CHAPTER XII.
THE ARCH LOAD
Fig. XXXV.
§ I. In the preceding enquiry we have always supposed either that the load upon the arch was perfectly loose, as of gravel or sand, or that it was Mont-Cenisian, and formed one mass with the arch voussoirs, of more or less compactness.
In practice, the state is usually something between the two. Over bridges and tunnels it sometimes approaches to the condition of mere dust or yielding earth; but in architecture it is mostly firm masonry, not altogether acting with the voussoirs, yet by no means bearing on them with perfectly dead weight, but locking itself together above them, and capable of being thrown into forms which relieve them, in some degree, from its pressure.
§ II. It is evident that if we are to place a continuous roof above the line of arches, we must fill up the intervals between them on the tops of the columns. We have at present nothing granted us but the bare masonry, as here at a, Fig. XXXV., and we must fill up the intervals between the semicircle so as to obtain a level line of support. We may first do this simply as at b, with plain mass of wall; so laying the roof on the top, which is the method of the pure Byzantine and Italian Romanesque. But if we find too much stress is thus laid on the arches, we may introduce small second shafts on the top of the great shaft, a, Fig. XXXVI., which may assist in carrying the roof, conveying great part of its weight at once to the heads of the main shafts, and relieving from its pressure the centres of the arches.
Fig. XXXVI.
§ III. The new shaft thus introduced may either remain lifted on the head of the great shaft, or may be carried to the ground in front of it, or through it, b, Fig. XXXVI.; in which latter case the main shaft divides into two or more minor shafts, and forms a group with the shaft brought down from above.
§ IV. When this shaft, brought from roof to ground, is subordinate to the main pier, and either is carried down the face of it, or forms no large part of the group, the principle is Romanesque or Gothic, b, Fig. XXXVI. When it becomes a bold central shaft, and the main pier splits into two minor shafts on its sides, the principle is Classical or Palladian, c, Fig. XXXVI. Which latter arrangement becomes absurd or unsatisfactory in proportion to the sufficiency of the main shaft to carry the roof without the help of the minor shafts or arch, which in many instances of Palladian work look as if they might be removed without danger to the building.
§ V. The form a is a more pure Northern Gothic type than even b, which is the connecting link between it and the classical type. It is found chiefly in English and other northern Gothic, and in early Lombardic, and is, I doubt not, derived as above explained, Chap. I. § XXVII. b is a general French Gothic and French Romanesque form, as in great purity at Valence.
The small shafts of the form a and b, as being northern, are generally connected with steep vaulted roofs, and receive for that reason the name of vaulting shafts.
§ VI. Of these forms b, Fig. XXXV., is the purest and most sublime, expressing the power of the arch most distinctly. All the others have some appearance of dovetailing and morticing of timber rather than stonework; nor have I ever yet seen a single instance, quite satisfactory, of the management of the capital of the main shaft, when it had either to sustain the base of the vaulting shaft, as in a, or to suffer it to pass through it, as in b, Fig. XXXVI. Nor is the bracket which frequently carries the vaulting shaft in English work a fitting support for a portion of the fabric which is at all events presumed to carry a considerable part of the weight of the roof.
§ VII. The triangular spaces on the flanks of the arch are called Spandrils, and if the masonry of these should be found, in any of its forms, too heavy for the arch, their weight may be diminished, while their strength remains the same, by piercing them with circular holes or lights. This is rarely necessary in ordinary architecture, though sometimes of great use in bridges and iron roofs (a succession of such circles may be seen, for instance, in the spandrils at the Euston Square station); but, from its constructional value, it becomes the best form in which to arrange spandril decorations, as we shall see hereafter.
§ VIII. The height of the load above the arch is determined by the needs of the building and possible length of the shaft; but with this we have at present nothing to do, for we have performed the task which was set us. We have ascertained, as it was required that we should in § VI. of Chap. III. (A), the construction of walls; (B), that of piers; (C), that of piers with lintels or arches prepared for roofing. We have next, therefore, to examine (D) the structure of the roof.
