Charles Pierre Claret de Fleurieu

Charles Pierre Claret, comte de Fleurieu (2 July 1738, Lyon – 18 August 1810) was a French explorer, hydrographer and politician. He was Minister of the Navy under Louis XVI, and a member of the Institut de France, as well as the brother of the botanist Marc Antoine Louis Claret de la Tourette.

Fleurieu was born in Lyon. Engaged in the Toulon company of the Garde-marine from the age of 13 and a half on 31 October 1755, he subsequently took part in the campaigns of the Seven Years' War— which ended in 1763— participating in the battles of Mahon, Lagos, and Les Sablettes and rising to brigadier in the gardes de la marine company, and then enseigne de vaisseau. In suggesting de Fleurieu's promotion to ensign, on 23 March 1762, the Minister wrote to the king :

On 1 July 1765 he was made Enseigne de port, and on 27 July he went to Paris to study horology with Ferdinand Berthoud.

He took part in a one-year sea campaign to test Berthoud's first marine chronometer, in an attempt to beat Britain in the race to find a reliable way to calculate longitude. The chronometers he thus refined with Ferdinand Berthoud for their later experiments were the object of major struggles with the king's horologer, Pierre Le Roy. Finally Claret de Fleurieu and Berthoud were entrusted with the task, setting out on the testing expedition from autumn 1768 to 11 October 1769 on the frigate Isis under Fleurieu's command. The chronometers almost invariably indicated the hour as accurately after the ship had left port, as if they were still on land. Knowing the actual local time at each present location by astronomy, they could easily determine the ship's exact position and longitude on a chart. The results of their observations was published in 1773 under the title Voyage fait par ordre du roi, pour éprouver les horloges marines ("Voyage made by order of the king, to test marine chronometers"). We can also cite among his major works le Neptune du Nord or l'Atlas du Cattegat et de la Baltique, an atlas of the Kattegat and the Baltic Sea that took him 25 years.

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