Before the age of electricity and intercoms, communication in a large house was facilitated by a system of cords and bells. The kitchen was usually the center of activity for domestic servants and where they could be signaled. A particular bell might have a specific origin so that a servant would know where to go. But it might also be connected to another pull cord in an intervening room of the house. So for instance if a bedroom was located directly above the library, they might share a common cord to the kitchen. The servant would then have to check more than one location to find where their services were required.