1900c Pair of Magdeburg Hemispheres by Otto Von Guericke

Description

Correct condition - Used in school. The images are part of the description
about 13cm. diameter
The Magdeburg hemispheres are a pair of hemispheres that are fitted with a coupling ring to form a sphere and are used to demonstrate the power of atmospheric pressure. The demonstration consisted of trying to separate both hemispheres by two shots of horses when the edges were sealed with grease and the air was extracted from their interior by means of a pneumatic machine or pump, creating a vacuum. The Magdeburg hemispheres were designed in 1656 by the German scientist and magdeburg burgomaster, 1 Otto von Guericke, to show the vacuum pump he had invented and the concept of atmospheric pressure. The first artificial vacuum had been produced a few years earlier by Evangelista Torricelli and had inspired Guericke to design the world's first vacuum pump, which consisted of a cylinder and piston with one-way butterfly valves. The hemispheres became popular in physics classes as an illustration of the power of air pressure and are still used in educational settings. A couple of the original hemispheres are kept in the Deutsches Museum in Munich.