Used with
permission of Maiken Naylor, University at Buffalo, Buffalo, NY, USA,
http://ublib.buffalo.edu/libraries/units/sel/exhibits/stamps
Otto von Guericke (1602-1686) was a German natural philosopher and writer who also became the mayor of Magdeburg. Inspired by the work of Torricelli and Galileo, he tried to create a vacuum and invented the air pump. He devised the astonishing spectacle of the Magdeburg Hemispheres, which brought him fame in his own time. Here two large metal hemispheres were joined together with a gasket and evacuated; two teams of horses pulling in opposite directions were unable to separate them. Once air was readmitted, they fell apart.