German physicist; born Sept. 21, 1801, at Potsdam; died March 10, 1874, at St. Petersburg. He was established as architect at Königsberg when, in 1835, he was appointed professor of architecture in the University of Dorpat. Called in 1837 to St. Petersburg, he became in 1842 an extraordinary member, and in 1847 full member, of the Russian Academy of Sciences, and later he received the title of "state councilor." His greatest merit was the discovery of galvanoplasty (1838). Besides his "Die Galvano-Plastik" (St. Petersburg, 1840) and Mémoire sur l'Application de l'Electromagnétisme au Mouvement des Machines" (ib. 1835), Jacobi published a large number of papers in the "Mémoires" of the Academy of St. Petersburg.