Helmholtz, Hermann Ludwig Ferdinand von, << HEHLM hohlts, HEHR mahn LOOT vihk FEHR dih nahnt fuhn >> (1821-1894), a German physicist, helped establish the law of the conservation of energy (see Energy (Conservation of energy) ). His research on sound ranked as the outstanding work of his time in acoustics. He was the first to apply physical methods to the study of the nervous system by measuring the speed of nerve impulses. Helmholtz also invented the ophthalmoscope, used by doctors to examine eyes. He was born on Aug. 31, 1821, in Potsdam. He died on Sept. 8, 1894. See also Color (The three-component theory) ; Ophthalmoscope ; Heat (Heat and energy) .
