Tessan, Urban Dortet de

Urbain Dortet de L'Espigarié de Tessan (August 25, 1804 - September 30, 1879) was a French physicist and Hydrographer Engineer active in Paris during the early to middle part of the 19th century. Tessan was considered among the most scientific of cartographers active at the time, and his work is notable for its meticulousness and precision. Tessan was born in Vigan, the scion of an old Languedoc family. He graduated from the École Polytechnique in 1825. On graduation, he was placed in the command of Beautemps-Beaupré (1824), under whom he participated in the Gironde estuary campaigns (surveying shifting sandbanks) and Bayonne (1825 - 26), before conducting seabed surveys at Saint-Malo and Saint-Brieuc. He was then reassigned to Lieutenant Commander A. Bérard of the brig Le Loiret; with whom he mapped the Algerian coast, devising in the process a new technique for offshore surveying (1831 - 33). From 1836 to 1839, he participated as expedition meteorlogist on the Abel Aubert Dupetit-Thouars (1793 - 1864) expedition, a scientific-naval westward circumnavigation of the globe on the frigate Vénus. After the circumnavigation, he worked mostly in and around France, retiring in 1852 as a first-class engineer. In 1861, he was voted a full member of l'Académie des Sciences. Tessan published several important works on physics, hydrography, astronomy, and more. Some of his more significant research presaged the invention of sonar over one hundred years later.