BUILDING FORMS AND THE BUILDERS

§ 1. ORIGINS.

It may be well to say a few words on the growth of the Byzantine architecture, of which Justinian’s church is the perfect flower. This building is often spoken of as if it were at once the first and the maturest essay in this great style, but this we might know would have been impossible, even though the links that led up to it were lost, which is not entirely the case. It is perfectly true, however, as Mr. Morris says, that “the style leaps into sudden completeness in this most lovely building.”

The new wants of the Church soon evolved the complete Christian basilica, which, it has been said must have been in the mind of the writer of the Apocalypse as the type of the entire arrangement of the altar, the twenty-four elders, and the great congregation, in his vision of the heavenly worship. In the time of Constantine, and in Rome, alongside of work which was entirely classic, the churches, with fewer ties to the past to limit development along truly rational lines, had developed a manner which was a more direct outcome of the necessities of building with a minimum of merely perfunctory “architectural” forms—those conventions for the thoughtless expenditure of the workers’ labour, which in still worse times make architecture a burden to them instead of a delight.

This transitional style is rightly called early Christian, or Constantinian. In the East, the vital part of the empire at this time, a greater change was taking place that brought back life once again to the arts of decoration; this may be expressed in a formula as the re-orientalization of classic art—the linking of simple massive Roman building to a new decoration, vividly alive and inventive, frank, bright, and full of colour, and yet as rational in its choice and application as the construction. In the modern sense the Romans may be said to have invented building, and the Byzantine-Greeks architecture.

The Roman system of arched building, covered with brick and concrete vaulted shells and domes, had been masked by non-functional pillars, tablements, and pediments in what was thought the true Athenian manner; at the same time many beautiful decorative expedients were also in use, such as the lining of walls with large thin marble slabs, or small pieces of glass of various forms and colours. Mosaic of gold glass seems to have been known before the time of Constantine.[329] Gold tesserae probably originated in an at first almost accidental use of portions of the Roman glass vessels which are decorated by patterns in gold leaf protected by a thin layer of glass over the surface. Parts of such vessels are found used decoratively in the Catacombs.

Byzantine architecture was developed by the use of brick in the frankest and fullest manner, especially in domical vaulting. Wide spans were kept in equipoise by other smaller domes. The more concentrated supports were marble monoliths, and the wall and vault surfaces were covered by incrustations of marble slabs and glass mosaic. Directness, an economy of labour relative to the results obtained, is perhaps the most essential characteristic of the art both in construction and decoration in the great period. This freedom and rationality mark it out from all other styles of building, or rather make it include all other styles, for this reaches the universal. M. Choisy rightly insists on the fact that the Byzantine builders endeavoured to suppress preparatory and auxiliary work, and to execute their vaults and domes without centring. “The greater number of their vaults,” he says “rose in space without any kind of support.... Their method is not a mere variation of that of the West, but it is quite a distinct system, not even derived from a Roman source, but Asiatic. Byzantine art is the Greek spirit working on Asiatic elements.” Here we have an extreme statement in one direction, and the word Roman must be used in a narrow sense; for these Asiatic elements in construction, of which alone M. Choisy seems to be speaking, whatever were their remote origins must have been completely absorbed into the larger Rome of the Empire, and we have no knowledge of any other system of construction in western Asia from the first to the fourth century than “Roman,” unless we subdivide this into Palmyrene, Herodian, or construct an imaginary Persian style out of what went before and came afterwards. Choisy himself shows that a large use of burnt brick was first made by the Romans, and that the system of building vaults in sections known in Assyria and Egypt had been adopted by Roman builders in the East in the time of Constantine. But this was the essential germ of Byzantine construction. It was the falling away of a dead scholasticism that left Roman building in the East free to be shaped into Byzantine architecture. Mr. Bury, who is extreme in the opposite direction, and makes the same claim for the continuity of Roman art as he does for the Empire, suggests that Romaic would be a better term than Byzantine. But whatever name is given to the political system we must remember that the arts are shaped by the people, and that the people were truly Greek who, in the age of Justinian, thought out and left to the modern world the last great gift of Hellenic genius—mediæval Greek architecture.

