Guericke, Otto Von (1602-1686)
German politician and physicist
Otto von Guericke, born in Magdeburg, Germany, was a scientific showman during the seventeenth century. He studied mathematics, law, and engineering. Following travels to England and France, Guericke returned to Magdeburg in 1627 and became a politician. Unfortunately, this was during the Thirty Years' War; Guericke and his family had to flee the city in 1631. Following the war, he returned and helped rebuild the city, becoming mayor in 1646. Twenty years later he became a noble and added "von" to his name.
Otto von Guericke spent his leisure time dabbling in science, and he became involved in discussions surrounding the possibility of the existence of a vacuum. Most scientists were inclined to disavow that a vacuum could exist, primarily because of the teachings of Aristotle. Aristotle's theory was a masterpiece of reverse logic; he believed that if the air became less dense, an object would be able to move faster. If there was a vacuum, he erroneously added, an object could move with infinite speed, but because infinite speed was not possible, a vacuum was not possible either.
Unlike scientists who blindly accepted the ancient teachings, Guericke attempted to get a definite answer by experimentation. In 1650, he built the first air pump and proceeded to put on his production.
Guericke's first vacuum experiment was with a bell. Placing it in a vessel from which he had removed the air, thereby creating a vacuum, he showed that the bell could not be heard. This proved one of Aristotle's theories, which stated that sound would not travel through a vacuum. In addition, Guericke showed that lit candles would go out, and animals could not live in a vacuum.
For added drama, Guericke tied a rope to a piston in a cylinder and had fifty men pulling on it as he created a vacuum on the other side of the piston. The piston was drawn down into the cylinder in spite of the men trying to pull it the other direction.
For his next trick, in 1657, Guericke fitted two 12–ft (3.6–m) diameter metal hemispheres together, removed the air and created a vacuum that held the halves in place. Sixteen horses were unable to pull the hemispheres apart, yet when air was returned to the sphere, the halves fell apart. Emperor Ferdinand III, in the audience, was impressed. Guericke had placed the air valve in the bottom of his sphere because he was under the impression that air, like water, would seek the lowest level. He discovered that air could be removed no matter where the valve was located. Obviously the air was evenly distributed throughout the sphere. This led him to speculate that air decreased in density as one's altitude above the earth increased. He used this knowledge to build a water barometer in 1672, and used it to forecast the weather.
In addition to his experiments with the vacuum, Guericke built a device that created static electricity, similar to Robert Van de Graaff's (1901–1967) generator. A sphere of sulfur was rotated on a shaft. When it was rubbed, it built up a static charge that caused sizeable electric sparks to discharge. Guericke did not realize the electrical effect was a special phenomenon, but he was responsible for instigating a century of investigation by others.
Guericke also was interested in astronomy, suggesting that comets were members of the solar system and made regular returns as they orbited around the sun. Edmond Halley jumped on this idea and became famous when his observed comet returned precisely when he predicted. Guericke also believed that a magnetic force caused celestial objects to interact with each other across empty space. Isaac Newton would show that interaction did occur, but not because of magnetism.
After holding the position of mayor of Magdeburg for 35 years, Guericke retired. He died in Hamburg, Germany at the age of 83.
Atmospheric Pressure; Electricity and Magnetism; Gravity and the Gravitational Field
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