WATER-RAISING MACHINES

Water-raising machines were (and are) used for a number of purposes, of which the most important was that of crop irrigation. They were also used for supplying water for private and communal purposes, for pumping flood water from mines and bilge water from ships. Our information on these machines comes from both archaeological and literary sources. Also, since several types are still in use today, their operation can be understood by examining working machines. It might be argued that the machines could have altered drastically over the centuries, but this is not the case. Descriptions given in the works of medieval Arabic writers tally closely with the design of machines constructed in the recent past.

Two devices date back to Antiquity. The well-windlass is the system whereby a rotatable wooden cylinder is erected over the mouth of the well. A rope with a bucket attached to its free end is caused to wind and unwind around the cylinder by a man turning a crank. Another early method was the shādūf. This was illustrated as early as 2500 BC in Akkadian reliefs and about 2000 BC in Egypt. It has remained in use to the present day and its application is world-wide, so that it is one of the most successful machines ever invented. Its success is due to its simplicity and its efficiency. It can easily be constructed by the village carpenter using local materials, and for low lifts it delivers substantial quantities of water. It consists of a long wooden pole suspended at a fulcrum to a wooden beam supported by columns of wood, stone or brick. At the end of the short arm of the lever is a counterweight made of stone or, in alluvial areas where stone is not available, of clay. The bucket is suspended to the other end by a rope. The operator lowers the bucket into the water and allows it to fill.