The Stones of Venice, Volume 1 (of 3)

But b c is allowed to be variable. Let it become b2 c2 at C, which is a length representing about the diameter of a shaft containing half the substance of the shaft B, and, therefore, able to sustain not more than half the weight sustained by B. But the slope b d and depth d e remaining unchanged, we have the capital of C, which we are to load with only half the weight of l, m, n, r, i. e., with l and r alone. Therefore the weight of l and r, now represented by the masses l2, r2, is distributed over the whole of the capital. But the weight r was adequately supported by the projecting piece of the first capital h f c: much more is it now adequately supported by i h, f2 c2. Therefore, if the capital of B was safe, that of C is more than safe. Now in B the length e f was only twice b c; but in C, e2 f2 will be found more than twice that of b2 c2. Therefore, the more slender the shaft, the greater may be the proportional excess of the abacus over its diameter.

Fig. XXIV.

§ XV. 2. The smaller the scale of the building, the greater may be the excess of the abacus over the diameter of the shaft. This principle requires, I think, no very lengthy proof: the reader can understand at once that the cohesion and strength of stone which can sustain a small projecting mass, will not sustain a vast one overhanging in the same proportion. A bank even of loose earth, six feet high, will sometimes overhang its base a foot or two, as you may see any day in the gravelly banks of the lanes of Hampstead: but make the bank of gravel, equally loose, six hundred feet high, and see if you can get it to overhang a hundred or two! much more if there be weight above it increased in the same proportion. Hence, let any capital be given, whose projection is just safe, and no more, on its existing scale; increase its proportions every way equally, though ever so little, and it is unsafe; diminish them equally, and it becomes safe in the exact degree of the diminution.

Let, then, the quantity e d, and angle d b c, at A of Fig. XXIII., be invariable, and let the length d b vary: then we shall have such a series of forms as may be represented by a, b, c, Fig. XXIV., of which a is a proportion for a colossal building, b for a moderately sized building, while c could only be admitted on a very small scale indeed.

§ XVI. 3. The greater the excess of abacus, the steeper must be the slope of the bell, the shaft diameter being constant.

This will evidently follow from the considerations in the last paragraph; supposing only that, instead of the scale of shaft and capital varying together, the scale of the capital varies alone. For it will then still be true, that, if the projection of the capital be just safe on a given scale, as its excess over the shaft diameter increases, the projection will be unsafe, if the slope of the bell remain constant. But it may be rendered safe by making this slope steeper, and so increasing its supporting power.

Fig. XXV.

Thus let the capital a, Fig. XXV., be just safe. Then the capital b, in which the slope is the same but the excess greater, is unsafe. But the capital c, in which, though the excess equals that of b, the steepness of the supporting slope is increased, will be as safe as b, and probably as strong as a.48

§ XVII. 4. The steeper the slope of the bell, the thinner may be the abacus.

The use of the abacus is eminently to equalise the pressure over the surface of the bell, so that the weight may not by any accident be directed exclusively upon its edges. In proportion to the strength of these edges, this function of the abacus is superseded, and these edges are strong in proportion to the steepness of the slope. Thus in Fig. XXVI., the bell at a would carry weight safely enough without any abacus, but that at c would not: it would probably have its edges broken off. The abacus superimposed might be on a very thin, little more than formal, as at b; but on c must be thick, as at d.

Fig. XXVI.

§ XVIII. These four rules are all that are necessary for general criticism; and observe that these are only semi-imperative,—rules of permission, not of compulsion. Thus Law 1 asserts that the slender shaft may have greater excess of capital than the thick shaft; but it need not, unless the architect chooses; his thick shafts must have small excess, but his slender ones need not have large. So Law 2 says, that as the building is smaller, the excess may be greater; but it need not, for the excess which is safe in the large is still safer in the small. So Law 3 says that capitals of great excess must have steep slopes; but it does not say that capitals of small excess may not have steep slopes also, if we choose. And lastly, Law 4 asserts the necessity of the thick abacus for the shallow bell; but the steep bell may have a thick abacus also.

§ XIX. It will be found, however, that in practice some confession of these laws will always be useful, and especially of the two first. The eye always requires, on a slender shaft, a more spreading capital than it does on a massy one, and a bolder mass of capital on a small scale than on a large. And, in the application of the first rule, it is to be noted that a shaft becomes slender either by diminution of diameter or increase of height; that either mode of change presupposes the weight above it diminished, and requires an expansion of abacus. I know no mode of spoiling a noble building more frequent in actual practice than the imposition of flat and slightly expanded capitals on tall shafts.

