I believe that the word "Jenny" has the same origin as "gin" (the
mechanical device, not the beverage).  In turn these derive from
"ingenious" which also gives us "engine" etc.  All from one Greek root.

"Engineer" has branched in several directions too.  In continental
Europe it means somebody who is ingenious, who devises the "engine",
and has come to mean a highly qualified professional person.  In the
UK it is often used to mean somebody who tends the engine and has
associations with oily rags.  In the US it also means the driver of
a railroad engine.

Greetings to all engineers.

Jeffrey Borinsky (Chartered Electrical Engineer)

 [ But see a good dictionary for the origins of jenny, Jane and
 [ jean (as in 'jeans', the trousers).  "Jenny Wren" doesn't seem
 [ at all related to the ingenious ingenieur/engineer.  -- Robbie