25 Facts About Augustin Fresnel


In 1801, Augustin Fresnel was sent to the Ecole Centrale at Caen, as company for Louis.

FactSnippet No. 990,454

About 1812, Augustin Fresnel was sent to Nyons, in the southern departement of Drome, to assist with the imperial highway that was to connect Spain and Italy.

FactSnippet No. 990,455

In March 1815, perceiving Napoleon's return from Elba as "an attack on civilization", Augustin Fresnel departed without leave, hastened to Toulouse and offered his services to the royalist resistance, but soon found himself on the sick list.

FactSnippet No. 990,456

In summary, in the spring of 1814, as Augustin Fresnel tried in vain to guess what polarization was, the corpuscularists thought that they knew, while the wave-theorists literally had no idea.

FactSnippet No. 990,457

In mid 1815, on his way home to Mathieu to serve his suspension, Augustin Fresnel met Arago in Paris and spoke of the wave theory and stellar aberration.

FactSnippet No. 990,458

On 12 July 1815, as Augustin Fresnel was about to leave Paris, Arago left him a note on a new topic:.

FactSnippet No. 990,459

Augustin Fresnel arrived in March 1816, and his leave was extended through the middle of the year.

FactSnippet No. 990,460

On 24 May 1816, Augustin Fresnel wrote to Young, acknowledging how little of his own memoir was new.

FactSnippet No. 990,461

Augustin Fresnel resumed his engineering duties in the spring of 1818; but from then on he was based in Paris, first on the Canal de l'Ourcq, and then with the cadastre of the pavements.

FactSnippet No. 990,462

On 15 January 1818, in a different context, Augustin Fresnel showed that the addition of sinusoidal functions of the same frequency but different phases is analogous to the addition of forces with different directions.

FactSnippet No. 990,463

Knowledge of this method was assumed in a preliminary note on diffraction, dated 19 April 1818 and deposited on 20 April, in which Augustin Fresnel outlined the elementary theory of diffraction as found in modern textbooks.

FactSnippet No. 990,464

In July or August 1816, Augustin Fresnel discovered that when a birefringent crystal produced two images of a single slit, he could not obtain the usual two-slit interference pattern, even if he compensated for the different propagation times.

FactSnippet No. 990,465

Augustin Fresnel gave details of the "mechanical solution" in a memoir read to the Academie des Sciences on 7 January 1823.

FactSnippet No. 990,466

Augustin Fresnel attended to these matters in his "second memoir" on double refraction, published in the Recueils of the Academie des Sciences for 1824; this was not actually printed until late 1827, a few months after his death.

FactSnippet No. 990,467

In 1826, the British astronomer John Herschel, who was working on a book-length article on light for the Encyclopædia Metropolitana, addressed three questions to Augustin Fresnel concerning double refraction, partial reflection, and their relation to polarization.

FactSnippet No. 990,468

Meanwhile, on 21 June 1819, Augustin Fresnel was "temporarily" seconded by the Commission des Phares on the recommendation of Arago, to review possible improvements in lighthouse illumination.

FactSnippet No. 990,469

In May 1824, Augustin Fresnel was promoted to secretary of the Commission des Phares, becoming the first member of that body to draw a salary, albeit in the concurrent role of Engineer-in-Chief.

FactSnippet No. 990,470

Augustin Fresnel was an examiner at the Ecole Polytechnique since 1821; but poor health, long hours during the examination season, and anxiety about judging others induced him to resign that post in late 1824, to save his energy for his lighthouse work.

FactSnippet No. 990,471

In 1825, Augustin Fresnel extended his fixed-lens design by adding a rotating array outside the fixed array.

FactSnippet No. 990,472

Also in 1825, Augustin Fresnel unveiled the Carte des Phares, calling for a system of 51 lighthouses plus smaller harbor lights, in a hierarchy of lens sizes, with different characteristics to facilitate recognition: a constant light, one flash per minute, and two per minute .

FactSnippet No. 990,473

In late 1825, to reduce the loss of light in the reflecting elements, Augustin Fresnel proposed to replace each mirror with a catadioptric prism, through which the light would travel by refraction through the first surface, then total internal reflection off the second surface, then refraction through the third surface.

FactSnippet No. 990,474

Meanwhile, in Britain, the wave theory was yet to take hold; Augustin Fresnel wrote to Thomas Young in November 1824, saying in part:.

FactSnippet No. 990,475

On 9 June 1825, Augustin Fresnel was made a Foreign Member of the Royal Society of London.

FactSnippet No. 990,476

Augustin Fresnel's last note to the Academie, read on 13 June 1825, described the first radiometer and attributed the observed repulsive force to a temperature difference.

FactSnippet No. 990,477

The memoir introducing the parallelepiped form of the Augustin Fresnel rhomb, read in March 1818, was mislaid until 1846, and then attracted such interest that it was republished in English.

FactSnippet No. 990,478