Achille Brocot (1817–1878) was a French clockmaker^{[1]} and amateur mathematician.^{[2]} He is known for his discovery (independently of and contemporaneously with German number theorist Moritz Stern) of the Stern–Brocot tree, a mathematical structure useful in approximating real numbers by rational numbers; this sort of approximation is an important part of the design of gear ratios for clocks.^{[3]} He also made many other horological innovations including refinement of his father LouisGabriel's Brocot escapement and the development of clocks with perpetual calendar mechanisms.^{[4]}^{[5]}