While the art of building in the East, particularly in Syria and Asia Minor, and possibly in Egypt, was still distinctly Roman, a ferment and change may be detected which cannot be matched in Rome itself. Both in construction and ornamentation there is much already at Palmyra and Baalbec that belongs to the new, and repudiates the rules of merely official art.

In Rome the dome never appears to have been finally adapted to a composite building by being directly applied to a square plan. The dome on pendentives, so far as we know, was invented and perfected entirely in the East. M. Choisy figures a building from Jerash, which may be of the third or fourth century which he considers the earliest known dome on pendentives. This building, although it is plainly early, has nothing characteristically Roman about it. A building of the same class however, recently discovered by the Palestine Exploration Society at Kusr en Nûeijîs in eastern Palestine,[330] is an ornate example of late Roman work; Ionic pilasters and carved entablature mask the outside, while within we have a perfected dome on pendentives covering a central square area, counterpoised by four barrel vaults. We agree with the Memoir that—“there can be little hesitation in ascribing this building to the second century A.D.” This building, probably a mausoleum, in adjustment of parts, and geometrical development might be a Byzantine church of three hundred years later. It is a little Sancta Sophia, and taken together with the Jerash building it makes a class invaluable as a fixed point to work from.[331] This however like most Syrian buildings is of stone.

A church at Koja Kalessi in Isauria,[332] Fig. 31, which there is a great reason to suppose of early fifth century work, furnishes an important link. We have here an approximation of the square domed building to the columned basilica which is most interesting. This church is substantially complete with women’s galleries opening to the nave by a second tier of arcades just as at S. Sophia.

The next building we should place in the sequence is the church of the Trinity at Ephesus of which Hübsch, Wood and Choisy give plans. The former furnishes a restoration, and speaks of it as probably one of the earliest of Christian churches, but there is no reason to suppose it earlier than the beginning of the fifth century. Choisy speaks of it as a curious monument of transition already Byzantine in structure. Before seeing Hübsch’s restoration, we had placed an arcade in the lateral arches, agreeing in every respect with his suggestions; and that this was the original form is strongly confirmed by the next church—as it seems to us—in the development. This is the church of S. Sophia at Salonica, which has long been assigned to Justinian’s reign at a time subsequent to the erection of S. Sophia, but is now thought to belong to the fifth century. M. Petros Papageorgios in the Hestia[333] of Athens for October 3rd and November 14th 1893, gives the mosaic inscription of this church, which he thinks definitely fixes its decoration in the year 495.[334]

The churches at Cassaba, Ancyra and Myra in Asia Minor engraved in Texier’s Asie Mineure, and repeated by Salzenberg relate themselves so closely to this chain of development that we believe they will be found to belong rather to the fifth and sixth centuries than to the seventh or eighth as those writers thought. The square type with a central dome persisted independently without coalescing with the basilica. Such was the domed church at Antioch founded by Constantine and completed by Constantius; here the central dome was surrounded by aisles, and formed an octagon. In the churches of St. George at Ezra, and St. Sergius at Bosra we have domes standing over a central octagon contained in an external square. These were built about 515, and they furnished the type that was followed at St. Sergius at Constantinople which was built only a few years before S. Sophia.

§ 2. THE BUILDERS OF THE CHURCH.

It is noteworthy that the architects who built S. Sophia as well as the historians who chronicle the work, all, so far as their birth-places are known, come from Syria and Asia Minor. The flourishing city of Ephesus was one of the great centres of the transformation of the art of building; and it was from the neighbouring cities of Tralles and Miletus, that Anthemius and Isidorus came to Constantinople.

