Auguste Bravais

{{Short description|French physicist}}

{{Infobox scientist

|name = Auguste Bravais

|image = Bravais2.gif

|caption = Auguste Bravais (c. 1850)

|birth_date = {{birth date|1811|8|23|df=y}}

|birth_place = Annonay, France

|death_date = {{death date and age|1863|3|30|1811|8|23|df=y}}

|death_place = Le Chesnay, France

|field = crystallography

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|alma_mater = École Polytechnique

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|known_for = Bravais lattices

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Auguste Bravais ({{IPA|fr|oɡyst bʁavɛ}}; 23 August 1811, Annonay, Ardèche – 30 March 1863, Le Chesnay, France) was a French physicist known for his work in crystallography, the conception of Bravais lattices, and the formulation of Bravais law. Bravais also studied magnetism, the northern lights, meteorology, geobotany, phyllotaxis, astronomy, statistics and hydrography.

He studied at the Collège Stanislas in Paris before joining the École Polytechnique in 1829, where he was a classmate of groundbreaking mathematician Évariste Galois, whom Bravais actually beat in a scholastic mathematics competition.Toti Rigatelli, L.: "Evariste Galois 1811–1832" {{ISBN|978-3-7643-5410-7}}, page 41 Towards the end of his studies he became a naval officer, and sailed on the Finistere in 1832 as well as the Loiret afterwards. He took part in hydrographic work along the Algerian Coast. He participated in the Recherche expedition and helped the Lilloise in Spitzbergen and Lapland.

Bravais taught a course in applied mathematics for astronomy in the Faculty of Sciences in Lyon, starting in 1840. He succeeded Victor Le Chevalier in the Chair of Physics at the Ecole Polytechnique from 1845 until 1856 when he was replaced by Henri Hureau de Sénarmont. In 1844 he published a paper on the statistical concept of correlation, and arrived at a definition of the correlation coefficient before Karl Pearson.Analyse Mathematique. [https://books.google.com/books?id=y3s_AAAAcAAJ&dq=Sur%20Les%20Probabilit%C3%A9s%20des%20Erreurs%20de%20Situation%20d'un%20Point&pg=PA1 Sur les probabilités des erreurs de situation d'un point] (tr. "On the probabilities of locational errors of a point") Mem. Acad. Roy. Sei. Inst. France, Sci. Math, et Phys., t. 9, p. 255–332. 1844Wright, S., 1921. Correlation and causation. Journal of agricultural research, 20(7), pp. 557–585 He is, however, best remembered for his work on Bravais lattices, particularly his 1848 discovery that there are 14 unique lattices in three-dimensional crystalline systems, correcting the previous scheme, with 15 lattices, conceived by Frankenheim three years before.Bravais, A.: Mémoire sur les systèmes formés par des points distribués regulièrement sur un plan ou dans l'espace, (tr. "Dissertation on systems formed by points regularly distributed on a plane or in space") Journal de l'Ecole Polytechnique 19: 1-128; in a German translation by C. et E. Blasius: Abhandlung über die Systeme von regelmässig auf einer Ebene oder im Raum vertheilten Punkten, Leipzig: Engelmann, 1897 (= Ostwalds Klassiker der exakten Wissenschaften (tr. "Ostwald's classics of the exact sciences"), Volume 90).

Bravais published a memoir about crystallography in 1847. A co-founder of the Société météorologique de France, he joined the French Academy of Sciences in 1854. Bravais also worked on the theory of observational errors, a field in which he is especially known for his 1846 paper "Mathematical analysis on the probability of errors of a point".

In one of his later studies, he investigated the conical pendulum and the effects upon it by the rotation of the Earth, an effect similar in principle to the (planar) Foucault pendulum. Soon after Foucault published his results, Bravais was inspired to experimentally test and to mathematically investigate the conical system, leading to the publication "Memoir on the influence exerted by the rotation of the Earth on the oscillatory motions of a conical pendulum", in 1854.A. Bravais: "Memoire sur l'influence qu'exerce la rotation de la Terre sur le mouvement d'un pendule à oscillations conique" [http://www.numdam.org/item?id=JMPA_1854_1_19__1_0 Journal de Mathematiques Pure et Appliquées, Vol 19, p.1-50, (1854)]

The mountain Bravaisberget, in Svalbard, is named after Bravais.{{cite web |url=http://placenames.npolar.no/stadnamn/Bravaisberget |title=Bravaisberget (Svalbard) |publisher=Norwegian Polar Institute |access-date=3 November 2013}}{{cite encyclopedia |encyclopedia=Norsk Fjelleksikon |title=Bravaisberget|editor-first=Per Roger |editor-last=Lauritzen |editor-link=Per Roger Lauritzen |page= |year=2009 |publisher=Friluftsforlaget |location=Arendal |language=Norwegian |isbn=978-82-91-49547-7}}