=Byzantine.=--The term Byzantine is applied to the style of architecture gradually developed in Byzantium after Constantine, in <small>A.D.</small> 324, transferred the capital of the Roman Empire to that city. Its distinctive features are the use of brick and stone in place of concrete; the use of imposts in connection with columns and arches; the character of the carved ornament applied to surfaces and, most important of all, a system of covering rectangular spaces with domes. It reached its highest point of development under the Emperor Justinian, between the years 527 and 565. The style was the result of evolution; a product of the combination of principles of construction derived from Roman, Early Christian and Syrian architecture, and from the traditional methods of the Iran builders of Assyria; affected in matters of decoration by the luxurious taste of the Orient. The favourite material of Byzantine builders was brickwork; the bricks being one and one-half inches in thickness, like the Roman, and laid between layers of mortar of similar thickness. In the case of cornices the bricks were moulded to the required contours and when used for the shafts of columns were circular in outline. The mortar was composed of sand, lime, and crushed pottery, tiles, or bricks. Except in the case of marble columns which were cut and put in place by masons, the whole of the preliminary work was done by bricklayers who constructed the entire “carcass” of the building. When this [Illustration: FROM THE INTERIOR OF SAN VITALE, RAVENNA SHOWING THE “IMPOST” ABOVE COLUMN, AND DECORATION. Pp. 202-204, 207] [Illustration: TOMB OF GALLA PLACIDIA, RAVENNA P. 201] [Illustration: SECTION OF SS. SERGIUS AND BACCHUS, CONSTANTINOPLE SHOWING FLUTED OR MELON-SHAPED DOME, SUPPORTED ON EIGHT ARCHES AND “SQUINCHES.” NOTE LIGHTS ROUND DOME. P. 206] [Illustration: DIAGRAM SHOWING HOW THE PENDENTIVES, RESTING ON FOUR ANGLES OF A SQUARE, PROVIDE A CIRCULAR BASE FOR THE DOME. P. 205] [Illustration: SECTION OF S. SOPHIA, CONSTANTINOPLE SHOWING PENDENTIVE DOME. P. 207. SMALL DIAGRAM, AT RIGHT, SHOWS HOW A DOME WAS MADE TO REST ON EIGHT PIERS ENCLOSING AN OCTAGON, BY NICHES OR SQUINCHES.] [Illustration: EXTERIOR OF S. SOPHIA SHOWING THE IMMENSE BUTTRESSES THAT SUSTAIN THE THRUST OF THE DOME. MINARETS ADDED LATER ARE OF CHARACTERISTICALLY TURKISH TYPE. P. 207] [Illustration: INTERIOR OF S. SOPHIA SHOWING PENDENTIVES AND THREE OF THE DOME ARCHES (TWO OF WHICH ARE CLOSED AND PIERCED WITH LIGHTS). NOTE ALSO RING OF LIGHTS ROUND NECK OF DOME. PP. 202, 205, 207] [Illustration: PLAN OF S. SOPHIA P. 208] [Illustration: PLAN OF S. MARK’S, VENICE P. 209] [Illustration: EXTERIOR OF S. MARK’S, VENICE SHOWING GOTHIC DETAILS IMPOSED ON BYZANTINE DESIGN. P. 209] had dried and settled, the masons and the decorators completed the work, by overlaying the walls, domes, and pediments of the interior with marble or mosaics.