§ XX. The reader must observe, also, that, in the demonstration of the four laws, I always assumed the weight above to be given. By the alteration of this weight, therefore, the architect has it in his power to relieve, and therefore alter, the forms of his capitals. By its various distribution on their centres or edges, the slope of their bells and thickness of abaci will be affected also; so that he has countless expedients at his command for the various treatment of his design. He can divide his weights among more shafts; he can throw them in different places and different directions on the abaci; he can alter slope of bells or diameter of shafts; he can use spurred or plain bells, thin or thick abaci; and all these changes admitting of infinity in their degrees, and infinity a thousand times told in their relations: and all this without reference to decoration, merely with the five forms of block capital!

§ XXI. In the harmony of these arrangements, in their fitness, unity, and accuracy, lies the true proportion of every building,—proportion utterly endless in its infinities of change, with unchanged beauty. And yet this connexion of the frame of their building into one harmony has, I believe, never been so much as dreamed of by architects. It has been instinctively done in some degree by many, empirically in some degree by many more; thoughtfully and thoroughly, I believe, by none.

§ XXII. We have hitherto considered the abacus as necessarily a separate stone from the bell: evidently, however, the strength of the capital will be undiminished if both are cut out of one block. This is actually the case in many capitals, especially those on a small scale; and in others the detached upper stone is a mere representative of the abacus, and is much thinner than the form of the capital requires, while the true abacus is united with the bell, and concealed by its decoration, or made part of it.

§ XXIII. Farther. We have hitherto considered bell and abacus as both derived from the concentration of the cornice. But it must at once occur to the reader, that the projection of the under stone and the thickness of the upper, which are quite enough for the work of the continuous cornice, may not be enough always, or rather are seldom likely to be so, for the harder work of the capital. Both may have to be deepened and expanded: but as this would cause a want of harmony in the parts, when they occur on the same level, it is better in such case to let the entire cornice form the abacus of the capital, and put a deep capital bell beneath it.

Fig. XXVII.

§ XXIV. The reader will understand both arrangements instantly by two examples. Fig. XXVII. represents two windows, more than usually beautiful examples of a very frequent Venetian form. Here the deep cornice or string course which runs along the wall of the house is quite strong enough for the work of the capitals of the slender shafts: its own upper stone is therefore also theirs; its own lower stone, by its revolution or concentration, forms their bells: but to mark the increased importance of its function in so doing, it receives decoration, as the bell of the capital, which it did not receive as the under stone of the cornice.

In Fig. XXVIII., a little bit of the church of Santa Fosca at Torcello, the cornice or string course, which goes round every part of the church, is not strong enough to form the capitals of the shafts. It therefore forms their abaci only; and in order to mark the diminished importance of its function, it ceases to receive, as the abacus of the capital, the decoration which it received as the string course of the wall.

This last arrangement is of great frequency in Venice, occurring most characteristically in St. Mark’s: and in the Gothic of St. John and Paul we find the two arrangements beautifully united, though in great simplicity; the string courses of the walls form the capitals of the shafts of the traceries; and the abaci of the vaulting shafts of the apse.

Fig. XXVIII.

§ XXV. We have hitherto spoken of capitals of circular shafts only: those of square piers are more frequently formed by the cornice only; otherwise they are like those of circular piers, without the difficulty of reconciling the base of the bell with its head.

§ XXVI. When two or more shafts are grouped together, their capitals are usually treated as separate, until they come into actual contact. If there be any awkwardness in the junction, it is concealed by the decoration, and one abacus serves, in most cases, for all. The double group, Fig. XXVII., is the simplest possible type of the arrangement. In the richer Northern Gothic groups of eighteen or twenty shafts cluster together, and sometimes the smaller shafts crouch under the capitals of the larger, and hide their heads in the crannies, with small nominal abaci of their own, while the larger shafts carry the serviceable abacus of the whole pier, as in the nave of Rouen. There is, however, evident sacrifice of sound principle in this system, the smaller abaci being of no use. They are the exact contrary of the rude early abacus at Milan, given in Plate XVII. There one poor abacus stretched itself out to do all the work: here there are idle abaci getting up into corners and doing none.

§ XXVII. Finally, we have considered the capital hitherto entirely as an expansion of the bearing power of the shaft, supposing the shaft composed of a single stone. But, evidently, the capital has a function, if possible, yet more important, when the shaft is composed of small masonry. It enables all that masonry to act together, and to receive the pressure from above collectively and with a single strength. And thus, considered merely as a large stone set on the top of the shaft, it is a feature of the highest architectural importance, irrespective of its expansion, which indeed is, in some very noble capitals, exceedingly small. And thus every large stone set at any important point to reassemble the force of smaller masonry and prepare it for the sustaining of weight, is a capital or “head” stone (the true meaning of the word) whether it project or not. Thus at 6, in Plate IV., the stones which support the thrust of the brickwork are capitals, which have no projection at all; and the large stones in the window above are capitals projecting in one direction only.

