Sakia

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The Persian wheel, c. 1905

A sakia (alternative spelling sakieh, also called "Persian wheel"; Arabic: ساقية‎, sāqīya), tympanum or tablia[1] is a water wheel, somewhat similar to a noria, and used primarily in Egypt. It is a large hollow wheel, normally made of galvanized sheet steel, with scoops or buckets at the periphery. Its unique characteristic is that water is dispensed near the hub rather than from the top. It is a method of irrigation frequently met within various parts of India.

Schematics of an ideal sakia (Fathi).

Sakias range in diameter from two to five metres. Though traditionally driven by draught animals, they are now increasingly attached to an engine. While animal-driven sakias can rotate at 2–4 rpm, motorised ones can make as much as 8–15 rpm.

A (animal driven) sakia can pump up water from 10 metres depth, and is thus considerably more efficient than a shadoof (which can only pump water from 3 metres).

History

The earliest evidence of a sakia is from a Hellenistic tomb painting in Ptolemaic Egypt which dates to the 2nd century BC. It shows a pair of yoked oxen driving a compartmented waterwheel, which is for the first time depicted, too.[2] The Hellenistic sakia gear system is already shown fully developed to the point that "modern Egyptian devices are virtually identical".[3] It is assumed that the scientists of the Museum of Alexandria, at the time the most active Greek research center, may have been involved in its invention.[4] An episode from the Alexandrian War in 48 BC tells of how Caesar's enemies employed geared waterwheels to pour sea water from elevated places on the position of the trapped Romans.[5]

Notes

  1. ↑ Water lifting devices book description
  2. ↑ Oleson 2000, pp. 234, 270
  3. ↑ Oleson 2000, pp. 234, 270
  4. ↑ Oleson 2000, pp. 271f.
  5. ↑ Oleson 2000, p. 271

References

  • Oleson, John Peter (2000), "Water-Lifting", in Wikander, Örjan, Handbook of Ancient Water Technology, Technology and Change in History 2, Leiden: Brill, pp. 217–302, ISBN 90-04-11123-9 

Further reading

  • Fraenkel, P., (1990) "Water-Pumping Devices: A Handbook for users and choosers" Intermediate Technology Publications.
  • Molenaar, A., (1956) "Water lifting devices for irrigation" FAO Agricultural Development Paper No. 60, Food and Agriculture Organization of the United Nations, Rome.

External links

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