DUPERREY, Louts Istnonz (1786-1865), a French navigator and. scientific investigator, was born at Paris, entered the navy in 1803, took part in the military operaduring that and the following year. From 1817 to 1820 he served under Freyeinet in his great voyage round tin, world, being intrusted with the hydrographic operations on board the " Urania ; " and lie contributed largely to the preservation of the crew and the scientific collections when his vessel was wrecked at the Malouin Islanas. In 1822 he attained the rank of lieutenant, and was intrusted with the connnand of the " Coquille," which during the next three years was engaged in scientific explorations in the South Pacific and along the coasts of South America. From this voyage he brought back not only great additions to cartography and. important data in regard to the currents of the Pacific, but also numerous pendulum observations, serv-ing to determine the magnetic equator, and to prove the equality of the flattening of the two hemispheres. During the rest of his life he devoted himself mainly to the investiga-tion of terrestrial magnetism ; and the value of his labours was recognized by his admission into the Academie des Sciences in 1842. He died. in August 1865.
The following are his principal works : - The Partie historique, the HydrograpItie, and the Physique of the Voyage autour Monde sur la Coquille, Paris 1826-1830 ; and extensive contributions to Becquerel's TraiM de l'Eleetrieite.