CHAPTER XIX.
SUPERIMPOSITION.
§ I. The reader has now some knowledge of every feature of all possible architecture. Whatever the nature of the building which may be submitted to his criticism, if it be an edifice at all, if it be anything else than a mere heap of stones like a pyramid or breakwater, or than a large stone hewn into shape, like an obelisk, it will be instantly and easily resolvable into some of the parts which we have been hitherto considering: its pinnacles will separate themselves into their small shafts and roofs; its supporting members into shafts and arches, or walls penetrated by apertures of various shape, and supported by various kinds of buttresses. Respecting each of these several features I am certain that the reader feels himself prepared, by understanding their plain function, to form something like a reasonable and definite judgment, whether they be good or bad; and this right judgment of parts will, in most cases, lead him to just reverence or condemnation of the whole.
§ II. The various modes in which these parts are capable of combination, and the merits of buildings of different form and expression, are evidently not reducible into lists, nor to be estimated by general laws. The nobility of each building depends on its special fitness for its own purposes; and these purposes vary with every climate, every soil, and every national custom: nay, there were never, probably, two edifices erected in which some accidental difference of condition did not require some difference of plan or of structure; so that, respecting plan and distribution of parts, I do not hope to collect any universal law of right; but there are a few points necessary to be noticed respecting the means by which height is attained in buildings of various plans, and the expediency and methods of superimposition of one story or tier of architecture above another.
§ III. For, in the preceding inquiry, I have always supposed either that a single shaft would reach to the top of the building, or that the farther height required might be added in plain wall above the heads of the arches; whereas it may often be rather expedient to complete the entire lower series of arches, or finish the lower wall, with a bold string course or cornice, and build another series of shafts, or another wall, on the top of it.
§ IV. This superimposition is seen in its simplest form in the interior shafts of a Greek temple; and it has been largely used in nearly all countries where buildings have been meant for real service. Outcry has often been raised against it, but the thing is so sternly necessary that it has always forced itself into acceptance; and it would, therefore, be merely losing time to refute the arguments of those who have attempted its disparagement. Thus far, however, they have reason on their side, that if a building can be kept in one grand mass, without sacrificing either its visible or real adaptation to its objects, it is not well to divide it into stories until it has reached proportions too large to be justly measured by the eye. It ought then to be divided in order to mark its bulk; and decorative divisions are often possible, which rather increase than destroy the expression of general unity.
§ V. Superimposition, wisely practised, is of two kinds, directly contrary to each other, of weight on lightness, and of lightness on weight; while the superimposition of weight on weight, or lightness on lightness, is nearly always wrong.
1. Weight on lightness: I do not say weight on weakness. The superimposition of the human body on its limbs I call weight on lightness: the superimposition of the branches on a tree trunk I call lightness on weight: in both cases the support is fully adequate to the work, the form of support being regulated by the differences of requirement. Nothing in architecture is half so painful as the apparent want of sufficient support when the weight above is visibly passive: for all buildings are not passive; some seem to rise by their own strength, or float by their own buoyancy; a dome requires no visibility of support, one fancies it supported by the air. But passive architecture without help for its passiveness is unendurable. In a lately built house, No. 86, in Oxford Street, three huge stone pillars in the second story are carried apparently by the edges of three sheets of plate glass in the first. I hardly know anything to match the painfulness of this and some other of our shop structures, in which the iron-work is concealed; nor, even when it is apparent, can the eye ever feel satisfied of their security, when built, as at present, with fifty or sixty feet of wall above a rod of iron not the width of this page.
§ VI. The proper forms of this superimposition of weight on lightness have arisen, for the most part, from the necessity or desirableness, in many situations, of elevating the inhabited portions of buildings considerably above the ground level, especially those exposed to damp or inundation, and the consequent abandonment of the ground story as unserviceable, or else the surrender of it to public purposes. Thus, in many market and town houses, the ground story is left open as a general place of sheltered resort, and the enclosed apartments raised on pillars. In almost all warm countries the luxury, almost the necessity, of arcades to protect the passengers from the sun, and the desirableness of large space in the rooms above, lead to the same construction. Throughout the Venetian islet group, the houses seem to have been thus, in the first instance, universally built, all the older palaces appearing to have had the rez de chaussée perfectly open, the upper parts of the palace being sustained on magnificent arches, and the smaller houses sustained in the same manner on wooden piers, still retained in many of the cortiles, and exhibited characteristically throughout the main street of Murano. As ground became more valuable and house-room more scarce, these ground-floors were enclosed with wall veils between the original shafts, and so remain; but the type of the structure of the entire city is given in the Ducal Palace.