Of the two master builders who appear to have been employed together by Justinian, it seems clear, from Procopius and the other writers, that Anthemius was more especially concerned in the preparation of the first draft or model, and that Isidorus, by birth a Milesian, was associated with him in the conduct of the works.

“Anthemius,” says Paulus, “skilled in setting out a plan, laid the foundation.” “Anthemius was the man who devised and worked at every part,” writes Agathias, and this author gives some account of his life. “Now this Anthemius was born at Tralles, and he was an inventor of machines; one of those who apply designs to material, and make models and imitations of real things. He was distinguished in this and had reached the summit of mathematical knowledge, just as his brother Metrodorus was distinguished in letters. Besides these there were three other brothers, Olympus, famous for his knowledge of law, and Dioscorus and Alexander, both skilled in medicine. Of these Dioscorus lived in his native land and Alexander in Old Rome. But the fame of the skill of Anthemius and Metrodorus reached the emperor, and they were invited to Constantinople, where they spent the rest of their lives, each presenting wonderful examples of his skill. One taught letters; the other raised wonderful buildings throughout the city and in many other places; these, I think, even if nothing were said about them, as long as they remained unharmed, would be sufficient to win for him perpetual glory.”

Stories of his mechanical ingenuity are told by Agathias one of which is as follows. Anthemius had a quarrelsome neighbour whose room overhung his ground. He placed here large kettles of water, with an arrangement of leather pipes and a tube like a trumpet up to the projecting part; and making the other parts secure, “he heated the water so that the whole thing burst up like an earthquake.”

As to the scheme prepared by the master builders for the building, an examination of the evidence seems to suggest the following antecedent conditions and governing ideas. 1. The ground levels required a short and wide church (ante, p. 186). 2. An old western apse possibly suggested the western hemicycle of the new church (ante, p. 19). 3. The plan, while a direct outcome of traditional forms as we have shown, seems a synthesis of the three types which were then current; the Basilican like S. John Studius; the square church with a dome like S. Sergius, and the cross plan of the Church of the Apostles.

At S. Sergius, the expedient of planning columned exedras to fill out the angles of the square beneath a domed vault had proved its utility and beauty. For the influence of the cross type we need only turn to the plan, and observe that the width across the “transepts” is exactly the same as the length included by the eastern and western hemicycles.

The master builders not only designed the church, they came “and worked at every part,” and lived with their building until their death; they certainly graduated as workmen, and we hear nothing of their honours or position, only of their genius.[335] In the words of M. Choisy, “In Justinian’s time, to build was the essential rôle of the architect.”

Both master builders are again mentioned as working together on the occasion of the fortifications of Dara in Mesopotamia, having been injured by floods. The emperor on hearing of it at Constantinople “straightway summoned those most celebrated architects Anthemius and Isidorus mentioned before, and inquired what might be devised.” The scheme of Chryses, the engineer of the works at Dara, was however adopted.[336]

The younger Isidorus who re-erected the dome of S. Sophia Procopius mentions as having been employed by Justinian in rebuilding the city of Zenobia in Mesopotamia with its fortifications, churches, baths and porticoes. “All this work was done under the superintendence of Isidorus and Joannes, of whom Johannes was a Byzantine and Isidorus a Milesian by birth, being the nephew of that Isidorus I mentioned before.”

To the master builders Procopius, Paulus, and Theophanes give the names mechanikos, polumechanos, mechanopoios, to which other writers add protooikodomos—“first of the builders,” magistros and maistor. The craftsmen appear to have been classed as technitai with a foreman over each subdivision. The Latin names of the different building crafts are given both in Theodosius’ code,[337] and in the edict of Diocletian,[338] which fixed their wages. This edict is bilingual, but unfortunately the Greek synonyms for the workmen are wanting. In the description of the building of S. Sophia, Procopius speaks of the lithologos or “stone-layer,” who built the big piers, Paulus and the Anonymous use laotoros and laotomos a “mason” and “stone-cutter,” wherever marble workers are mentioned, to which must also be added lithoxos “stone polisher.” The general bricklayers, &c. are comprised as oikodomoi. Tektonikos implies a carpenter. S. Gregory of Nyssa, in describing a church of S. Theodore, calls the craftsman who arranged the mosaic tesserae, ὁ συνθέτης τῶν ψηφίδων.

