work and fixing the rest of the wall upon them. We must again bear in mind that practically the northern wall was directly laid in the marshy ground and stood on the first fosse which reached up to it. Whitaker omitted to give the distances between the set of arches and their dimensions.
Towers.—The recent excavations at Ribchester and Melandra have shown the existence of four corner turrets built within the rounded angles of the walls. Their structure is particularly well shown at Melandra. They are built square and stand detached, 4 feet away from the angles, measuring 10 feet by 11 feet, the walls being 3 feet thick. Indications and traces of a similar turret were found at our station by Whitaker in 1768–9. He says: "A man hunting for treasures made trenches through the foundations of the stationary walls, near the south-east angle, and carrying his operations along the interior line came to a new and distinct wall, lying 3 feet to 4 feet from the wall, which proved to be 3 feet thick and 12 feet long, fairly curving at the angle." Whitaker followed up the work where the treasure seeker had left off, digging downwards for 1½ yards, and found this wall ranging parallel with the line of the station. It consisted of large and squarish flakes of red rock, and was cemented with a new species of clay mortar, a brown, compacted mass of sand and clay, tempered with some sprinkling of lime. Each irregular layer seemed to rest, he says, upon a course of fine sand, and the lowest was framed of the massiest stones and lay on a deep bed of sand that had been previously beaten and compacted together, each spade-depth of it appearing successively smooth and hard upon the surface and the third lying on the natural gravel. (See Whitaker, page 13.)