CHAPTER XIII.
THE ROOF
§ I. Hitherto our enquiry has been unembarrassed by any considerations relating exclusively either to the exterior or interior of buildings. But it can remain so no longer. As far as the architect is concerned, one side of a wall is generally the same as another; but in the roof there are usually two distinct divisions of the structure; one, a shell, vault, or flat ceiling, internally visible, the other, an upper structure, built of timber, to protect the lower; or of some different form, to support it. Sometimes, indeed, the internally visible structure is the real roof, and sometimes there are more than two divisions, as in St. Paul’s, where we have a central shell with a mask below and above. Still it will be convenient to remember the distinction between the part of the roof which is usually visible from within, and whose only business is to stand strongly, and not fall in, which I shall call the Roof Proper; and, secondly, the upper roof, which, being often partly supported by the lower, is not so much concerned with its own stability as with the weather, and is appointed to throw off snow, and get rid of rain, as fast as possible, which I shall call the Roof Mask.
§ II. It is, however, needless for me to engage the reader in the discussion of the various methods of construction of Roofs Proper, for this simple reason, that no person without long experience can tell whether a roof be wisely constructed or not; nor tell at all, even with help of any amount of experience, without examination of the several parts and bearings of it, very different from any observation possible to the general critic: and more than this, the enquiry would be useless to us in our Venetian studies, where the roofs are either not contemporary with the buildings, or flat, or else vaults of the simplest possible constructions, which have been admirably explained by Willis in his “Architecture of the Middle Ages,” Chap. VII., to which I may refer the reader for all that it would be well for him to know respecting the connexion of the different parts of the vault with the shafts. He would also do well to read the passages on Tudor vaulting, pp. 185-193, in Mr. Garbett’s rudimentary Treatise on Design, before alluded to.50 I shall content myself therefore with noting one or two points on which neither writer has had occasion to touch, respecting the Roof Mask.
§ III. It was said in § V. of Chapter III. that we should not have occasion, in speaking of roof construction, to add materially to the forms then suggested. The forms which we have to add are only those resulting from the other curves of the arch developed in the last chapter; that is to say, the various eastern domes and cupolas arising out of the revolution of the horseshoe and ogee curves, together with the well-known Chinese concave roof. All these forms are of course purely decorative, the bulging outline, or concave surface, being of no more use, or rather of less, in throwing off snow or rain, than the ordinary spire and gable; and it is rather curious, therefore, that all of them, on a small scale, should have obtained so extensive use in Germany and Switzerland, their native climate being that of the east, where their purpose seems rather to concentrate light upon their orbed surfaces. I much doubt their applicability, on a large scale, to architecture of any admirable dignity; their chief charm is, to the European eye, that of strangeness; and it seems to me possible that in the east the bulging form may be also delightful, from the idea of its enclosing a volume of cool air. I enjoy them in St. Mark’s, chiefly because they increase the fantastic and unreal character of St. Mark’s Place; and because they appear to sympathise with an expression, common, I think, to all the buildings of that group, of a natural buoyancy, as if they floated in the air or on the surface of the sea. But, assuredly, they are not features to be recommended for imitation.51
Fig. XXXVII.
§ IV. One form, closely connected with the Chinese concave, is, however, often constructively right,—the gable with an inward angle, occurring with exquisitely picturesque effect throughout the domestic architecture of the north, especially Germany and Switzerland; the lower slope being either an attached external penthouse roof, for protection of the wall, as in Fig. XXXVII., or else a kind of buttress set on the angle of the tower; and in either case the roof itself being a simple gable, continuous beneath it.
§ V. The true gable, as it is the simplest and most natural, so I esteem it the grandest of roofs; whether rising in ridgy darkness, like a grey slope of slaty mountains, over the precipitous walls of the northern cathedrals, or stretched in burning breadth above the white and square-set groups of the southern architecture. But this difference between its slope in the northern and southern structure is a matter of far greater importance than is commonly supposed, and it is this to which I would especially direct the reader’s attention.
