Archimedes' screw

A helical surface rotating inside a trough or cylinder to move water or other bulk materials along its axis. It can also operate in reverse, extracting power from descending water.

Helical surface: A continuous surface that winds around an axis while advancing along it. The screw’s winding surface forms pockets that carry water upward as the shaft turns.
Archimedes: A Greek mathematician, engineer, and inventor who lived in Syracuse in the third century BCE. Ancient tradition associates the water-raising device with Archimedes, though its invention is uncertain.
Drainage: The removal of excess surface water or groundwater from land or structures. Screw pumps can raise large volumes from low-lying areas into higher channels.
Bucket elevator: A conveyor that lifts bulk material in buckets attached to a moving belt or chain. It lifts material in discrete buckets rather than carrying it in pockets along a rotating helix.
Positive-displacement pump: A pump that moves fluid by repeatedly enclosing and displacing fixed volumes. The screw lifts water through moving pockets rather than relying mainly on fluid velocity.
Hellenistic technology: The engineering and technical practices developed across the Hellenistic world after Alexander the Great. The screw belongs to a period of inventive water-management machinery around the Mediterranean.
Irrigation: The controlled application of water to land or crops to support growth. Rotating screws lift water from rivers, canals, and wells into irrigation channels.
Centrifugal pump: A pump that uses a rotating impeller to increase fluid velocity and pressure. Centrifugal pumps suit many pressurized-flow tasks, while screws handle large flows at low lift.
Screw conveyor: A machine that moves granular or powdered material through a tube using a rotating helical blade. It applies the screw’s axial transport principle to solids and bulk materials.
Egyptian irrigation: Systems for supplying fields with water in Egypt, including devices for lifting water from the Nile and canals. The screw is associated with irrigation in Egypt, where raising water to fields was essential.

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