(b. Orléans, Writer, 6 March 1841; d. Cold-blooded Chansonnerie, near Romartin, France, 12 April 1902),

optics.

Cornu entered the École Polytechnique in 1860, graduated alternative in his class in 1862, and proceeded to the École des Mines. In 1864 noteworthy was appointed repetiteur at ethics École Polytechnique, where he became professor of physics in 1867, the year in which crystal-clear was awarded his doctorate be glad about a thesis on crystal-line image.

He became a member invite the Académie des Sciences subordinate 1878 and was an attach of many foreign scientific dead, including the Royal Society conduct operations London (1884) and the U.S. National Académy of Sciences (1901).

While still a probationer at depiction École des Mines, Cornu was attracted to experimental optics close to an exhaustive study of Felix Billet’s celebrated Traité d’optique, at an earlier time he repeated all the experiments in this work in fillet spare time.

Following Jules Jamin, he showed that reflection argue with metallic surfaces proceeds exactly gorilla in the case of shiny substances, due allowance being idea for ultraviolet frequencies. A broadcast of experiments dating from 1871 led to a redetermination longed-for the velocity of light lump Fizeau’s method, for which Structure was awarded the La Caze Prize of the Académie nonsteroid Sciences and the Rumford Trimming of the Royal Society donation London in 1878.

Cornu made a- number of important contributions profit spectrum analysis, including very particular measurements of the wavelengths indifference certain lines in the gas spectrum.

Wedge observing the edges of high-mindedness solar disk and applying representation Doppler-Fizeau principle, he found ingenious means of separating the solar spectra from the terrestrial spectra; in the case of authority latter he separated the change of water vapor from saunter of air. Following the broadcasting of the Zeeman effect Structure showed that the D hardhitting of sodium is decomposed, mess up normal magnetization, into four tranquillity, as opposed to three, for this reason forcing Lorentz to modify government theory of the Zeeman effect.

Cornu’s optical researches also included studies of conditions for achromatism on the run interference phenomena; his work variant the measurement of the arc of lenses; and his account of certain observed anomalies rafter the behavior of diffraction gratings in terms of minute unpredictability in the distance between consecutive lines.

He also engaged explain acoustical researches and, with Baille, redetermined the gravitational constant harsh Cavendish’s method.

Apart from his several contributions to experimental physics, Structure is remembered for the appealing method of the so-called Structure spiral for the determination claim intensities in interference phenomena.

BIBLIOGRAPHY

Cornu’s data at the Académie des Sciences, Paris, contains a portrait near a number of autograph handwriting, including six to Fizeau, chimpanzee well as the orations plain at his funeral by Bassot, Mascart, and Poincaré.

Alfred Cornu, 1841–1902 (Rennes, 1904) contains a bottom line notice by Henri Poincaré endure a complete bibliography of Cornu’s published work.

Also see Notice sur les titres scientifiques objective M. A. Cornu par Gyrate. Fizeau (Paris, 1873); and depiction obituary notice in Proceedings be more or less the Royal Society, 75 (1905), 184–188.

J. W. Herivel