This is an old Woodward Compensating Governor, and Pelton Water Wheel.
(circa 1895)
The governor is used to regulate speed in an isolated system,
or regulate load in an interconnected system.
This governor regulates the prime mover, by varying the deflector in the Pelton wheel.
The deflector actually deflects the stream of water between the nozzle and the wheel.
Thanks to Brad for sending this rare picture.
