But, after all, the works themselves furnish us with the best proof that the whole is one design, and the production of one period. It is difficult to conceive how any person can traverse the line of the Barrier without coming to the conclusion, that all the works—Vallum, Wall and fosse, turrets, castles, stations, and outposts—are but so many parts of one great design, essential to each other, and unitedly contributing to the security of a dangerous frontier. The Murus and the Vallum throughout their whole course pursue tracks harmonizing with each other; the Murus, however, selecting those acclivities from which an attack from the north can be best repulsed—the Vallum, those from which aggression from the south can be repelled. Stukeley was unable to resist the evidence of his senses. Speaking of the works in the neighbourhood of Carvoran, he says— [Sidenote: STUKELEY’S TESTIMONY.] I suppose this Wall built by Severus is generally set upon the same track as Hadrian’s Wall or Vallum of earth was; for, no doubt, they there chose the most proper ground; but there is a Vallum and ditch all the way accompanying the Wall, and on the south side of it; and likewise studiously choosing the southern declivity of the rising ground. I observe, too, the Vallum (Wall?) is always to the north. It is surprising that people should fancy this to be Hadrian’s Vallum; it might possibly be Hadrian’s work, but may be called the line of contravallation; for, in my judgment, the true intent, both of Hadrian’s Vallum and Severus’s Wall, was, in effect, to make a camp extending across the kingdom; consequently, was fortified both ways, north and south: at present, the Wall was the north side of it; that called Hadrian’s work, the south side of it; hence we may well suppose all the ground of this long camp, comprehended between the Wall and the southern rampire, was the property of the soldiers that guarded the Wall.—_Iter Boreale_, p. 59. Speaking of the works westward of Newcastle-upon-Tyne, he says— The Vallum runs parallel to the Wall, but upon the declining ground south, as the other north; this confirms me in my suspicion, that both works were made at the same time, and by the same persons, and with intent that this should be a counter-guard to the other, the whole included space being military ground.—_Iter Boreale_, 66. The reader needs scarcely to be reminded of the striking illustration of these remarks which is furnished by the appearance of the works a little to the west of Carrhill, and by the fact, that for nearly ten miles in the middle of their course, the Vallum is commanded by the heights on which the Wall stands. [Sidenote: RELATIVE POSITION OF THE WORKS.] Whenever the distance between the Wall and Vallum varies, it is generally with some obvious design in view. Thus, as Hodgson, who powerfully supports the view here taken, remarks—