Construction
An aqueduct is built to supply the citadel of Pergamon, built on a knoll with an elevation of 332 m (1089 ft), from a spring in the mountains at an elevation of 1173 m (3850 ft). Along the way, the aqueduct passes through two valleys with low points of 172 m (564 ft) and 195 m (639 ft) as well as the ridge of 233 m (764 ft) between them. This is accomplished by using a bronze or lead pipe to cross the low points of the aqueduct and using water pressure (as high as 20 atmospheres in the lowest point) and a siphon effect. See also 272 bce Construction; 144 bce Construction.
