Editing Augustin-Jean Fresnel (section)

== Early life ==

[[File:Augustin Fresnel buste Broglie.jpg|thumb|Monument to Augustin Fresnel on the facade of his birthplace at 2&nbsp;Rue Augustin Fresnel, [[Broglie, Eure|Broglie]] (facing Rue Jean François Mérimée),{{r|martan-2014}} inaugurated on 14 September 1884.{{r|bibmed|academie}} The inscription, when translated, says:<br>"Augustin Fresnel, engineer of Bridges and Roads, member of the Academy of Sciences, creator of lenticular lighthouses, was born in this house on 10 May 1788. The theory of light owes to this emulator of Newton the highest concepts and the most useful applications."{{hsp}}{{r|martan-2014|perchet-2011}}]]

=== Family ===

Augustin-Jean Fresnel (also called Augustin Jean or simply Augustin), born in Broglie, [[Normandy]], on 10 May 1788, was the second of four sons of the architect Jacques Fresnel{{r|favre}} and his wife Augustine, ''née'' Mérimée.{{r|jeanelie}} The family moved twice—in 1789/90 to [[Cherbourg-Octeville|Cherbourg]],<ref>Levitt (2013, p.&nbsp;23) says "in 1790". Silliman (1967, p.&nbsp;7) says "by 1790". Boutry (1948, p.&nbsp;590) says the family left Broglie in 1789.</ref> and in 1794{{hsp}}<ref name=silliman-p166>Silliman, 2008, p.&nbsp;166.</ref> to Jacques's home town of [[Mathieu, Calvados|Mathieu]], where Augustine would spend 25 years as a widow,<ref>Boutry, 1948, p.&nbsp;590.</ref> outliving two of her sons.

The first son, Louis, was admitted to the [[École Polytechnique]], became a lieutenant in the artillery, and was killed in action at [[Jaca]], Spain.{{r|jeanelie}} The third, Léonor,{{r|favre}} followed Augustin into civil [[engineer]]ing, succeeded him as secretary of the Lighthouse Commission,<ref>Levitt, 2013, p.&nbsp;99.</ref> and helped to edit his collected works.<ref>Fresnel, 1866–70.</ref> The fourth, [[Fulgence Fresnel]], became a linguist, diplomat, and orientalist, and occasionally assisted Augustin with negotiations.<ref>Levitt, 2013, p.&nbsp;72.</ref><ref name=":0">{{Cite book|last=Pillet|first=Maurice (1881–1964)|url=https://gallica.bnf.fr/ark:/12148/bpt6k5730001x|title=L'expédition scientifique et artistique de Mésopotamie et de Médie, 1851–1855|date=1922|publisher=Libraire Ancienne Honoré Champion |location=Accessed from Gallica – Bibliothèque nationale de France|language=FR}}</ref>  Fulgence died in Bagdad in 1855 having led a mission to explore Babylon.<ref name=":0" />

Madame Fresnel's younger brother, [[Jean François "Léonor" Mérimée]],{{r|jeanelie}} father of the writer [[Prosper Mérimée]], was a [[painter]] who turned his attention to the [[chemistry]] of painting. He became the Permanent Secretary of the [[École des Beaux-Arts]] and (until 1814) a professor at the École Polytechnique,<ref>Levitt, 2009, p.&nbsp;49.</ref> and was the initial point of contact between Augustin and the leading optical physicists of the day {{crossreference|(see [[#Rêveries|below]])}}.

=== Education ===

The Fresnel brothers were initially home-schooled by their mother. The sickly Augustin was considered the slow one, not inclined to memorization;<ref>Levitt, 2013, pp.&nbsp;24–25; Buchwald, 1989, p.&nbsp;111.</ref> but the popular story that he hardly began to read until the age of eight is disputed.<ref>That age was given by Arago in his elegy (Arago, 1857, p.&nbsp;402) and widely propagated (''Encyclopædia Britannica'', 1911; Buchwald, 1989, p.&nbsp;111; Levitt, 2013, p.&nbsp;24; etc.). But the reprint of the elegy at the end of Fresnel's collected works bears a footnote, presumably by Léonor Fresnel, saying that "eight" should be "five or six", and regretting "the haste with which we had to collect the notes that were belatedly requested for the biographical part of this speech" (Fresnel, 1866–70, vol.&nbsp;3, p.&nbsp;477n). Silliman (1967, p.&nbsp;9n) accepts the correction.</ref> At the age of nine or ten he was undistinguished except for his ability to turn tree-branches into toy bows and guns that worked far too well, earning himself the title ''l'homme de génie'' (the man of genius) from his accomplices, and a united crackdown from their elders.<ref>Levitt, 2013, p.&nbsp;25; Arago, 1857, p.&nbsp;402; Boutry, 1948, pp.&nbsp;590–591.</ref>

