SIEMENS, ERNST WERNER VON Ger man electrician, was born on Dec. 13, 1816, at Lenthe in Hanover. After attending the gymnasium at Liibeck, he entered the Prus sian army as a volunteer, and for three years was a pupil in the military academy at Berlin. Between 1838 and 1848 he served in the artillery, and was entrusted with many specialized works such as the fortification of Eckernforde harbour and the laying of the first telegraph line in Germany, that between Berlin and Frankfort-on-Main. Thenceforward he devoted his energies to furthering the interests of the newly founded firm of Siemens and Halske, which under his guidance became one of the most important electrical undertakings in the world, with branches in different countries that gave it an international influence.
As his entrance into commercial life was almost synchronous with the introduction of electric telegraphy into Germany, many of his inventions and discoveries relate to telegraphic apparatus. In 1847 he suggested the use of gutta-percha as a material for insulating metallic conductors. Then he investigated the electro static charges of telegraph conductors and their laws, and estab lished methods for testing underground and submarine cables and for locating faults in their insulation (see TELEGRAPH: Submarine Telegraphy) ; further, he carried out observations and experiments on electrostatic induction and the retardation it produced in the speed of the current. He also devised apparatus
for duplex and diplex telegraphy, and automatic recorders. He suggested that the unit of electrical resistance should be taken as the resistance of a column of pure mercury one metre high and one square millimetre in cross-section, at a temperature of o° C. Another task to which he devoted much time was the construction of a selenium photometer. He also claimed to have been, in 1866, the discoverer of the principle of self-excitation in dynamo-electric machines. Siemens wrote several papers on meterological subjects, discussing among other things the causa tion of the winds and the forces which produce, maintain and retard the motions of the air. In 1886 he devoted half a million marks to the foundation of the Physikalisch-Technische Reichs anstalt at Charlottenburg, and in 1888 he was ennobled. He died at Berlin on Dec. 6, 1892. His scientific memoirs and addresses were collected and published in an English translation in 1892, and three years later a second volume appeared, containing his technical papers.