Final answer:
Springers are the initial voussoirs in masonry vaults that rest on the support structures and where the curvature begins. They distribute the weight of the vault and provide support against lateral forces, acting as abutments.
Step-by-step explanation:
In the context of masonry vaults, springers are the lowest voussoirs in an arch or vault which rest on the supporting columns, piers, or walls, and from which the arch or vault starts to rise, or spring. These elements can be thought of as the vertical starting points from which the curvature of the arch or vault begins.
Springers serve a critical role in distributing the weight of the vault above. As the stones are carefully shaped and placed, the horizontal course of the springer forms the foundation for the continuing arch or vault, setting the angle for its trajectory. The role of springers as abutments is fundamental for the stability of a vault, as they provide the necessary support to counteract the lateral forces, known as the outward thrust of the arch, and direct that force downwards to the ground or outward to other methods of support such as flying buttresses.
Master masons in the medieval period were keenly aware of the importance of such elements without having the engineering theories of modern structural engineers. Instead, they relied on practical experience and rules of thumb to construct these elaborate and enduring structures. In the evolution of vaulting, such as in Gothic architecture, the pointed, ribbed arch was developed, which effectively funneled the weight more vertically, thereby reducing the need for heavy lateral supports.