§ VI. One main cause of it, the necessity of throwing off snow in the north, has been a thousand times alluded to: another I do not remember having seen noticed, namely, that rooms in a roof are comfortably habitable in the north, which are painful sotto piombi in Italy; and that there is in wet climates a natural tendency in all men to live as high as possible, out of the damp and mist. These two causes, together with accessible quantities of good timber, have induced in the north a general steep pitch of gable, which, when rounded or squared above a tower, becomes a spire or turret; and this feature, worked out with elaborate decoration, is the key-note of the whole system of aspiration, so called, which the German critics have so ingeniously and falsely ascribed to a devotional sentiment pervading the Northern Gothic: I entirely and boldly deny the whole theory; our cathedrals were for the most part built by worldly people, who loved the world, and would have gladly staid in it for ever; whose best hope was the escaping hell, which they thought to do by building cathedrals, but who had very vague conceptions of Heaven in general, and very feeble desires respecting their entrance therein; and the form of the spired cathedral has no more intentional reference to Heaven, as distinguished from the flattened slope of the Greek pediment, than the steep gable of a Norman house has, as distinguished from the flat roof of a Syrian one. We may now, with ingenious pleasure, trace such symbolic characters in the form; we may now use it with such definite meaning; but we only prevent ourselves from all right understanding of history, by attributing much influence to these poetical symbolisms in the formation of a national style. The human race are, for the most part, not to be moved by such silken cords; and the chances of damp in the cellar, or of loose tiles in the roof, have, unhappily, much more to do with the fashions of a man’s house building than his ideas of celestial happiness or angelic virtue. Associations of affection have far higher power, and forms which can be no otherwise accounted for may often be explained by reference to the natural features of the country, or to anything which habit must have rendered familiar, and therefore delightful; but the direct symbolisation of a sentiment is a weak motive with all men, and far more so in the practical minds of the north than among the early Christians, who were assuredly quite as heavenly-minded, when they built basilicas, or cut conchas out of the catacombs, as were ever the Norman barons or monks.
§ VII. There is, however, in the north an animal activity which materially aided the system of building begun in mere utility,—an animal life, naturally expressed in erect work, as the languor of the south in reclining or level work. Imagine the difference between the action of a man urging himself to his work in a snow storm, and the inaction of one laid at his length on a sunny bank among cicadas and fallen olives, and you will have the key to a whole group of sympathies which were forcefully expressed in the architecture of both; remembering always that sleep would be to the one luxury, to the other death.
§ VIII. And to the force of this vital instinct we have farther to add the influence of natural scenery; and chiefly of the groups and wildernesses of the tree which is to the German mind what the olive or palm is to the southern, the spruce fir. The eye which has once been habituated to the continual serration of the pine forest, and to the multiplication of its infinite pinnacles, is not easily offended by the repetition of similar forms, nor easily satisfied by the simplicity of flat or massive outlines. Add to the influence of the pine, that of the poplar, more especially in the valleys of France; but think of the spruce chiefly, and meditate on the difference of feeling with which the Northman would be inspired by the frostwork wreathed upon its glittering point, and the Italian by the dark green depth of sunshine on the broad table of the stone-pine52 (and consider by the way whether the spruce fir be a more heavenly-minded tree than those dark canopies of the Mediterranean isles).
