Читать книгу The Stones of Venice - John Ruskin - Страница 20

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§ I. We have now, in order, examined the means of raising walls and sustaining roofs, and we have finally to consider the structure of the necessary apertures in the wall veil, the door and window; respecting which there are three main points to be considered.

1. The form of the aperture, i.e., its outline, its size, and the forms of its sides.

2. The filling of the aperture, i.e., valves and glass, and their holdings.

3. The protection of the aperture, and its appliances, i.e., canopies, porches, and balconies. We shall examine these in succession.

§ II. 1. The form of the aperture: and first of doors. We will, for the present, leave out of the question doors and gates in unroofed walls, the forms of these being very arbitrary, and confine ourselves to the consideration of doors of entrance into roofed buildings. Such doors will, for the most part, be at, or near, the base of the building; except when raised for purposes of defence, as in the old Scotch border towers, and our own Martello towers, or, as in Switzerland, to permit access in deep snow, or when stairs are carried up outside the house for convenience or magnificence. But in most cases, whether high or low, a door may be assumed to be considerably lower than the apartments or buildings into which it gives admission, and therefore to have some height of wall above it, whose weight must be carried by the heading of the door. It is clear, therefore, that the best heading must be an arch, because the strongest, and that a square-headed door must be wrong, unless under Mont-Cenisian masonry; or else, unless the top of the door be the roof of the building, as in low cottages. And a square-headed door is just so much more wrong and ugly than a connexion of main shafts by lintels, as the weight of wall above the door is likely to be greater than that above the main shafts. Thus, while I admit the Greek general forms of temple to be admirable in their kind, I think the Greek door always offensive and unmanageable.

§ III. We have it also determined by necessity, that the apertures shall be at least above a man’s height, with perpendicular sides (for sloping sides are evidently unnecessary, and even inconvenient, therefore absurd) and level threshold; and this aperture we at present suppose simply cut through the wall without any bevelling of the jambs. Such a door, wide enough for two persons to pass each other easily, and with such fillings or valves as we may hereafter find expedient, may be fit enough for any building into which entrance is required neither often, nor by many persons at a time. But when entrance and egress are constant, or required by crowds, certain further modifications must take place.

Fig. XLIII

§ IV. When entrance and egress are constant, it may be supposed that the valves will be absent or unfastened—that people will be passing more quickly than when the entrance and egress are unfrequent, and that the square angles of the wall will be inconvenient to such quick passers through. It is evident, therefore, that what would be done in time, for themselves, by the passing multitude, should be done for them at once by the architect; and that these angles, which would be worn away by friction, should at once be bevelled off, or, as it is called, splayed, and the most contracted part of the aperture made as short as possible, so that the plan of the entrance should become as at a, Fig. XLIII.

§ V. Farther. As persons on the outside may often approach the door or depart from it, beside the building, so as to turn aside as they enter or leave the door, and therefore touch its jamb, but, on the inside, will in almost every case approach the door, or depart from it in the direct line of the entrance (people generally walking forward when they enter a hall, court, or chamber of any kind, and being forced to do so when they enter a passage), it is evident that the bevelling may be very slight on the inside, but should be large on the outside, so that the plan of the aperture should become as at b, Fig. XLIII. Farther, as the bevelled wall cannot conveniently carry an unbevelled arch, the door arch must be bevelled also, and the aperture, seen from the outside, will have somewhat the aspect of a small cavern diminishing towards the interior.

§ VI. If, however, beside frequent entrance, entrance is required for multitudes at the same time, the size of the aperture either must be increased, or other apertures must be introduced. It may, in some buildings, be optional with the architect whether he shall give many small doors, or few large ones; and in some, as theatres, amphitheatres, and other places where the crowd are apt to be impatient, many doors are by far the best arrangement of the two. Often, however, the purposes of the building, as when it is to be entered by processions, or where the crowd most usually enter in one direction, require the large single entrance; and (for here again the æsthetic and structural laws cannot be separated) the expression and harmony of the building require, in nearly every case, an entrance of largeness proportioned to the multitude which is to meet within. Nothing is more unseemly than that a great multitude should find its way out and in, as ants and wasps do, through holes; and nothing more undignified than the paltry doors of many of our English cathedrals, which look as if they were made, not for the open egress, but for the surreptitious drainage of a stagnant congregation. Besides, the expression of the church door should lead us, as far as possible, to desire at least the western entrance to be single, partly because no man of right feeling would willingly lose the idea of unity and fellowship in going up to worship, which is suggested by the vast single entrance; partly because it is at the entrance that the most serious words of the building are always addressed, by its sculptures or inscriptions, to the worshipper; and it is well, that these words should be spoken to all at once, as by one great voice, not broken up into weak repetitions over minor doors.

