V
Abriefintroduction to the history of bridges has so many difficulties that I creep through my work, a few hundred words in a long day. To try to plant an oak tree in a thimble would be more difficult, I suppose, but gleaning here and there over vast fields brings trouble enough to any writer. I go through scores of photographs, and turn over great piles of notes, and seek for a topic that is not too technical for the general reader, but that touches a really important phase in the evolution of bridge-building. There is a species of bridge to which the arches at Laroque belong; it may be called either freakish or very exceptional. Let me give a few examples.
There is one at Crowland, a curious three-branched structure which for many a year stood at the confluence of the Catwater drain and two streamlets, the Welland and the Nyne. To-day no water flows under this bridge, and common little modern houses do not make pretty pictures when they are framed by the arches. There are three pointed arches, with their abutments at the angles of an equilateral triangle; they meet in the middle, and form three roadways and three watercourses. They have three stone ribs apiece, and the nine ribs meet in the centreI note, too, that these arches were built not by a bridgeman, but by a mason skilled in church work, for their rings are moulded elaborately as in Gothic windows and doorways. As for the style of architecture, it is not older than the beginning of the fourteenth century; but a much earlier bridge at Crowland, probably of wood, was famed for its triangular shape, and mentioned in a charter of the year 943, when Edmund was King.
At the south-west entrance of Crowland Bridge, beyond the five steps, there is a rough-hewn statue that represents a crowned and bearded figure seated up high against the parapet walls, in an attitude of sorrow, with arms folded (and perhaps they may be bound together) over a long robe. Time has frayed and scarred this uncouth sculpture, but not without leaving some mellow lines and planes. The archæology of guesswork has called this effigy by various names, such as Ethelbald, and Saint Guthlac, and HenryII, but I prefer to look upon it as a simple Pietà chiselled by a mason who had been trained to do enniched figures for church decoration—work without detail, to make at a distance a broad effect. This conjecture is in accord with the ecclesiastical moulding of the archstones, and with the mediæval custom that united bridges to Christianity by means of sacred emblems. Crowland Abbey ruled over the district, so one of the Abbots may have built the bridge; and perhaps the pointed arches, three in number, with their triple ribs, and their three pathways, and the three streams of water, may have been intended as symbols of the Trinity.If so,—and there is nothing in this view to clash with the spirit of the Mediæval Church,—then a Pietà turned toward the west would be the most beautiful symbol of that Light which went down with the sun, and then rose again through the dark into the dusk, and through the dusk into a dawn where faith for ever dwells. On the other hand, if the crowned figure represents a mere earthly king, I know not why Ethelbald should be chosen, for his reign of two years was not a creative time and he died in 860, just eighty-three years before Crowland’s triangular bridge was alluded to in the charter of the year 943. Alfred, Edward the Elder, and Athelstan—these kings in succession were nearer to the charter, and their longer reigns were more notable than the short hours of Ethelbald. Alfred we should prefer, of course, but he has been passed over by the busy minds that have weaved around Crowland Bridge so many cobwebs of the study and so much haze of idle conjecture. My own views are conjectures also, but they are taken partly from the bridge itself and partly from the care and affection that the Church during the Middle Ages bestowed on bridge-building.
And now a technical matter ought to be considered in its bearing on the arches of Crowland Bridge. At a time when bridges were protected by the Church, their arches were affected by changes of style in ecclesiastical windows and doorways; but, of course, whatever shape was given to them, they were treated differently from doorways and windows, for these had to bear only a downwardthrust, while bridges had to withstand five trials: their own “spring,” the vibration caused by wheeled traffic, the lateral pressure of flowing water, the disturbance of gravity by immersion, and blows from drifting ice and timber. With these problems to be solved, bridgemen set no store by moulded archstones, a kickshaw of style. Sometimes they built the ring of an arch with two or three sets of voussoirs,[128]but their aim was practical, not ornamental; they wished to give greater resistance to their work, and not merely to spend time and money on a decorative effect. So when we find in the arches of Crowland Bridge such moulded handicraft as was used in church decoration, we may surmise that the architect and his masons were not bridge-builders, and that they worked only for the light foot-traffic of a village.
