I am research water powered mill sites on the Fort Knox Military Reservation
and am looking for information on particular types of mill wheels mentioned
in the 1880 Federal Manufacturing Census.  The wheels are referred to as
Parker and Leffel (spelled various ways) types.  They may be a type of turbine
wheel, but they are definitely water powered.  Does anyone have any references
that would give information on the development and operational aspects of these
wheels.