144 COMPARATIVE ARCHITECTURE. great apartment was lighted by clerestory windows, high in the walls, admitting light over the roofs of adjoining halls by means of the intersecting vault, which was constructed on a similar system to that described for the Basilica of Maxentius (page 139). S. George's Hall, Liverpool, is of similar dimensions to the Tepi- darium of Caracalla's Thermae, but with five bays instead of three. The Calidarium was roofed with a dome similar to that of the Pantheon. The Frigidarium was probably open to the sky, although as many tons of T iron were found below the surface of the bath, some suppose it to have been covered with a roof of iron joists (probably cased with bronze) and concrete. Viollet-le due has a drawing in his lectures of the Frigidarium restored, giving an excellent idea of its probable original appearance. The general adornment and color treatment of the interior must have been of great richness, and in marked contrast to the exterior, indicating a farther secession from Greek principles. Sumptuous internal magnificence was aimed at in all the great Thermae, the pavings were patterned with mosaic cubes of bright colors, either planned in geometrical patterns or with figures of athletes ; the lower parts of the walls were sheathed with many colored marbles, and the upper parts with enriched and modelled stucco bright with color ; the great columns on which rested the vault springers were either of granite, porphyry, giallo antico, alabaster or other rare marbles from the ^'Egean islands. Various colored marble columns were used constructively to support the upper balconies and the peristyle roofs, and decoratively to form with their entablatures and pediments frames for the superimposed niches in the walls. The surface of the great vaults was also richly ornamented by means of coffering, or covered with bold figures, decorations in black and white, or colored glass mosaic. In these magnificent halls thus sumptuously decorated some of the finest sculpture of antiquity was displayed. This was brought largely from Greece or executed in Rome by Greek artists, and at the excavation of the ThernicC during the Renaissance period much of it found its way into the Vatican and other museums in Rome, and in the principal European cities. Finally, additional interest was given to the interiors by the perpetual streams of running water, issuing from the mouths of sculptured lions in marble or brightly polished silver, falling into capacious marble basins and producing a delicious cooling effect in the hot sultry weather. The exteriors appear to have been treated very plainly in stucco, or more wisely left as impressive masses of plain brickwork, perhaps banded or dressed with bricks of a different color. The unbounded license of the public baths, and their connection