A list of the chief classes of workmen employed in the sixth century on a monumental building in Italy given by Cassiodorus,[339] names the following—Instructor-parietum, sculptor-marmorum, camerarum-rotator, gypsoplastes, and musivarius. The instructor-parietum is probably the man who set out the work, the camerarum-rotator is he who turned the vaults. The gypsoplastes, a literal transcription of γυψοπλάστης, signifies a worker or modeller in stucco, corresponding to the plastes-gypsarius of the edict of Diocletian. The musivarius is the “putter together of tesserae” of S. Gregory. Workmen who understood the mysteries of “vault turning” seem to have been especially appreciated, as Theophanes tells us that Isaurian workmen were employed to build the dome of S. Sophia.

In the humblest work the personality of the maker is often delightfully expressed. A Byzantine brick in the British Museum is stamped “ΧΡ. made by the most excellent Narsis,” and a late Roman glass cup bears the legend “Ennion made this. Think of it, O buyer.”

In his inquiry as to the methods of workmanship, M. Choisy says the Byzantine Greeks did not efface from buildings all traces of the workman’s individuality. “The workman is no mere passive instrument, obedient, without any regard to initiative or responsibility, to the workshop foreman; he is treated as an intelligent power, and finds in front of him liberty, and a field open to his imagination.”

In Roman times the system was that we call “division of labour.” “L’art roman est un fait d’organisation.” The workman was not an independent citizen working at his own pleasure for his daily wants; he was a functionnaire, and compulsorily a member of an association organised by the state on the model of military service. In the East an altogether freer system seems to have obtained. The guilds were independent associations, and in Palestine the Carpenter’s Son and the tentmaker followed their callings irrespective of state authority. “In Byzantine buildings the same name occurs in turn upon columns, capitals, or simply squared blocks of stone, and there is nothing to show that the foreman of the works kept one man at one particular kind of work. The East never changes; at present the absence of division of labour in Oriental buildings is most striking. The proprietor chooses a master workman (protomaistor); to this improvised architect he adds a certain number of head workmen (maistores) and their companions, and these same men will work at digging the foundations, at the masonry of the walls, and at the carpentry of the roof; even the ironwork and joinery is scarcely reserved for special workmen.” The terms masters and companions suggest an arrangement which merits consideration. Like western workmen the Greek artizans were affiliated to corporations which have lived to our days. These associations (sunergasiai) had a council, composed exclusively of those, who, by apprenticeship and trial, had earned the title of masters (maistores).

Each society was presided over by a “protomaistor” helped by secretaries (grammateus and kerux) to summon the meetings. It was at once a corporation of workmen, a religious brotherhood, and a mutual aid society: and such societies engaged in mutual acts of hospitality and assistance between one town and another.

All workers in the East seem to have been thus associated into guilds, and municipal life was organised on the guilds. This is evident at Constantinople as early as the Notitia, see p. 11 above. The members of the guilds had to help at fires, and Lydus gives the cry which brought them together, “Omnes Collegiati.” Demetrius, the silversmith of Ephesus, called together the Sunergasia when the craft was in danger; we even hear of strikes. Even unskilled labourers had their guilds, and Mr. Ramsay has described the Guild of Street Porters of Smyrna in Roman times (American Journal of Archæology, Vol. I.). The existence of the guilds is the most significant fact of the social history of the middle ages. In such craft organisation of labour, free of the financial middlemen who now rightly call themselves “Contractors,” we see the only hope that building for service, and ornamenting for delight, can again be made possible.