§ IX. Circumstance and sentiment, therefore, aiding each other, the steep roof becomes generally adopted, and delighted in, throughout the north; and then, with the gradual exaggeration with which every pleasant idea is pursued by the human mind, it is raised into all manner of peaks, and points, and ridges; and pinnacle after pinnacle is added on its flanks, and the walls increased in height, in proportion, until we get indeed a very sublime mass, but one which has no more principle of religious aspiration in it than a child’s tower of cards. What is more, the desire to build high is complicated with the peculiar love of the grotesque53 which is characteristic of the north, together with especial delight in multiplication of small forms, as well as in exaggerated points of shade and energy, and a certain degree of consequent insensibility to perfect grace and quiet truthfulness; so that a northern architect could not feel the beauty of the Elgin marbles, and there will always be (in those who have devoted themselves to this particular school) a certain incapacity to taste the finer characters of Greek art, or to understand Titian, Tintoret, or Raphael: whereas among the Italian Gothic workmen, this capacity was never lost, and Nino Pisano and Orcagna could have understood the Theseus in an instant, and would have received from it new life. There can be no question that theirs was the greatest school, and carried out by the greatest men; and that while those who began with this school could perfectly well feel Rouen Cathedral, those who study the Northern Gothic remain in a narrowed field—one of small pinnacles, and dots, and crockets, and twitched faces—and cannot comprehend the meaning of a broad surface or a grand line. Nevertheless the northern school is an admirable and delightful thing, but a lower thing than the southern. The Gothic of the Ducal Palace of Venice is in harmony with all that is grand in all the world: that of the north is in harmony with the grotesque northern spirit only.
§ X. We are, however, beginning to lose sight of our roof structure in its spirit, and must return to our text. As the height of the walls increased, in sympathy with the rise of the roof, while their thickness remained the same, it became more and more necessary to support them by buttresses; but—and this is another point that the reader must specially note—it is not the steep roof mask which requires the buttress, but the vaulting beneath it; the roof mask being a mere wooden frame tied together by cross timbers, and in small buildings often put together on the ground, raised afterwards, and set on the walls like a hat, bearing vertically upon them; and farther, I believe in most cases the northern vaulting requires its great array of external buttress, not so much from any peculiar boldness in its own forms, as from the greater comparative thinness and height of the walls, and more determined throwing of the whole weight of the roof on particular points. Now the connexion of the interior frame-work (or true roof) with the buttress, at such points, is not visible to the spectators from without; but the relation of the roof mask to the top of the wall which it protects, or from which it springs, is perfectly visible; and it is a point of so great importance in the effect of the building, that it will be well to make it a subject of distinct consideration in the following Chapter.
CHAPTER XIV.
THE ROOF CORNICE
§ I. It will be remembered that in the Sixth Chapter we paused (§ X.) at the point where the addition of brackets to the ordinary wall cornice would have converted it into a structure proper for sustaining a roof. Now the wall cornice was treated throughout our enquiry (compare Chapter VII. § V.) as the capital of the wall, and as forming, by its concentration, the capital of the shaft. But we must not reason back from the capital to the cornice, and suppose that an extension of the principles of the capital to the whole length of the wall, will serve for the roof cornice; for all our conclusions respecting the capital were based on the supposition of its being adapted to carry considerable weight condensed on its abacus: but the roof cornice is, in most cases, required rather to project boldly than to carry weight; and arrangements are therefore to be adopted for it which will secure the projection of large surfaces without being calculated to resist extraordinary pressure. This object is obtained by the use of brackets at intervals, which are the peculiar distinction of the roof cornice.
§ II. Roof cornices are generally to be divided into two great families: the first and simplest, those which are composed merely by the projection of the edge of the roof mask over the wall, sustained by such brackets or spurs as may be necessary; the second, those which provide a walk round the edge of the roof, and which require, therefore, some stronger support, as well as a considerable mass of building above or beside the roof mask, and a parapet. These two families we shall consider in succession.
§ III. 1. The Eaved Cornice. We may give it this name, as represented in the simplest form by cottage eaves. It is used, however, in bold projection, both in north, and south, and east; its use being, in the north, to throw the rain well away from the wall of the building; in the south to give it shade; and it is ordinarily constructed of the ends of the timbers of the roof mask (with their tiles or shingles continued to the edge of the cornice), and sustained by spurs of timber. This is its most picturesque and natural form; not inconsistent with great splendor of architecture in the mediæval Italian domestic buildings, superb in its mass of cast shadow, and giving rich effect to the streets of Swiss towns, even when they have no other claim to interest. A farther value is given to it by its waterspouts, for in order to avoid loading it with weight of water in the gutter at the edge, where it would be a strain on the fastenings of the pipe, it has spouts of discharge at intervals of three or four feet,—rows of magnificent leaden or iron dragons’ heads, full of delightful character, except to any person passing along the middle of the street in a heavy shower. I have had my share of their kindness in my time, but owe them no grudge; on the contrary, much gratitude for the delight of their fantastic outline on the calm blue sky, when they had no work to do but to open their iron mouths and pant in the sunshine.
