Asia: Terra incognita / Norias of Hama

PHOTO: gaigner 35 8'15.85" 3644'49.01"

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In the drier climates of North Africa and Spain, and elsewhere, the Romans were responsible for extensive irrigation systems, using the Archimedean screw and the noria (a water-powered scoop wheel) to raise water. This type of water wheel includes the largest water wheel in the world, being 90 feet in diameter and the oldest, being 900 to 1,000 years old. The wheel, along whose circumference were attached buckets or clay pots, and was powered by movement of the current. The current of the stream turned the water wheel, as it did the wheel rotates lowering the empty pots down into the stream where they were filled with water. As the wheel continued to turn the filled pots became upturned as they reached the upward rotation of the wheel emptying their contents into a trough or aqueduct that carried the water away. Then the empty pots would continue down ward to be filled once again, just like the grain or flour elevator of Oliver Evans. The wheels were solely used just to raise water. The lower recipients filled up by immersion and the upper ones emptied by gravity, feeding an aqueduct or a storage tank. Some water wheels, if the current of the stream allowed had double sets of pots on each side of their rims or simply two wheels on the same shaft. This allowed a single turning wheel to lift twice as much water as a wheel with only one rim with pots attached. The noria is a water powered machine that is most suitable in areas where there are fast flowing streams whose courses are some distance below the surrounding fields. The wheels are mounted between piers which carry the bearings for the axle. The diameter of the largest wheel is about 20 meters and there are 120 compartments in the rim. The wheel is turned by the impact of water on paddles mounted on the rim. The compartments dip into the water and are carried to the top where they discharge into a head tank connected to an aqueduct. The noria was already in use in Roman times and was described by Vitruvius in 1 BC.