VAULT, an arched roof, usually constructed of stone or brick-work. The simplest kind of vault is the plain wagon or tunnel vault, heino. a simple segmental or semicircu lar arch, thrown across a longitudinal apartment, and extending from one end to the other. Ordinary bridges show an example of this style of vaulting. Such vaults were commonly used by the Romans, who also built vaults with groins—i.e., vaults intersect ing one another. See GROINED VAULTING. The tunnel arch, of a pointed form, was of very ancient introduction, having been used by the Assyrians for vaulting their large drains.
The Egyptians are also said to have been acquainted with vaulting; but the earliest remains of ancient vaults of any magnitude are Roman works.
The Roman vaults, where groined, are usually constructed with carefully cut stone, so as to prevent the angle from chipping. The medbeval architects had not the costly materials or skill of the Romans at command, so they formed the groins only of dressed, stone, and the filling in of the vault with commoner materials. This led to the groin
becoming a prominent feature in medieval architecture, being generally ornamented with moldings and carved work. We have already traced the progress of Gothic vaulting under the heads GOTHIC ARCHITECTURE, FAN-TRACERY VAULTING, RIB, etc. Domical or hemispherical vaulting was also much used by the Romans. The Pantheon, in Rome, is the finest example remaining, being a circular building with a dome 142 ft. in diameter. Roman domes and vaults are frequently ornamented with sunk panels. During the renaissance period vaulting in great measure gave place to wooden roofs; but when employed, the domicil or plain groined vaults of Roman architecture are chiefly used. In modern works vaults and arches are gradually becoming superseded by the use of iron construction, both for roofs and for supporting floors, bridges, etc.