1-157-614 - Oxford Science Archive/Heritage Images

Von Guericke's demonstration of the strength of air pressure, 1672. In the mid 17th century Otto von Guericke used an air-pump to remove the air from between two large close-fitting copper hemispheres, known as Magdeburg hemispheres. The effect of the air pressure on the two hemispheres was such that two teams of 8 horses could not separate them. Once the air was let back into the enclosure, however, the hemispheres were parted easily. From Experimenta Nova by Otto von Guericke. (Amsterdam, 1672).