The Telegraph on a ship is used as a communicating device to transfer orders of change in speed or direction from the bridge to the engine control room. The initial movement of telegraph is always from the navigation bridge and is done by moving the lever in the required direction, which rings the telegraph bell of both the locations (Engine room and Bridge Room). Upon hearing the bell, the engineer acknowledges the telegraph of the engine room to the same position as that of the bridge which stops the ringing of the bell.