Editing Augustin-Jean Fresnel (section)

== Decline and death ==
[[File:Père-Lachaise - Division 14 - Fresnel 01.jpg|thumb|upright|Fresnel's grave at Père Lachaise Cemetery, Paris, photographed in 2018]]

Fresnel's health, which had always been poor, deteriorated in the winter of 1822–1823, increasing the urgency of his original research, and (in&nbsp;part) preventing him from contributing an article on polarization and double refraction for the ''[[Encyclopædia Britannica]]''.<ref>Levitt, 2013, pp.&nbsp;75–76; Silliman, 1967, pp.&nbsp;276–277.</ref> The memoirs on circular and elliptical polarization and optical rotation,{{r|fresnel-1822z}} and on the detailed derivation of the Fresnel equations and their application to total internal reflection,{{r|fresnel-1823a}} date from this period. In the spring he recovered enough, in his own view, to supervise the lens installation at Cordouan. Soon afterwards, it became clear that his condition was [[tuberculosis]].<ref name=levitt-p97 />

In 1824, he was advised that if he wanted to live longer, he needed to scale back his activities. Perceiving his lighthouse work to be his most important duty, he resigned as an examiner at the École Polytechnique, and closed his scientific notebooks. His last note to the Académie, read on 13 June 1825, described the first [[radiometer]] and attributed the observed repulsive force to a temperature difference.<ref>Boutry, 1948, pp.&nbsp;601–602; Silliman, 1967, p.&nbsp;278; Fresnel, 1866–70, vol.&nbsp;2, pp.&nbsp;667–672.</ref> Although his fundamental research ceased, his advocacy did not; as late as August or September 1826, he found the time to answer [[John Herschel|Herschel's]] queries on the wave theory.<ref>Fresnel, 1866–70, vol.&nbsp;2, pp.&nbsp;647–660.</ref> It was Herschel who recommended Fresnel for the Royal Society's Rumford Medal.<ref>Boutry, 1948, p.&nbsp;603.</ref>

Fresnel's cough worsened in the winter of 1826–1827, leaving him too ill to return to Mathieu in the spring. The Académie meeting of 30 April 1827 was the last that he attended. In early June he was carried to [[Ville-d'Avray]], {{nowrap|{{convert|12|km}}}} west of Paris. There his mother joined him. On 6 July, Arago arrived to deliver the Rumford Medal. Sensing Arago's distress, Fresnel whispered that "the most beautiful crown means little, when it is laid on the grave of a friend." Fresnel did not have the strength to reply to the Royal Society. He died eight days later, on [[Bastille Day]].<ref>Levitt, 2013, p.&nbsp;98; Silliman, 1967, p.&nbsp;279; Arago, 1857, p.&nbsp;470; Boutry, 1948, {{nowrap|pp.{{tsp}}602–603}}.</ref>

He is buried at [[Père Lachaise Cemetery]], Paris. The [[:File:Père-Lachaise - Division 14 - Fresnel 01.jpg|inscription on his headstone]] is partly eroded away; the legible part says, when translated, "To the memory of Augustin Jean Fresnel, member of the [[Institut de France|Institute of France]]".
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