Otto von Guericke

German physicist and engineer

• Born: November 20, 1602
• Birthplace: Magdeburg, Saxony (now in Germany)
• Died: May 11, 1686
• Place of death: Hamburg (now in Germany)

Guericke’s experiments with electricity and, especially, air pressure make him a foundational figure in the era of the scientific revolution. His experiments attempted to prove the existence of void, or a vacuum, in nature. His work on atmospheric pressure was significant for the development of the steam engine in the mid-eighteenth century.

Early Life

Otto von Guericke (OHT-toh fawhn GAY-rihk-eh) was the only son of Hans Guericke (or Gericke) and his second wife, Anna von Zweidorff. The elder Guericke was a prominent citizen and important city official of Magdeburg, who could afford to provide tutors for the elementary education of his son. In 1617, the fifteen-year-old Otto went to Leipzig and then, in 1620, to Helmstedt for studies that would prepare him for a higher education in philosophy.

The death of his father may have changed his plans, as he went to Jena to study law between 1621 and 1622. In 1623, he was in Leiden, the Netherlands, where he studied foreign languages, mathematics, geometry, mechanical arts, and the like. He completed his education with a tour through England and France before returning to Magdeburg to marry Margarethe Alemann in 1626. At about the same time, he entered city government as director of public works and soon became Magdeburg’s director of military affairs as well.

The Thirty Years’ War had begun in 1618, and Magdeburg was spared none of the evils of that particularly horrible war. Guericke warned that the city was in danger of attack by imperial Catholic troops and that it could not withstand such an attack. In May of 1631, his predictions came true as forces under Johan Tserclaes seized Magdeburg and forced the conversion of its forty thousand inhabitants to Catholicism. During the process, many people were killed and much of the city, including Guericke’s house, was sacked and burned. His youngest son was wounded and his family threatened with death. Finally, after paying a ransom of three hundred talers, he managed to leave for Erfurt, where he became an engineer for the Swedish army. In the spring of 1632, he returned to Magdeburg to help in the rebuilding of the city.

From about 1642, Guericke was diplomatic representative of Magdeburg in the negotiations for the reconstitution of Germany. In that capacity, he was successful in obtaining recognition of the former rights of the city and in completing other diplomatic missions for the next twenty years. In 1646, he began his thirty-year tenure as mayor of Magdeburg. An imperial patent of nobility dated January 4, 1666, allowed him to attach “von” to his name as an indication of noble status. In view of his active political life, it is remarkable that he was able to find time for the scientific experiments that are his greatest claim to fame.

Life’s Work

Guericke was interested in cosmology and, consequently, in two particular subjects—magnetism and the nature of space. Experiments concerning the latter subject led to his theories and famous experiments regarding atmospheric pressure.

In the seventeenth century, there was a continuing argument between the Aristotelian and the “new” natural philosophers concerning the emptiness of space. The Aristotelians maintained that forces of nature, such as magnetism or heat, could not operate through empty space. This view was a result of Aristotle’s explanation of physics, which was based on the notion that mechanical contact is necessary for an object to influence another object. The Aristotelians, therefore, believed that a true vacuum is impossible and that all space is filled with the aether—an undetectable but real substance. René Descartes had adopted the Aristotelian view and asserted that space is, in fact, matter.

On the other side of the issue, by inventing the barometer, the Galilean Evangelista Torricelli had shown that a vacuum could exist. He filled a glass tube open at one end with mercury and inverted it in a container of mercury. The mercury in the tube fell to an approximate height of thirty inches, leaving a space at the top of the tube that could contain nothing, since everything in the tube had been previously displaced by the mercury. Another aspect of the demonstration was the indication that the weight of the atmosphere suspended the column of mercury in the tube by acting on the surface of the liquid in the open container.

Since his student days at Leiden, Guericke had taken the side of the anti-Aristotelians. Torricelli’s experiments were apparently unknown to him, but he determined to conduct experiments of his own that would demonstrate the possibility of a vacuum and that space and matter were not the same. If Descartes and Aristotle were correct, the evacuation of the air from a hollow object should lead to its collapse, as it would be impossible to create a vacuum. Pursuing this line of reasoning, Guericke first invented the vacuum pump. It resembled a modern bicycle pump except that it worked in reverse. With this pump, he tried to evacuate a sealed barrel filled with water. The seals were insufficient, however, and air could be heard whistling into the barrel as the water was removed. He then tried placing a water-filled barrel inside a larger barrel also filled with water. His hope was that the outer barrel would act as a seal, but he could not prevent the surrounding water from leaking into the inner barrel as it was evacuated.

Having failed with wooden barrels, he turned to metal spheres. His first attempt was with a copper ball, but the copper proved too weak and collapsed as the air was pumped out of it. Although this seemed to substantiate the Aristotelian view, Guericke tried again with a stronger vessel, and this time he succeeded in creating a vacuum without collapsing its container. After this success, he proceeded to perform a number of experiments that were to shed light on the nature of atmospheric pressure and the properties of air.

At first he assumed from the example of water that the air sank as it was removed from the valve in the bottom of the vessel; changing the location of the valve seemed to make no difference in any of his results, however, and he concluded that the air remained evenly distributed in the sphere regardless of how little there was of it. He showed that a candle flame is extinguished and the sound of a bell becomes muffled as the air around them is depleted. Further experiments showed that floating objects sank lower as the density of the air was reduced.

