200 COMPARATIVE ARCHITECTURE. log feet by 92 feet over all, and has an interior arrangement very similar to S. Vitale (No. 83), but it has four niches only, and is inclosed in a square instead of an octagon (No. 79, e, f, g). The dome, 52 feet in diameter and 66 feet high, is visible externally, having no wooden roof, and is of a peculiar melon-like form caused by the formation of ridges and furrows from base to summit. This church, picturesquely situated on the shores of the Bosphorus, is in a ruinous condition, but was being partially restored by the Sultan at the time of the authors' visit in January, 1896. The beautiful frescoes and mosaics are, how- ever, irreparably damaged in consequence of the penetration of rain through the roof. S. Sophia, Constantinople (Hagia Sophia=" Divine Wis- dom") (Nos. 79, 80, 81), was built by order of Justinian, in a.d. 532-537, on the site of two successive churches of the same name, i.e. : — {a.) The wooden-roofed basilica, erected by Constantine, A.D. 360. {h.) The church erected by Theodosius, a.d. 415. The architects were Anthemius of Tralles and Isodorus of Miletus. The plan consists of a central space 107 feet square, bounded by four massive piers, 25 feet square, connected above by semi- circular arches, and supporting a dome 107 feet in diameter {cf. S. Paul, London). East and west are great semicircular spaces, crowned with semi-domes, and out of these are formed smaller exedrae, in their turn covered with semi-domes. The area thus formed is a great oval-ended nave 265 feet by 107 feet. Outside this central area are aisles over 50 feet wide, in two stories, north and south, the upper story being for women. These aisles bring the main building approximately to a square, which, excluding the apse and narthex, measures 250 feet by 237 feet. The narthex, to the west of the main building, was set apart for catechumens and penitents, and forms a grand apartment over 200 feet long by 30 feet wide; it is in two stories, the upper forming a gallery to the church. Further west is the outer narthex and atrium, with marble columns and brick pillars. To the north and south, forming continuations of the four great piers already mentioned, are massive buttresses, 25 feet wide by 70 feet long, pierced with double arches on the ground and upper story. These piers take the thrust of the main arches and dome on the two sides where there are no semi-domes. SS. Sergius and Bacchus would resemble S. Sophia in plan if it were cut in two and a dome on pendentives placed over an intervening square, and the whole doubled in size. The domical method of construction governs the plan, which is subservient to it. The square central space is crowned with a dome, 180 feet above the pavement, but in itself only 47 feet in height above its base {i.e., less than a semi-dome).
