École Polytechnique declared that being an admissions examiner was incompatible with teaching, so Lefébure had free time which he devoted to writing student textbooks.
- He began publishing a series of books in 1827 and over the next few years various texts appeared: Leçons de géométrie analytique Ⓣ(Lessons in analytic geometry) (1827), Théories du plus grand commun diviseur algébrique et de l'élimination entre deux équations à deux inconnue Ⓣ(Theories of the algebraic greatest common divisor and the elimination between two equations with two unknowns) (1827), Traité de géométrie descriptive Ⓣ(Treatise on descriptive geometry) (2 vols.
- 1829-1830), Éléments de trigonométrie Ⓣ(Elements of trigonometry) (1830), Leçons d'algèbre Ⓣ(Algebra lessons) (1833).
- Traité de géométrie descriptive Ⓣ(Treatise on descriptive geometry) was essentially translated into English by Thomas Grainger Hall, of King's College, London, when he wrote his book The elements of descriptive geometry (1841).
- In England it was unknown, as a branch of instruction, until lectures were given upon it by Mr Bradley, in the Engineering Department of King's College; and the present work has been undertaken to supply the students with a text book, that by it they might the more profitably attend to what they heard in the lecture room: and as an elementary book was necessary for beginners, it has been thought expedient to place before the students, in an English dress, one which has stood the test of experience.
- The treatise on Descriptive geometry, by Mr Lefébure de Fourcy has, therefore, been selected, and the following pages are, for the most part, translated from it.
- Lefébure's text was very popular and in 1881 the eighth edition of the book was published.
- By 1858 a seventh edition of Éléments de trigonométrie Ⓣ(Elements of trigonometry) was in print while Leçons d'algèbre Ⓣ(Algebra lessons), much revised over the years, was in its tenth edition in 1893.
- However, other have criticised them for being "totally devoid of original ideas." It would be tempting to believe that their popularity might have come from the fact that many students trying to gain entry to top education institutions had to be examined by Lefébure.
- However, the popularity of these texts continued long after Lefébure ceased being an examiner.
- As an examiner, Lefébure had a reputation which made the candidates extremely fearful.
- Together with Louis Benjamin Francoeur and Jean Nicolas Pierre Hachette, Lefébure examined Évariste Galois for his baccalaureate on 14 December 1828.
- By two votes to one, the decision of the examiners was that Galois should not enter the École Polytechnique.
- The professor cannot be considered a benevolent reviewer, his voice is harsh, his tone is dismissive, also he questioned in a very firm stiff manner, and showed no mercy for any errors of logic.
- It was not only with students that Lefébure was severe and demanding, but he behaved in the same way towards his own sons.
- In May 1843 Lacroix died and, in July of the same year, Lefébure succeeded him in the chair of differential and integral calculus at the Faculty of Science in Paris.
- It was around this time that his health began to fail and Lefébure retired from the Faculty of Science in September 1863.

Born 25 August 1787, Port-au-Prince, Saint-Domingue, now Haiti. Died 12 March 1869, Paris, France.

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Astronomy, Origin Haiti

**O’Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive