The Stones of Venice, Volume 1 (of 3)

§ X. The reader is now master of all that he need know about the construction of the general wall cornice, fitted either to become a crown of the wall, or to carry weight above. If, however, the weight above become considerable, it may be necessary to support the cornice at intervals with brackets; especially if it be required to project far, as well as to carry weight; as, for instance, if there be a gallery on top of the wall. This kind of bracket-cornice, deep or shallow, forms a separate family, essentially connected with roofs and galleries; for if there be no superincumbent weight, it is evidently absurd to put brackets to a plain cornice or dripstone (though this is sometimes done in carrying out a style); so that, as soon as we see a bracket put to a cornice, it implies, or should imply, that there is a roof or gallery above it. Hence this family of cornices I shall consider in connection with roofing, calling them “roof cornices,” while what we have hitherto examined are proper “wall cornices.” The roof cornice and wall cornice are therefore treated in division D.

We are not, however, as yet nearly ready for our roof. We have only obtained that which was to be the object of our first division (A); we have got, that is to say, a general idea of a wall and of the three essential parts of a wall; and we have next, it will be remembered, to get an idea of a pier and the essential parts of a pier, which were to be the subjects of our second division (B).

CHAPTER VII.

THE PIER BASE

§ I. In § III. of Chap. III. (#x3_pgepubid00024), it was stated that when a wall had to sustain an addition of vertical pressure, it was first fitted to sustain it by some addition to its own thickness; but if the pressure became very great, by being gathered up into Piers.

I must first make the reader understand what I mean by a wall’s being gathered up. Take a piece of tolerably thick drawing-paper, or thin Bristol board, five or six inches square. Set it on its edge on the table, and put a small octavo book on the edge or top of it, and it will bend instantly. Tear it into four strips all across, and roll up each strip tightly. Set these rolls on end on the table, and they will carry the small octavo perfectly well. Now the thickness or substance of the paper employed to carry the weight is exactly the same as it was before, only it is differently arranged, that is to say, “gathered up.”[35 - The experiment is not quite fair in this rude fashion; for the small rolls owe their increase of strength much more to their tubular form than their aggregation of material; but if the paper be cut up into small strips, and tied together firmly in three or four compact bundles, it will exhibit increase of strength enough to show the principle. Vide, however, Appendix 16 (#x15_x_15_i32), “Strength of Shafts.”] If therefore a wall be gathered up like the Bristol board, it will bear greater weight than it would if it remained a wall veil. The sticks into which you gather it are called Piers. A pier is a coagulated wall.

§ II. Now you cannot quite treat the wall as you did the Bristol board, and twist it up at once; but let us see how you can treat it. Let A, Fig. IX. (#x3_x_3_i94), be the plan of a wall which you have made inconveniently and expensively thick, and which still appears to be slightly too weak for what it must carry: divide it, as at B, into equal spaces, a, b, a, b, &c. Cut out a thin slice of it at every a on each side, and put the slices you cut out on at every b on each side, and you will have the plan at B, with exactly the same quantity of bricks. But your wall is now so much concentrated, that, if it was only slightly too weak before, it will be stronger now than it need be; so you may spare some of your space as well as your bricks by cutting off the corners of the thicker parts, as suppose c, c, c, c, at C: and you have now a series of square piers connected by a wall veil, which, on less space and with less materials, will do the work of the wall at A perfectly well.

Fig. IX.

§ III. I do not say how much may be cut away in the corners c, c,—that is a mathematical question with which we need not trouble ourselves: all that we need know is, that out of every slice we take from the “b‘s” and put on at the “a’s,” we may keep a certain percentage of room and bricks, until, supposing that we do not want the wall veil for its own sake, this latter is thinned entirely away, like the girdle of the Lady of Avenel, and finally breaks, and we have nothing but a row of square piers, D.

