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21 Guericke, Otto von
[br]b. 20 November 1602 Magdeburg, Saxony, Germanyd. 11 May 1686 Hamburg, Germany[br]German engineer and physicist, inventor of the air pump and investigator of the properties of a vacuum.[br]Guericke was born into a patrician family in Magdeburg. He was educated at the University of Leipzig in 1617–20 and at the University of Helmstedt in 1620. He then spent two years studying law at Jena, and in 1622 went to Leiden to study law, mathematics, engineering and especially fortification. He spent most of his life in politics, for he was elected an alderman of Magdeburg in 1626. After the destruction of Magdeburg in 1631, he worked in Brunswick and Erfurt as an engineer for the Swedish government, and then in 1635 for the Electorate of Saxony. He was Mayor of Magdeburg for thirty years, between 1646 and 1676. He was ennobled in 1666 and retired from public office in 168land went to Hamburg. It was through his attendances at international congresses and at princely courts that he took part in the exchange of scientific ideas.From his student days he was concerned with the definition of space and posed three questions: can empty space exist or is space always filled? How can heavenly bodies affect each other across space and how are they moved? Is space, and so also the heavenly bodies, bounded or unbounded? In c. 1647 Guericke made a suction pump for air and tried to exhaust a beer barrel, but he could not stop the leaks. He then tried a copper sphere, which imploded. He developed a series of spectacular demonstrations with his air pump. In 1654 at Rattisbon he used a vertical cylinder with a well-fitting piston connected over pulleys by a rope to fifty men, who could not stop the piston descending when the cylinder was exhausted. More famous were his copper hemispheres which, when exhausted, could not be drawn apart by two teams of eight horses. They were first demonstrated at Magdeburg in 1657 and at the court in Berlin in 1663. Through these experiments he discovered the elasticity of air and began to investigate its density at different heights. He heard of the work of Torricelli in 1653 and by 1660 had succeeded in making barometric forecasts. He published his famous work New Experiments Concerning Empty Space in 1672. Between 1660 and 1663 Guericke constructed a large ball of sulphur that could be rotated on a spindle. He found that, when he pressed his hand on it and it was rotated, it became strongly electrified; he thus unintentionally became the inventor of the first machine to generate static electricity. He attempted to reach a complete physical explanation of the world and the heavens with magnetism as a primary force and evolved an explanation for the rotation of the heavenly bodies.[br]Bibliography1672, Experimenta nova (ut vocantur) Magdeburgica de vacuo spatio (New Experiments Concerning Empty Space).Further ReadingF.W.Hoffmann, 1874, Otto von Guericke (a full biography).T.I.Williams (ed.), 1969, A Biographical Dictionary of Scientists, London: A. \& C.Black (contains a short account of his life).Chambers Concise Dictionary of Scientists, 1989, Cambridge.Dictionary of Scientific Biography, Vol. V, New York.C.Singer (ed.), 1957, A History of Technology, Vols. III and IV, Oxford University Press (includes references to Guericke's inventions).RLH -
22 magnetization reversal
flux reversal — перемагничивание; изменение знака потока
The English-Russian dictionary general scientific > magnetization reversal
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