The Stones of Venice, Volume 1 (of 3)

§ X. The second kind of apertures we have to examine are those of windows.

Window apertures are mainly of two kinds; those for outlook, and those for inlet of light, many being for both purposes, and either purpose, or both, combined in military architecture with those of offence and defence. But all window apertures, as compared with door apertures, have almost infinite licence of form and size: they may be of any shape, from the slit or cross slit to the circle;56 of any size, from the loophole of the castle to the pillars of light of the cathedral apse. Yet, according to their place and purpose, one or two laws of fitness hold respecting them, which let us examine in the two classes of windows successively, but without reference to military architecture, which here, as before, we may dismiss as a subject of separate science, only noticing that windows, like all other features, are always delightful, if not beautiful, when their position and shape have indeed been thus necessarily determined, and that many of their most picturesque forms have resulted from the requirements of war. We should also find in military architecture the typical forms of the two classes of outlet and inlet windows in their utmost development; the greatest sweep of sight and range of shot on the one hand, and the fullest entry of light and air on the other, being constantly required at the smallest possible apertures. Our business, however, is to reason out the laws for ourselves, not to take the examples as we find them.

§ XI. 1. Outlook apertures. For these no general outline is determinable by the necessities or inconveniences of outlooking, except only that the bottom or sill of the windows, at whatever height, should be horizontal, for the convenience of leaning on it, or standing on it if the window be to the ground. The form of the upper part of the window is quite immaterial, for all windows allow a greater range of sight when they are approached than that of the eye itself: it is the approachability of the window, that is to say, the annihilation of the thickness of the wall, which is the real point to be attended to. If, therefore, the aperture be inaccessible, or so small that the thickness of the wall cannot be entered, the wall is to be bevelled57 on the outside, so as to increase the range of sight as far as possible; if the aperture can be entered, then bevelled from the point to which entrance is possible. The bevelling will, if possible, be in every direction, that is to say, upwards at the top, outwards at the sides, and downwards at the bottom, but essentially downwards; the earth and the doings upon it being the chief object in outlook windows, except of observatories; and where the object is a distinct and special view downwards, it will be of advantage to shelter the eye as far as possible from the rays of light coming from above, and the head of the window may be left horizontal, or even the whole aperture sloped outwards, as the slit in a letter-box is inwards.

The best windows for outlook are, of course, oriels and bow windows, but these are not to be considered under the head of apertures merely; they are either balconies roofed and glazed, and to be considered under the head of external appliances, or they are each a story of an external semi-tower, having true aperture windows on each side of it.

§ XII. 2. Inlet windows. These windows may, of course, be of any shape and size whatever, according to the other necessities of the building, and the quantity and direction of light desired, their purpose being now to throw it in streams on particular lines or spots; now to diffuse it everywhere; sometimes to introduce it in broad masses, tempered in strength, as in the cathedral colored window; sometimes in starry showers of scattered brilliancy, like the apertures in the roof of an Arabian bath; perhaps the most beautiful of all forms being the rose, which has in it the unity of both characters, and sympathy with that of the source of light itself. It is noticeable, however, that while both the circle and pointed oval are beautiful window forms, it would be very painful to cut either of them in half and connect them by vertical lines, as in Fig. XLIV. The reason is, I believe, that so treated, the upper arch is not considered as connected with the lower, and forming an entire figure, but as the ordinary arch roof of the aperture, and the lower arch as an arch floor, equally unnecessary and unnatural. Also, the elliptical oval is generally an unsatisfactory form, because it gives the idea of useless trouble in building it, though it occurs quaintly and pleasantly in the former windows of France: I believe it is also objectionable because it has an indeterminate, slippery look, like that of a bubble rising through a fluid. It, and all elongated forms, are still more objectionable placed horizontally, because this is the weakest position they can structurally have; that is to say, less light is admitted, with greater loss of strength to the building, than by any other form. If admissible anywhere, it is for the sake of variety at the top of the building, as the flat parallelogram sometimes not ungracefully in Italian Renaissance.

