Magdeburg Hemispheres - Portable
To demonstrate forces arising from atmospheric air pressure.
Magdeburg hemispheres with hand pump and hose.
About 40 pumps will adequately evacuate the hemispheres, and the vacuum will last about one minute. The hemispheres have a diameter of about 5 inches, thus requiring a force of over 250 pounds to separate them when fully evacuated. A safety restraint prevents the two hemispheres from separating entirely.