In practice the matter has been, I suppose, regulated almost altogether by convenience, the western doors being single in small churches, while in the larger the entrances become three or five, the central door remaining always principal, in consequence of the fine sense of composition which the mediæval builders never lost. These arrangements have formed the noblest buildings in the world. Yet it is worth observing55 how perfect in its simplicity the single entrance may become, when it is treated as in the Duomo and St. Zeno of Verona, and other such early Lombard churches, having noble porches, and rich sculptures grouped around the entrance.

§ VII. However, whether the entrances be single, triple, or manifold, it is a constant law that one shall be principal, and all shall be of size in some degree proportioned to that of the building. And this size is, of course, chiefly to be expressed in width, that being the only useful dimension in a door (except for pageantry, chairing of bishops and waving of banners, and other such vanities, not, I hope, after this century, much to be regarded in the building of Christian temples); but though the width is the only necessary dimension, it is well to increase the height also in some proportion to it, in order that there may be less weight of wall above, resting on the increased span of the arch. This is, however, so much the necessary result of the broad curve of the arch itself, that there is no structural necessity of elevating the jamb; and I believe that beautiful entrances might be made of every span of arch, retaining the jamb at a little more than a man’s height, until the sweep of the curves became so vast that the small vertical line became a part of them, and one entered into the temple as under a great rainbow.

§ VIII. On the other hand, the jamb may be elevated indefinitely, so that the increasing entrance retains at least the proportion of width it had originally; say 4 ft. by 7 ft. 5 in. But a less proportion of width than this has always a meagre, inhospitable, and ungainly look except in military architecture, where the narrowness of the entrance is necessary, and its height adds to its grandeur, as between the entrance towers of our British castles. This law however, observe, applies only to true doors, not to the arches of porches, which may be of any proportion, as of any number, being in fact intercolumniations, not doors; as in the noble example of the west front of Peterborough, which, in spite of the destructive absurdity of its central arch being the narrowest, would still, if the paltry porter’s lodge, or gatehouse, or turnpike, or whatever it is, were knocked out of the middle of it, be the noblest west front in England.

§ IX. Further, and finally. In proportion to the height and size of the building, and therefore to the size of its doors, will be the thickness of its walls, especially at the foundation, that is to say, beside the doors; and also in proportion to the numbers of a crowd will be the unruliness and pressure of it. Hence, partly in necessity and partly in prudence, the splaying or chamfering of the jamb of the larger door will be deepened, and, if possible, made at a larger angle for the large door than for the small one; so that the large door will always be encompassed by a visible breadth of jamb proportioned to its own magnitude. The decorative value of this feature we shall see hereafter.

§ 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.

55 And worth questioning, also, whether the triple porch has not been associated with Romanist views of mediatorship; the Redeemer being represented as presiding over the central door only, and the lateral entrances being under the protection of saints, while the Madonna almost always has one or both of the transepts. But it would be wrong to press this, for, in nine cases out of ten, the architect has been merely influenced in his placing of the statues by an artist’s desire of variety in their forms and dress; and very naturally prefers putting a canonisation over one door, a martyrdom over another, and an assumption over a third, to repeating a crucifixion or a judgment above all. The architect’s doctrine is only, therefore, to be noted with indisputable reprobation when the Madonna gets possession of the main door.

56 The arch heading is indeed the best where there is much incumbent weight, but a window frequently has very little weight above it, especially when placed high, and the arched form loses light in a low room: therefore the square-headed window is admissible where the square-headed door is not.

57 I do not like the sound of the word “splayed;” I always shall use “bevelled” instead.