Fig. XLIV.

§ XIII. The question of bevelling becomes a little more complicated in the inlet than the outlook window, because the mass or quantity of light admitted is often of more consequence than its direction, and often vice versâ; and the outlook window is supposed to be approachable, which is far from being always the case with windows for light, so that the bevelling which in the outlook window is chiefly to open range of sight, is in the inlet a means not only of admitting the light in greater quantity, but of directing it to the spot on which it is to fall. But, in general, the bevelling of the one window will reverse that of the other; for, first, no natural light will strike on the inlet window from beneath, unless reflected light, which is (I believe) injurious to the health and the sight; and thus, while in the outlook window the outside bevel downwards is essential, in the inlet it would be useless: and the sill is to be flat, if the window be on a level with the spot it is to light; and sloped downwards within, if above it. Again, as the brightest rays of light are the steepest, the outside bevel upwards is as essential in the roof of the inlet as it was of small importance in that of the outlook window.

§ XIV. On the horizontal section the aperture will expand internally, a somewhat larger number of rays being thus reflected from the jambs; and the aperture being thus the smallest possible outside, this is the favorite military form of inlet window, always found in magnificent development in the thick walls of mediæval castles and convents. Its effect is tranquil, but cheerless and dungeon-like in its fullest development, owing to the limitation of the range of sight in the outlook, which, if the window be unapproachable, reduces it to a mere point of light. A modified condition of it, with some combination of the outlook form, is probably the best for domestic buildings in general (which, however, in modern architecture, are unhappily so thin walled, that the outline of the jambs becomes a matter almost of indifference), it being generally noticeable that the depth of recess which I have observed to be essential to nobility of external effect has also a certain dignity of expression, as appearing to be intended rather to admit light to persons quietly occupied in their homes, than to stimulate or favor the curiosity of idleness.

CHAPTER XVII.

FILLING OF APERTURE

§ I. Thus far we have been concerned with the outline only of the aperture: we were next, it will be remembered, to consider the necessary modes of filling it with valves in the case of the door, or with glass or tracery in that of the window.

1. Fillings of doors. We concluded, in the previous Chapter, that doors in buildings of any importance or size should have headings in the form of an arch. This is, however, the most inconvenient form we could choose, as respects the fitting of the valves of the doorway; for the arch-shaped head of the valves not only requires considerable nicety in fitting to the arch, but adds largely to the weight of the door,—a double disadvantage, straining the hinges and making it cumbersome in opening. And this inconvenience is so much perceived by the eye, that a door valve with a pointed head is always a disagreeable object. It becomes, therefore, a matter of true necessity so to arrange the doorway as to admit of its being fitted with rectangular valves.

§ II. Now, in determining the form of the aperture, we supposed the jamb of the door to be of the utmost height required for entrance. The extra height of the arch is unnecessary as an opening, the arch being required for its strength only, not for its elevation. There is, therefore, no reason why it should not be barred across by a horizontal lintel, into which the valves may be fitted, and the triangular or semicircular arched space above the lintel may then be permanently closed, as we choose, either with bars, or glass, or stone.

This is the form of all good doors, without exception, over the whole world and in all ages, and no other can ever be invented.

§ III. In the simplest doors the cross lintel is of wood only, and glass or bars occupy the space above, a very frequent form in Venice. In more elaborate doors the cross lintel is of stone, and the filling sometimes of brick, sometimes of stone, very often a grand single stone being used to close the entire space: the space thus filled is called the Tympanum. In large doors the cross lintel is too long to bear the great incumbent weight of this stone filling without support; it is, therefore, carried by a pier in the centre; and two valves are used, fitted to the rectangular spaces on each side of the pier. In the most elaborate examples of this condition, each of these secondary doorways has an arch heading, a cross lintel, and a triangular filling or tympanum of its own, all subordinated to the main arch above.

§ IV. 2. Fillings of windows.

