The Stones of Venice, Volume 1 (of 3)

CHAPTER III.

THE SIX DIVISIONS OF ARCHITECTURE

§ I. The practical duties of buildings are twofold.

They have either (1), to hold and protect something; or (2), to place or carry something.

1. Architecture of Protection. This is architecture intended to protect men or their possessions from violence of any kind, whether of men or of the elements. It will include all churches, houses, and treasuries; fortresses, fences, and ramparts; the architecture of the hut and sheepfold; of the palace and the citadel: of the dyke, breakwater, and sea-wall. And the protection, when of living creatures, is to be understood as including commodiousness and comfort of habitation, wherever these are possible under the given circumstances.

2. Architecture of Position. This is architecture intended to carry men or things to some certain places, or to hold them there. This will include all bridges, aqueducts, and road architecture; light-houses, which have to hold light in appointed places; chimneys to carry smoke or direct currents of air; staircases; towers, which are to be watched from or cried from, as in mosques, or to hold bells, or to place men in positions of offence, as ancient moveable attacking towers, and most fortress towers.

§ II. Protective architecture has to do one or all of three things: to wall a space, to roof it, and to give access to it, of persons, light, and air; and it is therefore to be considered under the three divisions of walls, roofs, and apertures.

We will take, first, a short, general view of the connection of these members, and then examine them in detail: endeavoring always to keep the simplicity of our first arrangement in view; for protective architecture has indeed no other members than these, unless flooring and paving be considered architecture, which it is only when the flooring is also a roof; the laying of the stones or timbers for footing being pavior’s or carpenter’s work, rather than architect’s; and, at all events, work respecting the well or ill doing of which we shall hardly find much difference of opinion, except in points of æsthetics. We shall therefore concern ourselves only with the construction of walls, roofs, and apertures.

§ III. 1. Walls.—A wall is an even and united fence, whether of wood, earth, stone, or metal. When meant for purposes of mere partition or enclosure, it remains a wall proper: but it has generally also to sustain a certain vertical or lateral pressure, for which its strength is at first increased by some general addition to its thickness; but if the pressure becomes very great, it is gathered up into piers to resist vertical pressure, and supported by buttresses to resist lateral pressure.

If its functions of partition or enclosure are continued, together with that of resisting vertical pressure, it remains as a wall veil between the piers into which it has been partly gathered; but if it is required only to resist the vertical or roof pressure, it is gathered up into piers altogether, loses its wall character, and becomes a group or line of piers.

On the other hand, if the lateral pressure be slight, it may retain its character of a wall, being supported against the pressure by buttresses at intervals; but if the lateral pressure be very great, it is supported against such pressure by a continuous buttress, loses its wall character, and becomes a dyke or rampart.

§ IV. We shall have therefore (A) first to get a general idea of a wall, and of right construction of walls; then (B) to see how this wall is gathered into piers; and to get a general idea of piers and the right construction of piers; then (C) to see how a wall is supported by buttresses, and to get a general idea of buttresses and the right construction of buttresses. This is surely very simple, and it is all we shall have to do with walls and their divisions.

Fig. I.

§ V. 2. Roofs.—A roof is the covering of a space, narrow or wide. It will be most conveniently studied by first considering the forms in which it may be carried over a narrow space, and then expanding these on a wide plan; only there is some difficulty here in the nomenclature, for an arched roof over a narrow space has (I believe) no name, except that which belongs properly to the piece of stone or wood composing such a roof, namely, lintel. But the reader will have no difficulty in understanding that he is first to consider roofs on the section only, thinking how best to construct a narrow bar or slice of them, of whatever form; as, for instance, x, y, or z, over the plan or area a, Fig. I. Having done this, let him imagine these several divisions, first moved along (or set side by side) over a rectangle, b, Fig. I., and then revolved round a point (or crossed at it) over a polygon, c, or circle, d, and he will have every form of simple roof: the arched section giving successively the vaulted roof and dome, and the gabled section giving the gabled roof and spire.

As we go farther into the subject, we shall only have to add one or two forms to the sections here given, in order to embrace all the uncombined roofs in existence; and we shall not trouble the reader with many questions respecting cross-vaulting, and other modes of their combination.

§ VI. Now, it also happens, from its place in buildings, that the sectional roof over a narrow space will need to be considered before we come to the expanded roof over a broad one. For when a wall has been gathered, as above explained, into piers, that it may better bear vertical pressure, it is generally necessary that it should be expanded again at the top into a continuous wall before it carries the true roof. Arches or lintels are, therefore, thrown from pier to pier, and a level preparation for carrying the real roof is made above them. After we have examined the structure of piers, therefore, we shall have to see how lintels or arches are thrown from pier to pier, and the whole prepared for the superincumbent roof; this arrangement being universal in all good architecture prepared for vertical pressures: and we shall then examine the condition of the great roof itself. And because the structure of the roof very often introduces certain lateral pressures which have much to do with the placing of buttresses, it will be well to do all this before we examine the nature of buttresses, and, therefore, between parts (B) and (C) of the above plan, § IV. So now we shall have to study: (A) the construction of walls; (B) that of piers; (C) that of lintels or arches prepared for roofing; (D) that of roofs proper; and (E) that of buttresses.

