Part 32 (2/2)

_Architectural Features_

The building is in two stories, and may be described as a chapel over a crypt. It points north-east, a peculiar orientation probably due to the adaptation of the chapel to the position of the residence with which it was a.s.sociated. The masonry is very fine and regular, built in courses of squared stone alternating with four courses of brick, all laid in thick mortar joints, and pierced with numerous putlog holes running through the walls. It presents a striking likeness to the masonry in the fortifications of the city. The lower story is an oblong hall covered with a barrel vault, and terminates in an arch and apse. In the west side of one of the jambs of the arch is a small niche. The vault for one-third of its height is formed by three courses of stone laid horizontally and cut to the circle; above this it is of brick with radiating joints. Here cows are kept.

The upper story is m. 3.75 above the present level of the ground. It is a single hall m. 8.80 in length and m. 3.70 wide, terminating in a bema and a circular apse in brick. Over the bema is a barrel vault. A dome, without drum or windows, resting on two shallow flat arches in the lateral walls and two deep transverse arches strengthened by a second order of arches, covers the building. In the wall towards the north-west there is a window between two low niches; and a similar arrangement is seen in the opposite wall, except that the door which communicated with the residence occupies the place of the window. The apsidal chambers, usual in a church, are here represented by two niches in the bema.

Externally the apse shows five sides, and is decorated by a flat niche pierced by a single light in the central side, and a blind concave niche, with head of patterned brickwork, in the two adjacent sides. The dome, apse, vaults, and transverse arches are in brick, laid in true radiating courses. The absence of windows in the dome is an unusual feature, which occurs also in the angle domes of S. Theodosia. The pendentives are in horizontal courses, corbelled out to the centre, and at each angle of the pendentives is embedded an earthenware jar, either for the sake of lightness, or to improve, as some think, the acoustics of the building. This story of the chapel is used as a hayloft.

A careful survey of the building shows clearly that the domical character of the chapel is not original, and that the structure when first erected was a simple hall covered with a wooden roof. Both the shallow wall arches and the deep transverse arches under the dome are insertions in the walls of an older fabric. They are not supported on pilasters, as is the practice elsewhere, but rest on corbels, and, in order to accommodate these corbels, the lateral niches, originally of the same height as the central window, have been reduced in height. A fragment of the original arch still remains, cut into by the wall arch of the dome. The flat secondary arches crossing the chapel at each end are similarly supported on corbels.

This view is confirmed by the examination of the plaster left upon the walls. That plaster has four distinct coats or layers, upon all of which eikons in tempera are painted.[499] The innermost coat is laid between the transverse dome arches and the walls against which they are built. Those arches, therefore, could not have formed parts of the building when the first coat of plaster was laid, but must be later additions.

In keeping with this fact, the second coat of painted plaster is found laid both on the arches and on those portions of the old work which the arches did not cover.

The secondary arches under the transverse arches at each end belong to a yet later period, for where they have separated from the arches above them, decorated plaster, which at one time formed part of the general ornamentation of the building, is exposed to view. At this stage in the history of the chapel the third coat of plaster was spread over the walls, thus giving three coats on the oldest parts where unaltered--two coats on the first alterations, and one coat on the second alterations.

The fourth coat of plaster is still later, marking some less serious repair of the chapel.

The _voussoirs_ of the lateral dome arches should be noticed. They do not radiate to the centre, but are laid flatter and radiate to a point above the centre. This form of construction, occurring frequently in Byzantine arches, is regarded by some authorities as a method of forming an arch without centering. But in the case of the lateral wall arches before us it occurs where centering could never have been required; while the apse arch, where centering would have had structural value, is formed with true radiating _voussoirs_. The failure of the _voussoirs_ to radiate to the centre therefore seems to be simply the result of using untapered _voussoirs_ in which the arch form must be obtained by wedge-shaped joints. For if these joints are carelessly formed, the crown may very well be reached before the requisite amount of radiation has been obtained. On the other hand, if full centering had been used, we should expect to find marks of the centering boards on the mortar in the enormously thick joints. But neither here nor in any instance where the jointing was visible have such marks been found. Still, when we consider the large amount of mortar employed in Byzantine work, it seems impossible that greater distortions than we actually meet with in Byzantine edifices would not have occurred, even during the building, had no support whatever been given. It seems, therefore, safe to a.s.sume the use of at any rate light scaffolding and centering to all Byzantine arches.[500]

[Ill.u.s.tration: FIG. 98.]

[484] [Greek: Meta ten halosin], p. 61; cf. Paspates, p. 361.

[485] _Tagebuch_, p. 456.

[486] Hypselantes, _ut supra_, p. 638.

[487] Archaeological Supplement to the _Proceedings of the Greek Syllogos of C.P._ vol. xviii. p. 8.

[488] Phrantzes, p. 307.

[489] _Tagebuch_, p. 456.

[490] See Chap. XII.

[491] P. 360.

[492] Constant. Christ. iv. p. 162.

[493] See Archaeological Supplement to the _Proceedings of the Greek Syllogos of C.P._ vol. xviii. p. 8.

[494] Ruy Gonzalez de Clavijo in 1403, _Vida de Gran Tamorlan y itinerario_, p. 50 (Madrid, 1782): 'San Juan del a Piedra esta cerca del palacio del Emperador' (_i.e._ near the palace of Blachernae).

[495] Miklosich et Muller, i. ii. pp. 21-23.

[496] Ducas, p. 288.

[497] _De top. C.P._ iv. c. 4.

[498] _Tagebuch_, p. 455.

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