Émile Lemoine field of work geometry
Émile Michel Hyacinthe Lemoine (French: [emil ləmwan]; 22 November 1840 – 21 February 1912) was a French civil engineer and a mathematician, a geometer in particular. He was educated at a variety of institutions, including the Prytanée National Militaire and, most notably, the École Polytechnique. Lemoine taught as a private tutor for a short period after his graduation from the latter school.
Lemoine is best known for his proof of the existence of the Lemoine point (or the symmedian point) of a triangle. Other mathematical work includes a system he called Géométrographie and a method which related algebraic expressions to geometric objects. He has been called a co-founder of modern triangle geometry, as many of its characteristics are present in his work.
For most of his life, Lemoine was a professor of mathematics at the École Polytechnique. In later years, he worked as a civil engineer in Paris, and he also took an amateur's interest in music. During his tenure at the École Polytechnique and as a civil engineer, Lemoine published several papers on mathematics, most of which are included in a fourteen-page section in Nathan Altshiller Court's College Geometry. Additionally, he founded a mathematical journal titled, L'Intermédiaire des Mathématiciens.Later years (1888–1912)
During his tenure as a civil engineer, Lemoine wrote a treatise concerning compass and straightedge constructions entitled, La Géométrographie ou l'art des constructions géométriques, which he considered his greatest work, despite the fact that it was not well-received critically. The original title was De la mesure de la simplicité dans les sciences mathématiques, and the original idea for the text would have discussed the concepts Lemoine devised as concerning the entirety of mathematics. Time constraints, however, limited the scope of the paper. Instead of the original idea, Lemoine proposed a simplification of the construction process to a number of basic operations with the compass and straightedge. He presented this paper at a meeting of the Association Française in Oran, Algeria in 1888. The paper, however, did not garner much enthusiasm or interest among the mathematicians gathered there. Lemoine published several other papers on his construction system that same year, including Sur la mesure de la simplicité dans les constructions géométriques in the Comptes rendus of the Académie française. He published additional papers on the subject in Mathesis (1888), Journal des mathématiques élémentaires (1889), Nouvelles annales de mathématiques (1892), and the self-published La Géométrographie ou l'art des constructions géométriques, which was presented at the meeting of the Association Française in Pau (1892), and again at Besançon (1893) and Caen (1894).After this, Lemoine published another series of papers, including a series on what he called transformation continue (continuous transformation), which related mathematical equations to geometrical objects. This meaning stood separately from the modern definition of transformation. His papers on this subject included, Sur les transformations systématiques des formules relatives au triangle (1891), Étude sur une nouvelle transformation continue (1891), Une règle d'analogies dans le triangle et la spécification de certaines analogies à une transformation dite transformation continue (1893), and Applications au tétraèdre de la transformation continue (1894).In 1894, Lemoine co-founded another mathematical journal entitled, L'intermédiaire des mathématiciens along with Charles Laisant, a friend whom he met at the École Polytechnique. Lemoine had been planning such a journal since early 1893, but thought that he would be too busy to create it. At a dinner with Laisant in March 1893, he suggested the idea of the journal. Laisant cajoled him to create the journal, and so they approached the publisher Gauthier-Villars, which published the first issue in January 1894. Lemoine served as the journal's first editor, and held the position for several years. The year after the journal's initial publication, he retired from mathematical research, but continued to support the subject. Lemoine died on 21 February 1912 in his home city of Paris.
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