It is worth noting that in the year 1752 a French architect named Beffara took a hint from Crowland Bridge, and then achieved fame with a daring structure built near Ardres, in the Pas-de-Calais. There are four branches tothis bridge, and they carry roads over two canals that intersect at right angles. One canal goes from Saint-Ouen to Calais and the other from Ardres to Gravelines. Beffara’s work is placed by Larousse among the fifty-four most notable bridges in the world, and this honour it seems to merit; but Frenchmen in their vanity have tried to make it into a pretentious bridge by giving to it a braggart name—Le Sans-Pareil. Gracious! It is fit for a café or for a battleship, in whose nomenclature bravado and bombast rule as customs. Poor Beffara! “Le Sans-Pareil,” like “Titanic” or like “Dreadnought,” defies the powers of Nature, inviting them to do their worst; and what good omen can there be in such bantam cockiness?
For a long time the old bridge at Bâle, over the Rhine, remarkable for its length and for its beautiful site, was not only freakish but exceedingly insolent. At one end, on the side of greater Bâle, was a tower decorated with a grotesque head called Laellenkoenig, which, in answer to the working of a clock, put out its tongue and rolled insulting eyes at the opposite bank. Eight or ten times an hour this abusive pantomime was repeated, and it never failed to anger little Bâle, which had the pugnacious vanity of a small organism. I do not know how many duels were fought, but at last a touch of Rabelaisian humour suggested a mechanical revenge, far more regular in its action than were fights and punctured bodies. A tall post was set up by the inhabitants of Bâle junior, and on the top of it stood a hateful statuethat affected to turn its back on the enemy with a shameless movement.
It is risky at the present time to say that a bridge has certain old characters: change is so rapid that no pontist can keep in touch with its vagaries; but I believe the old bridge at Bâle is alive, and that it keeps in use the Gothic tower, a triangular defence of red sandstone erected on the middle pier, and devoted now to a thermometer, a barometer, and a table of weights and measures. Laellenkoenig has gone, of course, and Bâle junior has grown much bigger and less techy.
The Bridge of Sighs, at Venice, must be included among the exceptional bridges, being equally celebrated in history and in art. Who can say how many times she has been etched and painted and engraved? She is not very important as a work of architecture, yet artists are drawn towards her invariably, and seldom do they fail to make her impressive. Brangwyn loves the Bridge of Sighs, and does her much more than justice in one of his finest etchings. There is something trivial in her Renaissance ornament, and her proportions are not great, being only two metres wide and six high; on the other hand, her abutments are famous buildings, the ducal palace and the State prison. It is from the second storey of the palace that we enter the gloom of her covered passage, concerning which a Frenchman writes as follows: “On pourrait presque le comparer, en agrandissant les proportions, à nos fourgons d’armée.”
It is said that only a prisoner here and there went overthis bridge more than once—in his compulsory walk from a dungeon in the prison to the Council of the Ten. Those who awaited their trial in the dungeons were looked upon as already condemned; their appearance before the Ten was a formality, at least in public opinion; and for this reason the dark corridor across the canal was called the Bridge of Sighs.
Among the bridges of the fourteenth century there are two that history has set down as very exceptional. One of them is a covered bridge over the Ticino at Pavia, erected under the care of Gian Galeazzo Visconti. Professor Fleeming Jenkin says of it: “This bridge, which still exists, has seven pointed brick arches, each 70ft.in span and 64ft.in height; the depth of the arch ring at the crown is 5ft.6in.The tympanum is pierced; the bricks used in the arches are formed to suit their position, and are hollow in the middle to diminish the weight. The roof of the roadway is carried by a hundred rough granite columns.”
This neat description is accurate, but in it the bridge is not visualised. Would that we had a Brangwyn sketch! I have by my side an engraving of the bridge, and the effect of the design is that of an open-work frieze. Each gracefully pointed arch is a repetition of the other six; the piers also are uniform and graceful, being all 16ft.3in.wide; and all the spandrils are pierced in the same triangular fashion. The point of each triangle is turned downwards, its sides are the inner surfaces of two archrings, and its base, turned upwards, and gracefully arched with seventeen long bricks, helps to support the parapet. On this parapet at equal intervals rise the hundred granite columns by which the covered roadway is carried. So the design is a clever feat not merely of repetitive decoration, but of repeating solids and voids that oppose each other in a harmony of contrasts; for the empty spandrils in their form oppose the leaf-shaped openings made by the arches, and all the curved solids of the bridge are foiled in a rugged manner by the upright columns, as well as by the long horizontal lines of the covered roadway. In the contrast between cold granite and warm brick there is colour also, and it suits the pulsating light and heat of Italy.
