Historical.— Tunnel vaulting has been used at least since the Egyptian period to the Caro lingian Empire days. The dome vault (cupola) is characteristic of the Byzantine architecture. In the Romanesque period (early 11th to middle 12th century) the naves and aisles of churches had three main forms of vaulting: the dome, the tunnel and the groined. And, as before stated, naves and aisles of stately Romanesque churches. There are four major schools of Romanesque tunnel-vaulted churches in France: Provence, Poitou, Auvergne and Burgundy (11th and part of 12th century). But with Poitou we come to tunnel-vaulted naves and groined vaults for aisles. In the Auvergne school we find the triforium has half-barrel vaulting. In the side aisles of the Burgundy school are, usually, groined vaults, some of slightly domical form. The nave arcade struc tural arches are pointed but the nave has a tunnel vault its entire length. Other Roman esque style churches have transverse tunnel vaults to replace those running longitudinally either in the nave or aisles; some have trans verse tunnel vaults over the aisles. A few Romanesque churches have groined vaulting over the nave though it is mostly restricted to the aisle bays. But the heavy, massive Roman esque construction was greatly transformed by the introduction of ribs and brought about the rectangular plan. In the second half of the 12th century we find the beginning of the Early Gothic evolving from the Romanesque; this phase is known as the Transition period. The light Gothic style. Lombardy has the earliest examples of ribbed vaults (end of 11th cen tury). The width of the nave now was enabled to take in the full width of the edifice, omitting the side aisles, the ribs aiding in the support. But the Anjou builders soon realized that domes could be erected almost. without centring and the ribs gradually diminished till they became mere decorative torus moldings for groins and ridges. In the 12th century we have the Norman sexpartite vaulting and its variants (eight part vaulting, etc.), and the use of flying buttresses assisted greatly in permitting fancy vault construction. The various kinds of vault ings exert a lateral as well as vertical thrust on the walls, hence the walls have to be strengthened either by an extra thickness of construction or by external addition of but tresses. The necessary solidity is sometimes af forded by a division into niches and piers and the vaulting is then specially constructed to bring the vertical and lateral thrust on the piers. leaving the walls that connect piers to fill the function of enclosing the room space only. The Ile-de-France architects at this time were elaborating the four-part cross-ribbed vault of • Gothic (see ARCHITECTURE) arch is ((pointed) hence we find in the Transition vaulting the pointed arch with its moldings decorated with Romanesque motifs. Renaissance vaulting.
This style retained all the Gothic essentials but made the arch elliptic or depressed. The arches are multiplied and often are adorned with cul de-lampes and pendentives (Fig. 7) hanging often like stalactites from the vaulting. In later Renaissance architecture the churches are frequently built in the form of large single chambers and ceiled with barrel vaulting, in which cases deeply recessed chapels between strong piers were introduced into the side walls, and above these the vault was pierced and lighted by lunettes. Decoration. The Romans gave the barrel vault a rich decorative appear ance by means of a bold cornice. With lines and cross-bands they then divided the vault surface into hays (similar to the later coffers) quently finely molded if the size admits it. In the Renaissance barrel-vaulted rooms the richly molded coffers are frequently of slight depth. In the later Renaissance period the roof was constructed of barrel vaulting and it re ceived divisions of flat bands continuing from the pilasters of the walls, the divided spaces being given plastic decoration or sometimes re ceiving painting. The dome vault was beauti fully decorated in several manners. That of the old Pantheon at Rome received majestic sedate ornament by encircling it with five hori zontal rings or zones each containing 28 coffers, which were surrounded with rich listels of foli age and, as centresi rosettes of bronze. Look ing upward in the direction of the opening in the centre the general impression is that the zones are of equal width but, in reality, they diminish all the way up as, of course, the square coffers being of same number in a smaller circle had to be smaller in proportion to the diminu tion of the circle. The perspective effect is perfect In the case of the temple of Minerva Medics, Rome, the dome is closed on top and the lighting is done by means of the circle of windows piercing the structure above the semi circular niches below.
Bibliography.— Babcock, C.,
(Boston 1884); Buehlmann, J., 'Classic and Renaissance Architecture) (New York 1910) ; Enlart, C., (Manuel d'archeologie
(Paris.1916); Caumont, M. A. de, (Abecidaire d'archeologie) (Caen 1859) • Komstedt, R.,