paper to the Duke of Praslin (1712–1785), Count of Choiseul, Minister of the Navy, explaining his plan to build the Number 6 and Number 8 Sea Clocks. He asked him for an allowance of £3,000 in consideration of his work on earlier sea clocks and in anticipation of his estimated costs for the production of two new sea clocks using English technology. The paper clearly set out Ferdinand Berthoud's ambitions to receive this allowance, together with the title of Horologist-Mechanic by appointment to the King and the Navy, and to devote himself to developing sea clocks and determining longitude at sea. On 24 July 1766, the King approved the project to build the two sea clocks and agreed to finance it.- To check the performance of the new sea watches, on 3 November 1768, the Duke of Praslin gave Sea Clocks numbers 6 and 8 to Charles-Pierre Claret, the 'Knight of Fleurieu' (1738–1810), explorer, hydrographer, and King's lieutenant, accompanied by Canon Pingré (1711–1796), navy astronomer and geographer and member of France's Royal Academy of Sciences. Their mission was to test the watches on the corvette Isis during a voyage from Rochefort to Santo Domingo and back. The voyage lasted ten months and the trials on the clocks were successful. The findings of Charles-Pierre Claret were published in 1773 under the title Voyage fait par ordre du roi, pour éprouver les horloges marines. In 1769, Ferdinand Berthoud sent for his nephew Pierre-Louis Berthoud (1754–1813), commonly known as Louis Berthoud, a talented young watchmaker and clockmaker, inviting him to come to Paris from Couvet, Switzerland, to pursue his apprenticeship. Louis helped Ferdinand manufacture and repair the sea clocks his uncle supplied to the French and Spanish navies. On 1 April 1770, following the successful sea trials of Sea Watches numbers 6 and 8, Ferdinand Berthoud received the title of Horologist-Mechanic by appointment to the King and the Navy, with an annual allowance of £3,000 and responsibility for inspecting the construction of sea clocks. He received a royal commission for 20 sea clocks. Ferdinand Berthoud's clocks soon became a success and were used on board ship for various test campaigns and charting voyages. 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. Count Chastenet de Puységur (1752–1809), captain of the corvette Espiègle, accompanied