§ IV. But have we yet arrived at the form which will spare most room, and use fewest materials. No; and to get farther we must apply the general principle to our wall, which is equally true in morals and mathematics, that the strength of materials, or of men, or of minds, is always most available when it is applied as closely as possible to a single point.

Let the point to which we wish the strength of our square piers to be applied, be chosen. Then we shall of course put them directly under it, and the point will be in their centre. But now some of their materials are not so near or close to this point as others. Those at the corners are farther off than the rest.

Now, if every particle of the pier be brought as near as possible to the centre of it, the form it assumes is the circle.

The circle must be, therefore, the best possible form of plan for a pier, from the beginning of time to the end of it. A circular pier is called a pillar or column, and all good architecture adapted to vertical support is made up of pillars, has always been so, and must ever be so, as long as the laws of the universe hold.

The final condition is represented at E, in its relation to that at D. It will be observed that though each circle projects a little beyond the side of the square out of which it is formed, the space cut off at the angles is greater than that added at the sides; for, having our materials in a more concentrated arrangement, we can afford to part with some of them in this last transformation, as in all the rest.

§ V. And now, what have the base and the cornice of the wall been doing while we have been cutting the veil to pieces and gathering it together?

The base is also cut to pieces, gathered together, and becomes the base of the column.

The cornice is cut to pieces, gathered together, and becomes the capital of the column. Do not be alarmed at the new word, it does not mean a new thing; a capital is only the cornice of a column, and you may, if you like, call a cornice the capital of a wall.

We have now, therefore, to examine these three concentrated forms of the base, veil, and cornice: first, the concentrated base, still called the Base of the column; then the concentrated veil, called the Shaft of the column; then the concentrated cornice, called the Capital of the column.

And first the Base:—

Fig. X.

§ VI. Look back to the main type, Fig. II. (#x3_x_3_i38), page 55, and apply its profiles in due proportion to the feet of the pillars at E in Fig. IX. (#x3_x_3_i94)p. 72 (#x3_x_3_i92): If each step in Fig. II. (#x3_x_3_i38) were gathered accurately, the projection of the entire circular base would be less in proportion to its height than it is in Fig. II. (#x3_x_3_i38); but the approximation to the result in Fig. X. (#x3_x_3_i108) is quite accurate enough for our purposes. (I pray the reader to observe that I have not made the smallest change, except this necessary expression of a reduction in diameter, in Fig. II. (#x3_x_3_i38) as it is applied in Fig. X. (#x3_x_3_i108), only I have not drawn the joints of the stones because these would confuse the outlines of the bases; and I have not represented the rounding of the shafts, because it does not bear at present on the argument.) Now it would hardly be convenient, if we had to pass between the pillars, to have to squeeze ourselves through one of those angular gaps or brêches de Roland in Fig. X. (#x3_x_3_i108) Our first impulse would be to cut them open; but we cannot do this, or our piers are unsafe. We have but one other resource, to fill them up until we have a floor wide enough to let us pass easily: this we may perhaps obtain at the first ledge, we are nearly sure to get it at the second, and we may then obtain access to the raised interval, either by raising the earth over the lower courses of foundation, or by steps round the entire building.

Fig. XI. (#x3_x_3_i112) is the arrangement of Fig. X. (#x3_x_3_i108) so treated.

Fig. XI.

§ VII. But suppose the pillars are so vast that the lowest chink in Fig. X. (#x3_x_3_i108) would be quite wide enough to let us pass through it. Is there then any reason for filling it up? Yes. It will be remembered that in Chap. IV. (#x3_pgepubid00025) § VIII. the chief reason for the wide foundation of the wall was stated to be “that it might equalise its pressure over a large surface;” but when the foundation is cut to pieces as in Fig. X. (#x3_x_3_i108), the pressure is thrown on a succession of narrowed and detached spaces of that surface. If the ground is in some places more disposed to yield than in others, the piers in those places will sink more than the rest, and this distortion of the system will be probably of more importance in pillars than in a wall, because the adjustment of the weight above is more delicate; we thus actually want the weight of the stones between the pillars, in order that the whole foundation may be bonded into one, and sink together if it sink at all: and the more massy the pillars, the more we shall need to fill the intervals of their foundations. In the best form of Greek architecture, the intervals are filled up to the root of the shaft, and the columns have no independent base; they stand on the even floor of their foundation.

§ VIII. Such a structure is not only admissible, but, when the column is of great thickness in proportion to its height, and the sufficient firmness, either of the ground or prepared floor, is evident, it is the best of all, having a strange dignity in its excessive simplicity. It is, or ought to be, connected in our minds with the deep meaning of primeval memorial. “And Jacob took the stone that he had put for his pillow, and set it up for a pillar.” I do not fancy that he put a base for it first. If you try to put a base to the rock-piers of Stonehenge, you will hardly find them improved; and two of the most perfect buildings in the world, the Parthenon and Ducal palace of Venice, have no bases to their pillars: the latter has them, indeed, to its upper arcade shafts; and had once, it is said, a continuous raised base for its lower ones: but successive elevations of St. Mark’s Place have covered this base, and parts of the shafts themselves, with an inundation of paving stones; and yet the building is, I doubt not, as grand as ever. Finally, the two most noble pillars in Venice, those brought from Acre, stand on the smooth marble surface of the Piazzetta, with no independent bases whatever. They are rather broken away beneath, so that you may look under parts of them, and stand (not quite erect, but leaning somewhat) safe by their own massy weight. Nor could any bases possibly be devised that would not spoil them.

§ IX. But it is otherwise if the pillar be so slender as to look doubtfully balanced. It would indeed stand quite as safely without an independent base as it would with one (at least, unless the base be in the form of a socket). But it will not appear so safe to the eye. And here for the first time, I have to express and apply a principle, which I believe the reader will at once grant,—that features necessary to express security to the imagination, are often as essential parts of good architecture as those required for security itself. It was said that the wall base was the foot or paw of the wall. Exactly in the same way, and with clearer analogy, the pier base is the foot or paw of the pier. Let us, then, take a hint from nature. A foot has two offices, to bear up, and to hold firm. As far as it has to bear up, it is uncloven, with slight projection,—look at an elephant’s (the Doric base of animality);[36 - Appendix 17 (#x15_x_15_i35), “Answer to Mr. Garbett.”] but as far as it has to hold firm, it is divided and clawed, with wide projections,—look at an eagle’s.

§ X. Now observe. In proportion to the massiness of the column, we require its foot to express merely the power of bearing up; in fact, it can do without a foot, like the Squire in Chevy Chase, if the ground only be hard enough. But if the column be slender, and look as if it might lose its balance, we require it to look as if it had hold of the ground, or the ground hold of it, it does not matter which,—some expression of claw, prop, or socket. Now let us go back to Fig. XI. (#x3_x_3_i112), and take up one of the bases there, in the state in which we left it. We may leave out the two lower steps (with which we have nothing more to do, as they have become the united floor or foundation of the whole), and, for the sake of greater clearness, I shall not draw the bricks in the shaft, nor the flat stone which carries them, though the reader is to suppose them remaining as drawn in Fig. XI. (#x3_x_3_i112); but I shall only draw the shaft and its two essential members of base, Xb and Yb, as explained at p. 65 (#x3_x_3_i66), above: and now, expressing the rounding of these numbers on a somewhat larger scale, we have the profile a, Fig. XII. (#x3_x_3_i119); b, the perspective appearance of such a base seen from above; and c, the plan of it.

§ XI. Now I am quite sure the reader is not satisfied of the stability of this form as it is seen at b; nor would he ever be so with the main contour of a circular base. Observe, we have taken some trouble to reduce the member Yb into this round form, and all that we have gained by so doing, is this unsatisfactory and unstable look of the base; of which the chief reason is, that a circle, unless enclosed by right lines, has never an appearance of fixture, or definite place,[37 - Yet more so than any other figure enclosed by a curved line: for the circle, in its relations to its own centre, is the curve of greatest stability. Compare § XX. of Chap. XX. (#x8_pgepubid00041)]—we suspect it of motion, like an orb of heaven; and the second is, that the whole base, considered as the foot of the shaft, has no grasp nor hold: it is a club-foot, and looks too blunt for the limb,—it wants at least expansion, if not division.

Fig. XII.

§ XII. Suppose, then, instead of taking so much trouble with the member Yb, we save time and labor, and leave it a square block. Xb must, however, evidently follow the pillar, as its condition is that it slope to the very base of the wall veil, and of whatever the wall veil becomes. So the corners of Yb will project beyond the circle of Xb, and we shall have (Fig. XII. (#x3_x_3_i119)) the profile d, the perspective appearance e, and the plan f. I am quite sure the reader likes e much better than he did b. The circle is now placed, and we are not afraid of its rolling away. The foot has greater expansion, and we have saved labor besides, with little loss of space, for the interval between the bases is just as great as it was before,—we have only filled up the corners of the squares.

But is it not possible to mend the form still further? There is surely still an appearance of separation between Xb and Yb, as if the one might slip off the other. The foot is expanded enough; but it needs some expression of grasp as well. It has no toes. Suppose we were to put a spur or prop to Xb at each corner, so as to hold it fast in the centre of Yb. We will do this in the simplest possible form. We will have the spur, or small buttress, sloping straight from the corner of Yb up to the top of Xb, and as seen from above, of the shape of a triangle. Applying such spurs in Fig. XII. (#x3_x_3_i119), we have the diagonal profile at g, the perspective h, and the plan i.

§ XIII. I am quite sure the reader likes this last base the best, and feels as if it were the firmest. But he must carefully distinguish between this feeling or imagination of the eye, and the real stability of the structure. That this real stability has been slightly increased by the changes between b and h, in Fig. XII. (#x3_x_3_i119), is true. There is in the base h somewhat less chance of accidental dislocation, and somewhat greater solidity and weight. But this very slight gain of security is of no importance whatever when compared with the general requirements of the structure. The pillar must be perfectly secure, and more than secure, with the base b, or the building will be unsafe, whatever other base you put to the pillar. The changes are made, not for the sake of the almost inappreciable increase of security they involve, but in order to convince the eye of the real security which the base bappears to compromise. This is especially the case with regard to the props or spurs, which are absolutely useless in reality, but are of the highest importance as an expression of safety. And this will farther appear when we observe that they have been above quite arbitrarily supposed to be of a triangular form. Why triangular? Why should not the spur be made wider and stronger, so as to occupy the whole width of the angle of the square, and to become a complete expansion of Xb to the edge of the square? Simply because, whatever its width, it has, in reality, no supporting power whatever; and the expression of support is greatest where it assumes a form approximating to that of the spur or claw of an animal. We shall, however, find hereafter, that it ought indeed to be much wider than it is in Fig. XII. (#x3_x_3_i119), where it is narrowed in order to make its structure clearly intelligible.

§ XIV. If the reader chooses to consider this spur as an æsthetic feature altogether, he is at liberty to do so, and to transfer what we have here said of it to the beginning of Chap. XXV. (#x10_pgepubid00046) I think that its true place is here, as an expression of safety, and not a means of beauty; but I will assume only, as established, the form e of Fig. XII. (#x3_x_3_i119), which is absolutely, as a construction, easier, stronger, and more perfect than b. A word or two now of its materials. The wall base, it will be remembered, was built of stones more neatly cut as they were higher in place; and the members, Y and X, of the pier base, were the highest members of the wall base gathered. But, exactly in proportion to this gathering or concentration in form, should, if possible, be the gathering or concentration of substance. For as the whole weight of the building is now to rest upon few and limited spaces, it is of the greater importance that it should be there received by solid masonry. Xb and Yb are therefore, if possible, to be each of a single stone; or, when the shaft is small, both cut out of one block, and especially if spurs are to be added to Xb. The reader must not be angry with me for stating things so self-evident, for these are all necessary steps in the chain of argument which I must not break. Even this change from detached stones to a single block is not without significance; for it is part of the real service and value of the member Yb to provide for the reception of the shaft a surface free from joints; and the eye always conceives it as a firm covering over all inequalities or fissures in the smaller masonry of the floor.

§ XV. I have said nothing yet of the proportion of the height of Yb to its width, nor of that of Yb and Xb to each other. Both depend much on the height of shaft, and are besides variable within certain limits, at the architect’s discretion. But the limits of the height of Yb may be thus generally stated. If it looks so thin as that the weight of the column above might break it, it is too low; and if it is higher than its own width, it is too high. The utmost admissible height is that of a cubic block; for if it ever become higher than it is wide, it becomes itself a part of a pier, and not the base of one.

§ XVI. I have also supposed Yb, when expanded from beneath Xb, as always expanded into a square, and four spurs only to be added at the angles. But Yb may be expanded into a pentagon, hexagon, or polygon; and Xb then may have five, six, or many spurs. In proportion, however, as the sides increase in number, the spurs become shorter and less energetic in their effect, and the square is in most cases the best form.

§ XVII. We have hitherto conducted the argument entirely on the supposition of the pillars being numerous, and in a range. Suppose, however, that we require only a single pillar: as we have free space round it, there is no need to fill up the first ranges of its foundations; nor need we do so in order to equalise pressure, since the pressure to be met is its own alone. Under such circumstances, it is well to exhibit the lower tiers of the foundation as well as Yb and Xb. The noble bases of the two granite pillars of the Piazzetta at Venice are formed by the entire series of members given in Fig. X. (#x3_x_3_i108), the lower courses expanding into steps, with a superb breadth of proportion to the shaft. The member Xb is of course circular, having its proper decorative mouldings, not here considered; Yb is octagonal, but filled up into a square by certain curious groups of figures representing the trades of Venice. The three courses below are octagonal, with their sides set across the angles of the innermost octagon, Yb. The shafts are 15 feet in circumference, and the lowest octagons of the base 56 (7 feet each side).

§ XVIII. Detached buildings, like our own Monument, are not pillars, but towers built in imitation of Pillars. As towers they are barbarous, being dark, inconvenient, and unsafe, besides lying, and pretending to be what they are not. As shafts they are barbarous, because they were designed at a time when the Renaissance architects had introduced and forced into acceptance, as de rigueur, a kind of columnar high-heeled shoe,—a thing which they called a pedestal, and which is to a true base exactly what a Greek actor’s cothurnus was to a Greek gentleman’s sandal. But the Greek actor knew better, I believe, than to exhibit or to decorate his cork sole; and, with shafts as with heroes, it is rather better to put the sandal off than the cothurnus on. There are, indeed, occasions on which a pedestal may be necessary; it may be better to raise a shaft from a sudden depression of plinth to a level with others, its companions, by means of a pedestal, than to introduce a higher shaft; or it may be better to place a shaft of alabaster, if otherwise too short for our purpose, on a pedestal, than to use a larger shaft of coarser material; but the pedestal is in each case a make-shift, not an additional perfection. It may, in the like manner, be sometimes convenient for men to walk on stilts, but not to keep their stilts on as ornamental parts of dress. The bases of the Nelson Column, the Monument, and the column of the Place Vendôme, are to the shafts, exactly what highly ornamented wooden legs would be to human beings.

§ XIX. So far of bases of detached shafts. As we do not yet know in what manner shafts are likely to be grouped, we can say nothing of those of grouped shafts until we know more of what they are to support.

