The Archimedean screw or cochlea is a water-raising device whose invention is attributed to Archimedes. It was mainly used for irrigation.

The lower opening of the helical tube coiled around the screw catches the water from an irrigation canal. When the screw is rotated—for example, by means of a waterwheel—the water tumbles from one coil into another but rises through the tube, flowing out of the upper opening.