Mr. Bell, of Irthington, tells me that in some places the foundation flags of the north side point upwards, at an angle of about twenty degrees, caused apparently by the settling of the ponderous mass. In this circumstance, we have an interesting confirmation of the supposition that the Wall was surmounted with a parapet on its north side. The foundation would have settled equally if both sides had been burdened alike. Footnote 48: Part II. v. iii. p. 294. Footnote 49: In some parts of the line, the joints of the Wall are at present filled with earthy matter instead of mortar, and it is the opinion of some authorities, and amongst them, the eminent architect and intelligent antiquary, Mr. Dobson, of Newcastle-upon-Tyne, that in these places, clay has been originally substituted for mortar. Very loath to suppose that the original builders of the Wall would leave any portion of it in so unsatisfactory a state, I have been in the habit of accounting for the apparent absence of mortar in the following way:—The upper part of the structure having been overthrown by a ruthless enemy, and the lower parts covered with the fallen rubbish, the whole heap would speedily become coated with vegetation. Roman mortar, with all its tenacity, would not be able to resist the powers of vitality; and the constant demands of the ferns and the foxgloves would, in the course of time, abstract the whole of the lime. The roots of the plants, by whose agency the work of abstraction had proceeded, yielding in due time to the process of decay, would themselves, in the form of vegetable earth, supply the place of the lime which they had withdrawn. Footnote 50: The only source of information which I have upon the subject of this wall, is a translation of an extract from a pamphlet by Professor Buchner, of Regensburg, in the first volume of the ‘Archæologia Æliana.’ The precise relation which the _Pfahl_ bears to the stone Wall does not very clearly appear from this paper; to all appearance, however, the analogy between the German and English barriers is very close. Footnote 51: Hodg. North’d. II. iii. 276. Footnote 52: Ibid. 284. Footnote 53: Iter Boreale, 67. ----- ------------------------------------------------------------------------ [Illustration] ~The Roman Barrier of the Lower Isthmus.~ PART III. LOCAL DESCRIPTION OF THE WORKS.