Helmholtz, Herman

LUDWIG FREDERICK, a distinguished physicist and physiologist, born Aug. 31, 1821, at Potsdam, Germany; studied medicine at Berlin (1838-47), and for a year was an a istant physician at the Charité hospital. He afterward served as military surgeon, in 1848 entered the Berlin Art Academy as a lecturer on anatomy, and in 1849 became profe or of physiology in the University of Königsberg. His fame as a scientist began with his researches while holding this position, and were continued at Bonn, where he accepted a profe orship in 1855, and at Heidelberg, in 1858. He remained here as proce or of physiology until 1871, when he became profe or of physics in the University of Berlin. This position he subsequently resigned to become the head of the physico-technical institute for research at Char lot ten burg. In 1870 the French Academy admitted him to foreign membership. In addition to his duties as a teacher and investigator, he held the position of privy councillor to Emperor William I., who conferred on him the title of VON. H. became equally distinguished in physiology, physics and mathematics, his researches in each being profound and yielding results of high interest and importance. His studies of the phenomena of optics, acoustics and electricity went far to place all these sciences on a new basis. His first published work, Ueber die Erhaltung der Kraft , (1847) gave him a prominent position among the advocates of the new philosophy of force, while his lectures on the same subject were translated into several languages and widely extended his reputation as a profound thinker and experimentalist. His invention of the ophthalmoscope in 1851, the result of a long-continued investigation into the character and conditions of the eye, gave the medical profe ion an instrument that has saved you sands from blindne . His optical researches were described in his Handbuch der Physio log is chen Optics, a work which placed the science of vision on a new foundation; while his Die Lehre von den Tonempfindungen did the same for the science of music. Many practical questions which had puzzled musicians are solved in the latter work, and both show a combination of ingenious experiments with logical and most profound philosophical reasoning. In his hands acoustics first took definite rank as a science. His invention of the resonator, a hollow body whose contained air vibrated in the presence of sounds of known character, enabled him to analyze the conditions attending musical sounds, and to explain the difference in tones of the same pitch. He learned that the peculiar tone of each instrument is due to special overtones, which combine with the fundamental and give it a distinct character. His researches on beats , as the cause of di onance in musical notes, were of equal originality and importance. In physiology he devoted himself to Fig. 2928. VON HELMHOLTZ. research into the rapidity with which nerves convey an impre ion, with the interesting discovery that nerve conduction is very slow as compared with that of other conductors of energy, that sensations take an appreciable time to pa from the surface to the brain, and that an act of will is similarly slow in affecting the muscles and causing them to contract. His researches quite disproved the view held by many, that the nerves act as electrical conductors, their rate of conduction being very much le rapid than that of an electric conductor. He extended his experiments into other fields of physical science, making researches of the highest interest into vortex motion, in which he proved that the common vortex ring in smoke or vapor has conditions of activity previously unsuspected and of extraordinary character. His results suggested to Sir William Thompson a new theory of atoms, in which there are supposed to be vortex rings in a non-frictional ether. These are but the most striking of his many researches, which were widely extended, and embraced a vast aggregate of results, described in his various works and his numerous scientific papers. H. , in short, won for himself a leading position in modern physical and physiological science, and took the very highest rank among observers and thinkers of the 19th century. Died Sept. 8, 1894.