Part 1 (2/2)

II. The Octagonal or Circular plan covered with a stone or brick dome, a type which may be subdivided according as (1) the dome rests upon the outer walls of the building, or (2) on columns or piers surrounded by an ambulatory.

The Pantheon and the so-called Temple of Minerva Medica at Rome are early examples of the first variety, the first circular, the second a decagon in plan. S. George at Salonica is a later circular example. An early instance of the second variety is found in S. Constanza at Rome, and a considerable number of similar churches occur in Asia Minor, dating from the time of Constantine the Great or a little later.

III. The Cross plan. Here we have a square central area covered by a dome, from which extend four vaulted arms const.i.tuting a cross. This type also a.s.sumes two distinct forms:

(1) Buildings in which the ground plan is cruciform, so that the cross shows externally at the ground level. Churches of this cla.s.s are usually small, and were probably sepulchral chapels rather than churches for public wors.h.i.+p. A good example is the tomb of Galla Placidia at Ravenna.

(2) In the second form of the Cross church the cross is enclosed within a square, and appears only above the roofs of the angle chambers. An example is seen in the late Roman tomb at Kusr en Nueijis in Eastern Palestine. In this instance the central square area is covered with a dome on continuous pendentives; the four arms have barrel-vaults, and the angles of the cross are occupied by small chambers, which bring the ground-plan to the square. The building is a.s.signed to the second century, and shows that true though continuous pendentives were known at an early date[10] (Fig. 8).

Another example is the Praetorium at Musmiyeh, in Syria,[11] which probably dates from between 160 and 169 A.D. At some later time it was altered to a church, and by a curious foreshadowing of the late Byzantine plan the walls of the internal cross have entirely disappeared from the ground-plan. The dome rests on four columns placed at the inner angles of the cross, and the vaulted cross arms rest on lintels spanning the s.p.a.ce between the columns and the outer walls.

From these three types of building are derived the various schemes on which the churches of the Byzantine Empire were planned.

Of the basilican form the only example in Constantinople that retains its original plan is S. John the Baptist of the Studion (p. 56), erected _c._ 463 A.D.

The church of SS. Sergius and Bacchus (p. 70) and the baptistery of S.

Sophia (p. 78) represent respectively the two varieties of the octagonal plan. In the former the dome rests on piers surrounded by an ambulatory; in the latter the dome rests upon the outer walls of the buildings. Both are foundations of Justinian the Great.

Of the Cross church plan showing the cross externally at the ground level no example survives in the city. But at least one church of that form was seen at Constantinople in the case of the church of the Holy Apostles. This was essentially a mausoleum, built originally by Constantine the Great and reconstructed by Justinian to contain the sarcophagi of the sovereigns and the patriarchs of New Rome.[12]

The church of S. Mark at Venice was built on the plan of the Holy Apostles. It is a cruciform church with aisles, but the galleries which might have been expected above them are omitted. The central dome rests on four piers, and four smaller domes cover the arms.

Professor Strzygowski gives examples of cross-planned cells in the catacombs of Palmyra,[13] and in many Eastern rock tombs.[14] Such cross plans are found also in the Roman catacombs. These subterranean chapels, of course, do not show the external treatment, yet there can be little doubt that the external cross plan was originally sepulchral, and owes its peculiar system of planning to that fact. On the other hand, it was adopted in such churches as S. Mark's at Venice and in the French examples of Perigord for aesthetic or traditional reasons.

In pa.s.sing now to a consideration of the distinct forms developed from these pre-Byzantine types of church building, the cla.s.sification adopted by Professor Strzygowski may be followed. In his _Kleinasien_ he has brought forward a series of buildings which show the manner in which a dome was fitted to the oblong basilica, producing the domed basilica (_Kuppelbasilica_), an evolution which he regards as h.e.l.lenistic and Eastern. In contrast to this, Strzygowski distinguishes the domed cross church (_Kreuzkuppelkirche_), of which S. Theodosia in Constantinople (p. 170) is the typical example and which is a Western development. A comparison of the two forms is of great importance for the study of certain Constantinople churches.

[Ill.u.s.tration: FIG. 1.--KASR IBN WARDAN (Strzygowski).]

The domed basilica, as the name indicates, is a basilica with nave and aisles, in which a square bay in the centre of the nave is covered by a dome on pendentives. To north and south, within the arches supporting the dome, appear the nave and gallery arcades of the basilica; and as the galleried basilica is a usual Eastern form galleries are usual in the domed basilica. As seen from the central area, therefore, the north and south dome arches are filled in with arcades in two stories, and the side aisles and galleries are covered with barrel vaults running parallel to the axis of the church. At the west end a gallery over the narthex may unite the two side galleries. At Kasr ibn Wardan, instanced by Strzygowski as a typical domed basilica,[15] there is such a western gallery (Fig. 1). According to Strzygowski the domed basilica is older than the fifth century.

The domed basilica remains always an oblong building, and whilst the two sides to north and south are symmetrical, the western end retains the basilican characteristics--it has no gallery or arcade communicating with the central area. The narthex communicates with the nave by doors, and if a gallery is placed above it, both narthex and gallery are covered by barrel vaults.

In the domed cross church (_Kreutzkuppelkirche_) the central dome rests on barrel vaults which extend to the outer walls of the building and form the arms of the cross, the eastern arm forming the bema. The lighting of the church is by windows in the gable walls which terminate the north, south, and west cross arms. The prothesis and diaconicon open off the side arms, and two small chambers in the western angles of the cross bring the plan externally to the usual rectangular form.

The domed cross church may have galleries, as in S. Theodosia (p. 170), or may be without them, as in SS. Peter and Mark (p. 193). Where galleries are present they are placed in the cross arms and are supported by arcades at the ground level. The vaults beneath the galleries are cross-groined. The domed cross church is a centrally planned church, in contrast to the domed basilica, which is oblong, and therefore we should expect that where galleries are used they will be formed in all three arms of the cross, as is the case in S. Theodosia.

There are a number of churches which vary from these types, but which can generally be placed in one cla.s.s or the other by the consideration of two main characteristics: if the dome arches extend to the outer walls the building is a domed cross church; if the galleries are screened off from the central area by arcades the building is a domed basilica.

The church at Dere Aghsy,[16] for instance, if we had only the plan to guide us, would appear to be a typical domed basilica (Fig. 2), but on examining the section we find that the north and south dome arches extend over the galleries to the outer walls and form cross arms (Fig.

3). The building is, in fact, a domed cross church with no gallery in the western arm. Above the narthex at the west end, and separated from the western cross arm, is a gallery of the type usual in the domed basilica, so that Dere Aghsy may be regarded as a domed cross church with features derived from the domed basilica. S. Sophia at Constantinople, the highest development of the domed basilica, has a very similar western gallery.

[Ill.u.s.tration: FIG. 2.--DERe AGHSY (Rott).]

The church of S. Nicholas at Myra[17] (Fig. 4) has a gallery at the west end, but the cross arms do not appear to be carried over the galleries.

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