In paragraph LII of Pneumatics, Alexandrian scientist Heron (I century A.D.) proposes the construction of a particular siphon inside a drinking horn, closed by a glass lid (MN) on top. Two small apertures H and F are made at the base of the lid to which two tubes are attached: HK ends inside the vessel and FG outside. A small hole is made on the handle where the spout XD is inserted to introduce water inside the container. When the drinking horn is filled with water through this aperture, the HK tube also fills until the liquid flows into the transparent glass cover MN, where we can observe the water flow out with a fountain effect and then descend through aperture F. Thus we can observe the effects of a siphon capable of attracting liquid upwards until reaching the glass lid; once the water and air contained in the lid reach the peak of their journey, they flow into the second tube and then begin their descent.