The second or middle ditch, also deep and wet, envelopes the middle bank very regularly. At present it is wanting on the south side, for a short distance, having been filled up and converted into a road when the railway was constructed. Outside this ditch is the third or outer _enceinte_, a steep bank, which forms the counterscarp of the middle ditch, and envelopes rather more than the northern half of the castle. It is about 10 feet broad above, and is strengthened outside by eight bastions, also of earth, placed at distances of from 60 feet to 150 feet, and each, at top, about 30 feet broad by 40 feet projection, and rounded. The five best marked of these, being steep and about 20 feet high, lie to the north-west. A small streamlet coming in from the north then cuts the line, and to the east of this, covering the north-east and east faces, the bank is continued for about 580 feet, strengthened by three bastions, which, however, are low, and have nothing of the sharpness of the others. These latter three have scarcely any ditch, but the other five have at their feet a ditch, which, even now, is boggy, and no doubt was once a formidable defence. West of this outer bank, and ranging with it so as to cover part of the west face of the castle, is an earthwork of very doubtful character. Its lines are rectangular, it has a ditch, and it much resembles the early ravelins which were common in the fifteenth century, and not unknown in the fourteenth and thirteenth. Connected with its ditch is a pond, which appears to have been a mill-pond and fish-stew. No doubt all these extensive ditches were turned to account, and fed the mill which is known to have been attached to the castle. Berkhampstead is altogether a very striking and a very peculiar fortification. The mound was no doubt an English burh, and, as was not uncommon, had its own defences. The inner _enceinte_, though not, as is usual, encircled by a bank, was encircled by a steep slope and ditch, which, with a palisade, would have been a very sufficient defence. These probably were the whole of the original works, and within them may well have been held the famous Council of Berkhampstead in 697. The two outer works seem to be later. The outer certainly, from its bastions, must be later than the Conquest, and the middle bank is far too slight in its construction and too sharply preserved to be of remote antiquity. But it is remarkable that there is no trace of any other than the inner _enceinte_ wall, and it is pretty evident that there was never any other. The earthworks, except the mound, would not have carried a wall, and had such been built it would have been liable to be mined and overthrown with very little trouble. Evidently these banks were crested with palisades, and probably careful cutting into them would show traces of the stakes.