Norias of Hama
The Norias of Hama (Arabic: نواعير حماة) are a number of norias ("wheels of pots") along the Orontes River in the city of Hama, Syria. Only seventeen of the original norias remain. They are mostly unused now and serve an aesthetic purpose. They were called "the most splendid norias ever constructed". The norias of Hama were submitted as a tentative World Heritage Site by the Syrian Arab Republic in June 1999.
The earliest evidence for norias in Hama suggests they were developed during the Byzantine era, although none of the norias in Hama today precede the Ayyubid period. However, a mosaic found at Apamea dating to 469 pictures a noria similar to those at Hama, suggesting they may have earlier origins. The surviving norias date back to the medieval Islamic period, when norias as large as 20 meters in diameter were built, with 120 water collection compartments and capable of raising more than 95 litres of water per minute. Now only 17 norias remain, unused.
A noria (Arabic: ناعورة, nā‘ūra) performs the function of moving water from a lower elevation to a higher elevation. In this it is similar to the saqiya and other pumps like the Persian wheel (Rahat in Urdu), but those are generally powered by other means or a combination, usually lifting water from a pond or well. Noria is similar to the modern hydraulic ram, which also uses the power of flowing water to pump some of the water out of the river.
Unlike the water wheels found in mills, a noria does not provide mechanical power to any other process. A few historical norias were hybrids, consisting of waterwheels assisted secondarily by animal power. A noria can raise water to a level that's less than its full height. The Hama noria is the largest in the world, with a diameter of about 20 meters.
The origin of this device is most likely is the Greek Byzantium. Many credible references can be found in medieval texts. Philo of Byzantium describes in Pneumatica a structure with similar functions. Hero of Alexandria in the 1st century B.C. tried a to make a distinction between a bucket-chain and wheel for raising water. However, it must be kept in mind that the principle of axial flow was well known in the Islamic world since 9th century when it was attested by the Banu Musa brothers who, in their Kitab al-hiyal (Book of Ingenious Devices) written in Baghdad in about 850 CE described a horizontal wheel placed in one of their fountains and driven from below by a number of vertical jets of water.
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