414

HISTORY OF ENGINEERING.

Book I.

blance to a wor* in carpentry, anil though executed in stone could only be deemed thecentre or contrivance on which was laid a bed of beton or concrete, which hardened into amass, and formed the solid construction of the bridge. The mason and carpenter duringthe middle ages employed the same principles ; wood and stone were often treated in asimilar manner, and the same mouldings and forms were given to both, without referenceto their different qualities.

Bishop Auckland Bridge over the Wear, erected in 1388, has two segmental arches, thelargest of which spans 100 feet 5 inches, and has a rise of 22 feet; the other has 91 feet5 inches span, and rises 20 feet. Each of these arches is built of three row’s of voussoirs,22 inches in depth : this example is, perhaps, the earliest in England where the segmentwas introduced. The three rows of voussoirs performed the office of as many ribs, and bythis arrangement a simple centre might be made to serve for the execution of the whole.

There are several small bridges remaining, in which the Gothic ribs are admirably pre-served ; that which crosses the moat at the palace at Eltham is a fine example : anotherover the Darenth at Eynesford in Kent , though small, is a good specimen.

Rochester Bridge , Kent . In a line with the principal streets of Rochester and Stroodformerly stood a wooden bridge, which is mentioned as existing at the commencement ofthe 13th century. Lambard, the historian of this county, has given several regulations forits repair, copied from manuscripts in the library of Rochester Cathedral, which werecollected by Bishop Ernulphus, who was elected to that see in the year 1115.

From these ancient writings we learn that the bridge consisted of nine stone piers,placed at equal distances, and the width of the river was 26£ rods, or 440 feet, nearly thesame breadth as it is at present.

'These ten divisions were each 43 feet from the centre of one pier to the centre of theother, so that the cills or beams were 43 feet long; and each bay had three of these timbersto make out the width of the bridge. Across these beams w’ere thick plankings, probablyabout 10 feet in extent. It would appear that the sides were not protected, as in theRegistrum Rolf, mention is made of a rash young man, son of Earl Aufrid, who, in thereign of Edward I. , not alighting from his hor^e, as w t hs customary, when passing thebridge, the beast took fright, leaped into the river, and both were drowned. A woodentower, constructed with marvellous skill at the east end of the bridge, was used as a gate aswell as a defence.

This bridge w’as probably erected at the cost of the proprietors of the manor, wdio after-wards kept it in repair. The manors are all mentioned, and two of the holders wereannually elected as wardens and overseers of the bridge.

This wooden structure was burnt in 1264, by Simon Montfort , Earl of Leicester, butthe timber work was soon after restored, for in the year 1281 we find, that after a severefrost, the ice struck with such impetuosity against the stone piers, that some of them wereswept away, and the others much damaged; in this state it was left until the reign ofEdward III , when it was again put into repair.

Sir Robert Knolles, after his return from France, where he had attended Edward III. ,in all his successful campaigns, founded a stone bridge at his own cost, probably about theyear 1387, for it was completed in the fifteenth year of Richard II. , as appears by a statutemade “for repairing and supporting the new stone bridge of Rochester,” which is statedto contain more in length than the old bridge. The sum of the various portions allotted tothe places and manors for the repairs in future amounts to 566 feet, 1] inch. Thisbridge was considered one of the finest at that time in England; the breadth was 14 feet;it had stone parapets and eleven arches, resting on substantial piers, well secured on eachside with starlings. At the east end, and fronting the passage over the bridge, is a chapelwhich was erected by Sir John de Cobham.

It appears that after this bridge was completed over the river, at about 40 yardshigher up the stream than the old bridge, it was enacted by two statutes, one made in thefifteenth, and the other in the twenty-first year of Richard II. , that it should be repairedby the manors and places there specified. 'flic statutes also enact that the persons,manors, places, and bounds, should be considered as a community, and that they shouldchoose two men annually, who should be called wardens, and have the superintendencyof, and provide for the repairs of the said bridge. It also allowed them to purchase landsto the amount of 2001. per annum, and to hold them as wardens of the said bridge; theywere to be accountable to auditors to examine the receipts, disbursements, &c.; and in theninth year of Henry V. a statute was made confirming the two former acts, and allowingthe wardens to have a common seal, and to plead in any court by the name of the War-dens of the New Bridge at Rochester.

Sixty years after it was finished, it required some repair, which was partly done by theprior and convent of Rochester, assisted by Henry VI. ; and in the year 1-189, JohnMorton, Archbishop of Canterbury, published a remission from purgatory for forty daysof all manner of fines, to such persons who would give any thing towards the repairs as atthat time the bridge was very much broken.