November 30, 2014
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Otto von Guericke (originally spelled Gericke) (November 20, 1602 – May 11, 1686 (Julian calendar); November 30, 1602 – May 21, 1686 (Gregorian calendar)) was a German scientist, inventor, and politician. His major scientific achievements were the establishment of the physics of vacuums and the discovery of electrostatic repulsion.

Guericke was born to a patrician family of Magdeburg, Germany. In 1617 he became a student at the Univerity of Leipzig. Owing to the outbreak of the Thirty Years War his studies at Leipzig were disrupted and subsequently he studied at the Academia Julia in Helmstedt and the universities of Jena and Leyden. At the last of these he attended courses on mathematics, physics and fortification engineering. His education was completed by a nine - month long trip to France and England. On his return to Magdeburg in 1626 he married Margarethe Alemann and became a member of the Ratscollegium of Magdeburg. He was to remain a member of this body until old age.

Von Guericke was personally distrustful of the city's enthusiasm for the cause of Gustavus Adolphus but was nonetheless a victim of the fall of Magdeburg to von Tilly's troops in May 1631. Destitute, but fortunate to escape with his life, he was an Imperial prisoner at a camp in Fermersleben until, through the good offices of Ludwig of Anhalt - Cothen, a ransom of three hundred thalers had been paid. Following a period of employment as engineer in the service of Gustavus Adolphus he and his family returned to Magdeburg in February 1632. For the next decade he was occupied rebuilding his own and the city's fortunes from the ruins of the fire of 1631. Under the Swedish and subsequently Saxon authorities he remained involved in the civic affairs of the city, becoming in 1641 a Kammerer and in 1646 Burgermeister, a position he was to hold for thirty years. His first diplomatic mission on behalf of the city, in September 1642, was to the court of the Elector of Saxony at Dresden to seek some mitigation of the harshness with which the Saxon military commander treated Magdeburg. Diplomatic missions, often dangerous as well as tedious, occupied much of his time for the next twenty years. A private scientific life, of which much remain unclear, was developing in parallel.

The scientific and diplomatic worlds finally met when, at the Reichstag in Regensburg in 1654, he was invited to demonstrate his experiments in the vacuum before the highest dignitaries of the Holy Roman Empire. One of them, the Archbishop Elector Johann Philip von Schonborn, bought von Guericke's apparatus from him and had it sent to his Jesuit run College at Wurzburg. One of the professors at the College, Fr. Gaspar Schott, entered into friendly correspondence with von Guericke and thus it was that, at the age of 55, von Guericke's work was first published as an Appendix to a book by Fr. Schott - Mechanica Hydraulico - pneumatica - published in 1657. This book came to the attention of Robert Boyle who, stimulated by it, embarked on his own experiments on air pressure and the vacuum, and in 1660 published New Experiments Physico - Mechanical touching the Spring of Air and its Effects. The following year this was translated into Latin and, made aware of it in correspondence with Fr. Schott, von Guericke acquired a copy.

In the decade following the first publication of his own work von Guericke, in addition to his diplomatic and administrative commitments, was scientifically very active. He embarked upon his magnum opus - Ottonis de Guericke Experimenta Nova (ut vocantur) Magdeburgica de Vacuo Spatio - which as well as a detailed account of his experiments on the vacuum, contains his pioneering electrostatic experiments in which electrostatic repulsion was demonstrated for the first time and sets out his theologically based view of the nature of Space. In the Preface to the Reader he claims to have finished the book in 1663 though publication was delayed for another nine years until 1672. In 1664, his work again appeared in print, again through the good offices of Fr. Schott, the first section of whose book Technica Curiosa, entitled Mirabilia Magdeburgica, was dedicated to von Guericke's work. The earliest reference to the celebrated Magdeburg's hemispheres experiment is on p. 39 of the Technica Curiosa where Fr. Schott notes that von Guericke had mentioned them in a letter of July 22nd 1656. Fr. Schott goes on to quote a subsequent letter of von Guericke of August 4th 1657 in which he states that he now had carried out the experiment, at considerable cost, with 12 horses.

