Siemens, Ernst Werner von (ĕrnst vĕrˈnər fən zēˈməns) [key], 1816–92, German electrical engineer and inventor. He was a founder and director of Siemens and Halske, a firm that made electrical apparatus. He was co-inventor of an electroplating process (1841), and alone developed an electric dynamo. He laid the first telegraph line and built the first electric railway in Germany and, with his brother Sir William Siemens, developed (1866) a widely used process of steelmaking. The Siemens unit of electrical conductance was proposed by him. In 1884 he founded a research laboratory at Charlottenburg.
See his Inventor and Entrepreneur (1892, tr. 1966) and his Scientific and Technical Papers (2 vol., tr. 1892–95).