ARCHIMEDES, SCREW OF, a machine for raising water, said to have been invented by Archimedes for the purpose of removing water from the hold of a large ship that had been built by King Hiero II. of Syracuse. It consists of a water-tight cylinder which encloses a helix, and has its lower open end placed in the water to be raised. The water is therefore lifted mechanically by the turning of the machine. Other forms have the helix revolving free in a fixed cylinder, or consist simply of a tube wound helically about a cylindrical axis. The same principle is sometimes used in machines for handling wheat, etc. (see CONVEYORS).