BORDA, Jean Charles, French navigator, born in Dax, 4 May 1733; died in Paris, 20 February 1799. He was a teacher of mathematics, and when a young man served in both the army and navy. He commanded the ship "Solitaire" with great distinction during the American war of independence, rose to the rank of Major-General of marines, and by his scientific knowledge was of great service to the Count d'Estaing. He was chosen a member of the academy in 1756, and contributed valuable papers to it on the subjects of projectiles and the construction of ships. In 1771 he was employed by the government on an expedition to ascertain the value of chronometers in determining longitudes. In 1771, 1774, and at a later period, he made voyages to America for scientific purposes, of which he published an account. He was one of the commissioners, with Delambre and Mechain, to determine an arc of the meridian as a basis for the metric system of weights and measures, and was sent on several expeditions to decide this question. He founded the school of naval architecture in France, and invented an instrument for measuring the inclination of the magnetic needle. His corrections of the seconds pendulum are still in use; but his reputation rests principally on his improvement of the reflecting circle, on which instrument he published a work (2 vols., Paris, 1787). He also published several able treatises on hydraulics, wrote on mathematics and navigation, and constructed logarithmic tables for the centesimal division of the quadrant.