François Arago

François Jean Dominique Arago (February 26, 1786 – October 2, 1853) was a French mathematician, physicist, astronomer, and politician.

Scientific work

Arago had succeeded in preserving the records of his survey; and his first act on his return home was to deposit them in the Bureau des Longitudes at Paris. As a reward for his adventurous conduct in the cause science, he was elected a member of the Academy of Sciences, at the remarkably early age of twenty-three, and before the close of 1809 he was chosen by the council of the polytechnic school to succeed Gaspard Monge in the chair of analytical geometry. At the same time he was named by the emperor one of the astronomers of the Royal Observatory, which was accordingly his residence till his death, and it was in this capacity that he delivered his remarkably successful series of popular lectures in astronomy, which were continued from 1812 to 1845.

Related Topics:
Bureau des Longitudes - Paris - Academy of Sciences - Gaspard Monge - Analytical geometry - 1812 - 1845

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In 1816, along with Joseph Louis Gay-Lussac, he started the Annales de chemie et de physique, and in 1818 or 1819 he proceeded along with Biot to execute geodetic operations on the coasts of France, England and Scotland. They measured the length of the seconds-pendulum at Leith, Scotland, and in the 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.

Related Topics:
1816 - Joseph Louis Gay-Lussac - 1818 - 1819 - Leith - Scotland - Shetland Islands - 1821

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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 what has been called rotatory magnetism, and the fact that most bodies could be magnetized; these discoveries were completed and explained by Michael Faraday. He warmly supported Jean-Augustin Fresnel's optical theories, helping to confirm Fresnel's wave theory of light by observing what is now known as the spot of Arago. The two philosophers conducted together those experiments on the polarization of light which led to the inference that the vibrations of the luminiferous ether were transverse to the direction of motion, and that polarization consisted in a resolution of rectilinear motion into components at right angles to each other. The subsequent invention of the polariscope and discovery of rotatory polarization are due to Arago. The general idea of the experimental determination of the velocity of light in the manner subsequently effected by Hippolyte Fizeau and Leon Foucault was suggested by him in 1838, but his failing eyesight prevented his arranging the details or making the experiments.

Related Topics:
Pressure - Steam - Temperature - Velocity - Sound - 1818 - 1822 - Magnet - 1823 - 1826 - Rotatory magnetism - Michael Faraday - Jean-Augustin Fresnel - Optical - The spot of Arago - Polarization - Light - Vibration - Luminiferous ether - Motion - Polariscope - Rotatory polarization - Hippolyte Fizeau - Leon Foucault - 1838

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Nearly all the mathematical work of the "French school" was done before the year 1830. They are the direct successors of the French writers who flourished at the beginning of the nineteenth century, and seem to have been out of touch with the great German mathematicians of the early part of it, on whose researches much of the best work of that century is based; they are thus placed here, though their writings are in some cases of a later date than those of Gauss, Abel and Jacobi.

Related Topics:
1830 - Gauss - Abel - Jacobi

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