A book of bridges

by Walter Shaw Sparrow

During the building of this pretty structure an unsuccessful attempt was made to ground the piers while eleven men baled water from the river. Then a dam was built, and trenches were dug to prevent the water from overflowing the dam. This I gather from the ballad, but the wording is not at all graphic in any technical matter.[106] We are not told why cofferdams[107] were not tried. In the Middle Ages cofferdams were known as brandryths or brandereths; by this name they are mentioned in the Contract Deed for the building of Catterick Bridge over the Swale, A.D. 1421; and they were large enough to obstruct most rivers, for they had to surround enormous piers, and the thickness of their sides was never less than from four to six feet. It is interesting to note, in this connection, that during the construction of Old London Bridge, between 1176 and 1209, the Thames “was turned another way about by a trench,” which, according to Stow, began east near “Rotherhithe, as is supposed, and ended in the west about Patricksey, now termed Battersea.” In those days no embankments controlled the Thames at London; wide shores, littered with the odds and ends of a waterside life, were playgrounds for the ebb and flow of the tidal waters; and the main purpose of the “trench” or canal was to lessen the risk of floods while the huge piers were being founded. Stow’s words give us to understand that all the water in the Thames “was turned another way about”; a very important feat of civil engineering. Perhaps the purpose of the canal was not so thorough; perhaps it drew from the river sufficient water to lower its normal level by several feet and to diminish the force of the tidal current. In any case, however, Stow’s evidence has great interest.

One of Brangwyn’s animated drawings, the Pont des Consuls at Montauban, comes in here to illustrate the many troubles of mediæval bridge-building. In 1144, when Montauban passed from an unknown village into a known town, its patron or founder, Alphonse Jourdain, Count of Toulouse, commanded that a bridge should be made at once, and that the little township should keep it in repair; but, somehow, for many generations, nothing was done. Sometimes poverty was pleaded as an excuse, and sometimes the Albigeois wars were blamed; but at last, in 1264, the good men of Montauban ventured on a little action. Indeed, they stretched themselves yawningly, and said that a bridge over the Tarn would be a boon indeed. Their ferry was a slow nuisance, we may presume, and their trade ought to be increased by better communications. For twenty-seven years they repeated these truisms; then, in 1291, they bought the island of Castillons or of Pissotte to serve as a foundation for several piers. Tired by this unwonted exertion, Montauban wished to take a long holiday, but Philip the Fair came forward and asserted himself as a king. A bridge over the Tarn must be built! It should have three fortified towers, one at each end, the other in the middle; and these towers were to be garrisoned by royal troops, so that no harm should happen to the king’s authority. In order to collect money for the bridge-building a tax was to be levied on all visitors to Montauban, and two consuls were to overseer the work. His Majesty chose Mathieu de Verdun, a citizen, and Étienne de Ferrières, who was keeper of the town. They seemed to be honest men, but funds collected for the bridge were used for other purposes, and I know not if this action was justified. It was in 1304 that Philip the Fair gave his instructions, and the bridge was not finished till 1335. Still, the dilatory township had achieved a very fine work of art, noble in design and very well constructed.

It is a brick bridge, 250 m.[108] 50 cm. in length. The bricks are excellent in quality, and measure 50 centimetres in thickness, 40 centimetres in length, and 28 centimetres in width. The roadway is nearly flat, and its height above the level of the Tarn is 18 metres. There are seven pointed arches with an average span of 22 metres; and the six piers armed with cutwaters at both sides are 8 m. 55 cm. in thickness. Note how the spandrils are pierced with high arched bays to facilitate the passage of water during floods. These relief arches were copied from Roman models. As for the defensive towers they exist no longer, but the strongest one kept watch and ward over the entrance across the river; it was square in shape, and its summit was a crenellated platform fringed with machicolations. The other end tower—the one on the town side—was also square in form, while the central defence was triangular. It stood on the middle buttress on the side looking downstream, and the lower part of it was used as a chapel dedicated to St. Catherine. A flight of winding steps went down to a postern, cut through the buttress a little above water-level; and at the other side of the pier, just below the arched bay, was an instrument of torture, a see-saw that carried an iron cage in which blasphemers were ducked in the river.

The Pont des Consuls has one quality that Englishmen ought to study with the greatest care; it is in scale with a great river. To build a vast bridge for a little township was in part a just tribute to the beauty of a noble site, and in part a prophetic compliment paid to the future history of Montauban. How differently we have acted in our London bridges! We have disgraced the Thames with the Railway Viaduct from Charing Cross, for instance, and neither Waterloo nor London Bridge does justice to the size of our Nation-City. There are three or four good bridges on the Thames, notably those at Maidenhead and Richmond, but they are nothing more than delicate works of refined engineering. Not one is inspired by awe, the only feeling that can bring home to our minds the wondrous grey antiquity of the Thames and the immensity of London. So we have feared to be great in the historic symbolism of bridge-building, unlike the citizens of Montauban, who were lifted far above their indolence by a brave inspiration as ample as was the Tarn after a flood.

LE PONT DES CONSULS OVER THE TARN AT MONTAUBAN IN FRANCE, FOURTEENTH CENTURY

In 1823-4, when George Rennie designed New London Bridge, London was probably two hundred times as big as was Montauban in the fourteenth century; and certainly the Thames was not inferior to the Tarn as a historic inspiration. Yet Rennie failed to understand the importance of being large in scale. In less than fifty years his work was “insufficiently wide for the traffic”;[109] and since then, on a good many occasions, we have been asked to disfigure London Bridge with overhanging footpaths. “London can well afford to pay for new bridges, but can by no means afford to part with a single object of real beauty.”[109] For Rennie’s bridge, despite all errors of scale, has points of charming interest. Her roadway has a graceful curvature that delights the eye, her arches have an excellent shape, and the variation in their size could not well be bettered.[110] Later we shall see ([p. 325]) that much money was ill-spent on hammer-dressing the whole external face of the masonry; but an engineer with a very weak feeling for scale was afraid to use either scabbled stone or stone with a rough-axed facing. Rennie learnt all that he could learn by studying fine models of style, such as the Roman bridge at Rimini, but his own equipment as an artist was terrene.

Would that we had in England an old bridge equal to the Pont des Consuls! Would that old London Bridge had been delivered down to our sixpences and shillings! Yet I suppose we must consider ourselves lucky in the fact that historic bridges in Great Britain, though much inferior to those on the Continent, are fairly numerous in districts where there has been but little increase of traffic. We possess three bridges with defensive gateways (Stirling, Warkworth, and the Monnow Bridge at Monmouth); five with chapels, or with relics of chapels (St. Ives in Huntingdonshire, Derby, Bradford-on-Avon in Wiltshire, Wakefield, Rotherham); and many good specimens exist of bridges with angular recesses built out from parapets and forming part of the piers.[111] These recesses were designed not only as shelter places for wayfarers, but because they lessened the cost of production, inasmuch as they gave width to narrow footways; and so their value in an old bridge is very similar to that of bay-windows in cottage rooms.

Very often the modern engineer has misunderstood their origin, and, regarding them as decorations, he has used safety recesses to ornament his wide bridges, just as he has put battlements on iron parapets and stuck machicolations on defenceless gateways. Brangwyn has drawn for us three or four big Gothic bridges with safety recesses. Among them is a fine structure over the Main at Würzburg, in Bavaria; there are eight arches, and the length is 650 ft. This bridge dates from the year 1474, but his adornment with statues of saints belongs to later times. Indeed, the architecture and decoration take us from the end of the Middle Ages to the year 1607, when the spirit of the Renaissance was active and generative.