Final answer:
In compound walls, ties or connecting elements, often made of metal, are used to attach the two layers together and enhance wall strength.
Step-by-step explanation:
In compound walls, ties or connecting elements such as metal ties or bonding stones are used to attach the two layers together and give strength to the wall. These elements help in distributing the load and ensuring the stability of the wall structure.
Similar to how the cell walls in biology contain filaments of crystalline cellulose connected by hemicellulose polymers and are embedded in pectin polymers to provide strength and resist expansion, the physical walls in construction use ties for tensile strength.
In the context of historical building techniques like Cyclopean masonry, the massive stone blocks used in the walls of Mycenaean citadel sites were built for protection and did not typically rely on additional ties, reflecting a different approach to wall construction.