François Arago

Source: Wikipedia, the free encyclopedia.

François Arago
Minister of the Navy
In office
24 February 1848 – 4 May 1848
PresidentJacques-Charles Dupont de l'Eure
Preceded byLouis Napoléon Lannes
Succeeded byJoseph Grégoire Casy
Personal details
Born(1786-02-26)26 February 1786
Estagel, Roussillon, France
Died2 October 1853(1853-10-02) (aged 67)
Paris, Seine, France
Resting placePère Lachaise Cemetery, Paris
Political partyModerate Republican
Spouse
Lucie Carrier-Besombes
​
​
(m. 1811; died 1829)​
Children
Eddy currents
Fresnel–Arago laws
Arago spot
Arago's rotations
Arago telescope
AwardsCopley Medal
Scientific career
FieldsAstronomy, mathematics, physics
InstitutionsBureau des Longitudes, French Academy of Sciences, Paris Observatory
PatronsSiméon Denis Poisson
Pierre-Simon Laplace
Signature

Dominique François Jean Arago (

freemason,[1] supporter of the Carbonari revolutionaries[2]
and politician.

Early life and work

Arago was born at Estagel, a small village of 3,000[3] near Perpignan, in the département of Pyrénées-Orientales, France, where his father held the position of Treasurer of the Mint. His parents were François Bonaventure Arago (1754–1814) and Marie Arago (1755–1845).

Arago was the eldest of four brothers. Jean (1788–1836) emigrated to North America and became a general in the Mexican army. Jacques Étienne Victor (1799–1855) took part in Louis de Freycinet's exploring voyage in the Uranie from 1817 to 1821, and on his return to France devoted himself to his journalism and the drama. The fourth brother, Étienne Vincent (1802–1892), is said to have collaborated with Honoré de Balzac in The Heiress of Birague, and from 1822 to 1847 wrote a great number of light dramatic pieces, mostly in collaboration.[4]

Showing decided military tastes, François Arago was sent to the municipal college of

École Polytechnique. Within two years and a half he had mastered all the subjects prescribed for examination, and a great deal more, and, on going up for examination at Toulouse, he astounded his examiner by his knowledge of J.-L. Lagrange 's work.[4][5]

Towards the close of 1803, Arago entered the

Siméon Poisson, he received the appointment of secretary to the Paris Observatory
. He now became acquainted with
meridian arc of Delambre and Méchain
). Arago and Biot left Paris in 1806 and began operations along the mountains of Spain. Biot returned to Paris after they had determined the latitude of Formentera, the southernmost point to which they were to carry the survey.[4] Arago continued the work until 1809, his purpose being to measure a meridian
arc
in order to determine the exact length of a metre.

After Biot's departure, the political ferment caused by the entrance of the French into Spain extended to the

Palamos.[4][5]

After three months' imprisonment, Arago and the others were released on the demand of the dey of Algiers, and again set sail for Marseille on 28 November, but then within sight of their port they were driven back by a northerly wind to Bougie on the coast of Africa. Transport to Algiers by sea from this place would have occasioned a weary delay of three months; Arago, therefore, set out over land, guided by a Muslim priest, and reached it on Christmas Day. After six months in Algiers he once again, on 21 June 1809, set sail for Marseille, where he had to undergo a monotonous and inhospitable quarantine in the lazaretto, before his difficulties were over. The first letter he received, while in the lazaretto, was from Alexander von Humboldt; and this was the origin of a connection which, in Arago's words, "lasted over forty years without a single cloud ever having troubled it."[4]

Scientific studies

Arago had succeeded in preserving the records of his survey; and his first act on his return home was to deposit them in the

analytical geometry. At the same time he was named by the emperor one of the astronomers of the Paris Observatory, which was accordingly his residence till his death. It was in this capacity that he delivered his remarkably successful series of popular lectures in astronomy, which were continued from 1812 to 1845.[4]

In 1818 or 1819 he proceeded along with Biot to execute

Shetland Islands, the results of the observations being published in 1821, along with those made in Spain. Arago was elected a member of the Bureau des Longitudes immediately afterwards, and contributed to each of its Annuals, for about twenty-two years, important scientific notices on astronomy and meteorology and occasionally on civil engineering, as well as interesting memoirs of members of the Academy.[4]

Arago's earliest physical researches were on the pressure of steam at different temperatures, and the velocity of sound, 1818 to 1822. His magnetic observations mostly took place from 1823 to 1826. He discovered rotatory magnetism, what has been called Arago's rotations, and the fact that most bodies could be magnetized; these discoveries were completed and explained by Michael Faraday.

