Turner describes in the following terms a bridge for foot passengers of an extraordinary construction. “It was composed of two chains stretched parallel to each other across the river, distant four feet from each other, and on either side resting upon a pile of stones, raised upon each bank about eight feet high; they were carried down with an easy slope and buried in the rock, where, being fastened round a large stone, they were confined by a quantity of broken rock heaped upon them. A plank about eight inches broad hung longitudinally suspended across the river by means of roots and creepers wound over the chains with a slackness sufficient to allow the centre to sink to the depth of four feet below the chains. This bridge, called Selo-cha-zum, measured, from one side of the water to the other, 70 feet. The creepers are changed annually, and the planks are all loose; so that if the creepers give way in any part, they can be removed, and the particular part repaired without disturbing the whole.”
Numerous suspension bridges formed of iron chains exist also in China; and though the accounts which travellers have transmitted respecting them are less detailed and explicit than would have been desirable, descriptions of two of them have been furnished, which are sufficiently minute and intelligible to excite considerable interest. The first to which I refer is contained in Kircher’s China Illustrata. The following is a translation of the author’s words: “In the province of Junnan, over a valley of great depth, and through which a torrent of water runs with great force and rapidity, a bridge is to be seen, said to have been built by the Emperor Mingus, of the family of the Hamæ, in the year of Christ 65, not constructed of brickwork, or of blocks of stone cemented together, but of chains of beaten iron and hooks, so secured to rings from both sides of the chasm, that it forms a bridge by planks placed upon them. There are 20 chains, each of which is 20 perches or 300 palms in length. When many persons pass over together, the bridge vibrates to and fro, affecting them with horror and giddiness, lest whilst passing it should be struck with ruin. It is impossible to admire sufficiently the dexterity of the architect Sinensius, who had the hardihood to attempt a work so arduous, and so conducive to the convenience of travelling.” Another suspension bridge in this country is described in the 6th vol. of the “Histoire Generale des Voyages.” The following is a translation: “The famous Iron Bridge (such is the name given to it) at Quay-Cheu, on the road to Yun-Nan (Junnan?) is the work of an ancient Chinese general. On the banks of the Pan-Ho, a torrent of inconsiderable breadth, but of great depth, a large gateway has been formed between two massive pillars, 6 or 7 feet broad, and from 17 to 18 feet in height. From the two pillars of the east depend four chains attached to large rings, which extend to the two pillars of the west, and which being connected together by smaller chains, assume in some measure the appearance of a net. On this bridge of chains a number of very thick planks have been placed, some means of connecting which, have been adopted in order to obtain a continuous platform; but as a vacant space still remains between this platform and the gateways and pillars, on account of the curve assumed by the chains, especially when loaded, this defect has been remedied by the aid of planking supported on trusses or consoles. On each side of this planking small pilasters of wood have been erected, which support a roof of the same material, the two extremities of which rest on the pillars that stand on the banks of the river.” The writer proceeds to remark, that “the Chinese have made several other bridges in imitation of this. One, on the river Kin-cha-Hyang, in the ancient canton of Lo-Lo, which belongs to the province of Yun-Nan, is particularly known. In the province of Se-Chuen there are one or two others, which are sustained only by ropes; but though of an inconsiderable size, they are so unsteady and so little to be trusted that they cannot be crossed without sensations of fear.”
While our attention is directed to early accounts and to the origin of suspension bridges, it may be proper to remark, that although, as we have seen, the inhabitants of the mountainous districts of South America, or the wild and barbarous regions of Thibet, appear to have been well acquainted with the purposes for which these structures are best adapted, and to have practised their construction from the most remote ages, neither the Greeks, the Romans, nor the Egyptians, according to all we know of those nations, had any knowledge of their uses or properties, or ever employed them as a means for crossing a river, or other natural impediment. It is not, therefore, from these celebrated nations of antiquity that the engineer has derived his first hints for the construction of suspension bridges, but from those rude and unpolished people, the results of whose ingenuity have just been described.
But it will now be interesting to inquire how far we can trace back the antiquity of suspension bridges in more civilized countries—on the Continent, in the British Isles, and in the United States of America. Scamozzi speaks of suspension bridges existing in Europe in the beginning of the seventeenth century, but it is very questionable if he employed that term to designate the same structure to which it is now applied; and this is rendered the more improbable, as no such bridges are now in existence, and other writers are totally silent upon the subject. It does not appear, then, that suspension bridges of other than recent erection have existed on the Continent, and in England the oldest of which we have any account has not been constructed more than a century. The first suspension bridge in the United States was erected in the year 1796. In England the oldest bridge of the kind is believed to have been the Winch Chain Bridge, suspended over the Tees, and thus forming a communication between the counties of Durham and York. Mr Stevenson (Edinburgh Philosophical Journal) expresses his regret at not having been able to learn the precise date of the erection of this bridge; from good authority, however, he concludes it to be about the year 1741. It may also be mentioned here, that at Carric-a-rede, near Ballintoy, in Ireland, there is a rope bridge, which in 1800 was reported to have been in use longer than the present generation could remember.
In the years 1816 and 1817, some wire suspension bridges were executed in Scotland, and, though not of great extent, are the first example of this species of bridge architecture in Great Britain. As, however, full descriptions of these bridges are to be met with elsewhere, it will not be necessary to notice them further.
In 1818, Mr Telford was consulted by government as to the practicability of erecting a suspension bridge over the Menai Strait, and was commissioned to prepare a design, if upon an examination of the localities he found the project feasible. Having accordingly surveyed the spot, he was led to propose the construction of a suspension bridge near Bangor Ferry, and in 1819 an act was obtained, authorising the erection of the bridge, a sum of money having been previously voted by Parliament for that purpose. This structure, which will always be regarded as a monument of the engineering abilities of Telford, was commenced in August 1819, and opened to the public on the 30th January 1826, having occupied six and a half years in its erection. The Union Bridge across the Tweed was designed and executed by Captain Brown, and was the first bar chain bridge of considerable size that was completed in this country. It was commenced in August 1819, and finished in the month of July 1820. After the completion of the Menai Bridge, bridges on the suspension principle began to be universally adopted throughout Europe; but it was not till iron wires had been proved to be more firm than bars of a greater thickness that these bridges received their most extensive applications. Since 1821, Messrs Sequin have constructed more than fifty wire bridges in France with the most complete success. The wire suspension bridge at Freyburg, in Switzerland, the largest in the world, was erected by Mons. Challey, and depends across the valley of the Sarine. It was commenced in 1831, and thrown open to the public in 1834. A suspension bridge has also been erected at Montrose, the size of which is scarcely inferior to that of the Menai Bridge. At Clifton a very large suspension bridge is now in progress of erection by Mr Brunel, and a suspension bridge of 1600 feet in length is about to be erected over the Danube, between Pest and Offen, the design for which is the production of Mr W. Tierney Clark, and under whose able superintendence its construction will be effected.—Civil Engineer and Architect’s Journal.
REMONSTRANCE WITH THE SNAILS.
Ye little Snails,
With slippery tails,
Who noiselessly travel