He was born in the village of Lenthe, today part of Gehrden, near Hanover, Germany, where his father, Christian Ferdinand Siemens (July 31 1787-January 16 1840), a tenant farmer, farmed an estate belonging to the Crown. His mother was Eleonore Deichmann (1792-July 8 1839), and William, or Carl Wilhelm, was the fourth son of a family of fourteen children. Of his siblings, Ernst Werner Siemens, the fourth child, became a famous electrician and was associated with William in many of his inventions. He is also a brother of Carl Heinrich von Siemens and a cousin of Alexander Siemens.
On July 23, 1859, Siemens was married at St. James's, Paddington, to Anne Gordon, the youngest daughter of Mr. Joseph Gordon, Writer to the Signet, Edinburgh, and brother to Mr. Lewis Gordon, Professor of Engineering in the University of Glasgow. He used to say that on March 19 of that year he took oath and allegiance to two ladies in one day — to the Queen and his betrothed. He was knighted – becoming Sir William – a few months before his death. He died on the evening of Monday November 19, 1883, at nine o'clock and was buried on Monday November 26, in Kensal Green Cemetery.
Siemens had been trained as a mechanical engineer, and his most important work at this early stage was non-electrical; the greatest achievement of his life, the regenerative furnace, was non-electrical. Though in 1847 he published a paper in Liebig's Annalen der Chemie on the 'Mercaptan of Selenium,' his mind was busy with the new ideas upon the nature of heat which were promulgated by Carnot, Clapeyron, Joule, Clausius, Mayer, Thomson, and Rankine. He discarded the older notions of heat as a substance, and accepted it as a form of energy. Working on this new line of thought, which gave him an advantage over other inventors of his time, he made his first attempt to economise heat, by constructing, in 1847, at the factory of John Hick, of Bolton, an engine of four horse-power, having a condenser provided with regenerators, and utilising superheated steam. Two years later he continued his experiments at the works of Messrs. Fox, Henderson, and Co., of Smethwick, near Birmingham, who had taken the matter in hand. The use of superheated steam was attended with many practical difficulties, and the invention was not entirely successful; nevertheless, the Society of Arts, in 1850, acknowledged the value of the principle, by awarding Siemens a gold medal for his regenerative condenser. In 1859 William Siemens devoted a great part of his time to electrical invention and research; and the number of telegraph apparatus of all sorts – telegraph cables, land lines, and their accessories – which have emanated from the Siemens Telegraph Works (at Charlton, SE London) has been remarkable. In 1872 Sir William Siemens became the first President of the Society of Telegraph Engineers which became the Institution of Electrical Engineers, the forerunner of the Institution of Engineering and Technology
The regenerative furnace is the greatest single invention of Charles William Siemens, using a process known as the Siemens-Martin process. The electric pyrometer, which is perhaps the most elegant and original of all William Siemens's inventions, is also the link which connects his electrical with his metallurgical researches. Siemens pursued two major themes in his inventive efforts, one based upon the science of heat, the other based upon the science of electricity; and the electric thermometer was, as it were, a delicate cross-coupling which connected both. Imbued with the idea of regeneration, and seeking in nature for that thrift of power which he, as an inventor, had always aimed at, Siemens suggested a hypothesis on which the sun conserves its heat by a circulation of its fuel in space, afterwards reprinting the controversy in a volume, On the Conservation of Solar Energy.