When windows are large, and to be filled with glass, the sheet of glass, however constructed, whether of large panes or small fragments, requires the support of bars of some kind, either of wood, metal, or stone. Wood is inapplicable on a large scale, owing to its destructibility; very fit for door-valves, which can be easily refitted, and in which weight would be an inconvenience, but very unfit for window-bars, which, if they decayed, might let the whole window be blown in before their decay was observed, and in which weight would be an advantage, as offering more resistance to the wind.

Iron is, however, fit for window-bars, and there seems no constructive reason why we should not have iron traceries, as well as iron pillars, iron churches, and iron steeples. But I have, in the “Seven Lamps,” given reasons for not considering such structures as architecture at all.

The window-bars must, therefore, be of stone, and of stone only.

§ V. The purpose of the window being always to let in as much light, and command as much view, as possible, these bars of stone are to be made as slender and as few as they can be, consistently with their due strength.

Fig. XLV.

Let it be required to support the breadth of glass, a, b, Fig. XLV. The tendency of the glass sustaining any force, as of wind from without, is to bend into an arch inwards, in the dotted line, and break in the centre. It is to be supported, therefore, by the bar put in its centre, c.

But this central bar, c, may not be enough, and the spaces a c, c b, may still need support. The next step will be to put two bars instead of one, and divide the window into three spaces as at d.

But this may still not be enough, and the window may need three bars. Now the greatest stress is always on the centre of the window. If the three bars are equal in strength, as at e, the central bar is either too slight for its work, or the lateral bars too thick for theirs. Therefore, we must slightly increase the thickness of the central bar, and diminish that of the lateral ones, so as to obtain the arrangement at f h. If the window enlarge farther, each of the spaces f g, g h, is treated as the original space a b, and we have the groups of bars k and l.

So that, whatever the shape of the window, whatever the direction and number of the bars, there are to be central or main bars; second bars subordinated to them; third bars subordinated to the second, and so on to the number required. This is called the subordination of tracery, a system delightful to the eye and mind, owing to its anatomical framing and unity, and to its expression of the laws of good government in all fragile and unstable things. All tracery, therefore, which is not subordinated, is barbarous, in so far as this part of its structure is concerned.

§ VI. The next question will be the direction of the bars. The reader will understand at once, without any laborious proof, that a given area of glass, supported by its edges, is stronger in its resistance to violence when it is arranged in a long strip or band than in a square; and that, therefore, glass is generally to be arranged, especially in windows on a large scale, in oblong areas: and if the bars so dividing it be placed horizontally, they will have less power of supporting themselves, and will need to be thicker in consequence, than if placed vertically. As far, therefore, as the form of the window permits, they are to be vertical.

§ VII. But even when so placed, they cannot be trusted to support themselves beyond a certain height, but will need cross bars to steady them. Cross bars of stone are, therefore, to be introduced at necessary intervals, not to divide the glass, but to support the upright stone bars. The glass is always to be divided longitudinally as far as possible, and the upright bars which divide it supported at proper intervals. However high the window, it is almost impossible that it should require more than two cross bars.

§ VIII. It may sometimes happen that when tall windows are placed very close to each other for the sake of more light, the masonry between them may stand in need, or at least be the better of, some additional support. The cross bars of the windows may then be thickened, in order to bond the intermediate piers more strongly together, and if this thickness appear ungainly, it may be modified by decoration.