Our studies have convinced us that “shop production” went on side by side with the building organisation. This shop production will be at once allowed for such things as gold cups and altars, lamps and bronze doors, but we believe that decorative marble work was largely produced in this way, and that just as enamelled cups and damascened doors were “ordered” in Constantinople, so also were sculptured slabs and capitals. It would be possible to account for mere resemblance by “influence,” but absolute likeness between the capitals and sculptured or inlaid slabs found in contemporary buildings, at cities so far apart as Constantinople, Salonica, Parenzo, Ravenna, and Rome show that in the fifth and sixth centuries such works were dispersed from a common centre. So early as the fourth century S. Gregory Nazianzenus speaks of a priest who came to Constantinople “from Thasos bringing with him the gold of the church wherewith to buy slabs (plakes) of Proconnesian marble.”[340] These things were not only bought, but specially commissioned; for instance, the marbles of St. Clemente, which are almost certainly Constantinople work, bear fine monograms of John, afterwards elected pope in 532. The great contributing cause for this, besides the political and artistic position of Constantinople, was doubtless its possession of an absolutely perfect material in boundless profusion—the coarse white marble, which we may see to-day so delightfully wrought in small shops into the tombs, each of which has its carved tree of cypress, palm, or rose.

§ 3. ORIGINAL FORM OF THE CHURCH.

Dome, &c.—Agathias tells us that when Justinian rebuilt the dome it was made higher, and that large alterations were made to the sustaining arches on the north and south sides. Salzenberg cites Theophanes and Zonaras who give the increase of height as twenty and twenty-five feet respectively. If we examine the longitudinal section we shall see that the great semidomes of the hemicycles and the apsoid of the bema show much less of their curvature outside than the present central dome. The windows in these do not stand above a cornice, but are pierced through the vaults at middle height; the domical surface being unbroken by any cornice from springing to crown. The cupola of the baptistery is also continuous with the pendentives. A dome of this kind, however, continuing the pendentives, would seem to be impossibly flat, and would be some thirty feet less than the present height—see A in Fig. 4, the existing dome rising to B. If a curve between these two be obtained by lowering the crown of the dome about fifteen feet to C, it may be noticed that a straight line tangential to the curve of the eastern apsoid, and also to the great semidome would form similar contact with the dome.

Salzenberg, understanding an account of Cedrenus as to a strengthening of the abutments of the dome to refer to the great buttress masses which rise above the gynaeceum roof, considers that the external parts of these masses were additions made at the time of Justinian’s restoration. These great vertical piles are so essential to the structure, to the logical beauty of the design, and to the staircase service of the building; moreover the preparation for them beneath is so adequate, that we cannot accept this suggestion, and therefore follow Choisy in considering them original. Now Choisy, examining the external base of the dome where it forms a square, found that the four angles had been increased, and that it did not originally form a square, but rose above the piers and the lateral arches as shown in Fig. 34, and in Fig. 37, where the first base is shown by hatching and the additions by dotted lines, A A. “This alteration,” he writes, “is not hypothetical. I verified the entire absence of bond between the first base of the dome and the added work” (p. 138). These additions were built on the lateral arches, and on the top of the piers, altering the form shown in our Fig. 35 to the present form given by Salzenberg. That Choisy is right, is borne out by seeing the resemblance of treatment that there would have been between the growth of the dome on the north and south and the semidome on the west (see Fig. 34).

Again, Salzenberg hardly makes it sufficiently clear that the large arches in the walls which fill the great vertical semicircles over the arcades on north and south sides, are in fact the inner surfaces of the arches which pass between the pairs of piers on north and south sides (seventy-two feet apart in this direction), and being the whole width of those piers (fifteen feet eight inches) on soffite they form the immense arches so well known on the outside. The semicircles of wall, each of which contains twelve windows, are now filled in beneath these arches, flush with their inner faces, and the arches therefore do not show to the interior through the decoration (Figs. 4, 36, 38).

