Hermann Ludwig von Helmholtz
(1821 - 1894)

born: August 31, 1821 in Potsdam died: September 8, 1894 in Charlottenburg (Berlin) German physicist and physiologist. Professor of physiology in Königsberg, Bonn and Heidelberg. After 1871 professor of physics in Berlin. In 1888 he became the head of the newly founded Physikalisch-Technische Reichsanstalt in Charlottenburg. He worked on accoustics, hydrodynamics, electrodynamics, thermodynamics, meteorology, optics, non-euclidian geometry and philosophy of natural sciences. He is known for his invention of the first ophthalmoscope ("Beschreibung eines Augenspiegels", Berlin, 1851). In 1847 he formulated (independently of R. Mayer and J.P. Joule) the law of conservation of energy: "Über die Erhaltung der Kraft" (Berlin, 1847, a popular version: "Über die Wechselwirkungen der Naturkräfte", Königsberg, 1854)