§ IX. We have thus arrived at the idea of a vertical frame work of subordinated bars, supported by cross bars at the necessary intervals, and the only remaining question is the method of insertion into the aperture. Whatever its form, if we merely let the ends of the bars into the voussoirs of its heading, the least settlement of the masonry would distort the arch, or push up some of its voussoirs, or break the window bars, or push them aside. Evidently our object should be to connect the window bars among themselves, so framing them together that they may give the utmost possible degree of support to the whole window head in case of any settlement. But we know how to do this already: our window bars are nothing but small shafts. Capital them; throw small arches across between the smaller bars, large arches over them between the larger bars, one comprehensive arch over the whole, or else a horizontal lintel, if the window have a flat head; and we have a complete system of mutual support, independent of the aperture head, and yet assisting to sustain it, if need be. But we want the spandrils of this arch system to be themselves as light, and to let as much light through them, as possible: and we know already how to pierce them (Chap. XII. § VII.). We pierce them with circles; and we have, if the circles are small and the stonework strong, the traceries of Giotto and the Pisan school; if the circles are as large as possible and the bars slender, those which I have already figured and described as the only perfect traceries of the Northern Gothic.58 The varieties of their design arise partly from the different size of window and consequent number of bars; partly from the different heights of their pointed arches, as well as the various positions of the window head in relation to the roof, rendering one or another arrangement better for dividing the light, and partly from æsthetic and expressional requirements, which, within certain limits, may be allowed a very important influence: for the strength of the bars is ordinarily so much greater than is absolutely necessary, that some portion of it may be gracefully sacrificed to the attainment of variety in the plans of tracery—a variety which, even within its severest limits, is perfectly endless; more especially in the pointed arch, the proportion of the tracery being in the round arch necessarily more fixed.

§ X. The circular window furnishes an exception to the common law, that the bars shall be vertical through the greater part of their length: for if they were so, they could neither have secure perpendicular footing, nor secure heading, their thrust being perpendicular to the curve of the voussoirs only in the centre of the window; therefore, a small circle, like the axle of a wheel, is put into the centre of the window, large enough to give footing to the necessary number of radiating bars; and the bars are arranged as spokes, being all of course properly capitaled and arch-headed. This is the best form of tracery for circular windows, naturally enough called wheel windows when so filled.

§ XI. Now, I wish the reader especially to observe that we have arrived at these forms of perfect Gothic tracery without the smallest reference to any practice of any school, or to any law of authority whatever. They are forms having essentially nothing whatever to do either with Goths or Greeks. They are eternal forms, based on laws of gravity and cohesion; and no better, nor any others so good, will ever be invented, so long as the present laws of gravity and cohesion subsist.

§ XII. It does not at all follow that this group of forms owes its origin to any such course of reasoning as that which has now led us to it. On the contrary, there is not the smallest doubt that tracery began, partly, in the grouping of windows together (subsequently enclosed within a large arch59), and partly in the fantastic penetrations of a single slab of stones under the arch, as the circle in Plate V. above. The perfect form seems to have been accidentally struck in passing from experiment on the one side, to affectation on the other; and it was so far from ever becoming systematised, that I am aware of no type of tracery for which a less decided preference is shown in the buildings in which it exists. The early pierced traceries are multitudinous and perfect in their kind,—the late Flamboyant, luxuriant in detail, and lavish in quantity,—but the perfect forms exist in comparatively few churches, generally in portions of the church only, and are always connected, and that closely, either with the massy forms out of which they have emerged, or with the enervated types into which they are instantly to degenerate.

§ XIII. Nor indeed are we to look upon them as in all points superior to the more ancient examples. We have above conducted our reasoning entirely on the supposition that a single aperture is given, which it is the object to fill with glass, diminishing the power of the light as little as possible. But there are many cases, as in triforium and cloister lights, in which glazing is not required; in which, therefore, the bars, if there be any, must have some more important function than that of merely holding glass, and in which their actual use is to give steadiness and tone, as it were, to the arches and walls above and beside them; or to give the idea of protection to those who pass along the triforium, and of seclusion to those who walk in the cloister. Much thicker shafts, and more massy arches, may be properly employed in work of this kind; and many groups of such tracery will be found resolvable into true colonnades, with the arches in pairs, or in triple or quadruple groups, and with small rosettes pierced above them for light. All this is just as right in its place, as the glass tracery is in its own function, and often much more grand. But the same indulgence is not to be shown to the affectations which succeeded the developed forms. Of these there are three principal conditions: the Flamboyant of France, the Stump tracery of Germany, and the Perpendicular of England.