Now Agathias (see page 30) says that at the restoration after the earthquake in 558, at the north and south arches they brought towards the inside “the portion of the building which was on the curve.” This, we think, must refer to the filling wall, in the arches of seventy-two feet span, which we suppose was formerly on the exterior, and thus left an upper gallery twelve feet wide and seventy-two feet long open to the interior. “And they made the arches wider to be in harmony with the others, thus making the equilateral symmetry more perfect. They thus reduced the vast space and formed an oblong design.” That is the arches of seventy-two feet, when filled up on the inside, were no longer visible, and the dome appeared to stand over arches of 100 feet span on north and south, as already on east and west, the transverse dimension of the church being lessened between these points by some twenty-four feet. Salzenberg understanding Agathias to refer to the apparent arches of 100 feet span on north and south is unable to offer any explanation.

The actual evidence in the church, we believe, fully bears out the interpretation here suggested. What we have called the secondary order of columns would pass exactly beneath the position given to this wall. These columns on the gallery floor are very strong, and a very strong row of arches runs along over them (see Fig. 38). Moreover the curtain walls in every other instance throughout the church are flush with the exterior.

That this space is not available to the interior of S. Sophia has caused Choisy to criticise the design in this respect as “a solution undecided, moyen terme, fâcheux; the large arches by a departure from ordinary rule being thrown on the outside so that the space covered by them was lost. S. Sophia Salonica redressed this error.” We wonder that Choisy’s views as to the original base of the dome did not cause him to take the further step we have here suggested. The present form, in which the lateral arches support the square base of the dome, is at least a possible one; but that the arches when they carried nothing and thus were actually vaults (as before shown by Choisy) were not filled with a screen but were mere arches twelve feet on soffite, lying against the sides of the building seems inconceivable. In our Figure 34 we have amended Choisy’s view in this respect. Looking on these lateral arches as vaults we have filled them with a window like the western vault, and the harmony which results between the sides and the west end amply verifies our conclusions. One point further. The upper surface of the base of the dome on the west side should not be wholly level as shown in Fig. 34, the central third curves up following the line of the top of semidome. In other words, the great arch of the interior pushes itself up through the base of the dome, and this treatment thus recurred at various heights—over large windows of aisles, over western and lateral lunettes, as we have shown, and over the semidome.

Originally, before the interior was narrowed in the way we have explained, there was a much clearer suggestion of a cross plan: barrel vaults at north and south being filled at their ends with large lunettes like the west vault. We suppose that the failure was mainly in the secondary order, and that the window screen and all possible weight was entirely removed and transferred to the great order. Salzenberg was satisfied that there had been great alterations in this part of the building, and Choisy’s view of the window-wall, Plate xxv., entirely confirms his opinion. If it could be shown that the alteration spoken of by Agathias will not bear the interpretation we put on it, there were earlier troubles at this part mentioned by Procopius. The best proof, however, we suggest is found in the design. It has been before pointed out that Choisy and other writers have too hastily assumed that S. Sophia Salonica was built after the great church of Constantinople. That it preceded it enforces the present argument. Grelot (1680) writes that upper galleries remained in the church in these positions, but he based his assertion on the row of seven arched recesses just above the main cornice which he thought were formerly open. It is clear however from an examination of the section that the arches could only have opened to the vault of the first floor gynaeceum. That these small arches did open to the vault of the first floor, seems to be borne out by the fact that above the centre of the secondary order, where its arch is low, a similar piercing is made, through which (or the higher arches on each side) and through the seven arches, a mysterious perspective into the immensity of the dome might have been obtained by those in the gynaeceum (see Figs. 4, 36, 38). Shallow arched recesses merely used decoratively seem to have been little known to early Byzantine art, and arches on the first floor through the great piers are blocked in a similar way. Moreover such openings would explain why the vault between the two orders of columns is so much stilted up into mere darkness.

