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Fig. 11: Illustration from "Technik Curiosa", published in 1664 by Professor Caspar Schott from Würzburg.
© Caspar Schott
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En passant: Portrayal of vacuums in history

The Greek philosopher Aristotle (c. 384 – 322 B.C.) proposed the theory that nature abhors empty spaces, which he described as "horror vacui" (lat.: horror of emptiness), whereby empty spaces always try to suck in gas or liquids. According to Christian theology, a "gap" in God’s creation was unthinkable. Otto von Guericke (1602 – 1686), who was a diplomat, scientist and mayor of Magdeburg, refuted this theory with an impressive experiment: 16 horses, eight harnessed in one direction and eight in the other, were unable to pull apart a sphere made of two metal hemispheres void of air. Guericke therefore proved that materials are not sucked in by vacuums but are pushed in by the ambient pressure.

For the experiment he used two hemispheres made of approximately 2-cm-thick copper sheet with a 60 cm diameter. The rims were smoothed with fine sand and placed together to form a sphere. Using the vacuum pump developed by him, he was able to largely remove (evacuate) the air from inside the sphere. The pressure of the ambient atmosphere now pressed the two halves together. From 1657 onwards he repeated this experiment with differently sized spheres and a different number of horses – at that time horses provided the strongest tractive force available.

These days vacuum technology is a proven and long-established technology that has become indispensable in diverse industrial processes and research techniques. In industrial production, its range of uses extends from annealing and melting metals to vapour depositing metals and drying processes for differentmaterials. In physical- and chemicalbased investigations, mass spectrometers, particle accelerators and electron microscopy all make use of vacuums.

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