ON November 18, the centenary occurs of the distinguished German physicist August Adolph Eduard Eberhard Kundt, the successor of Helmholtz at Berlin. Born at Schworin, Mecklenburg, he studied at Leipzig under Hankel, Bruhns and Neumann, and at Berlin under Encke and Förster, first devoting himself to astronomy. Entering the laboratory of Magnus, in 1864 lie graduated with a thesis on the polarization of light. He became a Privat Docent in Berlin in 1867 and then was successively professor of physics at Zurich Federal Technical Highschool (1868), at Würzburg (1870), and at Strasburg (1872), where he took a prominent part in the organization of the new university; of this he became rector in 1877. Finally, in 1888, he was chosen to succeed Helmholtz in the chair of experimental physics and as director of the Physical Institute at Berlin. He died at Israelsdorf near Lübeck on May 21, 1894, a few months before Helmholtz. His original researches were mainly in the domains of light and sound. By an ingenious method lie was able to determine the velocity of sound in various gases. In light, he made inquiries into the problems of anomalous dispersion by liquids and vapours and by very thin films of metal. ‘Kundt's phenomenon’ is the rotation observed, under the influence of magnetic force, of the plane of polarization in certain vapours and gases. For his experiments on dispersion by metal films he made no fewer than 2,000 prisms prepared by electrolytic deposition upon platinized glass.