SCREW OF

See also:

• ARCHIMEDES (c. 287–212 B.C.)
• SCREW OF ARCHIMEDES

ARCHIMEDES  , 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, enclosing a chamber walled off by spiral divisions running from end to end, inclined to the horizon, with its lower open end placed in the water to be raised . The water, while occupying the lowest portion in each successive division of the spiral chamber, is lifted mechanically by the turning of the machine . Other forms have the spiral revolving free in a fixed cylinder, or consist simply of a tube wound spirally about a cylindrical axis . The same principle is sometimes used in machines for handling wheat, &c . (see CONVEYORS) .