JACOB, Louis Leon (zhah-kobe'), French naval officer, born in Tonnay, France, 11 November, 1768; died in Paris, 16 March, 1854. He entered the navy in 1784, and made several voyages to the West Indies and South America. He was appointed lieutenant in 1790, served during the troubles in Santo Domingo, and in 1795 was brevetted commander after a successful combat in the waters of the island against several English men-of-war. Three years later he assumed command of the station of Santo Domingo, where he rendered great services in protecting the whites against the negro insurgents. He invented in 1803 signals that are yet used in the French navy, and was promoted rear-admiral in 1812. He commanded the station of Martinique in 1821, and again rendered great services to the white population of Hayti. He governed Guadaloupe from 1823 till 1826, and suppressed several negro insurrections in that island. He was commissioned vice-admiral in 1827, and created count and peer of France in 1831. Jacob was also secretary of the navy from 1834 till 1836. He published "Les signaux metaphoriques" (Paris, 1806), and several other works.