Page:Medieval Military Architecture in England (volume 1).djvu/184

 168 MedicEval Military Architecture in England. Caerphilly, the barbican partakes of the character of a horn- work. The Tower barbican, called the Spurgate, is a regular low gatehouse, with flanking drum towers or bastions covering the head of the bridge, and itself protected by a loop from the main ditch. At Bridgenorth the barbican contained a kitchen, ordered to be repaired, 17 Hen. III. At Canterbury the barbican, temp. Ed. II., was used as a prison. Spelman defines a barbican or "ante-murale" as "munimen a fronte castri aliter ante murale dictum ; etiam foramen in urbium castrorumque moeniis ad trajicienda missilia.-" A palisaded embrasure in front of the barbican was known as the barriers." They are well represented at the Tower by the stockade covering the entrance. The drawbridge was an important feature in the defence of a castle. In its most simple form it was a platform of timber turning upon two gudgeons or trunnions at the inner end ; when up, it concealed the portal, and when down, dropped upon a pier in the ditch or upon the counterscarp. Its span varied from 8 to 12 feet. The contrivances for working it were various. Sometimes chains attached to its outer end passed through holes above the portal, and were worked within by hand or by a counterpoise. Occasionally there was a frame above the bridge, also on trunnions. In the larger castles the arrangements were very elaborate. Sometimes the bridge was the only connexion between the gateway and the oppo- site pier ; at others the parapets or face walls rested on a fixed arch, and the bridge dropped between them. A fine example of this kind of bridge is seen at the Constable's Gate, Dover Castle. At Goderich the details are tolerably perfect. The ditch was crossed by a stone bridge, apparently of two arches, but only the outer one is permanent. The roadway of the inner one was a drawbridge. At Caerphilly, in the ditch in front of the main gate, is a large stone pier from which a bridge fell each way. Probably it carried a tower of timber. In Henry III.'s accounts is mention of a bretascJie on the bridge of the great tower at Winchester, and of another, covered with lead, upon the new bridge. The portcullis, the " altera securitas of the badge of the House of Somerset, always present in the castles of Henry and Edward, was an important part of the defence. It was a strong grating, in the smaller gateways of iron, in the larger of oak, strengthened and shod with iron spikes, and sus- pended in grooves by two cords or chains, which passed over two sheaves, or sometimes through a single central block, and either were attached to counterpoises or worked, as at the Tower and York gates, by a winch. The grooves are generally