Atrium.—To explain the present confused arrangement of the exterior, we must remember that from the time of the description of the church by the Silentiary to its description by Gyllius was a thousand years—as long as from the time of Alfred to the present day—and in this time we may well expect alterations and accretions.

In Chapter IX. we have shown that the present form of the exonarthex, with its great external piers, was an alteration, made about the time the belfry was added in the ninth century. Before that time the atrium was alike on all four sides—a true quadriporticus—one of the most beautiful features of the ancient churches. (See Figs. 3 and 25.)

North and South Porches.—Much of the confusion at the north-west and south-west angles is the result of Turkish attachments, including the western minarets, which were built in the last quarter of the sixteenth century. The plan of gynaeceum floor furnishes the best key to the former arrangement, for where there is Byzantine work above, it must once have existed below. Comparing the first floor and roof plans in Salzenberg with the ground plan, it becomes apparent that the main block was originally finished both at north-west and south-west angles to the general square of building. The two staircases now at these angles were added as extra buttressing masses; the original stairs being the four in the piers of north and south sides. The north and south porches, with extra building above the latter on the first floor, were also additions. Besides the irregularity and inferior style of these buildings the following evidence should be noticed. The actual form of the north-west angle on the gallery floor; and the natural reading of the three plans when laid one over the other; broad arches, which pass across the porches; the fact that the arch in south porch (dotted in C on Figure 24, see also Fossati, Plate i.) now has no office; and that above the door at this end of narthex, there is a window which now merely opens into the south porch.

An examination of the exterior on the south side shows that the south-west staircase was built before the porch, or the part above it at least, because a straight joint in the walling, and the form of the roofing, here clearly make evident that the apex of the gable roof was originally over the centre of the staircase, and that the slope has been subsequently run forward to cover the part above the porch.

In considering all the other irregularly attached buildings, together with the historical evidence, it seems clear that the church as designed and first built was externally a regular parallelogram, interrupted only by the projection of the apse at the east end; which was itself masked by a range of low chambers against the east wall, through which there were two entrances to the church as at present, and to which other two doors, in the east wall, still visible but now blocked, gave access. The other external doors, besides those from narthex, being two on the north and one in the south wall; together with two external doors at the gynaeceum level, one of which probably gave access to the gallery along which the emperor passed to the church, and the other, to the north, may have led to the cells of the clergy.

Baptistery and Loggia.—Of early buildings detached from the church we have the round building at the north-east, which we regard as having descended from the earlier church, and the south-west baptistery, with a loggia attached to its north side. The space between the church and the baptistery on plan looks like a covered way, leading from the church with a screen in the middle, but the part next the church is, and always must have been, open. The part next the baptistery is covered with a large semicylindrical vault, arched transversely to the “screen,” and penetrated by a less cylinder in the direction of the length of the loggia. Rebates (on baptistery side) round the doorway which stands between the pair of columns show that there was a door, and strips down the sides of the pillars, which stand above the transom, show that pierced slabs or other closures filled the arched front of the vault. If we add breast-high closures in the lateral openings, as in the portico of St. John Studius, the whole becomes an inclosed loggia against the baptistery. Salzenberg states that there was a door in the north wall of baptistery, and Labarte places another in the western compartment of south aisle of church, but for the latter there does not appear to be a particle of evidence; and consequently the court and loggia cannot have formed a direct passage to the baptistery. 1. Salzenberg on his plan draws the transverse axis of the baptistery, and that of the western bay of the church; these do not agree by a foot or two, but the doorway of “screen” agrees with neither, nor is it a mean between them, but varies by excess. 2. In the section (Salzenberg, Plate xi.) it is seen that the present level of floor in this loggia is that of baptistery, and is below that of church; but the columns have no bases, therefore the loggia floor was beneath both church and baptistery. 3. A large arch is shown between the church and west pier of this loggia, from which it springs properly, while at the other end it is cut off incomplete by the wall of the church. These reasons together lead us to suggest that the loggia is possibly older than the church, and that it may be a part of an arcade retained when the present church was built. The style of the screen would readily allow of its being twenty or thirty years older than S. Sophia. The capitals are not found elsewhere in the church, while similar ones form the chief order at S. Sergius; and the door is inserted between the two columns, exactly as in the portico of S. John Studius. We do not however insist on its being earlier than the church so much as on the evidence pointing to its being part of a continuous arcade (see plan, Fig. 39). Doubtless it might be determined from a careful examination whether the loggia or the baptistery was built first.

