Engine order telegraph

An engine order telegraph or E.O.T., often also chadburn, is a communications device used on a ship (or submarine) for the pilot on the bridge to order engineers in the engine room to power the vessel at a certain desired speed. In early vessels, from the 19th century until about 1950, the device usually consisted of a round dial about nine inches (~20 centimetres) in diameter with a knob at the center attached to one or more handles, and an indicator pointer on the face of the dial. There would also be a revolutions per minute indicator, worked by a hand crank. Modern E.O.T.s on vessels which still use them use electronic light and sound signals.