The wheels were powered by the current of the flowing river.
Gravity then lead the water along aqueducts to its destination in various parts of the city.
Photo credit:Alessandra Kocman/Flickr
Its difficult to say when and where the first noria came into existence.
Norias became increasingly popular throughout the Middle East.
The norias at Hama are the largest surviving example of this medieval technology.
They are still in good working condition, although the water from these wheels is no longer used.
Photo credit:Franco Pecchio/Flickr
Photo credit:Johan Siegers/Flickr
Photo credit:Martin Gotthard/Flickr
Sources:Wikipedia/Famous Wonders/Machinery Lubrication
