Fig. 144.—Carving from the Forum of Nerva, Rome.
CHAPTER X.
ROMAN ARCHITECTURE.
Analysis.
THE Plan (or floor-disposition).—The plans of Roman buildings are striking from their variety and the vast extent which in some cases they display, as well as from a certain freedom, mastery, and facility of handling which are not seen in earlier work. Their variety is partly due to the very various purposes which the buildings of the Romans were designed to serve: these comprised all to which Greek buildings had been appropriated, and many others, the product of the complex and luxurious civilisation of the Empire. But independent of this circumstance, the employment of such various forms in the plans of buildings as the ellipse, the circle, and the octagon, and their facile use, seem to denote a people who could build rapidly, and who looked carefully to the general masses and outlines of what they built, however carelessly they handled the minute details. The freedom with which these new forms were employed arises partly also from the fact that the Romans were in possession of a system of construction which rendered them practically independent of most of the restrictions which had fettered the genius of the Egyptians, Assyrians, and Greeks. Their vaulted roofs could be supported by a comparatively small number of piers of great solidity, placed far apart; and accordingly in the great halls of the Thermæ and elsewhere we find planning in which, a few stable points of support being secured, the outline of the spaces between them is varied at the pleasure of the architect in the most picturesque and pleasing manner.
The actual floor received a good deal of attention from the Romans. It was generally covered with tesselated pavement, often with mosaic, and its treatment entered into the scheme of the design for most interiors.
The Walls.
The construction of these was essentially different from that adopted by most earlier nations. The Romans rather avoided than cultivated the use of large blocks of stone; they invented methods by which very small materials could be aggregated together into massive and solid walls. They used mortar of great cementing power, so much so that many specimens of Roman walling exist in this country as well as in Italy or France, where the mortar is as hard as the stones which it unites. They also employed a system of binding together the small materials so employed by introducing, at short distances apart, courses of flat stones or bricks, called “bond courses,” and they further fortified such walls by bands of flat materials placed edgeways after the manner popularly known as herring-bone work. The result of these methods of construction was that the Roman architect could build anywhere, no matter how unpromising the materials which the locality afforded; that he could put the walls of his building together without its being requisite to employ exclusively the skilled labour of the mason, and that both time and expense were thus saved. This economy and speed were not pushed so far as to render the work anything but durable; they had, however, a bad effect in another direction, for these rough rubble walls were habitually encased in some more sightly material, in order to make them look as though they were something finer than they really were; and accordingly, the exterior was often faced with a thin skin of masonry, and not infrequently plastered. The interior was also almost invariably plastered, but to this little exception can be taken. This casing of the exteriors was, however, the beginning of a system of what may be called false architecture, and one which led to much that was degrading to the art.
The walls were in many cases, it has been already observed, gathered into strong masses, such as it is customary to term piers, in order to support the vaulted roofs at the proper points. They were often carried to a much greater height than in Greek buildings, and they played altogether a far more important part in the design of Roman buildings than they had done in that of the Greeks.