§ VII. 3. Apertures.—There must either be intervals between the piers, of which intervals the character will be determined by that of the piers themselves, or else doors or windows in the walls proper. And, respecting doors or windows, we have to determine three things: first, the proper shape of the entire aperture; secondly, the way in which it is to be filled with valves or glass; and thirdly, the modes of protecting it on the outside, and fitting appliances of convenience to it, as porches or balconies. And this will be our division F; and if the reader will have the patience to go through these six heads, which include every possible feature of protective architecture, and to consider the simple necessities and fitnesses of each, I will answer for it, he shall never confound good architecture with bad any more. For, as to architecture of position, a great part of it involves necessities of construction with which the spectator cannot become generally acquainted, and of the compliance with which he is therefore never expected to judge,—as in chimneys, light-houses, &c.: and the other forms of it are so closely connected with those of protective architecture, that a few words in Chap. XIX. respecting staircases and towers, will contain all with which the reader need be troubled on the subject.

CHAPTER IV.

THE WALL BASE

§ I. Our first business, then, is with Wall, and to find out wherein lies the true excellence of the “Wittiest Partition.” For it is rather strange that, often as we speak of a “dead” wall, and that with considerable disgust, we have not often, since Snout’s time, heard of a living one. But the common epithet of opprobrium is justly bestowed, and marks a right feeling. A wall has no business to be dead. It ought to have members in its make, and purposes in its existence, like an organized creature, and to answer its ends in a living and energetic way; and it is only when we do not choose to put any strength nor organization into it, that it offends us by its deadness. Every wall ought to be a “sweet and lovely wall.” I do not care about its having ears; but, for instruction and exhortation, I would often have it to “hold up its fingers.” What its necessary members and excellences are, it is our present business to discover.

§ II. A wall has been defined to be an even and united fence of wood, earth, stone, or metal. Metal fences, however, seldom, if ever, take the form of walls, but of railings; and, like all other metal constructions, must be left out of our present investigation; as may be also walls composed merely of light planks or laths for purposes of partition or inclosure. Substantial walls, whether of wood or earth (I use the word earth as including clay, baked or unbaked, and stone), have, in their perfect form, three distinct members;—the Foundation, Body or Veil, and Cornice.

§ III. The foundation is to the wall what the paw is to an animal. It is a long foot, wider than the wall, on which the wall is to stand, and which keeps it from settling into the ground. It is most necessary that this great element of security should be visible to the eye, and therefore made a part of the structure above ground. Sometimes, indeed, it becomes incorporated with the entire foundation of the building, a vast table on which walls or piers are alike set: but even then, the eye, taught by the reason, requires some additional preparation or foot for the wall, and the building is felt to be imperfect without it. This foundation we shall call the Base of the wall.

§ IV. The body of the wall is of course the principal mass of it, formed of mud or clay, of bricks or stones, of logs or hewn timber; the condition of structure being, that it is of equal thickness everywhere, below and above. It may be half a foot thick, or six feet thick, or fifty feet thick; but if of equal thickness everywhere, it is still a wall proper: if to its fifty feet of proper thickness there be added so much as an inch of thickness in particular parts, that added thickness is to be considered as some form of buttress or pier, or other appliance.33

In perfect architecture, however, the walls are generally kept of moderate thickness, and strengthened by piers or buttresses; and the part of the wall between these, being generally intended only to secure privacy, or keep out the slighter forces of weather, may be properly called a Wall Veil. I shall always use this word “Veil” to signify the even portion of a wall, it being more expressive than the term Body.

§ V. When the materials with which this veil is built are very loose, or of shapes which do not fit well together, it sometimes becomes necessary, or at least adds to security, to introduce courses of more solid material. Thus, bricks alternate with rolled pebbles in the old walls of Verona, and hewn stones with brick in its Lombard churches. A banded structure, almost a stratification of the wall, is thus produced; and the courses of more solid material are sometimes decorated with carving. Even when the wall is not thus banded through its whole height, it frequently becomes expedient to lay a course of stone, or at least of more carefully chosen materials, at regular heights; and such belts or bands we may call String courses. These are a kind of epochs in the wall’s existence; something like periods of rest and reflection in human life, before entering on a new career. Or else, in the building, they correspond to the divisions of its stories within, express its internal structure, and mark off some portion of the ends of its existence already attained.