Lastly; we have throughout our reasoning upon the base supposed the pier to be circular. But circumstances may occur to prevent its being reduced to this form, and it may remain square or rectangular; its base will then be simply the wall base following its contour, and we have no spurs at the angles. Thus much may serve respecting pier bases; we have next to examine the concentration of the Wall Veil, or the Shaft.

CHAPTER VIII.

THE SHAFT

§ I. We have seen in the last Chapter how, in converting the wall into the square or cylindrical shaft, we parted at every change of form with some quantity of material. In proportion to the quantity thus surrendered, is the necessity that what we retain should be good of its kind, and well set together, since everything now depends on it.

It is clear also that the best material, and the closest concentration, is that of the natural crystalline rocks; and that, by having reduced our wall into the shape of shafts, we may be enabled to avail ourselves of this better material, and to exchange cemented bricks for crystallised blocks of stone. Therefore, the general idea of a perfect shaft is that of a single stone hewn into a form more or less elongated and cylindrical. Under this form, or at least under the ruder one of a long stone set upright, the conception of true shafts appears first to have occurred to the human mind; for the reader must note this carefully, once for all, it does not in the least follow that the order of architectural features which is most reasonable in their arrangement, is most probable in their invention. I have theoretically deduced shafts from walls, but shafts were never so reasoned out in architectural practice. The man who first propped a thatched roof with poles was the discoverer of their principle; and he who first hewed a long stone into a cylinder, the perfecter of their practice.

§ II. It is clearly necessary that shafts of this kind (we will call them, for convenience, block shafts) should be composed of stone not liable to flaws or fissures; and therefore that we must no longer continue our argument as if it were always possible to do what is to be done in the best way; for the style of a national architecture may evidently depend, in great measure, upon the nature of the rocks of the country.

Our own English rocks, which supply excellent building stone from their thin and easily divisible beds, are for the most part entirely incapable of being worked into shafts of any size, except only the granites and whinstones, whose hardness renders them intractable for ordinary purposes;—and English architecture therefore supplies no instances of the block shaft applied on an extensive scale; while the facility of obtaining large masses of marble has in Greece and Italy been partly the cause of the adoption of certain noble types of architectural form peculiar to those countries, or, when occurring elsewhere, derived from them.

We have not, however, in reducing our walls to shafts, calculated on the probabilities of our obtaining better materials than those of which the walls were built; and we shall therefore first consider the form of shaft which will be best when we have the best materials; and then consider how far we can imitate, or how far it will be wise to imitate, this form with any materials we can obtain.

§ III. Now as I gave the reader the ground, and the stones, that he might for himself find out how to build his wall, I shall give him the block of marble, and the chisel, that he may himself find out how to shape his column. Let him suppose the elongated mass, so given him, rudely hewn to the thickness which he has calculated will be proportioned to the weight it has to carry. The conditions of stability will require that some allowance be made in finishing it for any chance of slight disturbance or subsidence of the ground below, and that, as everything must depend on the uprightness of the shaft, as little chance should be left as possible of its being thrown off its balance. It will therefore be prudent to leave it slightly thicker at the base than at the top. This excess of diameter at the base being determined, the reader is to ask himself how most easily and simply to smooth the column from one extremity to the other. To cut it into a true straight-sided cone would be a matter of much trouble and nicety, and would incur the continual risk of chipping into it too deep. Why not leave some room for a chance stroke, work it slightly, very slightly convex, and smooth the curve by the eye between the two extremities? you will save much trouble and time, and the shaft will be all the stronger.

Fig. XIII.

This is accordingly the natural form of a detached block shaft. It is the best. No other will ever be so agreeable to the mind or eye. I do not mean that it is not capable of more refined execution, or of the application of some of the laws of æsthetic beauty, but that it is the best recipient of execution and subject of law; better in either case than if you had taken more pains, and cut it straight.

§ IV. You will observe, however, that the convexity is to be very slight, and that the shaft is not to bulge in the centre, but to taper from the root in a curved line; the peculiar character of the curve you will discern better by exaggerating, in a diagram, the conditions of its sculpture.