The machine is very popular in Egypt nowadays...

The machine is very popular in Egypt nowadays, and engineers at a research laboratory near Cairo have been trying to improve the shape of the scoop in order to achieve maximal output. Although it appears very modern in design, this is not the case; a 12th-century miniature from Baghdad shows a spiral scoop wheel driven by two oxen. These machines are still in use in many oil-poor middle eastern countries because for many purposes they are at least as efficient as diesel-driven pumps.

Moreover, they do not require imported fuels, spare parts or labour. Vital time can therefore be saved, when the loss of even a single day’s operation of a machine can kill a crop, making reliable performance literally a matter of life and death. Given the importance of water-raising devices to the economy of many Islamic societies, it is hardly surprising that attempts were made to introduce new designs or modify existing ones.

Some of the most interesting innovations are found in one section of Ibn al-Razzaz al-Jazari’s great book, The book of knowledge of Ingenious Mechanical Devices, which was completed in Diyar Bakr in Upper Mesopotamia in 1206 AD. From our point of view, the most significant aspect of these machines is the ideas and components that they embody. For example, one of them is explicitly designed to eliminate out-of-balance loading and so produce a smoother operation.

Another incorporates a crank, the first known example of the non-manual use of this important component. Some of these devices functioned as curiosities. The invention containing the most features of relevance for the development of mechanical design, however, was intended as the practical machine for high-lift duties: a twin cylinder, water-driven pump. A stream turned a paddle wheel meshing with a horizontal gear wheel, which was installed above a sump that drained into the stream.

The horizontal wheel contained a slot into which a vertical pin fitted near the perimeter of the wheel. The turning wheel moved two connecting rods back and forth, thus driving opposing pistons made of copper disks spaced about six centimetres apart, the gap being packed with hemp. The pistons entered copper cylinders, each one having a suction and delivery pipe. One piston began its suction stroke while the other began its delivery stroke.