The origin of this mode of building is variously attributed by various writers; some will have it that it is but a modi fication of the Basilican style, with the addition of the dome, • which necessitated the shortening of the oblong of the Basilica ; but this, which is considered as merely an addition, is the principal feature both in construction and design. It is true, the plan of the Basilica was an oblong, and that of the Byzantine buildings a square, but surely it does not fol low that the latter should have been borrowed from the former ; as a matter of fact it may be so, but there is no prima facie evidence in thvour of such an opinion, from the mere similarity of plan. Others attribute its origin to the baptisteries, or to the sepulchral chapels built by Constantine, such as that of S. CA')stanza, the burial-place of Constantia, his (laughter, or the Holy Sepulchre at Jerusalem, and it must be confessed that these offer a greater resemblance to the Greek churches than do the Basilicas: others again are of (pinion that this was entirely a new style without any previous model, owing its origin to the skill and concep tion of the Byzantine architects. The question remains, how are these differences to be settled ? Not, we presume, by following any one opinion to the exclusion of the others, but by granting a moderate credit to all. We believe that they all speak truly, but that no one of them speaks the whole truth ; it is probable that Byzantine architecture owes its origin to each and all of the above sources,—to one per haps more than another, but not to one to the exclusion of another. We would say that it owed its existence not a little to the two first causes, but more especially to the last, for as Mr. Knight; in describing the church of S. Vitale, says, ‘• The chief architectural novelty in this building, is the dome. No vaulting or any kind had ever been hitherto employed in the roofs of churches, much less that most skil ful and admired of all vaulting, the cupola, or dome ; a mode of covering buildings perfectly well understood by the Romans, but discontinued as art declined, and, for the first time, reproduced by th3 Greek architects of Constantinople, in the instance of S. Sophia." With the insufficient materials we have to work upon, it would be futile to attempt a detailed classification of the examples belonging to this style. It is to be regretted that our knowledge on the subject is so scanty, but we trust that soia.. of our travellers will take an interest in those hitherto neglected remains of Christian art. That there is a seareity of examples, we can hardly suppose ; we believe that Asia Minor would afford ample materials for a proper investigation. The only writer we know of who has essayed an arrangement of known examples, and their division into classes, is M. Couchand in his book on the Eglises B•zan tines en Greee. It is true he seem: to include some examples under this style which other authors do not suppose to belong to it. but he has given considerable attention to the subject, and his opinions cannot but be worth consideration. He commences by dividing the buildings into three classes, to each of which he assigns a particular period. The first period is comprised between the fourth and sixth centuries, the second between the sixth and eleventh, and the third be tween the eleventh and the invasion by the Ottomans. We cannot do better than follow his own description as closely as possible.
Few of the churches of the first period, says he, are now extant ; but we learn from the historian Eusebius that they were in plan either round or octagon, and were surmounted by a dome. Of this description was the church erected by Constantine at Antioch, which was of the latter class, and that erected by his mother Helena, in Syria, of the circular form. The churches of S. Marcellin and S. Constance at Rome, as well as that of S. Vitale at Ravenna, afford further examples of the historian's descrip tion. The plans in both cases, whether circular or octagonal, terminated of a square form, and upon the plans thus pro. duced were erected the facades ; the most ancient of which are simple parallelopipeds, terminated at their summit by a cornice of stone or marble, and sometimes of bricks, so placed as to form salient and re-entering angles. Pediments showing the slope of the roof do not appear in the facades, for the use of timber had already been discarded by the Greeks in the formation of their roofs, which were now either flat or spherical. One or more gates gave admittance into the church, and these were generally adorned with deep mouldings; the lintels were relieved by an arch of discharge.
We have said that all the churches of this period were sur mounted by domes ; these were pierced at their lower extremity by a multitude of apertures which lighted the interior of the cupola. According to Eusebius and S. Paul of Seleucia, the domes were covered with lead and occasionally gilded, but all those which are still to be found in Greece are covered with tiles of terra cotta. The lateral facades differ little from the principal one; they are each of them provided with an entrance. The apsides, generally three in number, symbolizing the three Persons of the Holy Trinity, were of a simple plan, which was more frequently circular than polygonal : their sides were pierced with one or more apertures or windows. In the interior of the church the nave was always preceded by a porch or vestibule. A gallery for the female portion of the congregation was carried along the nave as fir as the sanctuary, and was lighted by windows situated over the principal facade, and sometimes by others in the side facades. The principal difference. between the styles of the two empires, is shown in the length of the nave, which in the Greek. churches is much shorter than in the basilicas of the west. In the centre of the church were four piers supporting the dome, which was erected on a square plan, the angles being filled up by very ingenious contrivances technically termed pendentive:. The extremi ties of the nave were covered by two hemispherical cupolas.
Such are the principal features of the edifices which were erected from the time of Constantine to the middle of the sixth century.
An enumeration of the peculiarities of the second period will help to give us an idea of Bic progress made by Justinian in the Christian architecture of this era.
The first edifice which presents itself to our notice is the smaller church of S. Sophia at Constantinople, converted into a mosque after the 111 V:1,4011 of the Ottomans. The plan of the exterior is that of a square surrounding an octagon. the form of that of S. Vitale at Ravenna. In the interior the galleries for females were carried round the first story, and the nave covered, as in the preceding period, with a dome. From this let us pass on to the larger church of the same name, a building erected by Justinian to replace one which had not long previously been destroyed by fire. In plan this is similar to the smaller church, with the exception that the octagon is slightly prolonged. The interior gal leries are similar to those described, hut the dome is more rich and beautiful than in all previous examples, and pierced with a larger number of apertures. The effect pro• duced by this building was great, as is evidenced by the influence which it obtained throughout the Eastern empire. At a later time, the form of the interior was repeated in the exterior ; this combination, which was first applied to the naye and transepts, at last became so general, that externally you could scarcely discover a straight line towards the summit of the building. The churches of " the Almighty," and of the monastery at Constantinople, which still preserve the roof of this period, otier remarkable examples of this combination of vaulting ; and the method, which was employed in a great number of instances, is still to be seen in most of the isles of the Archipelago. In this period the domes were increased in number, and at last were carried even over the porch ; the side facades follow the same form as the principal one, and the rear end of the edifice terminates in a polygonal apsis, pierced with windows of two Or three compartments. In the interior decoration mosaics took the place of the marble slabs previously employed. which were retained only in the surbasements. The nave was simplified ; square piers were substituted for columns, which gradually disappeared, and the pendenti yes were modified and somewhat varied. The vaults were divided by horizontal rings, and decorated with paint ings; the centre of the cupola being occupied by a colossal head of Christ, surrounded by angels. The domes belonging to the latter portion of this period differed from the preceding, inasmuch as the windows encroached upon the spherical part, whereas before they had been confined to the base. This second period, as may readily be seen, added greatly to the embellishment of Byzantine architecture, and eventually con siderably modified its character.