Archimedes’ screw

[fototag id=”Archimedes”]

Attributed to inventor and polymath Archimedes in the third century BCE, the Archimedes’ screw works by utilising the angular frequency and speed of a rotating thread to transfer water from a low-lying plane to a higher one.

The machine consists of a hollow pipe angled at 45 degrees with a threaded screw encased within, which rotates once wound. The bottom of the cylinder is submerged in the water on the lower plane while the top end empties out into a channel or basin. As the screw rotates, the screw scoops up water at the bottom and, as it is encased within the cylinder, is forced to slowly slide up the thread to the top and onto the higher plane. In addition, any water lost through the small gaps between the screw and the cylinder are recollected by the thread directly below the one that lost it, ensuring mechanical equilibrium while in operation.

Traditionally Archimedes’ screws were used for irrigation, allowing water to be artificially transported to ditches, and were operated by hand. Modern variants are now primarily used for drainage.