Evangelista Torricelli (Rome, 1608 – Florence, 1647), a pupil of Galileo Galilei, was the first to demonstrate the weight of air, using a glass tube full of mercury: when the tube was turned upside down and the open end immersed in a container full of mercury, the column of liquid metal fell, leaving an empty space above, until it was about 76 cm high, corresponding to an equilibrium between the pressures exerted by the air outside and the column of mercury. As well as measuring atmospheric pressure, this demonstrated the existence of a vacuum, which had been denied by many philosophers.
Subsequently, many experiments were conducted throughout Europe to verify Torricelli’s discovery and the effects of reduced air pressure, assisted by the invention in 1654 of a vacuum pump by Otto von Guericke (Magdeburg, 1602 – Hamburg, 1686), a politician, jurist and physicist.
From the initial model devised by von Guericke, pumps evolved additional features that enabled increased rarefaction of the air.
Teaching laboratories inevitably contained a vacuum pump – and various accessories – for demonstrating the effects of atmospheric pressure.
Together with the pump on display, built between 1791 and 1793, the Collegio Mariano and Liceo Paolo Sarpi physics collection inventories list a number of other pumps with progressively advanced features.
The study of fluids also includes the use of devices to show the properties of liquids, and the phenomena deriving from these properties such as, for example, the buoyancy of bodies, the operation of pumps, capillarity phenomena, etc.