These mounds, where they have descended to us, and have undergone no change at the hands of the Norman architect, are mere green hillocks, clear indeed in their simplicity, though having lost by time the sharpness of their profile, and more or less of their height and of the depth of their ditches. No masonry has ever been observed upon them which could by any possibility be attributed to their founders, or which could be supposed to be part of their original design. It is evident, however, that the earthwork was only the support of some additional defence. On the mound was certainly a residence, and both its crest and base, as well as the appended courts, must have been encircled by some sort of barrier besides the earth-bank. We read that Towcester was defended by a wall, which however was built very quickly, and probably was like a field wall, without mortar. But with or without mortar, no wall could have been placed upon a fresh heap of earth, and that spoken of must have stood upon the natural ground at or around the base of the mound. No doubt Exeter was walled by Æthelstan, and Colchester had walls, partly, as we see, Roman, but partly no doubt, English; and Derby had gates, though of what material is not stated. At Corfe is some masonry, certainly older than the Conquest, and part of its outer defences; but Corfe is a natural hill. It is well known that the English were from a remote period conversant with masonry, and constructed churches of stone or timber as suited them best; and nothing is more natural than that they should have employed the former where the object was to resist an attack. But upon a burh, or upon an artificial earthwork of any height, masonry of any kind was obviously out of the question. Timber, and timber alone, would have been the proper material. Timber was always at hand, and it was a material of which, possibly from their early maritime habits, the English were very fond. Also the rapidity with which these burhs were constructed shows that timber must have been largely employed. They were thrown up, completed, attacked, burnt, and restored, all within a few months. There are not wanting descriptions of these timber-defended works. M. de Caumont cites a curious passage from Ernaldus Nigellus, an author of the ninth century, who relates an expedition under Louis le Debonnaire against the Breton king, Marman, whose strongholds were protected by ditches and palisades. “Est locus hinc silvis, hinc flumine cinctus amoeno. Sepibus et sulcis atque palude situs.” Intus opima domus....