Ferdinand Berthoud (born 18 March 1727, in Plancemont-sur-Couvet, Principality of Neuchâtel; died 20 June 1807, in Groslay, Val d'Oise), was a scientist and watchmaker. He became master watchmaker in Paris in 1753. Berthoud, who held the position of Horologist-Mechanic by appointment to the King and the Navy, left behind him an exceptionally broad body of work, in particular in the field of marine chronometers. History Ferdinand Berthoud was born on 18 March 1727, in Plancemont, Val-de-Travers, in the Principality of Neuchâtel, which then belonged to the Kingdom of Prussia, into a distinguished family of watch and clock makers. His father, Jean Berthoud, was a master carpenter and architect. He was a burgher of Couvet, burgher of Neuchâtel, and justice of the peace for Val-de-Travers from 1717 to 1732. His mother, Judith Berthoud (1682–1765) was born in Couvet. Ferdinand had four brothers: Abraham (1708-?); Jean-Henry (1710–1790), justice of the peace for Val-de-Travers, clerk of the court in Les Verrières, barrister in Cressier, and an expert watchmaker and clockmaker; Jean-Jacques (1711–1784), a draughtsman, and Pierre (1717-?), a farmer and clockmaker. Pierre was a councillor in Couvet, and married Marguerite Borel-Jaquet in 1741. With her, Pierre had two sons, Pierre Louis (born in Paris in 1754, died 1813), and Henri (born ? in Paris, died in 1783); their career was to be closely linked to that of their uncle Ferdinand Berthoud. Ferdinand also had two sisters: Jeanne-Marie (1711–1804) and Suzanne-Marie (1729-?). In 1741, when he was fourteen, Ferdinand Berthoud became clockmaking apprentice to his brother Jean-Henry in Couvet, at the same time receiving a sound scientific education. On 13 April 1745, Ferdinand Berthoud finished his training and was awarded a watchmaking and clockmaking apprenticeship certificate. In 1745, aged 18, Ferdinand Berthoud moved to Paris to improve his skills as a watchmaker and clockmaker. He exercised his talents as a journeyman, working with master watchmakers in the Paris community. There is some suggestion in the literature that Ferdinand Berthoud worked for a time for Julien Le Roy, where he is said to have made strikingly swift progress, alongside Pierre Le Roy, his master's son, who later became his rival. On 4 December 1753, by order of the French Royal Council, in an exception to guild rules and by special favour of the King, Ferdinand Berthoud became a master at the age of 26, receiving the official title of Master Watchmaker. From 1755 onwards, Ferdinand