Borda, captain of Boussole, in an expedition to the Canaries and the coast of Africa in 1774 and 1775. 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. The clocks taken on board were lost at sea in the wreck of the Astrolabe in 1788 off the coast of Vanikoro in the Santa Cruz Islands, near the Solomon Islands. 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. In 17951, Berthoud was elected First Class Resident Member of the Mechanical Arts section of France's National Institute (Institut de France). Following the French Revolution, Berthoud moved in to the Louvre and received an allowance from the State, continuing to work on his clocks and maintain sea clocks. His most important priority, however, was the publication of his most significant work: Histoire de la Mesure du temps2 (1802). On 17 July 1804, Napoleon made Berthoud a Knight of the Legion of Honour, as a member of the Institute. On 20 June 1807, Ferdinand Berthoud died childless at the age of 80. He was buried in Groslay, in the Montmorency Valley (Val d'Oise), where a monument commemorates him. Works 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]. French Academy members Charles Étienne Camus (1699–1768), a mathematician and astronomer, and Pierre Boger (1698–1758), a mathematician, physicist, and famous hydrographer, wrote a glowing report on the quality of his work.- Ferdinand Berthoud filed various sealed envelopes with the French Royal Academy of Sciences. On 20 November 1754, he filed the plan for a Machine for measuring time at sea, in a sealed envelope that was never published[5]. This was his first plan for a sea clock. The envelope was not opened until 1976 by the President of the Academy. On 13 December 1760, Ferdinand Berthoud filed his Mémoire sur les principes de construction d'une Horloge de Marine1 with the French Royal Academy of Sciences to present his legendary Sea Clock Number 1, the construction of which was completed in