Photogravure after a painting by Franz Seraph von Lenbach of Ernst Werner von Siemens (1816-1892), German electrical engineer. Siemen's use of gutta-percha (a fibrous gum) to insulate cables in 1847 made the first underground and submarine telegraph cables posible. He was responsible for both the first telegraph line (1848) and the first electric railway in Germany, and together with his brother Sir William Siemens (1823-1883), developed a widely used proces of steelmaking. In 1888 Siemens was made a member of the nobility (with the addition of 'von' to his name). The standard scientific unit (SI) of electrical conductance, the Siemens (S), was named after him. Published by Photographische Gesellschaft, Berlin, c 1910. Dimensions: 460mm x 340mm.
© Science Museum / Science & Society Picture Library