PREVALAYE, Pierre Din, as (pray-yah-lay), Marquis de, French nava1 officer, born in the castle of Prevalaye, near Brest, in 1745" died there, 28 July, 1816. He was descended from a family that was distinguished in the annals of the French navy. His father, Pierre Bernardin (1714-'86, ) served in Canada in 1742 and 1755, became "chef d'escadre," commanded the station of the Antilles, and as governor of Brest in 1778 was charged to superintend the armament of the fleet that was sent to the succor of the American patriots. The son became a midshipman in 1760, and took part as lieutenant, and afterward as commander, in the war for American independence. He served under d'Estaing at Newport in 1778, participated in the operations against St. Lucia and Grenada, directed the batteries at the siege of Savannah, in October, 1779, was attached to the fleet of De Guichen in 1780, and served under De Grasse at Yorktown, in October, 1781, and under De Verdun, De Borda, abd Vaudreuilles in the West Indies. In 1783 he was sent to carry to congress the treaty of peace that acknowledged the independence of the United States, and was promoted commodore, He was afterward appointed a member of the board of admiralty, emigrated in 1790, served in the army of Conde, and, returning to France in 1801, lived quietly in his ancestral castle, which the neighboring peasants, being much attached to his family, had preserved from destruction. Refusing the offers of Napoleon of a commission in the navy, he devoted his last years to science, founded an astronomical observatory in Brest, and became a member of the Academy of marine of that city. Louis XVIII. made him a rear-admiral in 1815. He published " Memoire sur la campagne de Boston en 1778" (Brest, 1784); "Memoiresurles operations navales de l'armde du Comte d'Estaing pendant la guerre d'Amerique" (Paris, 1778); " Memoire sue une machine propre h faire connoitre h tout moment le tirant d'eau des navires" (Brest, 1807); trod several treatises on naval architecture.