have crossed the area obliquely from east to west, and likewise obliquely from north to south. The cause of this deviation is probably to be sought in the physical exigencies of the ground with which the builders had to deal.
Foundations.—I shall first speak of the substructure of the walls. Whitaker fortunately examined three sides. He found the foundation of the western side laid on two beds of blue, well-worked clay, the lower being nearly a foot in depth, and remarkably stiff and solid (pages 32 and 33, edition 1770). The southern side was laid in two courses, not a foot in depth, not of actual clay but of claymortar, clay and sand incorporated together, and both lying upon a deep bed of river sand. The eastern side rose from two courses of boulder stones cemented with clay. The northern side has been trenched at various points during the extensive railway operations from May, 1897, to September, 1898; at the east and west side of Collier Street. These I have carefully watched. The trenches were carried down into the underlying new red sandstone rock, and were made 40 feet long and 28 feet apart from each other. At trench No. 3[1] they penetrated a little into the castral area, cutting the Roman wall obliquely.
I give a cross section.[2] Starting from the surface we have on its eastern side:—
- 36 inches modern rubbish;
- 5.6 „rough, irregular blocks of sandstone;
- 2¼„a course of brownish-black Roman mortar, mixed with mould;
- 5½„oblong, dressed blocks of red sandstone;
- 1¼„a course of mortar;
- 6„yellow-brown, stiff boulder clay;
