Guericke , Otto von

(1602–1686) German physicist and engineer

Guericke, who was born in Magdeburg, Germany, trained in law and mathematics before becoming an engineer in the army of Gustavus Adolphus of Sweden. After the Thirty Years' War he returned to Magdeburg as mayor, there carrying out numerous dramatic experiments on vacuums and the power of the atmosphere.

In 1650 Guericke constructed the first air pump by modifying a water pump. He used this device to create a vacuum in various containers and performed a number of novel experiments. Guericke was the first to show that sound would not travel in a vacuum, and furthermore that a vacuum would not support combustion or animal life. In 1654 Guericke gave an impressive demonstration in front of the emperor Ferdinand III, of the force of atmospheric pressure. Two identical copper hemispheres 12 feet (3.66 m) in diameter were joined together. When the air was pumped out, 16 horses could not pull them apart although when the air reentered the hemispheres they fell apart by themselves. He also showed that 20 men could not hold a piston in a cylinder once the air had been evacuated from one end of it. The results of these and other experiments were published in his Experimenta nova Magdeburgica de vacuo spatio (1672; New Magdeburg Experiments Concerning Empty Space). In 1663 he built the first electrical friction machine by rotating a sulfur globe against a cloth.