Content deleted Content added
Test. |
Test. |
||
Line 64:
=== Family ===
Augustin-Jean Fresnel (also called Augustin Jean or simply Augustin), born in [[Broglie, Eure|Broglie]], [[Normandy]], on 10 May 1788, was the second of four sons of the architect Jacques Fresnel (1755–1805){{r|favre}} and his wife Augustine, ''née'' Mérimée (1755?–1833).{{r|jeanelie}} In 1790, following the [[French Revolution|Revolution]], Broglie became part of the [[Departments of France|département]] of [[Eure]]. The family moved twice — in 1790 to [[Cherbourg-Octeville|Cherbourg]],<ref>Levitt, 2013, p.{{hsp}}23.</ref> and in 1794{{r|silliman-2008|p=166}} to Jacques' home town of [[Mathieu, Calvados|Mathieu]], where Madame Fresnel remained as a widow,{{r|boutry-1948|p=590}} outliving two of her sons.
The first son, Louis (1786–1809), was admitted to the [[École Polytechnique]], became a lieutenant in the artillery, and was killed at [[Jaca]], [[Spain]], the day before his 23rd birthday.{{r|jeanelie}} The third, Léonor (1790–1869),{{r|favre}} followed Augustin into civil [[engineer]]ing, succeeded him as Secretary of the Lighthouse Commission,<ref>Levitt, 2013, p.{{hsp}}99.</ref> and helped to edit his collected works.<ref>Fresnel, 1866–70</ref>. The fourth, [[Fulgence Fresnel]] (1795–1855), became a noted linguist, diplomat, and orientalist, and occasionally assisted Augustin with negotiations.<ref>Levitt, 2013, p.{{hsp}}72.</ref>
Line 72:
=== Education ===
Augustin and his brothers were initially home-schooled by their mother. Augustin, a sickly child, was considered the slow one, just beginning to read at the age of eight. At ten he was undistinguished except for his ability to turn tree-branches into toy bows and cannon that were too dangerous to play with, provoking a crackdown from his elders.<ref>Levitt, 2013, pp.{{nnbsp}}24–5.</ref>{{r|boutry-1948|p=590–91}}
In 1801, Augustin was sent to the ''École centrale'' at [[Caen]], as company for Louis. But Augustin lifted his performance: in 1804 he was accepted into the École Polytechnique, being placed 17th in the entrance examination, in which his solutions to geometry problems impressed the examiner, [[Adrien-Marie Legendre]]. As the surviving records of the École Polytechnique begin in 1808, we know little of Augustin Fresnel's time there, except that he apparently excelled in geometry and drawing — in spite of continuing poor health — and made few if any friends. Graduating in 1806, he 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 ordinair aspirant'' (ordinary engineer in training). Directly or indirectly, the "Corps des Ponts" would be his sole or main employer for the rest of his life.{{r|chisholm-1911-fresnel}}<ref>Levitt, 2013, pp.{{nnbsp}}25–7.</ref>{{r|boutry-1948|p=591–2,601}}
=== Influence of religion ===
Line 174:
=== Prototypes ===
Meanwhile, in June 1819, Fresnel was engaged by the ''Commission des phares'' (Commission of Lighthouses) on the recommendation of Arago (a member of the Commission since 1813), to review possible improvements in lighthouse illumination.{{r|tag-fres}} The Commission had been established by Napoleon in 1811, and placed under the
On 29 August 1819, unaware of the Buffon-Condorcet-Brewster proposal,{{r|ripley-dana-1879|tag-fres}} Fresnel presented his first report, in which he recommended what he called ''lentilles à échelons'' (lenses by steps) to replace the reflectors then in use, which reflected only about half of the incident light.<ref>Levitt, 2013, pp.{{nnbsp}}56,58.</ref> One of the assembled commissioners, [[Jacques Charles]], recalled Buffon's suggestion. Fresnel was disappointed to discover that he had again "broken through an open door".<ref>Levitt, 2013, p.{{hsp}}59.</ref> But, whereas Buffon's version was [[Lens (optics)#Types of simple lenses|biconvex]] and in one piece, Fresnel's was [[Lens (optics)#Types of simple lenses|plano-convex]] and made of multiple prisms for easier construction. With an official budget of 500 francs, Fresnel approached three manufacturers. The third, François Soleil, found a way to remove defects by reheating and remolding the glass. Arago assisted Fresnel with the design of a modified [[Argand lamp]] with concentric wicks (a concept that Fresnel attributed to [[Benjamin Thompson|Count Rumford]]{{r|fresnel-1822-phares|p=11}}), and accidentally discovered that fish glue was heat-resistant, making it suitable for use in the lens. The prototype, with a lens panel 55cm square, containing 97 polygonal (not annular) prisms, was finished in March 1820 — and so impressed the Commission that Fresnel was asked for a full eight-panel version. Completed a year later, largely at Fresnel's personal expense, this model had panels 72cm square. In a public spectacle on the evening of 13 April 1821, it was demonstrated by comparison with the most recent reflectors, which it suddenly rendered obsolete.<ref>Levitt, 2013, pp.{{nnbsp}}59–66.</ref>
Line 184:
[[File:Fresnel lighthouse lens diagram.png|thumb|246px|Cross-section of a first-generation Fresnel lighthouse lens, with sloping mirrors ''m,n'' above and below the refractive panel ''RC'' (with central segment ''A''). If the cross-section in every vertical plane through the lamp ''L'' is the same, the light is spread evenly around the horizon.]]
