Achille Brocot was a French

French people

The French are a nation that share a common French culture and speak the French language as a mother tongue. Historically, the French population are descended from peoples of Celtic, Latin and Germanic origin, and are today a mixture of several ethnic groups...

 clockmaker

Clockmaker

A clockmaker is an artisan who makes and repairs clocks. Since almost all clocks are now factory-made, most modern clockmakers only repair clocks. Modern clockmakers may be employed by jewellers, antique shops, and places devoted strictly to repairing clocks and watches...

 and amateur mathematician. 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 number

Real number

In mathematics, a real number is a value that represents a quantity along a continuum, such as -5 , 4/3 , 8.6 , √2 and π...

s by rational number

Rational number

In mathematics, a rational number is any number that can be expressed as the quotient or fraction a/b of two integers, with the denominator b not equal to zero. Since b may be equal to 1, every integer is a rational number...

s; this sort of approximation is an important part of the design of gear ratio

Gear ratio

The gear ratio of a gear train is the ratio of the angular velocity of the input gear to the angular velocity of the output gear, also known as the speed ratio of the gear train. The gear ratio can be computed directly from the numbers of teeth of the various gears that engage to form the gear...

s for clocks. He also made many other horological innovations including refinement of his father Louis-Gabriel's Brocot escapement and the development of clocks with perpetual calendar

Perpetual calendar

A perpetual calendar is a calendar which is good for a span of many years, such as the Runic calendar.- General information :...

mechanisms.