Magdeburg hemispheres, 2000

Museum of the History of Science, Geneva, Switzerland. Magdeburg hemispheres, demonstration set. The hemispheres are mated and connected to a vacuum; the valve is opened until the space within is evacuated. The valve is closed and observers are challenged to separate the hemispheres, which they cannot. When the valve is opened, the spheres fall apart of their own weight. This demonstration was first performed by the mayor of Magdeburg, Germany, Otto von Guericke, in 1654.