Fresnel's next lens was a rotating apparatus with eight "bull's-eye" panels, made in annular arcs by [[Saint-Gobain]],<ref>Levitt, 2013, p.{{hsp}}71.</ref>
In 1824, Fresnel designed the first ''fixed'' lens — for spreading light evenly around the horizon{{r|tag-fres}} while minimizing waste above or below. This had the familiar reflecting (''catoptric'') rings above and below the refracting (''dioptric'') panels. But the curved refracting surfaces were segments of toroids about a common vertical axis, so that the dioptric panel looked like a cylindrical drum and the entire apparatus looked like a beehive.
Line 227:
== Decline and death ==
[[File:Tombe d'Augustin Fresnel - Père Lachaise.JPG|thumb|Fresnel's grave at [[Père Lachaise Cemetery]], Paris, photographed in 2014
Rumford medal, which was
presented to him upon his deathbed by his friend
and collaborator Arago.{{r|ripley-dana-1879}}
Fresnel is buried at [[Père Lachaise Cemetery]], Paris. The inscription on his headstone is partly [[commons:category:Grave of Augustin Fresnel (Père-Lachaise, division 14)|eroded away]]; the legible part says, when translated, "To the memory of Augustin Jean FRESNEL, member of the Institut de France|Institute of France]]."
{{clear}}
Line 251 ⟶ 253:
* MacCullagh, as early as 1830, wrote that Fresnel's mechanical theory of double refraction "would do honour to the sagacity of Newton".{{r|macCullagh-1830|p=78}}.
* Lloyd, after his experimental confirmation of conical refraction, lived for another 48 years. In 1834, in his ''Report on the progress and present state of physical optics'' for the [[British Association for the Advancement of Science|British Science Association]], he wrote:<blockquote>The theory of Fresnel… will, I am persuaded, be regarded as the finest generalization in physical science which has been made since the discovery of universal gravitation.{{r|lloyd-1834|p=382}}</blockquote>In 1841 Lloyd published his ''Lectures on the Wave-theory of Light'', in which he described Fresnel's transverse-wave theory as "the noblest fabric which has ever adorned the ___domain of physical science, Newton's system of the universe alone excepted."{{r|lloyd-1841}} The same description was retained in the "second edition", published under the title ''Elementary Treatise on the Wave-theory of Light'' (1857), and in the "third edition",{{r|lloyd-1873}} which appeared in the same year as Maxwell's ''Treatise on Electricity and Magnetism'' (1873).<br style="margin-bottom: 1ex;" />
* [[William Whewell]], in all three editions of his ''History of the Inductive Sciences'' (1837, 1847, and 1857), at the end of Book IX, compared the histories of physical astronomy and physical optics and concluded:{{quote|It would, perhaps, be too fanciful to attempt to establish a parallelism between the prominent persons who figure in these two histories. If we were to do this, we must consider Huyghens and Hooke as standing in the place of Copernicus, since, like him, they announced the true theory, but left it to a future age to give it development and mechanical confirmation; Malus and Brewster, grouping them together, correspond to [[Tycho Brahe]] and [[Johannes Kepler|Kepler]], laborious in accumulating observations, inventive and happy in discovering laws of phenomena; and Young and Fresnel combined, make up the Newton of optical science.{{r|whewell-1857|p=370-71}} }}
Line 273 ⟶ 275:
<ref name=appleton-1861>D. Appleton & Co., "Sea-lights", ''Dictionary of Machines, Mechanics, Engine-work, and Engineering'', 1861, [https://archive.org/details/appletonsdiction02appl v.2].</ref>
<ref name=boutry-1948>G.-A. Boutry, "Augustin Fresnel: His time, life and work, 1788–1827", ''Science Progress'', v.36, no.144 (October 1948), pp. 587–604; [http://www.jstor.org/stable/43413515 jstor.org/stable/43413515].</ref>
<ref name=brock-1909>H.M. Brock, [[s:Catholic Encyclopedia (1913)/Augustin-Jean Fresnel|"Fresnel, Augustin-Jean"]], ''Catholic Encyclopedia'', 1907–12, v.6 (1909).</ref>
| |||