FRESNEL, Augustin Jean (1788-1827), an illustrious French physicist, the son of an architect, was born at Broglie, in the department of Eure, in France, May 10,1788. His early progress in learning was slow, and when eight years old he was still, unable to read. At the age of thirteen he entered the Ecole Centrale in Caen, and at sixteen and a half the École Polytechnique, where he acquitted himself with distinction. Thence he went to the Ecole des Ponts et Chaussées. He served as an engineer successively in the departments of Vendée, Drome, and Ille-et-Villaine; but his espousal of the cause of the Bourbons in 1814 occasioned, on Napoleon’s reaccession to power, the loss of his appointment. On the second restoration he obtained a post as engineer in Paris, where much of his life from that time was spent. His researches in optics, continued until his death, appear to have been begun about the year 1814, when he prepared a paper on the aberration of light, which, however, was not published. In 1818 he read his celebrated memoir on diffraction, for which in the ensuing year he received the prize of the Academy of Sciences at Paris. He was in 1823 unanimously elected a member of the Academy, and in 1825 he became a member of the Royal Society of London, which in 1827, at the time of his last illness, awarded him the Rumford medal. In 1819 he was nominated a commissioner of lighthouses, for which he was the first to construct compound lenses as substitutes for mirrors (see Lighthouses). Fresnel died of consumption at Ville-d’Avray, near Paris, July 14, 1827. The undulatory theory of light enunciated by Hooke, and upheld by Huygens and Euler, but first founded upon experimental demonstration by Thomas Young, was extended to a large class of optical phenomena, and ...