Jean-Marie Constant Duhamel (5.02.1797-29.04.1872) was a French physicist and mathematician and a member of the Paris Academy of Sciences (1840). He was born in Saint-Malo. He studied at the École Polytechnique and at the Collège Louis-le-Grand in Paris. In 1830 — 69 he worked at the École Polytechnique (professor from 1834), and he also taught at the École Normale and at the Sorbonne.
His research concerned mechanics, heat, acoustics and mathematical physics. In 1845, in his “Course of Mechanics”, he introduced a way of determining the mass of a body as the ratio of the force applied to it to the acceleration it acquires (m = F/a). He constructed a theory of the propagation of heat in crystals. He improved Navier's equation in the theory of elasticity. He studied the vibrations of strings and of air in pipes, and harmonic overtones. He invented a recording apparatus (1840).