[547] Ribchester.
[548] Blackrode.
[549] Carlisle.
[550] The wall of Severus. The exact site of the barrier erected by Severus against the northern tribes, has furnished matter of dispute to many of our antiquaries. The researches of others, particularly Horsley, have, however, set this question at rest. From their information, joined to the scanty evidence of history, it has been proved that three walls or ramparts were erected by the Romans at different times, to secure the northern frontier of their dominions in Britain.
The first was a rampart of earth, from the Solway Frith to the Tine, raised by Hadrian about the year 120; but its form and construction have not been satisfactorily ascertained. It was, however, evidently nothing more than a line intended to obstruct the passage of an enemy between the stations which constituted the real defences of the frontier.
The second was raised by Lollius Urbicus under the reign of Antoninus Pius, about 140, between the Friths of Forth and Clyde. This was likewise of earth, though perhaps faced with stone, and, like that of Hadrian, seems to have been intended as a line connecting the chain of stations, which formed a new barrier on the advance of the Roman arms. In the course of both these was a military road communicating from station to station.
The last and most important is that begun by Severus, after his expedition against the Caledonians, about 208. It runs nearly over the same ground as that of Hadrian; but is a complete and well combined system of fortification. From an examination of its remains it appears to have been built of stone, fifteen feet high and nine thick. It had parapet and ditch, a military road, and was defended by eighteen greater stations placed at intervals of three to six miles; eighty-three castles at intervals of six to eight furlongs, and, as it is imagined, a considerable number of turrets placed at shorter distances.
Either from superior sagacity or superior information, Richard clearly distinguishes these three walls, which so much puzzled later writers, though it must be confessed that in other places he has suffered himself to be led into some errors in regard to their situation, and the persons by whom they were erected.—See b. ii. ch. 1, sect. 22, 27, 36, 37; ch. 2, sect. 17, 23. For a detailed account of these works the reader is referred to Horsley's Britannia Romana; Warburton's Account of the Roman Wall; Hutchinson's Northumberland; Roy's Military Antiquities; Hutton's Account of the Roman Wall.
[551] These were the Helvetii, whose emigration is mentioned in Cæs. Comm. de Bell. Gal. lib. i. We have not discovered from what authority Richard draws his account of their emigration to Ireland.
[552] Caracalla.