Regensburg vacuum experiment. Illustration of the piston vacuum experiment carried out in 1654 in Regensburg by German engineer and physicist Otto von Guericke (1602-1686). This demonstration of atmospheric pressure had over 20 men pulling on ropes failing to prevent a piston closing as air is pumped out from a cylinder, forming a vacuum. This is similar to the famous Magdeburg hemispheres experiment that used horses to try and pull apart two brass hemispheres. Artwork from 'Chaudieres et Machines a Vapeur' (1911) by French civil engineer Max de Nansouty (1854-1913), part of the 'Les merveilles de la science' series of 1867-1891 by Louis Figuier.