BORDA, Jean Charles, French engineer and afterward a captain in the French marine, famous for his mathematical talents: b. Dax, department of Landes, 4 May 1733; d. 20 Feb. 1799. In 1756 he was chosen a member of the Academy of Sciences and occupied himself in making experiments on the resistance of fluids, the velocity of motion and other topics relating to dynamical science. In 1767 he published a dissertation on hydraulic wheels and afterward one on the construction of hydraulic machinery. In 1771, with Verdun de la Crenne and Pingre, he made a voyage to America to determine the longitude and latitude of several coasts, isles and shoals, and to try the utility of several as tronomical instruments. In 1774 he visited the Azores the Cape Verde Islands and the coast of Africa for the same purpose. In the Ameri can war he was very useful to the Count d'Estaing by his knowledge of navigation.
Borda was the founder of the schools of naval architecture in France. He invented an instru ment, of a very small diameter, which measures angles with the greatest accuracy and which has been used in measuring the meridian; the re flecting circle, which has made his name im mortal, besides an instrument for measuring the inclination of the compass-needle, and many others. On the establishment of the National Institute he became one of its members and was occupied with other men of science in fram ing the new system of weights and measures adopted in France under the republican govern ment. Among the latest of his labors was a series of experiments to discover the length of a pendulum which should vibrate seconds in the latitude of Paris. His principal are 'His Voyage' and 'Tables Trigonometriques Decimales.'