Hermann Ludwig Ferdinand von Helmholtz

Helmholtz, Hermann Ludwig Ferdinand von (1821–94), German physiologist and physicist. In the course of his physiological studies he formulated the law of conservation of energy (1847). He was the first to measure the speed of nerve impulses, and he invented the ophthalmoscope (both 1850). He also made important contributions to the study of electricity, non-euclidean geometry, and musical acoustics.

See also: Ophthalmoscope.