Chapter IX: 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lime which they had withdrawn.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.

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~The Roman Barrier of the
Lower Isthmus.~