Ferdinand Berthoud (French pronunciation: [fɛʁdinɑ̃ bɛʁtu]; 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.

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.

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.

); 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-?

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.

In 1763, Ferdinand Berthoud was appointed by the King to inspect the H4 sea watch made by John Harrison (1693–1776) in London, in the company of mathematician Charles-Etienne Camus (1699–1768), a member of the French Royal Academy of Sciences, and astronomer Joseph-Jérôme Lefrancois de La Lande (1732–1807).

[7] Although Berthoud was not able to see Harrison's famous H4 in London, his trip did offer him a way into English scientific circles, due to the importance of his works and publications in the field of watchmaking.

[9] In 1765, Ferdinand Berthoud undertook a second trip to London to meet Harrison through the offices of Count Heinrich von Brühl (1700–1763), Minister of Saxony.

The findings of Charles-Pierre Claret were published in 1773 under the title Voyage fait par ordre du roi, pour éprouver les horloges marines.

Louis helped Ferdinand manufacture and repair the sea clocks his uncle supplied to the French and Spanish navies.

In 1771, Borda boarded the frigate Flore, under Lieutenant Verdun de la Crenne, for a campaign of tests on sea chronometers, sailing from the Canary Islands to the Caribbean.

[15] On 1 August 1785, Ferdinand Berthoud gave five clocks to the captain of the Astrolabe, Lapérouse, as he was leaving on an expedition around the world with the aim of adding to the discoveries of James Cook in the Pacific Ocean.

In 1791, Berthoud supplied four marine chronometers to Antoine Bruni d'Entrecasteaux, to aid his expedition to search for Lapérouse with the frigates Recherche and Espérance.

[19] In 1752 at the age of 25, seven years after he arrived in Paris, Ferdinand Berthoud submitted an equation clock to the Royal Academy of Sciences, thus demonstrating his extraordinary proficiency in the art of watchmaking4].

On 29 August of the same year, Ferdinand Berthoud filed another envelope entitled Construction d'une montre marine... His work was characterised by regular projects accompanied by detailed requests.

Following successful experiments with them, Ferdinand Berthoud received the title of "Horologist-Mechanic by appointment to the King and the Navy for the inspection of the construction of sea clocks" on 1 August 1770.

It helped seal the reputation of Berthoud's work, in particular with respect to his competitors in longitude at sea research, such as Harrison and Pierre Le Roy (1717–1785).

In 1802, Ferdinand Berthoud published one of his most important works: Histoire de la mesure du temps par les horloges, in which he demonstrates his outstanding knowledge of the art of horological mechanics.

Gifted with a genuine spirit of scientific engineering and an extraordinary capacity for work, Ferdinand Berthoud performed more experiments than any other watchmaker of his day.

The titles, privileges, and testimonials of recognition throughout his career, extending from the reign of Louis XV through to the First Empire, as well as the tributes and studies that highlight his critical renown through to the present day, reflect the importance of his place in the long quest for accuracy.