Archimedes’ screw is a hand-operated machine used by the Ancient Greeks (and other cultures since their time) to raise water from low-lying bodies to higher elevations, usually for the purposes of irrigation. Also known as a screw pump, Archimedes’ screw is a simple yet effective device, modern variations of which can still be found in use today.
Invented By, Or Merely Credited To?
The invention of the screw pump is commonly attributed to Archimedes of Syracuse, a Greek polymath who lived in the 3rd Century BCE. However, historical records describe similar devices being used by the Assyrians over 350 years prior to Archimedes’ birth. It is possible that the device was simply unknown to the Greeks prior to that time, and that Archimedes merely mimicked the design of water pumps he saw in use during a visit to Egypt.
Either way, he must’ve done something right, because the device is still called the Archimedes’ screw 2,000-plus years later.
Simple, Yet Effective
A typical Archimedes’ screw is comprised of a flat, helical surface winding around a cylindrical center shaft (like a spiral staircase anchored to a center pole) enclosed in a hollow pipe. As the shaft turns, the bottom end of the screw surface scoops up water and slides it up the pipe until it reaches the top, where it pours out.
Originally, screw pumps were operated by hand, but windmill- or water-powered designs soon followed. Some designs had the screw attached to the inside of the tube itself, with the whole device rotating as one, rather than the screw turning independently of the stationary tube. It is believed that this variation allowed the apparatus to be powered by human treading (i.e. people walking in place on top of the casing as it rotated).
Common Applications & Legacy
In addition to feeding irrigation systems, Archimedes’ screw was also used to drain water out of mines and other low lying areas. In the Netherlands, it was used to drain land that was underwater to create agricultural polders.
The auger device at the front of a snow blower is essentially an Archimedes’ screw turned on its side. Modern Archimedes’ screws are used in sewage treatment facilities. In 2001, a screw pump was used by British engineer John Burland to stabilize the Leaning Tower of Pisa. Perhaps most importantly of all, Archimedes’ screws are used in chocolate fountains.
Photo credit: ARG_Flickr / Foter / Creative Commons Attribution 2.0 Generic (CC BY 2.0)