5. The Archimedean Screw: Making Water Climb
Water wants to run downhill. The Archimedean screw offered a beautifully straightforward way to persuade it to go the other way.
A spiral inside an inclined cylinder traps water in a succession of pockets. Rotate the assembly, or the screw in an appropriate housing, and those pockets carry water upward until it spills out at the top. The result is a pump driven by turning rather than by hauling one bucket at a time.
The device was known in antiquity and became associated with Archimedes, although its exact origins and his role in inventing it are debated. That uncertainty does not diminish the design. Its great appeal is how clearly the moving parts explain the job: a turning spiral raises a liquid. Among ancient inventions, it is an especially satisfying example of a difficult practical problem answered with a mechanism you can understand by watching it.
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