The automatic dispenser of Philon (3rd c. B.C.)
The first automatic dispenser device in history
It was a vessel with a tap which automatically allowed the flow of a certain quantity of liquid (e.g. wine) every time a visitor opened it.
Inside, it contained an additional sealed vessel, which led to a tap on one side, and to a non-return port on the other. The port was linked to a small rod, which extended to the tap’s latch. When the tap was closed, the latch pressed the rod and the non-return port and, as a result, the liquid entered the inner vessel until the pressure of the entrapped air matched the pressure of the liquid. When the tap opened, its latch released the rod. As a result, the non-return port closed due to gravity, whereas a certain amount of liquid flowed due to the pressure difference of the compressed air in the inner vessel and the air in the outside. Visitors closed and opened the open tap of the vessel to get the predetermined amount of liquid by the device.