Glossary · C
Capstone
The stone that closes the top of a corbelled vault or dome, or the great slab laid over the chamber of a dolmen.
See also: Corbelled vault, Dolmen
Rules that use the word
Keep each half of a corbel vault over its wall. In a corbelled vault each course may project only a little beyond the one below, and each overhanging half must have its centre of gravity behind the inner face of its wall; load the tails of the stones with heavy hearting until the capstone is set.
The chamber is as wide as the capstone is long. In a megalithic chamber the room can be no wider than the largest slab the builders can raise over it; the upright stones are set to suit the capstone, not the other way round.
The corbelled dome: rings stepping inward. Build a round chamber of horizontal courses, each ring projecting a little beyond the one below, dress the inner face to a smooth curve, close the top with a capstone, and heap earth over the whole.
Where it appears in the book
In the chapters Post and Lintel, The Ancient World, The Americas.
Nearby in the glossary
Cai · Callimachus · Cantilever · Capital · Carpet bedding · Cartouche · Casement · Catena d’acqua