His most famous experiments showed the effect of air pressure. They became famous because of their scientific importance and, perhaps more significant, because of their dramatic appeal. Guericke’s travels within Germany as a representative of Magdeburg also helped spread his reputation as he performed his experiments before several dignitaries. One of his demonstrations involved a piston closely fitted inside a tube. When an air valve at the bottom of the closed end of the tube was open, the piston could be lifted easily by means of a rope passing through a pulley and attached to a ring on top of the piston. With the valve closed, several men could lift the piston only part of the way up in the cylinder and, as the air was pumped from the bottom of the tube, they could not prevent its descent. Guericke performed this demonstration before the imperial court in 1654.

Another of Guericke’s devices was a water barometer. He constructed brass tubes, filled them with water, and used them in the same way that Torricelli had used his smaller mercury-filled tubes. Guericke realized that changes in the weather produced changes in the height of the water and used his device to make weather predictions. Yet the experiment with which his name is most often associated utilized the so-called Magdeburg hemispheres. These were two copper hemispheres about 20 inches in diameter and constructed in such a way that they could be placed together to form a sphere with surfaces matching so well that a gasket between them formed an airtight seal. He first wrote of the hemispheres on July 22, 1656, when he described how “six strong men could not separate them” after he had evacuated the air from them. In 1657, he repeated the experiment with two teams of horses attempting the separation. He demonstrated the phenomenon for the imperial court in Berlin in 1663.

Guericke’s purpose in these experiments was to understand the nature of space. In this connection, he became interested in magnetism because of the argument about how forces could act across empty space. He was inspired by the work of William Gilbert to construct a variety of spheres with magnetic properties. Finally, he made a sphere of pure sulfur that could be caused to act as a magnet by rubbing it while it was spinning. He noted that objects such as feathers were attracted to it but were also repelled after they had touched it. Gilbert had denied the existence of repulsion and believed that gravity was actually magnetism with the earth acting as a huge magnet. Guericke, on the other hand, concluded that gravity is related to electricity because his sphere had to be rubbed to induce its magnetic properties. He realized that electricity was different from magnetism because he saw sparks and heard the crackling of electrical discharge. He also demonstrated that a charge could be made to travel through a linen string coming from the ball.

Guericke’s cosmological conclusions from these experiments were that the universe consists of a large number of stars (suns), each with its own planetary system; these solar systems are held together by a gravitational force centered in each system; and the space in which they are contained is empty and infinite. Earlier speculations on the infinity of space had run into religious objections because only God was believed to be infinite and his creations finite. Guericke neatly solved this problem by maintaining that nothingness (space) already existed when God began filling it with creations. In 1681, Guericke retired and went to live in Hamburg with his son. He died there in 1686 at the age of eighty-three.

Significance

In his day, Guericke was an important political figure in his own small sphere of central Germany. During a long and productive life, he led his city of Magdeburg through some of the most troubled years in its history. In addition to his political activities, he was able to establish a reputation as an ingenious inventor of experiments that became famous throughout Europe.

He also offered scientific theories about the nature of the universe, but his scientific theories were to prove much less important than his experiments. Many more famous scientists, such as Irish chemistRobert Boyle and Dutch scientist Christiaan Huygens , were stimulated by his work with air pressure and vacuum pumps to duplicate and continue it with important results. It may be said that those who speculated about the possibility of creating an engine that worked by means of atmospheric pressure were inspired by Guericke. This line of inquiry led directly to the steam engine, without which the Industrial Revolution would have been impossible.

Although writers in the eighteenth century noted his importance, Guericke’s work with electricity has not been recognized as much as it deserves because it has been maintained that he did not fully understand his observations. As with the experiments regarding atmospheric pressure, the example of his investigations of electrical phenomena is more important than his conclusions. The hints about conduction and induction, generation of electricity, transmission lines, and the construction of a crude generator led to the works of Benjamin Franklin and later experimenters.

Bibliography

Barrow, John D. The Book of Nothing: Vacuums, Voids, and the Latest Ideas About the Origins of the Universe. New York: Pantheon Books, 2000. Includes a six-page discussion of Torricelli’s influence on Guericke, and Guericke’s experiments with vacuums.

Genz, Henning. Nothingness: The Science of Empty Space. Translated by Karin Heusch. Reading, Mass.: Perseus Books, 1998. An account by a German theoretical physicist of theories of the void from the time of the Greeks to modern theory of superstrings. Includes discussion of Guericke’s infamous experiment trying to prove the existence of empty space (a vacuum) in nature. Bibliography, index.

Guericke, Otto von. The New (So-Called) Magdeburg Experiments of Otto von Guericke. Translated by Margaret Glover Foley Ames. Boston: Kluwer Academic, 1994. The first English translation of Experimenta nova (ut vocantur) Magdeburgica de vacuo spatio (1672), Guericke’s account of his vacuum experiments. Also contains a foreword examining Guericke and his work.

Karwatka, Dennis. “Otto von Guericke.” Tech Directions 51, no. 4 (November, 1997): 14. Profile of Guericke and explanations of his experiments with vacuum pumps and space.

Krafft, Fritz. “Otto von Guericke.” In Dictionary of Scientific Biography, edited by Charles Coulston Gillispie, vol. 5. New York: Charles Scribner’s Sons, 1972. Reprint. 1981. The entry on Guericke includes very little biographical information but provides a concise overview of his scientific work. Describes Guericke as a “convinced Copernican” and emphasizes the extent to which his Copernicanism directed his “attempt to reach a complete physical world view.”

Lindberg, David C., and Ronald L. Numbers, eds. When Science and Christianity Meet. Chicago: University of Chicago Press, 2003. Emphasizes the complexity of the relationship between science and Christianity throughout history. Includes a guide to further reading and an index.