RUDDER
A vertically hinged plate of metal, fiberglass, or wood mounted at the stern of a ship or boat for directing its course.

PROPELLER
A machine for propelling an aircraft or boat, consisting of a power-driven shaft with radiating blades that are placed so as to thrust air or water in a desired direction when spinning.

DAMPER

An adjustable plate, as in the flue of a furnace or stove, for controlling the draft.

PANTOGRAPH
An instrument for copying a plane figure to a desired scale, consisting of styluses for tracing and copying mounted on four jointed rods in the form of a parallelogram with extended sides.

CHRONOMETER
An exceptionally precise timepiece.