§ XIV. Of these the first arose, by the most delicate and natural transitions, out of the perfect school. It was an endeavor to introduce more grace into its lines, and more change into its combinations; and the æsthetic results are so beautiful, that for some time after the right road had been left, the aberration was more to be admired than regretted. The final conditions became fantastic and effeminate, but, in the country where they had been invented, never lost their peculiar grace until they were replaced by the Renaissance. The copies of the school in England and Italy have all its faults and none of its beauties; in France, whatever it lost in method or in majesty, it gained in fantasy: literally Flamboyant, it breathed away its strength into the air; but there is not more difference between the commonest doggrel that ever broke prose into unintelligibility, and the burning mystery of Coleridge, or spirituality of Elizabeth Barrett, than there is between the dissolute dulness of English Flamboyant, and the flaming undulations of the wreathed lines of delicate stone, that confuse themselves with the clouds of every morning sky that brightens above the valley of the Seine.

§ XV. The second group of traceries, the intersectional or German group, may be considered as including the entire range of the absurd forms which were invented in order to display dexterity in stone-cutting and ingenuity in construction. They express the peculiar character of the German mind, which cuts the frame of every truth joint from joint, in order to prove the edge of its instruments; and, in all cases, prefers a new or a strange thought to a good one, and a subtle thought to a useful one. The point and value of the German tracery consists principally in turning the features of good traceries upside down, and cutting them in two where they are properly continuous. To destroy at once foundation and membership, and suspend everything in the air, keeping out of sight, as far as possible, the evidences of a beginning and the probabilities of an end, are the main objects of German architecture, as of modern German divinity.

§ XVI. This school has, however, at least the merit of ingenuity. Not so the English Perpendicular, though a very curious school also in its way. In the course of the reasoning which led us to the determination of the perfect Gothic tracery, we were induced successively to reject certain methods of arrangement as weak, dangerous, or disagreeable. Collect all these together, and practise them at once, and you have the English Perpendicular.

Fig. XLVI.

As thus. You find, in the first place (§ V.), that your tracery bars are to be subordinated, less to greater; so you take a group of, suppose, eight, which you make all exactly equal, giving you nine equal spaces in the window, as at A, Fig. XLVI. You found, in the second place (§ VII.), that there was no occasion for more than two cross bars; so you take at least four or five (also represented at A, Fig. XLVI.), also carefully equalised, and set at equal spaces. You found, in the third place (§ VIII.), that these bars were to be strengthened, in order to support the main piers; you will therefore cut the ends off the uppermost, and the fourth into three pieces (as also at A). In the fourth place, you found (§ IX.) that you were never to run a vertical bar into the arch head; so you run them all into it (as at B, Fig. XLVI.); and this last arrangement will be useful in two ways, for it will not only expose both the bars and the archivolt to an apparent probability of every species of dislocation at any moment, but it will provide you with two pleasing interstices at the flanks, in the shape of carving-knives, a, b, which, by throwing across the curves c, d, you may easily multiply into four; and these, as you can put nothing into their sharp tops, will afford you a more than usually rational excuse for a little bit of Germanism, in filling them with arches upside down, e, f. You will now have left at your disposal two and forty similar interstices, which, for the sake of variety, you will proceed to fill with two and forty similar arches: and, as you were told that the moment a bar received an arch heading, it was to be treated as a shaft and capitalled, you will take care to give your bars no capitals nor bases, but to run bars, foliations and all, well into each other after the fashion of cast-iron, as at C. You have still two triangular spaces occurring in an important part of your window, g g, which, as they are very conspicuous, and you cannot make them uglier than they are, you will do wisely to let alone;—and you will now have the west window of the cathedral of Winchester, a very perfect example of English Perpendicular. Nor do I think that you can, on the whole, better the arrangement, unless, perhaps, by adding buttresses to some of the bars, as is done in the cathedral at Gloucester; these buttresses having the double advantage of darkening the window when seen from within, and suggesting, when it is seen from without, the idea of its being divided by two stout party walls, with a heavy thrust against the glass.