Magdeburg Hemispheres

2 men pulling on a ball that has a vacuum inside of it.

PIRA: 2B30.30

Materials: Magdeburg Spheres, Vacuum Pump

The Magdeburg Hemispheres make up the two halves of a hollow sphere that can be evacuated through a nozzle on one of the hemispheres. When placed together, they make an airtight seal. There is nothing between the two other than a rubber or plastic gasket (no glue). Yet when the gas inside is removed, the hemisphere's "stick" together strongly enough that no pair of volunteers should be able to separate them. With almost no outward pressure from inside, the two hemispheres are pinned together by the enormous inward pressure from the surrounding atmosphere.