§ VI. Finally, on the top of the wall some protection from the weather is necessary, or some preparation for the reception of superincumbent weight, called a coping, or Cornice. I shall use the word Cornice for both; for, in fact, a coping is a roof to the wall itself, and is carried by a small cornice as the roof of the building by a large one. In either case, the cornice, small or large, is the termination of the wall’s existence, the accomplishment of its work. When it is meant to carry some superincumbent weight, the cornice may be considered as its hand, opened to carry something above its head; as the base was considered its foot: and the three parts should grow out of each other and form one whole, like the root, stalk, and bell of a flower.

These three parts we shall examine in succession; and, first, the Base.

§ VII. It may be sometimes in our power, and it is always expedient, to prepare for the whole building some settled foundation, level and firm, out of sight. But this has not been done in some of the noblest buildings in existence. It cannot always be done perfectly, except at enormous expense; and, in reasoning upon the superstructure, we shall never suppose it to be done. The mind of the spectator does not conceive it; and he estimates the merits of the edifice on the supposition of its being built upon the ground. Even if there be a vast table land of foundation elevated for the whole of it, accessible by steps all round, as at Pisa, the surface of this table is always conceived as capable of yielding somewhat to superincumbent weight, and generally is so; and we shall base all our arguments on the widest possible supposition, that is to say, that the building stands on a surface either of earth, or, at all events, capable of yielding in some degree to its weight.

Fig. II.

§ VIII. Now, let the reader simply ask himself how, on such a surface, he would set about building a substantial wall, that should be able to bear weight and to stand for ages. He would assuredly look about for the largest stones he had at his disposal, and, rudely levelling the ground, he would lay these well together over a considerably larger width than he required the wall to be (suppose as at a, Fig. II.), in order to equalise the pressure of the wall over a large surface, and form its foot. On the top of these he would perhaps lay a second tier of large stones, b, or even the third, c, making the breadth somewhat less each time, so as to prepare for the pressure of the wall on the centre, and, naturally or necessarily, using somewhat smaller stones above than below (since we supposed him to look about for the largest first), and cutting them more neatly. His third tier, if not his second, will probably appear a sufficiently secure foundation for finer work; for if the earth yield at all, it will probably yield pretty equally under the great mass of masonry now knit together over it. So he will prepare for the wall itself at once by sloping off the next tier of stones to the right diameter, as at d. If there be any joints in this tier within the wall, he may perhaps, for further security, lay a binding stone across them, e, and then begin the work of the wall veil itself, whether in bricks or stones.

§ IX. I have supposed the preparation here to be for a large wall, because such a preparation will give us the best general type. But it is evident that the essential features of the arrangement are only two, that is to say, one tier of massy work for foundation, suppose c, missing the first two; and the receding tier or real foot of the wall, d. The reader will find these members, though only of brick, in most of the considerable and independent walls in the suburbs of London.

§ X. It is evident, however, that the general type, Fig. II., will be subject to many different modifications in different circumstances. Sometimes the ledges of the tiers a and b may be of greater width; and when the building is in a secure place, and of finished masonry, these may be sloped off also like the main foot d. In Venetian buildings these lower ledges are exposed to the sea, and therefore left rough hewn; but in fine work and in important positions the lower ledges may be bevelled and decorated like the upper, or another added above d; and all these parts may be in different proportions, according to the disposition of the building above them. But we have nothing to do with any of these variations at present, they being all more or less dependent upon decorative considerations, except only one of very great importance, that is to say, the widening of the lower ledge into a stone seat, which may be often done in buildings of great size with most beautiful effect: it looks kind and hospitable, and preserves the work above from violence. In St. Mark’s at Venice, which is a small and low church, and needing no great foundation for the wall veils of it, we find only the three members, b, c, and d. Of these the first rises about a foot above the pavement of St. Mark’s Place, and forms an elevated dais in some of the recesses of the porches, chequered red and white; c forms a seat which follows the line of the walls, while its basic character is marked by its also carrying certain shafts with which we have here no concern; d is of white marble; and all are enriched and decorated in the simplest and most perfect manner possible, as we shall see in Chap. XXV. And thus much may serve to fix the type of wall bases, a type oftener followed in real practice than any other we shall hereafter be enabled to determine: for wall bases of necessity must be solidly built, and the architect is therefore driven into the adoption of the right form; or if he deviate from it, it is generally in meeting some necessity of peculiar circumstances, as in obtaining cellars and underground room, or in preparing for some grand features or particular parts of the wall, or in some mistaken idea of decoration,—into which errors we had better not pursue him until we understand something more of the rest of the building: let us therefore proceed to consider the wall veil.