Archimedes screw

The Archimedes screw, a spiral screw turned inside a cylinder, was once commonly used to lift water from canals. The screw is still used to lift water in the Nile delta in Egypt, and is often used to shift grain in mills and powders in factories.

One of the earliest kinds of pump, associated with the Greek mathematician Archimedes. It consists of a large spiral screw revolving inside a close-fitting cylinder. It is used, for example, to raise water for irrigation.

The lowest portion of the screw just dips into the water, and as the cylinder is turned a small quantity of water is scooped up. The inclination of the cylinder is such that at the next revolution the water is raised above the next thread, whilst the lowest thread scoops up another quantity. The successive revolutions, therefore, raise the water thread by thread until it emerges at the top of the cylinder.

The Archimedes screw is of very ancient origin (c. 250 BC) and has been widely used over the centuries to raise irrigation water and for land drainage. Of robust and simple construction, it has the advantage of being able to shift water which contains mud, sand, gravel, and even larger debris.