Otto von Guericke
Magdeburg hemispheres
1650, Otto von Guericke, mayor of Magdeburg (Germany), pumped the air out of two iron hemispheres in his famous experiment. The air pressure pressed with an enormous force on the vacuum inside that several horses didn't succeed in seperating the two hemispheres. You can test here your own Magdeburg hemispheres, chose the size and you can see, which strain they could stand.