As for the second bridge of the fourteenth century, which architects regard as very uncommon, it exists in drawings only, for it was destroyed by Carmagnola. Its founder was a duke of Milan, Bernabò Visconti, and it crossed the Adda at Trezzo. According to Hann and Hosking, it had “a single arch of granite, very well constructed of stones in two courses, the innermost 3¼ft.thick in the direction of the radius, the outermost 9in., the span at low water 251ft.; the river rises sometimes 13ft.” The radius of the arch was 133ft.A span of 251ft.in a stone bridge was a noble achievement. It is the largest that I remember. The Grosvenor Bridge at Chester has a span of 200ft., just thirty yards wider than the central arch of Trajan’s Bridge over the Tagus. New London Bridge in her finest arch attains a span of 152ft., beating WaterlooBridge by nearly eleven yards. Two French bridges of the eighteenth century—the Pont de Lavaur and the Pont de Gignac—have spans of 160ft.; and let me refer you also to the Pont de Neuilly-sur-Seine (p.338).
Many uncommon bridges have been attributed to the Chinese, and I know not what to say about some of them. Let me quote from Marco Polo, giving also the excellent notes written by his editor Colonel Yule. In the twenty-seventh chapter of his travels Marco Polo speaks “of the river named Pulisangan, and of the bridge over it.” This river, whose name is written variously, is believed to be the Hoen-ho of the Jesuits’ map, which, uniting with another stream from the north-west, forms the Pe-ho or White River. When Marco Polo comes to the Pulisangan[129]he finds “a very handsome bridge of stone, perhaps unequalled by another in the world.” “Its length is three hundred paces, and its width eight paces; so that ten men can ride abreast without inconvenience.[130]It has twenty-four arches, supported by twenty-five piers erected in the water, all of serpentine stone, and built with great skill.On each side, and from one extremity to the other, there is a handsome parapet, formed of marble slabs and pillars arranged in a masterly style. At the commencement of the ascent the bridge is something wider than at the summit, but from the part where the ascent terminates, the sides run in straight lines and parallel to each other.[131]Upon the upper level there is a massive and lofty column, resting upon a tortoise of marble, and having near its base a large figure of a lion, with a lion also on the top.[132]Towards the slope of the bridge there is another handsome column or pillar, with its lion, at the distance of a pace and a half from the former; and all the spaces between one pillar and another, throughout the whole length of the bridge, are filled up with slabs of marble, curiously sculptured, and mortised into the next adjoining pillars, which are, in like manner, a pace and a half asunder, and equally surmounted with lions,[133]forming altogether a beautiful spectacle. Theseparapets serve to prevent accidents, that might otherwise happen to passengers. What has been said applies to the descent as well as to the ascent of thebridge.”[134]
I do not understand why this description is considered very difficult to understand. It depicts a gabled bridge with a flat top, not an uncommon form of bridge in China, I believe. The footway ascends to the beginning of the middle arch, where it becomes flat and level; it continues so for the full width of the arch, and then it descends toward the abutment across the river. With this picture in mind it is easy to decorate the bridge over the Pulisangan, or Hoen-ho, with the accessories described by Marco Polo. The parapets have coping stones of sculptured marble, and pillars are carefully set along the parapets at an equal distance from each other. These pillars are of two sorts. Those above the flat part of the roadway, where the parapets also are horizontal, are tall and massive. On each side, at the brow of the ascent, there is a tall pillar upon the summit of which is astone lion; and in the middle of each parapet, on this level part of the road, there is a taller and heavier column, whose pedestal is a marble tortoise, and whose summit carries a symbolic lion. Another lion is placed near the tortoise, perhaps on a ledge of stone corbelled out from the parapet. As for the parapets that slope up from the abutments to the point where they become level, or horizontal, they, too, have their emblematic lions carried by pillars, and these ornaments, in accordance with the logic of design, are much smaller than those on the summit of the steep bridge. For the rest, Marco Polo speaks of twenty-four arches and of twenty-five piers; and if we give to the arches an average span of fifty-two feet, and to the piers an average width of thirteen feet, we get a bridge 1573ft.long, or seventy-three feet longer than the five hundred yards suggested by Colonel Yule. Viewed in this way, apart from the vague glamour of enthusiastic words, there is nothing extravagant in Marco Polo’s description.