§ XXVIII. The reader is now master of all he need know respecting construction of capitals; and from what has been laid before him, must assuredly feel that there can never be any new system of architectural forms invented; but that all vertical support must be, to the end of time, best obtained by shafts and capitals. It has been so obtained by nearly every nation of builders, with more or less refinement in the management of the details; and the later Gothic builders of the North stand almost alone in their effort to dispense with the natural development of the shaft, and banish the capital from their compositions.

They were gradually led into this error through a series of steps which it is not here our business to trace. But they may be generalised in a few words.

§ XXIX. All classical architecture, and the Romanesque which is legitimately descended from it, is composed of bold independent shafts, plain or fluted, with bold detached capitals, forming arcades or colonnades where they are needed; and of walls whose apertures are surrounded by courses of parallel lines called mouldings, which are continuous round the apertures, and have neither shafts nor capitals. The shaft system and moulding system are entirely separate.

The Gothic architects confounded the two. They clustered the shafts till they looked like a group of mouldings. They shod and capitaled the mouldings till they looked like a group of shafts. So that a pier became merely the side of a door or window rolled up, and the side of the window a pier unrolled (vide last Chapter, § XXX.), both being composed of a series of small shafts, each with base and capital. The architect seemed to have whole mats of shafts at his disposal, like the rush mats which one puts under cream cheese. If he wanted a great pier he rolled up the mat; if he wanted the side of a door he spread out the mat: and now the reader has to add to the other distinctions between the Egyptian and the Gothic shaft, already noted in § XXVI. of Chap. VIII., this one more—the most important of all—that while the Egyptian rush cluster has only one massive capital altogether, the Gothic rush mat has a separate tiny capital to every several rush.

§ XXX. The mats were gradually made of finer rushes, until it became troublesome to give each rush its capital. In fact, when the groups of shafts became excessively complicated, the expansion of their small abaci was of no use: it was dispensed with altogether, and the mouldings of pier and jamb ran up continuously into the arches.

This condition, though in many respects faulty and false, is yet the eminently characteristic state of Gothic: it is the definite formation of it as a distinct style, owing no farther aid to classical models; and its lightness and complexity render it, when well treated, and enriched with Flamboyant decoration, a very glorious means of picturesque effect. It is, in fact, this form of Gothic which commends itself most easily to the general mind, and which has suggested the innumerable foolish theories about the derivation of Gothic from tree trunks and avenues, which have from time to time been brought forward by persons ignorant of the history of architecture.

§ XXXI. When the sense of picturesqueness, as well as that of justness and dignity, had been lost, the spring of the continuous mouldings was replaced by what Professor Willis calls the Discontinuous impost; which, being a barbarism of the basest and most painful kind, and being to architecture what the setting of a saw is to music, I shall not trouble the reader to examine. For it is not in my plan to note for him all the various conditions of error, but only to guide him to the appreciation of the right; and I only note even the true Continuous or Flamboyant Gothic because this is redeemed by its beautiful decoration, afterwards to be considered. For, as far as structure is concerned, the moment the capital vanishes from the shaft, that moment we are in error: all good Gothic has true capitals to the shafts of its jambs and traceries, and all Gothic is debased the instant the shaft vanishes. It matters not how slender, or how small, or how low, the shaft may be: wherever there is indication of concentrated vertical support, then the capital is a necessary termination. I know how much Gothic, otherwise beautiful, this sweeping principle condemns; but it condemns not altogether. We may still take delight in its lovely proportions, its rich decoration, or its elastic and reedy moulding; but be assured, wherever shafts, or any approximations to the forms of shafts, are employed, for whatever office, or on whatever scale, be it in jambs or piers, or balustrades, or traceries, without capitals, there is a defiance of the natural laws of construction; and that, wherever such examples are found in ancient buildings, they are either the experiments of barbarism, or the commencements of decline.

CHAPTER X.

THE ARCH LINE

§ I. We have seen in the last section how our means of vertical support may, for the sake of economy both of space and material, be gathered into piers or shafts, and directed to the sustaining of particular points. The next question is how to connect these points or tops of shafts with each other, so as to be able to lay on them a continuous roof. This the reader, as before, is to favor me by finding out for himself, under these following conditions.

Let s, s, Fig. XXIX. opposite, be two shafts, with their capitals ready prepared for their work; and a, b, b, and c, c, c, be six stones of different sizes, one very long and large, and two smaller, and three smaller still, of which the reader is to choose which he likes best, in order to connect the tops of the shafts.

