Francois Arago, French Astronomer

Francois Jean Dominique Arago (February 26, 1786 - October 2, 1853), was a French mathematician, physicist, astronomer and politician. He was elected a member of the French Academy of Sciences, at the age of 23, and given a position as one of the astronomers of the Royal Observatory, where he gave lectures in astronomy, which were continued from 1812 to 1845. The invention of the polariscope and discovery of Rotary polarization are due to Arago. He invented the first polarization filter in 1812. In 1816, along with Joseph Louis Gay-Lussac, he started the Annales de chimie 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. 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. His fame as an experimenter and discoverer rests mainly on his contributions to magnetism and still more to optics. He showed that a magnetic needle, made to oscillate over nonferrous surfaces falls more rapidly in the extent of its oscillations according as it is more or less approached to the surface. In 1852, suffering first from diabetes, then from Bright's disease, complicated by dropsy, he resigned his post as astronomer rather than take the oath of allegiance to Napoleon III. He died in 1853 at the age of 67

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