would admit. It skilfully takes advantage of high ground
commanding, throughout almost its entire course, a valley or
low-lying ground in front. Occasionally, it passes over ridges
of a considerable elevation above sea level,1 as at Castlehill,
Barr Hill, Croy Hill, and Westerwood. The three points last
named stand close on the watershed of the isthmus—the Kelvin
flowing westward and the Bonny eastward almost from their
base. To the east of Westerwood, the line of the vallum
never reaches a height of 250 feet, but occupies a line of great
natural strength, with the carses of the Forth lying in front
of and at a considerable depth beneath it, until close on
the terminal point at Bridgeness where it sinks rapidly, to end
itself on the shores of the Firth.
The lines of the poet'2 who sang of the "Danewerk" traversing
Schleswig, are so apt that they might have been written to describe
the Vallum of Antonine, which, even more literally than its
Cimbric analogue, with high and curving ridge crosses an isthmus
and unites the shores of an eastern and a western sea.
1 At Castlehill of Kilpatrick it is 387 feet above sea level; at Barr Hill, 475
feet; at Croy Hill, 460 feet; and at Westerwood, 382 feet.
2 Lmtus, quoted in the notes to Saxo Grammaticus, ed. Stephanii, 1644, p. 200—
Muniit arva, solique ingens e corpore
Eruit, immani quod se curvamine longos
Ineitat in tractns, mediumque peram-
Et maris Eoi ripas cum litore jungit
He fortified the fields with a vallum
and dug up from the bowels of the
earth a huge ridge, which, with im-
mense curve, impels itself over long
tracts, strides across the midst of the
isthmus and joins the coasts of the
Eastern sea with the Western shore.