|Decorative Lion Head Keystone|
|Location of Keystone-Architectural Arch|
From Wikipedia, the free encyclopedia:
A keystone is the wedge-shaped stone piece
at the apex of a masonry vault or arch, which
is the final piece placed during construction
and locks all the stones into position, allowing
the arch to bear weight.
Although a masonry arch or vault cannot be
self-supporting until the keystone is placed,
the keystone experiences the least stress
of any of the voussoirs,
due to its position at the apex.
|Keystone, Springers, Voussoirs StLouis Brick Building|
at the apex of an arch.
- The keystone is the center stone or masonry unit
- The springer is the lowermost voussoir,