§ IV. When, however, light is more valuable than shadow, or when the architecture of the wall is too fair to be concealed, it becomes necessary to draw the cornice into narrower limits; a change of considerable importance, in that it permits the gutter, instead of being of lead and hung to the edge of the cornice, to be of stone, and supported by brackets in the wall, these brackets becoming proper recipients of after decoration (and sometimes associated with the stone channels of discharge, called gargoyles, which belong, however, more properly to the other family of cornices). The most perfect and beautiful example of this kind of cornice is the Venetian, in which the rain from the tiles is received in a stone gutter supported by small brackets, delicately moulded, and having its outer lower edge decorated with the English dogtooth moulding, whose sharp zigzag mingles richly with the curved edges of the tiling. I know no cornice more beautiful in its extreme simplicity and serviceableness.
§ V. The cornice of the Greek Doric is a condition of the same kind, in which, however, there are no brackets, but useless appendages hung to the bottom of the gutter (giving, however, some impression of support as seen from a distance), and decorated with stone symbolisms of raindrops. The brackets are not allowed, because they would interfere with the sculpture, which in this architecture is put beneath the cornice; and the overhanging form of the gutter is nothing more than a vast dripstone moulding, to keep the rain from such sculpture: its decoration of guttæ, seen in silver points against the shadow, is pretty in feeling, with a kind of continual refreshment and remembrance of rain in it; but the whole arrangement is awkward and meagre, and is only endurable when the eye is quickly drawn away from it to sculpture.
§ VI. In later cornices, invented for the Greek orders, and farther developed by the Romans, the bracket appears in true importance, though of barbarous and effeminate outline: and gorgeous decorations are applied to it, and to the various horizontal mouldings which it carries, some of them of great beauty, and of the highest value to the mediæval architects who imitated them. But a singularly gross mistake was made in the distribution of decoration on these rich cornices (I do not know when first, nor does it matter to me or to the reader), namely, the charging with ornament the under surface of the cornice between the brackets, that is to say, the exact piece of the whole edifice, from top to bottom, where ornament is least visible. I need hardly say much respecting the wisdom of this procedure, excusable only if the whole building were covered with ornament; but it is curious to see the way in which modern architects have copied it, even when they had little enough ornament to spare. For instance, I suppose few persons look at the Athenæum Club-house without feeling vexed at the meagreness and meanness of the windows of the ground floor: if, however, they look up under the cornice, and have good eyes, they will perceive that the architect has reserved his decorations to put between the brackets; and by going up to the first floor, and out on the gallery, they may succeed in obtaining some glimpses of the designs of the said decorations.
§ VII. Such as they are, or were, these cornices were soon considered essential parts of the “order” to which they belonged; and the same wisdom which endeavored to fix the proportions of the orders, appointed also that no order should go without its cornice. The reader has probably heard of the architectural division of superstructure into architrave, frieze, and cornice; parts which have been appointed by great architects to all their work, in the same spirit in which great rhetoricians have ordained that every speech shall have an exordium, and narration, and peroration. The reader will do well to consider that it may be sometimes just as possible to carry a roof, and get rid of rain, without such an arrangement, as it is to tell a plain fact without an exordium or peroration; but he must very absolutely consider that the architectural peroration or cornice is strictly and sternly limited to the end of the wall’s speech,—that is, to the edge of the roof; and that it has nothing whatever to do with shafts nor the orders of them. And he will then be able fully to enjoy the farther ordinance of the late Roman and Renaissance architects, who, attaching it to the shaft as if it were part of its shadow, and having to employ their shafts often in places where they came not near the roof, forthwith cut the roof-cornice to pieces and attached a bit of it to every column; thenceforward to be carried by the unhappy shaft wherever it went, in addition to any other work on which it might happen to be employed. I do not recollect among any living beings, except Renaissance architects, any instance of a parallel or comparable stupidity: but one can imagine a savage getting hold of a piece of one of our iron wire ropes, with its rings upon it at intervals to bind it together, and pulling the wires asunder to apply them to separate purposes; but imagining there was magic in the ring that bound them, and so cutting that to pieces also, and fastening a little bit of it to every wire.