I suppose he will first try if he can lift the great stone a, and if he can, he will put it very simply on the tops of the two pillars, as at A.

Very well indeed: he has done already what a number of Greek architects have been thought very clever for having done. But suppose he cannot lift the great stone a, or suppose I will not give it to him, but only the two smaller stones at b, b; he will doubtless try to put them up, tilted against each other, as at d. Very awkward this; worse than card-house building. But if he cuts off the corners of the stones, so as to make each of them of the form e, they will stand up very securely, as at B.

But suppose he cannot lift even these less stones, but can raise those at c, c, c. Then, cutting each of them into the form at e, he will doubtless set them up as at f.

Fig. XXIX.

§ II. This last arrangement looks a little dangerous. Is there not a chance of the stone in the middle pushing the others out, or tilting them up and aside, and slipping down itself between them? There is such a chance: and if by somewhat altering the form of the stones, we can diminish this chance, all the better. I must say “we” now, for perhaps I may have to help the reader a little.

The danger is, observe, that the midmost stone at f pushes out the side ones: then if we can give the side ones such a shape as that, left to themselves, they would fall heavily forward, they will resist this push out by their weight, exactly in proportion to their own particular inclination or desire to tumble in. Take one of them separately, standing up as at g; it is just possible it may stand up as it is, like the Tower of Pisa: but we want it to fall forward. Suppose we cut away the parts that are shaded at h and leave it as at i, it is very certain it cannot stand alone now, but will fall forward to our entire satisfaction.

Farther: the midmost stone at f is likely to be troublesome chiefly by its weight, pushing down between the others; the more we lighten it the better: so we will cut it into exactly the same shape as the side ones, chiselling away the shaded parts, as at h. We shall then have all the three stones k, l, m, of the same shape; and now putting them together, we have, at C, what the reader, I doubt not, will perceive at once to be a much more satisfactory arrangement than that at f.

§ III. We have now got three arrangements; in one using only one piece of stone, in the second two, and in the third three. The first arrangement has no particular name, except the “horizontal:” but the single stone (or beam, it may be,) is called a lintel; the second arrangement is called a “Gable;” the third an “Arch.”

We might have used pieces of wood instead of stone in all these arrangements, with no difference in plan, so long as the beams were kept loose, like the stones; but as beams can be securely nailed together at the ends, we need not trouble ourselves so much about their shape or balance, and therefore the plan at f is a peculiarly wooden construction (the reader will doubtless recognise in it the profile of many a farm-house roof): and again, because beams are tough, and light, and long, as compared with stones, they are admirably adapted for the constructions at A and B, the plain lintel and gable, while that at C is, for the most part, left to brick and stone.

§ IV. But farther. The constructions, A, B, and C, though very conveniently to be first considered as composed of one, two, and three pieces, are by no means necessarily so. When we have once cut the stones of the arch into a shape like that of k, l, and m, they will hold together, whatever their number, place, or size, as at n; and the great value of the arch is, that it permits small stones to be used with safety instead of large ones, which are not always to be had. Stones cut into the shape of k, l, and m, whether they be short or long (I have drawn them all sizes at n on purpose), are called Voussoirs; this is a hard, ugly French name; but the reader will perhaps be kind enough to recollect it; it will save us both some trouble: and to make amends for this infliction, I will relieve him of the term keystone. One voussoir is as much a keystone as another; only people usually call the stone which is last put in the keystone; and that one happens generally to be at the top or middle of the arch.

§ V. Not only the arch, but even the lintel, may be built of many stones or bricks. The reader may see lintels built in this way over most of the windows of our brick London houses, and so also the gable: there are, therefore, two distinct questions respecting each arrangement;—First, what is the line or direction of it, which gives it its strength? and, secondly, what is the manner of masonry of it, which gives it its consistence? The first of these I shall consider in this Chapter under the head of the Arch Line, using the term arch as including all manner of construction (though we shall have no trouble except about curves); and in the next Chapter I shall consider the second, under the head, Arch Masonry.

§ VI. Now the arch line is the ghost or skeleton of the arch; or rather it is the spinal marrow of the arch, and the voussoirs are the vertebræ, which keep it safe and sound, and clothe it. This arch line the architect has first to conceive and shape in his mind, as opposed to, or having to bear, certain forces which will try to distort it this way and that; and against which he is first to direct and bend the line itself into as strong resistance as he may, and then, with his voussoirs and what else he can, to guard it, and help it, and keep it to its duty and in its shape. So the arch line is the moral character of the arch, and the adverse forces are its temptations; and the voussoirs, and what else we may help it with, are its armor and its motives to good conduct.