Charles Babbage, Account of the repetition of M. Arago's experiments on the magnetism manifested by various substances during the act of rotation, 1825

Arago warmly supported

polarimetric observation of a comet when he discovered polarized light from the tail of the Great Comet of 1819.[7]

The general idea of the experimental determination of the

velocity of light in the manner subsequently effected by Hippolyte Fizeau and Léon Foucault
was suggested by Arago in 1838, but his failing eyesight prevented his arranging the details or making the experiments.

François Arago

Arago's fame as an experimenter and discoverer rests mainly on his contributions to magnetism in the co-discovery with

aurora borealis and the variations of the magnetic elements.[4] In 1827 he was elected an associated member of the Royal Institute of the Netherlands, when that institute became the Royal Netherlands Academy of Arts and Sciences in 1851, he became foreign member.[12] In 1828, he was elected a foreign member of the Royal Swedish Academy of Sciences
.

In optics, Arago not only made important optical discoveries on his own, but is credited with stimulating the genius of

Jean-Augustin Fresnel, with whose history, as well as that of Étienne-Louis Malus and Thomas Young
, this part of his life is closely interwoven.

Shortly after the beginning of the 19th century the labours of at least three philosophers were shaping the doctrine of the

undulatory, or wave, theory of light. Fresnel's arguments in favour of that theory found little favour with Laplace, Poisson and Biot, the champions of the emission theory; but they were ardently espoused by Humboldt and by Arago, who had been appointed by the Academy to report on the paper.[4] This was the foundation of an intimate friendship between Arago and Fresnel, and of a determination to carry on together further fundamental laws of the polarization of light known by their means. As a result of this work, Arago constructed a polariscope, which he used for some interesting observations on the polarization of the light of the sky. He also discovered the power of rotatory polarization exhibited by quartz.[13]

Among Arago's many contributions to the support of the undulatory hypothesis, comes the experimentum crucis which he proposed to carry out for measuring directly the velocity of light in air and in water and glass. On the emission theory the velocity should be accelerated by an increase of density in the medium; on the wave theory, it should be retarded. In 1838 he communicated to the Academy the details of his apparatus, which utilized the relaying mirrors employed by Charles Wheatstone in 1835 for measuring the velocity of the electric discharge; but owing to the great care required in the carrying out of the project, and to the interruption to his labours caused by the revolution of 1848, it was the spring of 1850 before he was ready to put his idea to the test; and then his eyesight suddenly gave way. Before his death, however, the retardation of light in denser media was demonstrated by the experiments of H. L. Fizeau and B. L. Foucault, which, with improvements in detail, were based on the plan proposed by him.[4]

Politics and legacy

Paris Meridian
for 9.2 km (6 mi), in memorial to Arago and his work on the meridian and his measurements of the Earth.

In 1830, Arago, who always professed liberal opinions of the

Fermat and Laplace
, the acquisition of the museum of Cluny, the development of railways and electric telegraphs, the improvement of the reneile. In 1839, Arago reported the invention of photography to stunned listeners of a joint meeting of the academies of Arts and Sciences.

In 1830, Arago also was appointed director of the Observatory, and as a member of the chamber of deputies he was able to obtain grants of money for rebuilding it in part, and for the addition of magnificent instruments. In the same year, too, he was chosen perpetual secretary of the Academy of Sciences, the place of Joseph Fourier. Arago threw himself into its service, and by his faculty of making friends he gained at once for it and for himself a worldwide reputation. As perpetual secretary it was his duty to pronounce historical eulogies on deceased members; and for this duty his rapidity and facility of thought, and his happy piquancy of style, and his extensive knowledge peculiarly adapted him. He was elected a Foreign Honorary Member of the American Academy of Arts and Sciences in 1832.[14]

In 1834, Arago again visited

French colonies
.

On 10 May 1848, Arago was elected a member of the

Louis Napoleon
required an oath of allegiance from all its functionaries, Arago peremptorily refused, and sent in his resignation of his post as astronomer at the Bureau des Longitudes. This, however, the prince president declined to accept, and made "an exception in favour of a savant whose works had thrown lustre on France, and whose existence the government would regret to embitter."

