Helmholtz

HELMHOLTZ, helm'holts, Hermann Lud wig Ferdinand von, German scientist: b. Pots dam, 31 Aug. 1821; d. Charlottenburg, 8 Sept. 1894. He studied medicine in Berlin, and re ceived the appointment of assistant surgeon in the Charite Hospital there in 1842. Next year he went to Potsdam as a military surgeon, but in 1848 he returned to Berlin to assume the duties of teacher of anatomy at the Academy of Art and assistant in the Anatomical Museum. He was called to the chair of physiology at Konigsberg in 1849, and six years later went to Bonn as professor of anatomy and physi ology. In 1858 he was appointed professor of physiology at Heidelberg, whence he returned in 1871 to Berlin as professor of physics. In 1888 he was appointed to the post of president of the new Physikalisch-Technische Reichsan stalt (Imperial Physico-Technical Institute) in Charlottenburg. Helmholtz was distinguished alike in physical science, in mathematics and in physiology; but his most valuable and most original work was done in those departments of physics which stand in intimate relations with physiology, especially acoustics and optics. In 1851 he invented the opthalmoscope, a most useful device and now in universal use. He developed the electromagnetic theory of light and indicated its possibilities. He invented new apparatus in practical physics. He had an emi nently philosophical mind, and his works are no less valuable for their masterly exposition of the methods of experimental science than for the important results contained in them. His scientific fame was securely established as early as 1847, when he published (Ober die Erhaltung der Kraft' (On the Conservation of Energy).

This subject was pursued further in <13ber die Wechselwirkungen der Naturkraftel (On the Interactions of Natural Forces) (1854). His greatest works are the (Handbook of Physiological Optics) (1856-66) ; and (Die Lehre von den Tonempfindungen) (1862; 5th ed., 1896), trans lated into English by Ellis under the title (Sen sations of Tone as a Physiological Basis for the Theory of Music' (1875). A collection of (Vortrage and Reden' reached a fourth edition in 1896, and has been translated into English as Lectures on Scientific Subjects' (1873-81). An edition of his scientific treatises was published at Leipzig in three volumes (1882-95), and in 1897 his on Theo retical Physics> appeared in one volume. In his (1851) he described the ophthalmoscope he had recently invented. In 1883 he was ennobled by the Ger man emperor. He visited the United States in 1893, when he was selected an honorary presi dent of the International Congress of Electri cians at the Columbian Exposition, Chicago. He contributed papers to the principal scientific Journals of the world. Consult Hall, G. S., (Founders of Modern Psychology' (New York 1912) ; Konigsberger, (Hermann von Helm holtz' (Leipzig 1902; Eng. trans., Oxford 1906) ; McKendrick,