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981 Polhem, Christopher
SUBJECT AREA: Mining and extraction technology[br]b. 18 December 1661 Tingstade, Gotland, Sweden d. 1751[br]Swedish engineer and inventor.[br]He was the eldest son of Wolf Christopher Polhamma, a merchant. The father died in 1669 and the son was sent by his stepfather to an uncle in Stockholm who found him a place in the Deutsche Rechenschule. After the death of his uncle, he was forced to find employment, which he did with the Biorenklou family near Uppsala where he eventually became a kind of estate bailiff. It was during this period that he started to work with a lathe, a forge and at carpentry, displaying great technical ability. He realized that without further education he had little chance of making anything of his life, and accordingly, in 1687, he registered at the University of Uppsala where he studied astronomy and mathematics, remaining there for three years. He also repaired two astronomical pendulum clocks as well as the decrepit medieval clock in the cathedral. After a year's work he had this clock running properly: this was his breakthrough. He was summoned to Stockholm where the King awarded him a salary of 500 dalers a year as an encouragement to further efforts. Around this time, one of increasing mechanization and when mining was Sweden's principal industry, Pohlem made a model of a hoist frame for mines and the Mines Authority encouraged him to develop his ideas. In 1693 Polhem completed the Blankstot hoist at the Stora Kopparberg mine, which attracted great interest on the European continent.From 1694 to 1696 Polhem toured factories, mills and mines abroad in Germany, Holland, England and France, studying machinery of all kinds and meeting many foreign engineers. In 1698 he was appointed Director of Mining Engineering in Sweden, and in 1700 he became Master of Construction in the Falu Mine. He installed the Karl XII hoist there, powered by moving beams from a distant water-wheel. His plan of 1697 for all the machinery at the Falu mine to be driven by three large and remote water-wheels was never completed.In 1707 he was invited by the Elector of Hanover to visit the mines in the Harz district, where he successfully explained many of his ideas which were adopted by the local engineers. In 1700, in conjunction with Gabriel Stierncrona, he founded the Stiersunds Bruk at Husby in Southern Dalarna, a factory for the mass production of metal goods in iron, steel and bronze. Simple articles such as pans, trays, bowls, knives, scissors and mirrors were made there, together with the more sophisticated Polhem lock and the Stiersunds clock. Production was based on water power. Gear cutting for the clocks, shaping hammers for plates, file cutting and many other operations were all water powered, as was a roller mill for the sheet metal used in the factory. He also designed textile machinery such as stocking looms and spinning frames and machines for the manufacture of ribbons and other things.In many of his ideas Polhem was in advance of his time and Swedish country society was unable to absorb them. This was largely the reason for the Stiersund project being only a partial success. Polhem, too, was of a disputatious nature, self-opinionated almost to the point of conceit. He was a prolific writer, leaving over 20,000 pages of manuscript notes, drafts, essays on a wide range of subjects, which included building, brick-making, barrels, wheel-making, bell-casting, organ-building, methods of stopping a horse from bolting and a curious tap "to prevent serving maids from sneaking wine from the cask", the construction of ploughs and threshing machines. His major work, Kort Berattelse om de Fornamsta Mechaniska Inventioner (A Brief Account of the Most Famous Inventions), was printed in 1729 and is the main source of knowledge about his technological work. He is also known for his "mechanical alphabet", a collection of some eighty wooden models of mechanisms for educational purposes. It is in the National Museum of Science and Technology in Stockholm.[br]Bibliography1729, Kort Berattelse om de Fornamsta Mechaniska Inventioner (A Brief Account of the Most Famous Inventions).Further Reading1985, Christopher Polhem, 1661–1751, TheSwedish Daedalus' (catalogue of a travelling exhibition from the Swedish Institute in association with the National Museum of Science and Technology), Stockholm.IMcN
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