German physicist and politician. He invented the air pump and demonstrated the pressure of the atmosphere. He also constructed the first machine for generating static electricity.
Air pump Guericke constructed an air pump in an attempt to produce a vacuum, to test the French mathematician René Descartes's idea that space was matter. In 1647 Guericke imploded a copper sphere from which he pumped the air via an outlet at the bottom. But when he built a stronger vessel, he succeeded in evacuating it without causing it to collapse. He also demonstrated that a candle is extinguished as the air is removed, and gradually the theory that a vacuum cannot exist was discarded.
Atmospheric pressure Demonstrating the immense force that the pressure of the atmosphere exerts on an evacuated vessel, Guericke set up various public experiments. In 1657, two copper hemispheres with tight-fitting edges were placed together and the air pumped out. Two teams of horses were then harnessed to the hemispheres and proved unable to pull them apart. Once air was admitted to the hemispheres, they fell apart instantly. Guericke went on to investigate the decrease of pressure with altitude, and the link between atmospheric pressure and the weather. In 1660 he was making weather forecasts with a water barometer and proposing a string of meteorological stations contributing data to a forecasting system.
Other discoveries While experimenting with a globe of sulphur constructed to simulate the magnetic properties of the Earth, Guericke discovered that it produced static electricity when rubbed; he went on to develop a primitive machine for the production of static electricity. He also demonstrated the magnetization of iron by hammering in a north–south direction. Another first with which he is credited is the observation of coloured shadows.
Life Guericke was born in Magdeburg and attended several German universities, before returning to Magdeburg and becoming alderman of the city. In 1631, most of Magdeburg's population of 40,000 were butchered in the Thirty Years' War, and Guericke moved to Brunswick and Erfurt, where he worked as engineer to the Swedish government and later for that of Saxony as well. He was able to serve Magdeburg as envoy to various occupying powers – alternately French, Habsburg, and Swedish – and represented his city at various conferences. He was mayor of Magdeburg 1646–76.