regards the outer mound, Horsley expresses himself as dissatisfied
with Gordon's opinion, and makes the following remark1:—"The
rubbish thrown out of the ditch seemed in some parts to have
been designedly levelled or plained so as to form somewhat like
a terrass; on the north of which again is sometimes a gradual
descent almost like a modern glacis which appears in other places
where there is no such terrass. This, I believe, was mostly
natural, though I imagined that in some places it had been
improved by art. At one place, this elevation appeared just like
a heap of rubbish thrown out of the ditch. But it is not for any
considerable space or in many places that there is any appearance
at all of this kind."
General Roy, in his magnificent folio,2 posthumously pub-
lished in 1793, while giving an excellent general account of the
structure as a whole, entertained a feeling too near akin to
contempt for its vallum to do it justice. He laid all the stress
on the fosse. Of the vallum, he wrote3 that "the work was
originally executed of earth; that is to say, it was cespititious or
composed of the materials promiscuously taken from the ditch,"
and, he added, " it is evident that the magnitude of the ditch
must have constituted the principal defence: the rampart, with
its parapet, as far as can be discerned from the imperfect remains
of them seeming everywhere to have been slight and inconsider-
able. Thus the superior part of the work requiring but a small
quantity of earth for its construction, it became absolutely
necessary to obtain so great a ditch to throw a large proportion
of the earth northwards along the common slope whereon the
wall hath been constructed, thereby rendering the natural glacis
somewhat steeper." Commenting on the stone foundation he
observed4:—" Where its course lay along rocky or stony ground,
as in some places between Old Kilpatrick and Simmerston, and
again at Bar-hill and Croy-hill, the excavation of the ditch
affording a greater quantity of stone in proportion, there the
Romans seem to have disposed of such part as was not wanted
■'Britannia Eomana, p. 163.
2 Military Antiquities of the Romans in Britain, by Major-General William Roy.
3 Roy, p. 156 ; also p. 149.
4 Roy, p. 156.