Two pressed-steel hemispheres, each with a sturdy handle, make up the device. One hemishpere has a gasket seal; the other has a stopcock for attaching to a vacuum pump. Fit the two hemispheres together, and evacuated the air with a vacuum pump. It is hard, if not impossible, to pull them apart. Open the stopcock and let air in, the hemispheres separate.
|Magdeburg hemispheres||017-3D (in wooded box)|