The 1660's saw the final collapse of Magdeburg's aim, to which von Guericke had devoted some twenty years of diplomatic effort, of achieving the status of a Free City within the Holy Roman Empire. On behalf of Magdeburg, he was the first signatory to the Treaty of Klosterberg (1666) whereby Magdeburg accepted a garrison of Brandenburg troops and the obligation to pay dues to the Great Elector, Friedrich Wilhelm I of Brandenburg. Despite the Elector's crushing of Magdeburg's political aspirations, the personal relationship of von Guericke and Friedrich Wilhelm remained warm. The Great Elector was a patron of scientific scholarship; he had employed von Guericke's son, Hans Otto, as his Resident in Hamburg and in 1666 had named Otto himself to the Brandenburg Rat. When the Experimenta Nova finally appeared it was prefaced with a fulsome dedication to Friedrich Wilhelm. The year 1666 also saw von Guericke's enoblement by Leopold I, Holy Roman Emperor when he changed the spelling of his name from "Gericke" to "Guericke" and when he became entitled to the prefix "von". In a book by Schimank von Guericke's petition to Leopold requesting the prefix "von" and the change of spelling is reproduced.

In 1677 von Guericke, after repeated requests, was reluctantly permitted to step down from his civic responsibilities. In January 1681, as a precaution against an outbreak of plague then affecting Magdeburg, he and his second wife Dorothea moved to the home of his son Hans Otto in Hamburg. There he died peacefully on May 11th (Julian) 1686, 55 years to the day after he had fled the flames in 1631. His body was returned to Magdeburg for interment in the Ulrichskirche on May 23rd (Julian).

There are only three important contemporary sources describing Von Guericke's scientific work - Fr. Schott's Mechanica Hydraulico - pneumatica and Technica Curiosa of 1657 and 1664 and his own Experimenta Nova of 1672. His scientific concerns may be divided into three areas (a) the nature of space and the possibility of the void (b) the experimental work on the production of vacua, the pressure of air and the Earth's atmosphere (c) the investigation into electrostatic forces. Book II of the Experimenta Nova is dedicated to (a), Book III to (b) and Book IV to (c).

Book II of the Experimenta Nova is an extended philosophical essay in which von Guericke puts forward a view of the nature of Space similar to that later espoused by Newton. He is explicitly critical of the plenist views of Aristotle and of their adoption by his younger contemporary Descartes. A particular and repeated target of his criticism is the manner in which the "nature abhors a vacuum" principle had migrated from simply a matter of experiment to a high principle of physics which could be invoked to explain phenomena such as suction but which itself was above question. In setting out his own view, von Guericke, while acknowledging the influence of previous philosophers such as Lessius (but not Gassendi), makes it clear that he considers his thinking on this topic to be original and new.

In 1650 he invented a vacuum pump consisting of a piston and an air gun cylinder with two - way flaps designed to pull air out of whatever vessel it was connected to, and used it to investigate the properties of the vacuum in many experiments. Guericke demonstrated the force of air pressure with dramatic experiments. He had joined two copper hemispheres of 51 cm diameter (Magdeburg hemispheres) and pumped the air out of the enclosure. Then he harnessed a team of eight horses to each hemisphere and showed that they were not able to separate the hemispheres. When air was again let into the enclosure, they were easily separated. He repeated this demonstration in 1663 at the court of Friedrich Wilhelm I of Brandenburg in Berlin, using 24 horses.

With his experiments Guericke disproved the hypothesis of "horror vacui", that nature abhors a vacuum, which for centuries was a problem for philosophers and scientists. Guericke proved that substances were not pulled by a vacuum, but were pushed by the pressure of the surrounding fluids.

Guericke applied the barometer to weather prediction and thus prepared the way for meteorology. His later works focused on electricity, but little is preserved of his results. He invented the first electrostatic generator, the "Elektrisiermaschine", of which a version is illustrated in an engraving by Hubert - François Gravelot, c. 1750. Von Guericke describes his work on electrostatics in Book IV of the Experimenta Nova.

Guericke died on May 11, 1686 in Hamburg, Germany. The Otto von Guericke University of Magdeburg is named after him.