Consists of a pair of hollow brass hemisphere with a handle on each. There's a gasket around the circumference, so that when they're put together they make a seal. When put together, the air inside may be evacuated with a pipe fitting and a valve.
Demonstrates the power of atmospheric pressure.
Suction cups can be thought of as Magdeburg Hemispheres that create their own vacuum in the action of pressing them onto a surface.
Demo room information