The most striking feature in the plan, both of the Murus and the Vallum, is the determinate manner in which they pursue their straight-forward course. The Vallum makes fewer deviations from a right line than the stone Wall; but as the Wall traverses higher ground, this remarkable tendency is more easily detected in it than in the other. Shooting over the country, in its onward course, it only swerves from a straight line to take in its route the boldest elevations. So far from declining a hill, it uniformly selects it. For nineteen miles out of Newcastle, the road to Carlisle runs upon the foundation of the Wall, and during the summer months its dusty surface contrasts well with the surrounding verdure. Often will the traveller, after attaining some of the steep acclivities of his path, observe the road stretching for miles in an undeviating course to the east and the west of him, resembling, as Hutton expresses it, a white ribbon on a green ground. But if it never moves from a right line, except to occupy the highest points, it never fails to seize them, as they occur, no matter how often it is compelled, with this view, to change its direction. It never bends in a curve, but always at an angle. Hence, along the craggy precipices between Sewingshields and Thirlwall, it is obliged to pursue a remarkably zig-zag course; for it takes in its range, with the utmost pertinacity, every projecting rock. This mode of proceeding involves another peculiarity. It is compelled to accommodate itself to the depressions of the mountainous region over which it passes. Without flinching, it sinks into the ‘gap,’ or pass, which ever and anon occurs, and, having crossed the narrow valley, ascends unfalteringly the steep acclivity on the other side. The antiquary, in following it into these ravines, is often compelled to step with the utmost caution, and in clambering up the opposite ascent, he is as frequently constrained to pause for breath. After crossing the river Irthing, in Cumberland, the Wall is opposed in its course westward by a precipice of upwards of one hundred feet in height. It cannot now be ascertained, whether or not the Wall was taken up the edge of this cliff, for the stratum is of a soft and yielding nature, and is continually being removed by the river below. Certain, however, it is, that the Wall, accompanied by its ditch, is still to be seen on the very brink of its summit. If it did not climb this steep, it is the only one which, in the course of the line from sea to sea, it refused—and if it did ascend it, it would more nearly resemble a leaning tower than a barrier wall. [Sidenote: THE HEIGHT OF THE WALL.]