Werner von Siemens

Siemens revolutionised electricity generation, invented the moving-coil loudspeaker, did much to advance international telegraphy, and helped found the electrical engineering industry. His gold and silver electro-plating technology was sold by his brother Wilhelm (later William) to a Birmingham industrialist. Helmholtz, a lifelong friend, was met initially in the circle around Siemens’ teacher Magnus (who, impressed by Siemens’ dynamo, offered to make a public presentation about it). Siemens, together with Helmholtz, Clausius, Kirchhoff and Wiedemann, was active in the Physical Society of Berlin, founded by du Bois-Reymond (who became a good friend).