A siphon (also spelled syphon) is a continuous tube that allows liquid to drain from a reservoir through an intermediate point that's higher, or lower, than the reservoir, the flow being driven only by the difference in hydrostatic pressure without any need for pumping. It is necessary that the final end of the tube be lower than the liquid surface in the reservoir. History It is probable that Ctesibius was the discoverer of the principle of the siphon. (External Link) His student, Hero of Alex… (More on Siphon)