GLASGOW ARCHAEOLOGICAL SOCIETY.
frontier wall of a province, it would be unwise to exclude from
the archaeological examination of the latter the evidence of
Vegetius as to the construction of the former. We shall not go
far amiss if, with these sections in the Wall of Antonine open
before our eyes, we turn to Vegetius and contrast his descriptions
with what we see. Can our vallum have been made in the
second mode mentioned by him—a ditch dug and the upcast
earth piled into an agger on the inner bank ? We think not,
and for three main reasons :—(1) Because the soil in the vallum,
especially having regard to its relative stonelessness, is not the
promiscuous but generally homogeneous soil which the ditch
could have yielded; (2) because on the theory of the soil of the
vallum being the promiscuous soil of the ditch, it is impossible to
account for the series of parallel dark lines found all through
the vallum; and (3) because the soil that came from the ditch
appears to be wholly accounted for by the outer mound.
Measurements, for example, taken at Seabeg section No. 2 show
that just so much soil is in the outer mound as answers, to the
quantity excavated from the ditch. The content of the ditch there
was 224 square feet; that of the outer mound above the original
surface line was 231 square feet. Excavated soil naturally
occupies a little more space after excavation than it did before.
On no point in our investigations are we more satisfied than
on this, that the vallum was not made of terra egesta, the
promiscuous upcast earth from the ditch.
But when we consider the observations of Vegetius on the
first kind of rampart mentioned by him, the vallum of sods built
like a wall, we are struck by their suggestiveness. The " cespi-
ticious" theory1 certainly offers explanations of most of the
peculiar phenomena disclosed by the sections. The dark lines in
the vallum so puzzling on any other hypothesis are the strong
point of this theory. A great rampart built regularly of sods,
course upon course like a wall of stone, would necessarily at the
time of its construction have all through it an orderly succession
of parallel rows of sods each with a heathy surface. There
1 First propounded by Mr. Neilson in a paper read to the Glasgow Archaeological
Society on 19th March, 1891, and published in the Antiquary for June, 1891,
vol. xxiii., p. 250.