[1] In the 18th century, British country houses grew in size and servants were moved to separate service wings.
Servants were further moved out of sight with the use of service tunnels, basement walkways and utility rooms.
A system of wires connected the pull to a bell in a service area, in stairwells or outside servants' rooms.
A pendulum connected to the spring continued to swing so servants could see which bell had rung.
[1] Marilyn Palmer commented: "No object is more evocative of historic household communication than the sprung bell.