Glasgow Archaeological Society   [Hrsg.]
The Antonine Wall report: being an account of excavations, etc., made under the direction of the Glasgow Archæological Society during 1890 - 93 — Glasgow, 1899

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THE ANTONINE WALL REPORT.

137

than the natural angle of repose of the soil. Had it been other-
wise, there would have been no sufficient data obtainable for the
inferences now drawn as to the shape and angle of the fosse.
The storms of sixteen centuries have left its primal slope for
miles at a time very little impaired, except by the mossy growth
which fills up the angle of the bottom. The engineer had
admirably gauged the capacity of his material.

One outstanding feature of the ditch, first clearly demonstrated
by the sections, and subsequently found to be an almost invari-
able fact along the whole work, is that the counterscarp is to no
small extent "made up." It has all along been heightened by
the very natural process of piling the earth from the ditch on
the north side. A discussion of some of the peculiarities in the
doing of this will be found under the next head. It is apparent
that this process would serve several purposes. Chiefly, it
widened and deepened the fosse. The existence of this system
is a powerful testimony to the Roman's belief in the high, if
not paramount, importance of the ditch in the scheme of defence,
a belief which modern military opinion emphatically indorses.

The ditch thus constructed has been stated1 to " average
about 40 feet in width by some 20 in depth." This general-
isation clearly leaves out of account that part of the ditch
where it runs at the foot of the crags at Croy Hill, and where
its average width is under 20 feet. Where the normal con-
ditions exist, the fosse does not fall far short of the alleged
average of 40 feet in breadth. The alleged depth of 20 feet,
however, is very distinctly in excess of the fact. It is doubtful

forms the edge of a ditch. In modern military work the slope of the ditch is
always higher considerably than that of the rampart—the former being soil in situ,
the latter soil displaced. Thus Philips (Art. 127), dealing with the scarp or inner
side of the ditch, says—"Its slope in ordinary ground is i sometimes it can be
made steeper, but in weak soils and where works are required to last a consider-
able time, it will generally be impracticable to give the escarp a steeper slope
than * unless it is artificially supported." ^ = 45°, being, of course, very greatly
steeper than Bankine's JLj and i.J, For a structure of displaced earth, Philips
(Art. 124) says—" The exterior slope of a parapet, which is the slope most exposed
to fire, should not be steeper than what is termed the natural slope of the earth,
or the slope at which the earth used will stand without artificial support. With
the generality of soils this slope is 1 In works which are expected to be exposed
to a heavy fire of artillery (such as the batteries at a siege, &c.), the exterior slope
should have an increased basis given to it."
1 Stuart, 278.
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