1911 Encyclopædia Britannica/Cornu, Marie Alfred
CORNU, MARIE ALFRED (1841–1902), French physicist, was born at Orleans on the 6th of March 1841, and after being educated at the École Polytechnique and the École des Mines, became in 1867 professor of experimental physics in the former institution, where he remained throughout his life. Although he made various excursions into other branches of physical science, undertaking, for example, with J. B. A. Baille about 1870 a repetition of Cavendish’s experiment for determining the mean density of the earth, his original work was mainly concerned with optics and spectroscopy. In particular he carried out a classical redetermination of the velocity of light by A. H. L. Fizeau’s method, introducing various improvements in the apparatus, which added greatly to the accuracy of the results. This achievement won for him, in 1878, the prix Lacaze and membership of the Academy of Sciences in France, and the Rumford medal of the Royal Society in England. In 1899, at the jubilee commemoration of Sir George Stokes, he was Rede lecturer at Cambridge, his subject being the undulatory theory of light and its influence on modern physics; and on that occasion the honorary degree of D.Sc. was conferred on him by the university. He died at Paris on the 11th of April 1902.