§ VIII. Thus much may serve us to know respecting the first family of wall cornices. The second is immeasurably more important, and includes the cornices of all the best buildings in the world. It has derived its best form from mediæval military architecture, which imperatively required two things; first, a parapet which should permit sight and offence, and afford defence at the same time; and secondly, a projection bold enough to enable the defenders to rake the bottom of the wall with falling bodies; projection which, if the wall happened to slope inwards, required not to be small. The thoroughly magnificent forms of cornice thus developed by necessity in military buildings, were adopted, with more or less of boldness or distinctness, in domestic architecture, according to the temper of the times and the circumstances of the individual—decisively in the baron’s house, imperfectly in the burgher’s: gradually they found their way into ecclesiastical architecture, under wise modifications in the early cathedrals, with infinite absurdity in the imitations of them; diminishing in size as their original purpose sank into a decorative one, until we find battlements, two-and-a-quarter inches square, decorating the gates of the Philanthropic Society.
§ IX. There are, therefore, two distinct features in all cornices of this kind; first, the bracket, now become of enormous importance and of most serious practical service; the second, the parapet: and these two features we shall consider in succession, and in so doing, shall learn all that is needful for us to know, not only respecting cornices, but respecting brackets in general, and balconies.
Fig. XXXVIII.
§ X. 1. The Bracket. In the simplest form of military cornice, the brackets are composed of two or more long stones, supporting each other in gradually increasing projection, with roughly rounded ends, Fig. XXXVIII., and the parapet is simply a low wall carried on the ends of these, leaving, of course, behind, or within it, a hole between each bracket for the convenient dejection of hot sand and lead. This form is best seen, I think, in the old Scotch castles; it is very grand, but has a giddy look, and one is afraid of the whole thing toppling off the wall. The next step was to deepen the brackets, so as to get them propped against a great depth of the main rampart, and to have the inner ends of the stones held by a greater weight of that main wall above; while small arches were thrown from bracket to bracket to carry the parapet wall more securely. This is the most perfect form of cornice, completely satisfying the eye of its security, giving full protection to the wall, and applicable to all architecture, the interstices between the brackets being filled up, when one does not want to throw boiling lead on any body below, and the projection being always delightful, as giving greater command and view of the building, from its angles, to those walking on the rampart. And as, in military buildings, there were usually towers at the angles (round which the battlements swept) in order to flank the walls, so often in the translation into civil or ecclesiastical architecture, a small turret remained at the angle, or a more bold projection of balcony, to give larger prospect to those upon the rampart. This cornice, perfect in all its parts, as arranged for ecclesiastical architecture, and exquisitely decorated, is the one employed in the duomo of Florence and campanile of Giotto, of which I have already spoken as, I suppose, the most perfect architecture in the world.
§ XI. In less important positions and on smaller edifices, this cornice diminishes in size, while it retains its arrangement, and at last we find nothing but the spirit and form of it left; the real practical purpose having ceased, and arch, brackets and all, being cut out of a single stone. Thus we find it used in early buildings throughout the whole of the north and south of Europe, in forms sufficiently represented by the two examples in Plate IV.: 1, from St. Antonio, Padua; 2, from Sens in France.
Fig. XXXIX.