Siemens, Sir William, 1823–83, English electrical engineer, b. Germany; brother of Ernst Werner von Siemens. Originally his name was Carl Wilhelm Siemens. After visiting England to introduce an electroplating device he devised with his brother Ernst he returned in 1844 and became (1859) a naturalized British subject. He was head of the English branch of the Siemens firm, which made telegraphic and other electrical apparatus and handled electrical engineering projects. Among his important inventions were a water meter (1851) and a device for reproducing printing that remained standard until the development of photography, and he was one of the first to apply (1883) electric power to railways. With his brother Frederick he developed an improved regenerative furnace that was used to produce steel; the process, and a variation of it introduced by Pierre Martin, came to be known as the open-hearth process. He was knighted in 1883.