The water eductor or water dredge is an archaeological tool which harnesses a powerful flow of a water under pressure and various principles of fluid dynamics, in particular the Venturi effect which was named after its discoverer, the Italian physicist Giovanni Battista Venturi. It exploits the depression created by the faster-flowing water particles to suck up underwater sediment. A similar tool is the airlift or suction dredge which uses compressed air drawn from the surface to the site of the excavation. Bursts of air are injected into the dredge through a low-pressure pipe and the resulting bubbles return to the surface up the pipe of the dredge, carrying with them the sediment which gets sucked into the mouth of the dredge.