Helmholtz, HERMANN VON, a very distinguished scientist, was born at Potsdam, 31st August 1821; he was ennobled by the Emperor of Germany in 1883. He was at first a surgeon in the army, then assistant in the Berlin Anatomical Museum, and was a professor of Physiology from 1849 at Königsberg, from 1855 at Bonn, and from 1858 at Heidelberg. In 1871 he became professor of Physics in Berlin. Helmholtz is equally distinguished in physiology, in mathematics, and in experimental and mathematical physics. His physiological works are principally connected with the eye, the ear, and the nervous system. Thus, we have his exhaustive treatise on Physiological Optics, his Speculum for the examination of the Retina, his Discourse on Human Vision, and various papers on the means of measuring small periods of time, and their application to find the rate of propagation of nerve-disturbances. Of a semi-physical nature we have his Analysis of the Spectrum, his explanation of Vowel Sounds (Klangfarbe der Vocalen; see SOUND), and his papers on the Conservation of Energy with reference to Muscular Action. In physical science he is known by his paper on Conservation of Energy (Ueber d. Erhaltung d. Kraft, 1847, translated [badly] in Taylor's Scientific Memoirs, new series); by a popular lecture on the same subject (1854); by two memoirs in Crelle's Journal, on Vortex-motion in fluids, and on the Vibrations of Air in open pipes, &c., and by several researches into the development of electric current within a galvanic battery. His Populäre wissenschaftliche Vorträge appeared in 1865-76 (Eng. trans. by Atkinson, with Introduction by Tyndall, 1881); his great work on Die Lehre der Tonempfindungen (Eng. trans. by Alex. J. Ellis, The Sensations of Tone) in 1862; his Wissenschaftliche Abhandlungen in 1881-83; and his Reden und Vorträge in 1884. He died 8th September 1894.
See Clerk-Maxwell in Nature, vol. xv.; Rücker in Nature, vol. li.; and Bezold's German monograph (1895).