In 1801, Augustin was sent to the ''École Centrale'' at [[Caen]], as company for Louis. But Augustin lifted his performance: in late 1804 he was accepted into the École Polytechnique, being placed 17th in the entrance examination.<ref>Levitt, 2013, pp.&nbsp;25–26; Silliman, 1967, pp.&nbsp;9–11.</ref>{{r|chisholm-1911-fresnel}} As the detailed records of the École Polytechnique begin in 1808, we know little of Augustin's time there, except that he made few if any friends and—in spite of continuing poor health—excelled in drawing and geometry:<ref>Boutry, 1948, p.&nbsp;592.</ref> in his first year he took a prize for his solution to a geometry problem posed by [[Adrien-Marie Legendre]].<ref>Silliman, 1967, p.&nbsp;14; Arago, 1857, p.&nbsp;403. Fresnel's solution was printed in the ''Correspondance sur l'École polytechnique'', No.&nbsp;4 (June–July 1805), [https://books.google.com/books?id=IbU-AAAAcAAJ&pg=PA78 pp.&nbsp;78–80], and reprinted in Fresnel, 1866–70, vol.&nbsp;2, pp.&nbsp;681–684. Boutry (1948, p.&nbsp;591) takes this story as referring to the entrance examination.</ref> Graduating in 1806, he then enrolled at the [[École des ponts ParisTech|École Nationale des Ponts et Chaussées]] (National School of Bridges and Roads, also known as "ENPC" or "École des Ponts"), from which he graduated in 1809, entering the service of the [[Corps of Bridges, Waters and Forests|Corps des Ponts et Chaussées]] as an ''ingénieur ordinaire aspirant'' (ordinary engineer in training). Directly or indirectly, he was to remain in the employment of the "Corps des Ponts" for the rest of his life.<ref>Levitt, 2013, pp.&nbsp;26–27; Silliman, 2008, p.&nbsp;166; Boutry, 1948, pp.&nbsp;592,{{tsp}}601.</ref>

=== Religious formation ===
Fresnel's parents were [[Catholic Church|Roman Catholics]] of the [[Jansenism|Jansenist]] sect, characterized by an extreme [[Augustine of Hippo|Augustinian]] view of [[original sin]]. Religion took first place in the boys' home-schooling. In&nbsp;1802, his mother said:
{{Blockquote|I pray God to give my son the grace to employ the great talents, which he has received, for his own benefit, and for the God of all. Much will be asked from him to whom much has been given, and most will be required of him who has received most.<ref>Kneller, tr.&nbsp;Kettle, 1911, p.&nbsp;147.&nbsp; Kneller interprets the quote as referring to Augustin; but Verdet (in Fresnel, 1866–70, vol.&nbsp;1, pp.&nbsp;xcviii–xcix), cited by Silliman (1967, p.&nbsp;8), gives it a different context, referring to Louis's academic success.</ref>}}
Augustin remained a Jansenist.<ref>Levitt, 2013, p.&nbsp;24.</ref> He regarded his intellectual talents as gifts from God, and considered it his duty to use them for the benefit of others.<ref>Kneller, 1911, p.&nbsp;148.</ref> According to his fellow engineer Alphonse Duleau, who helped to nurse him through his final illness, Fresnel saw the study of nature as part of the study of the power and goodness of God. He placed virtue above science and genius. In his last days he prayed for "strength of soul," not against death alone, but against "the interruption of discoveries… of which he hoped to derive useful applications."{{hsp}}<ref>Kneller, 1911, pp.&nbsp;148–149n; cf.&nbsp;Arago, 1857, p.&nbsp;470.</ref>

Jansenism is considered [[heresy|heretical]] by the Roman Catholic Church, and Grattan-Guinness suggests this is why Fresnel never gained a permanent academic teaching post;<ref>Grattan-Guinness, 1990, pp.&nbsp;914–915.</ref> his only teaching appointment was at the [[Athénée de Luxembourg|Athénée]] in the winter of 1819–20.{{r|brock-1909}}<ref>Fresnel, 1866–70, vol.&nbsp;1, p.&nbsp;xcvii.</ref> The article on Fresnel in the ''[[Catholic Encyclopedia]]'' does not mention his Jansenism, but describes him as "a deeply religious man and remarkable for his keen sense of duty."{{hsp}}{{r|brock-1909}}