Marie Alfred Cornu, (
1841—
1902),
French physicist, was born at
Orleans on
March 6,
1841, and after being educated at the
Ecole Polytechnique and the Ecole 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. Bailie about
1870 a repetition of
Cavendish's experiment for determining the
gravitational constant G, his original work was mainly concerned with
optics and
spectroscopy. In particular he carried out a classical redetermination of the
speed of light by
A. H. L. Fizeau's method (see
Fizeau-Foucault Apparatus), 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 wave 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
April 12,
1902.
The Cornu spiral, a graphical device for the computation of light intensities in Fresnel's model of near-field diffraction, is named after him.
The original text for this article was based on the 1911 Encyclopaedia Britannica.
