THE PAST AND FUTURE OF THE ESSEX FIELD CLUB. 75
age and character of the building we have lost. But in the case of
an earthwork only actual excavations can give us really unquestion-
able information, and if it be entirely levelled in the name of agricul-
tural improvement we may be left without any evidence whatever as
to its age and character. The danger of such a destruction, together
with the difference between conclusions obtained from actual investi-
gation and those derived from a mere consideration of documentary
evidence utterly insufficient to settle anything, are well illustrated in
the following example. In the year 1870, Col. A. Lane Fox (now
Lieut-General Pitt Rivers) visited the Oxford Dorchester to prevent,
if possible, the threatened destruction of those well-known earth-
works, the Dorchester Dykes. In the "Journal of the Ethnological
Society" for January, 1871, appears his account of these dykes, with
a plan and sections. Dorchester is on the north or Oxfordshire side
of the Isis, on low ground, just above the junction of Isis and
Thame. About three-quarters of a mile above this junction the Isis,
which has been flowing nearly from north to south, takes an easterly
course, and as the Thame near its outfall flows from north to south,
a piece of ground is enclosed between the two streams which is open
only on its northern side. The Dorchester dykes range from Isis to
Thame, so as to enclose a strip of flat ground between themselves
and the Isis where that river flows eastward. The ground on which
the dykes stand may be from 15 to 20 feet above the average level
of the river. Rather less than half-a-mile south of the easterly bend
of the Isis is the ancient hill fort known as Sinodun, standing
perhaps 250 feet above the level of the stream. There was an old
ford in the Isis between Sinodun and the dykes, and the latter are a
few yards south-west of the town of Dorchester. The threatened
destruction of the dykes produced a certain amount of comment in
the newspapers, both on the demolition of the earthworks and their
probable age and the purpose of their constructors. A writer in the
"Saturday Review" (July 2, 1870) remarked : "There can be little
doubt that the intrenchment by the river marks the position of the
Roman besiegers while engaged in the reduction of this Celtic
stronghold" (Sinodun). He added that Mr. James Parker had
tried to show that the Roman intrenchment was the work of Aulus
Plautius, etc., but that he (the reviewer) felt some doubts as to the
accuracy of this view. However, he remarks that "whether the
Dorchester Dykes were made by Aulus Plautius, or by any later
Roman general, there can be no doubt that they are genuine Roman