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Omer · #9 Saturday, September 29, 2007

Water Raising Machines

Throughout history, the supply of water for drinking, domestic, irrigation and industrial purposes has always been a vital consideration in Muslirn countries. The problem has always consisted of finding effective means of raising water from its source.
Early examples of water raising machines includethe shaduf (fig 1), saqiya (fig 2) and noria (fig 3). The shaduf was known in ancient times in Egypt and Assyria. It consists of a long beam supported between two pillars by a wooden horizontal bar. A counterweight was attached to the short arm of the beam. A bucket suspended by a rope or a pole was attached to the long arm of the beam. The bucket was lowered into the water by bearing down on the rope/pole and the counterweight raised the full bucket. The shaduf is still widespread in Egypt.
The saqiya is a animal powered machine. The central mechanism consists of two gears- a large vertical cogwheel and a horizontal lantern pinion-meshing at right angles. The vertical cogwheel is mounted over the source of the water and drives another wheel carrying a chain of earthenware pots ('potgarland') secured by rope. An animal- donkey, mule or camel- is used to turn the horizontal lantern pinion. As the animal walks in a circular path the potgarland wheel turns. The pots dip into the water, raise it to the surface and discharge it into a tank. The saqiya was known in Roman times. Almost certainly it was in use in Arabia before the advent of Islam. The machine was probably transmitted to Spain from Syria
when Muslims introduced their irrigation methods to Spain. The saqiya is still in use in the Muslim world and in the Iberian peninsula and the Balearic islands.
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 20m 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. References in the works of Arab geographers show that norias were in use throughout the Muslirn world. Although the machines are now rarely used, some fine examples can still be seen, notably on the River Orontes at Hama in Syria.
At an early stage Muslim engineers were exploring new methods for increasing the effectiveness of water raising machines. Al-Jazari and Taqi al-Din both described water-raising machines that show an awareness of the need to develop machines with a greater output than these traditional ones.
Al-Jazari was responsible for the design of five machines in the thirteenth century C.E. His first two machines were modifications of the shaduf. The machines used a flume-beam: instead of a pole, an open channel is connected to a scoop, which has its spout elongated into a flume. The scoop dips into the water and when the beam rises the water runs back through the channel and discharges into the irrigation system. The machines were animal powered as in the saqiya.
Al-Jazari's third machine was a development of the saqiya in which water power replaced animal power. Flowing water turned a water wheel which via a system of perpendicular gears caused a chain of pots to raise the water. One such machine was located on the River Yazid in Damascus (13th century) and is thought to have supplied the needs of a nearby hospital.
The fourth machine again used a flume-beamand was animal powered. The beam was moved up and down by an intricate mechanism involving gears and a crank. This is the first known instance of the use of a crank as part of a machine- the earliest appearance in Europe of a crank as part of a machine occured in the fifteenth century C.E.
Al-Jazari's fifth machine, a water-driven pump was a more radical device. A water wheel turned a vertical cog wheel which in turn turned a horizontal wheel. The latter caused two opposing copper pistons to oscillate. The cylinders of the pistons were connected to suction and delivery pipes which were guarded by one-way clack valves (i.e. hinged at one end). The suction pipes drew water from a water sump down below and the delivery pipes discharged the water into the supply system about 12m above the installation. This pump is an early example of the double-acting principle (while one piston sucks the other delivers) and the conver sion of rotatory to reciprocating motion.
Taqi al-Din describes a slightly modifred version of Al Jazari's fifth machine in his book on machines (l6th century). Even more remarkable is Taqi al-Din's six-cylinder 'monobloc' pump driven by water power (fig 4). The water wheel was attached to a long horizontal axle. The axle had six cams spaced along its length. Opposite each cam was a lever-arm, supported in the middle and pin-jointed at the other end to a vertical piston rod. The upper end of each piston rod carried a lead weight. The bottom of each piston cylinder had a clack valve. When the water wheel rotated, each lever arm was raised in succession by the cams, water was then drawn up by the piston through the valve. When the lever was released the lead weight ejected the water up through the delivery system .
It is of note that Taqi al-Din's book which also includes a steam-driven spit antedates the famous book of machines, Le diverse et artificiose machine of Agostine Ramelli published in 1588 in Paris.