Many writers have been astonished by another Chinese bridge, called the Bridge of Cho-gan, in the province of Shen-si. Its great arch is said to have had an unrivalled span. I am told that it was built with huge blocks of stone, cut into voussoirs, the joints of which converged towards a common centre, as in our own bridges. This may be true, though in photographs of Chinese bridges which I have seen the voussoirs do not resemble ours; not only are they much longer, they are much narrower also, and recall to my memory a good description written by Barrow, whoseimpressions of China are invaluable to students. Barrow speaks of archstones from five to ten feet long, and says that each stone “is cut so as to form a segment of the arch.” “There is no keystone” when an arch is built in this manner. Again, “ribs of wood fitted to the convexity of the arch are bolted through the stones by iron bars, fixed in the solid part of the bridge”; sometimes no wood is employed, and then “the curved stones are mortised into long transverse blocks of stone.” It would be ridiculous to speak of this technical method as one that employs voussoirs, since the arch ring is built with a few segmental stones and without a keystone; and possibly the Bridge of Cho-gan was constructed in this fashion. A drawing of it is given in Kircher’s“La Chine Illustrée”—or, rather, in Dalquié’s translation of Kircher’s book, published in 1670 at Amsterdam. It is not a geometrical drawing, and the dimensions are given in Chinese measures, which do not help us to love Kircher and Dalquié. M. Degrand is baffled by these measures;[135]but he admits that the Bridge of Cho-gan must have been a grandiose structure dating from a very remote time.
Gauthey speaks with admiration of the“Pont de Fo-Cheu sur le Min”—a bridge not less than 7935 metres long by 19 metres 50 wide, with a hundred arches, all semicircular, and thirty-nine metres in their average span. The piers were nearly as broad, and their height was thirty-nine metres. Here is a bridge that Dean Swift ought to haveput into his pictures of Brobdingnag. Gauthey seems to have faith in it, while M. Degrand has doubts. He says: “Even if we admit that there is no flagrant exaggeration in the documents from which the account of this bridge is taken, the workmanship in its general character, as shown in the drawing given by Gauthey, has a near resemblance to that in Roman bridges, and ought not to be assigned to a period earlier than theirs.” Gauthey describes the decorative treatment. Under the parapet of white marble ran a line of consoles; the piers were surmounted by figures of lions in black marble, cut from blocks seven metres long; and above each twentieth arch the footway was guarded by a gateway,un arc de triomphe.
For the rest, as I wanted to learn something more about this bridge of a hundred vast arches over the Min at Fo-Cheu, I wrote to theRev.O. M. Jackson, whose kind help I have already acknowledged (p.248). There is a river Min in Sichuan, but no news of such a bridge has reached Mr. Jackson, though he has worked in Western China for more than twenty years, and has travelled on foot over a very wide area in the province of Sichuan. Again, Mr. Jackson does not recognise the spelling “Fo-Cheu,” but refers me to the city of Fu Chow in the coast province of Fukien. One day, perhaps, research will bring me in touch with the colossal masterpiece described by Gauthey, though at present I am baffled by the variety of geographical names that travellers have given to the bridges of China. Still, the Chinese have been greatbridge-builders, and some of their stone arches have been very high and very wide. Perhaps the one described by Kircher may have been as wide as Trezzo Bridge, over the Adda, with its wonderful span of 251 feet.
My favourite bridge in the class of exceptional merit is the Ponte della Trinità over the Arno at Florence, designed in 1566 by the architect of the Pitti Palace, Bartolomeo Ammanati, a devoted admirer of Michelangelo. Both in science and in art the Ponte della Trinità is complete as an original success. Its vaulting—I ought to sayhisvaulting, for in this bridge the male qualities of genius are much stronger than the female—his vaulting, then, if not the most scientific in the world, is not excelled by any other work either ancient or modern. There are three arches, and their curves are cycloids; the rise from the springing level is only a trifle more than one-sixth of the span. How Ammanati managed to get his effect of perfect balance and symmetry is a question very hard to answer, for there is a considerable difference between the width of his arches, the central one being 96ft.in span, and the others 86ft.and 88ft.This fact has been established by measured drawings, but do you notice it out of doors, in the magic of this beautiful bridge? The piers are simple and excellent. Their width, twenty-six feet, is not too much for the spates of a freakish river, nor too heavy for the bridge as a linear composition; on the upstream side they have stern cutwaters, good foils in a piece of architecture that blends an alert grace with a supple vigour. Another point worthnoting is the gradient of a roadway that starts out from low abutments. Ammanati was bent upon being a friend to the traffic of Florence, and with the help of his cycloid arches he kept the road on a mild curve. To-day this good point attracts little attention, as most of us forget that steep bridges were in vogue till late in the eighteenth century.
A Victorian pontist, William Hosking, endeavoured to prove that Ammanati made one mistake in the Ponte della Trinità. It seemed to Hosking that the piers were too bulky, so he cut them down in a sketch and spoilt the whole bridge by altering the proportions. Architects told him so, but Hosking crowed over his little sketch and published it with pride, as you will find by turning to his “Architectural Treatise on Bridge Building”—a valuable work from other standpoints.