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A HISTORY OF LONDON dressed stone. On the outside is laid a chamfered plinth formed of blocks of red sandstone, about i ft, to 2 ft. 6 in. long, 9 in. high, and i ft. to i ft. 6 in. thick, above which, but set back about 4 in., which is the width of the chamfer, are usually four, but in some parts five courses of carefully squared ragstones, making together a height of from 2 ft. to 2 ft. 6 in. ; the lowest stones are slightly larger than the rest, the succeeding courses diminishing in size, and on the average measuring about 6 in. in depth, while the width varies considerably. The corresponding face on the inside has a similar arrange- ment, but instead of the sandstone plinth there are three rows of tiles placed one above another, but not carried through the thickness of the wall so as to form a bond. With a set-ofF of about 3 in. the dressed stones of the inner face are carried up in the same way as on the outer face. Between these two faces the core of the wall is composed of pieces of ragstone of irregular size and shape, arranged roughly in herring-bone fashion. Mortar is plentifully spread over the successive layers ; it does not, however, run thoroughly between the stones, but leaves many cavities. The thickness of the wall at this point is usually 8 ft. to 8 J ft. Above this first stone band a bond of tiles is carried through the wall. There are usually three courses of tiles shown on the face in the first bond, and in some parts in the second bond ; but all the higher bonds have two tiles, and in exceptional cases the lower bonds have also been found to be of two tiles only. While the edges of these tiles are quite regular on the face, the arrangement within the core is often very irregular, but so deeply are they embedded in mortar that the whole forms a bond of great strength and solidity. Further interspaces of five or six courses of roughly squared ragstone, alternated with bonding courses, follow regularly, and are of similar construction, though the upper interspaces are deeper than the first, measuring about 3 ft., and the stones are smaller and less regular. On the inner face the stone is set back about 3 in. above each bonding course, while the outer face is carried up vertically from the top of the plinth. In several of the published diagrams, the outer face is shown with set-offs like the inside, but this would appear to be due to a misapprehension arising from the fact that the bonding courses have been less affected by weathering than the more loosely-built stone, for in parts where the outer face has been covered up at an early period it has been found to be quite perpendicular (Fig. 20). The inner face, however, is usually in far better preservation than the outer, because of the earlier rise in the surface within the City, or possibly because the wall was originally protected on the inside by an earthen bank. Those portions of the outside of the wall which have from any cause been covered in remote times show that the outer face was constructed with equal regularity and care, but from its greater liability to damage from attack and from the action of the weather, it has suffered to a greater extent than the inner face by refacing in later times, when it was also generally dressed back. The core throughout the height of the wall is much the same as that already described, the only stone employed in the original fabric being ragstone with rarely an occasional flint. The greatest height at which the Roman masonry has actually been found is about 16 ft. above the Roman ground level. The top has nowhere been preserved and there is no 46