Cape Gregory in

Saint Gregory, the saint of that day; it was renamed Cape Arago after François Arago.[15]

Last years

Arago remained a consistent republican to the end, and after the coup d'état of 1852, though suffering first from

Napoleon III gave directions that the old man should be in no way disturbed, and should be left free to say and do what he liked. In the summer of 1853 Arago was advised by his physicians to try the effect of his native air, and he accordingly set out to the eastern Pyrenees, but this was ineffective and he died in Paris. His grave is at the famous Père Lachaise Cemetery in Paris. Arago was an atheist.[16]

Named after Arago

The François Arago of 1882

Honours

Publications

Grave of Arago at Père Lachaise Cemetery in Paris

Arago's works were published after his death under the direction J. A. Barral, in 17 vols., 8vo, 1854–1862 (F. Arago (1854),

Wikidata Q51430135
); also separately his Astronomie populaire, in 4 vols.; Notices biographiques, in 3 vols.; Indices scientifiques, in 5 vols.; Voyages scientifiques, in 1 vol.; Grimoires scientifiques, in 2 vols.; Mélanges, in I vol.; and Tables analytiques et documents importants (with portrait), in 1 vol.

English translations of the following portions of Arago's works have appeared:

See also

References

  1. ^ Victor SCHOELCHER Républicain et franc-maçon, Anne GIROLLET, ed. Maçonnique Française, p. 26
  2. ^ Dictionnaire universel de la Franc-Maçonnerie By Monique Cara, Jean-Marc Cara, Marc Jode
  3. ^ "Francois Arago". The Canadian Journal. 2: 159. 1854. Retrieved 3 May 2013.
  4. ^ a b c d e f g h i j  One or more of the preceding sentences incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Arago, Dominique François Jean". Encyclopædia Britannica. Vol. 2 (11th ed.). Cambridge University Press. pp. 312–313.
  5. ^
    Wikidata Q51427133
  6. ISBN 0671621300
    .
  7. ISBN 978-1-107-04390-9
    .
  8. ^ Annales de chimie et de physique (1824), vol. 27, page 363: "M. Arago communique verbalement les résultats de quelques expériences qu'il a faites sur l'influence que les métaux et beaucoup d'autres substances exercent sur l'aiguille aimantée, et qui a pour effet de diminuer rapidement l'amplitude des oscillations sans altérer sensiblement leur durée. Il promet, à ce sujet, un Mémoire détaillé." (Mr. Arago orally communicates the results of some experiments that he has conducted on the influence that metals and many other substances exert on a magnetic needle, which has the effect of rapidly reducing the amplitude of the oscillations without altering significantly their duration. He promises, on this subject, a detailed memoir.)
  9. ^ Arago (1826). ""Note concernant les Phénomènes magnétiques auxquels le mouvement donne naissance" (Note concerning magnetic phenomena that motion creates)". Annales de chimie et de physique. 32: 213–223.
  10. doi:10.1098/rstl.1825.0023
    .
  11. ^ Philosospical magazine 1840
  12. ^ "Dominique François Jean Arago (1786 - 1853)". Royal Netherlands Academy of Arts and Sciences. Retrieved 7 May 2020.
  13. ^ Arago (1811) "Mémoire sur une modification remarquable qu'éprouvent les rayons lumineux dans leur passage à travers certains corps diaphanes et sur quelques autres nouveaux phénomènes d'optique" (Memoir on a remarkable modification that light rays experience during their passage through certain translucent substances and on some other new optical phenomena), Mémoires de la classe des sciences mathématiques et physiques de l'Institut Impérial de France, 1st part : 93–134.
  14. ^ "Book of Members, 1780–2010: Chapter A" (PDF). American Academy of Arts and Sciences. Retrieved 22 April 2011.
  15. ISBN 978-0875952772
    .
  16. ^ "The same Arago who spent his time criticizing unfounded myths now peddled them. Arago the atheist now spoke of souls." Theresa Levitt, The shadow of enlightenment: optical and political transparency in France, 1789–1848, page 105.
  17. ISBN 978-3-642-29718-2
    .
  18. ^ Almanach royal officiel de Belgique/1841 p118
  19. ISBN 3-7861-6189-5
    .

Further reading

External links

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Political offices
Preceded by
Jacques-Charles Dupont de l'Eure
Chairman of the Provisional Government of the French Republic
Pierre Marie (de Saint-Georges)
 Succeeded by
Louis-Eugène Cavaignac
President of the Council of Ministers
Preceded by
Minister of War

5 April -11 May 1848 		Succeeded by
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