How did public fountains, like those in Rome, work without any type of motor to pump the water?

古罗马收到所有的窟er (according toEncarta, about 38 million gallons a day) through a system ofaqueducts. All water flowed to the city bygravity, but because it was arriving from surrounding hills, it could be stored in largecisternsvery similar in concept to today's water towers (the main difference is that cisterns are filled from the top).

Water flowed from the cisterns either through pipes to individual houses or to public distribution points.Fountainsserved both decorative and functional purposes, since people could bring their buckets to the fountain to collect water. The cisterns provided the height needed to generate water pressure for the fountains to spray. As discussed inHow Water Towers Work, a foot of height generates 0.43 pounds per square inch (psi) of water pressure, so a cistern does not have to be that tall to develop enough pressure to give a fountain a reasonable display.