CORNU, MARIE ALFRED (1841-1902), French physi cist, was born at Orleans and was professor of experimental physics in the Ecole Polytechnique, Paris, from 1867 until his death. 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 con cerned with optics and spectroscopy. He carried out a classical redetermination of the velocity of light by A. H. L. Fizeau's method, introducing various im provements in the apparatus, which added greatly to the accu racy of the results.