Hermann von Helmholtz

Hermann von Helmholtz was a German physician and physicist. He contributed to many fields, including physiology, fluid dynamics, the theory of electricity and magnetism, and thermodynamics. His formulation of the principle of conservation of energy influenced a generation of physicists. He invented the ophthalmoscope, which revolutionized the field of ophthalmology; and he invented a resonator to show the strength of various tones. In his philosophy of physiology, he emphasized experience as important for the formation of perception.