The American Cyclopædia (1879)/Jacobi, Karl Gustav Jakob

'''JACOBI. I. Karl Gustav Jakob''', a German mathematician, born in Potsdam, Dec. 10, 1804, died in Berlin, Feb. 18, 1851. In 1825, on the recommendation of Hegel, he was sent to Königsberg as instructor in mathematics, and in 1827 was appointed professor of mathematics there. In 1842 he made a journey to England, but on his return was obliged by ill health to resign his professorship, and after visiting Italy resided in Berlin. His importance in the history of mathematics is chiefly due to his discoveries in the theory of elliptic functions, and his principal work is the Fundamenta Nova Theoriæ Functionum Ellipticarum (Königsberg, 1829), besides which he wrote many special memoirs. Under him, Bessel, and Neumann, the university of Königsberg enjoyed a reputation as a school of mathematics surpassed by none in Europe. '''II. Moritz''' Hermann, a German savant resident in Russia, brother of the preceding, born in Potsdam, Sept. 21, 1801, died in St. Petersburg, March 10, 1874. At the age of 28 he went to Russia to seek his fortune, and soon attracted attention by his researches in physics. In 1830 he constructed a short electric telegraph in St. Petersburg, and in 1832 one of 18 miles between two of the imperial residences, on which he made many experiments, and the important discovery that the earth could be used to complete the electric circuit. In 1837, simultaneously with Thomas Spencer of Liverpool, he invented the process of electrotyping; and in 1840 he published Die Galvanoplastik, which gained him admittance into the imperial academy of St. Petersburg. He soon after proposed to the czar the formation of a regiment of galvanic sappers, to be trained in the management of electricity. An immense battery was constructed for him, and he received the title of colonel in the galvanic regiment. He published many memoirs on the applications of electro-magnetism in the collections of the academy of St. Petersburg.