The way by which the “Great Baptistery” was reached from the bema, as mentioned in the Ceremonies was probably by this cloister, which perhaps inclosed one of the courts on the sides of the church, spoken of by Procopius and the Silentiary. The portion drawn by Salzenberg still remains, although sadly plastered over and mutilated.

§ 4. STRUCTURAL SYSTEM AND VAULTING.

The geometrical scheme of this building, which in its final form must be the result of hundreds of adjustments, modifications, and expedients, to meet newly discovered emergencies, is withal so seemingly simple, that it may be read as a bare mechanical solution of the primary conditions.

The great central area, excepting only the narrow bema, is surrounded by two stories of vaults; the thrust of the dome over the square of about 100 feet is not only resisted by these, but by the four immense buttressing masses (or rather chambers for they are built hollow) which, pierced by arches, pass right across the aisles. East and west the dome is sustained by the semidomes of the great hemicycles, and these in turn by the vaults of the three subdivisions of the hemicycles. The thrusts are thus distributed in a regular pyramid. The external wall, which incloses the whole, being built out to the extremity of the great buttress piers of the north and south sides, and the lesser piers east and west, is thus little more than a screen, inclosing the more active parts of the structure.

One of the most remarkable expedients of this marvellously planned building is that by which the vaults of the side aisles,—which, having large spans, necessarily spring comparatively low down—are received on the secondary order of columns, standing behind the pillars of the great order. This allows of the stately colonnade on either side of the central space and those in the four exedras being only controlled by the height of the upper floor, which is forty-four feet above the area as is explained by Figs. 36, 38. These secondary pillars also transform the spaces left by the exedras into square compartments.

Arch Forms.—The great arches under the dome have their centres two feet six inches above the springing line. Those in the principal arcade appear to be semicircular. In the adjoining exedras, the porphyry columns not being nearly so long as the green ones, they were set on pedestals, and the arches are “horseshoe” in form, at least towards the nave, for they are built “winding,” so as to approach a square impost on their caps. We say approach, for there is a gradual modification; the caps being an inch or two wider towards the aisles, the impost increases this by a few inches more. The openings from gynaeceum at west end are segmental, some arches to the side windows and the lateral windows of west elevation, Fig. 25, are bluntly pointed. The transverse arching of narthex is semielliptical, or rather three-centred, a segment with the curve at the ends quickened to become tangential to the wall. The pointed arch is used in the great aqueduct near Constantinople and in one of the city cisterns: both appear to be of the age of Justinian.[341]

Vaulting.—The vaulting is executed with the mastery and freedom that comes of confidence in direct methods. Certain portions are cylindrical, and others are formed by cylindrical cross-penetrations. The octagon of the baptistery, and the square compartments of the gynaeceum, are covered by domes which penetrate down into the angles with continuous pendentives. The larger compartments of the vaults of the aisles require some explanation.

Where four semicircular arches open about a square or oblong space, and it is desired to make the vault conform exactly to them, this may be accomplished by a semispherical dome, the span of which is equal to the diagonal of the compartment to be covered; such a vault presents an unbroken surface. Or two cylindrical vaults may penetrate at right angles, when the vault is broken by the intersection into four surfaces. At S. Sophia it was evidently desired to keep the springing high for the sake of the monolith columns, and yet to maintain, so far as possible, a domical surface.