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["WILLIAM JONES" <billj AT harborside.com>]

Don Bowen wrote:> An Archimedean screw is simply a wedge wound around a 
shaft.  It can be 
> enclosed in a tube or sit in a trough.  For pumping water either will 
> work but the end is not moved in and out of the water.  What ever air is 
> moved is incidental to the process, not a part of it.Now I know we're 
> talking apples and oranges.  Maybe we should call it a "spiral manometer"
to distinguish it from the invention attributed to Archimedes.  This is 
definitely a closed tube,
not an open trough, wound in the shape of a spiral, not a helix.  Inside each 
loop of hose the
pressure is higher than in its neighbor.  The snout, the open hose end, 
alternately gathers water
and air as it turns.  You can read about it 
here:http://lurkertech.com/water/pump/belcher/fish/Here's an ironic tale.  My 
sixth-grade teacher's husband suggested we do a project on this as a
class.  But the picture in the magazine was actually just a cut-away, so we 
couldn't figure out
how it could possibly build pressure.