Boris Semyonovich Jacobi (21.09.1801-27.02.1874) was a Russian physicist and electrical engineer and a member of the St Petersburg Academy of Sciences (1847). He was born in Potsdam. He studied at the University of Göttingen. In 1834 he moved to Königsberg, in 1835 he was professor at the University of Dorpat, and from 1837 he lived in St Petersburg.
His work was in electromagnetism and its practical application. In 1834 he invented an electric motor with a rotating working shaft, discovered the appearance of a back e.m.f., and built a boat with an electric motor of 1 horsepower. In 1838 he invented electrotyping and did much to introduce it into printing and coinage and into the making of works of art. He designed a number of telegraph instruments and was one of the first to build underground (cable) telegraph lines, in particular the St Petersburg — Tsarskoye Selo line, about 25 km long. He did much to create domestic electrical equipment and built a number of electrical instruments: a voltmeter, a wire resistance standard, several designs of galvanometer, a resistance regulator and so on. Jacobi's work played an important part in organising electrical-engineering education in Russia.