The walls of a Norman building are usually strong and massive, and built of small stones. They have a plain BASE-COURSE, of little projection, and are generally finished above with a CORBEL-TABLE, consisting sometimes of a series of small arches, on rude heads, and sometimes of a projecting horizontal table resting on a series of rudely sculptured blocks. Upon this Corbel-table is a plain PARAPET and COPING where these are left, which is rarely the case. The compartments are divided by a shallow BUTTRESS or PILASTER STRIP. The WINDOWS are low and broad, and have usually a single shaft set in an angular recess, carrying a cubical capital and a single roll. The STRING-COURSES, when not plain, have frequently indented ornaments of different kinds--such as the _billet_, the _saw-tooth_, the _star_, and the _chevron_. The CLERE-STORY WINDOWS, in the larger and richer buildings, are usually placed in an arcade, consisting of three or more arches, of which the centre one, filled by the window, is the largest. _Interior Compartment._ The proportions of the interior are invariably heavy and massive. The PIERS consist either of a stout cylindrical column, or of a rectangular mass, having semicircular shafts attached to its different faces. They are sometimes, when circular, scored and ornamented with zig-zag, spiral, and other mouldings. The CAPITALS are formed of a cubical block, rounded off on the lower side from the square to the circle, and are ordinarily of a heavy cumbrous character, and sometimes ornamented with rude sculpture of leaves and animals, carved in slight relief on the surface of the block. The PIER-ARCHES, in early examples, are perfectly plain, and square edged, without mouldings or ornament; but more frequently they carry one or more heavy rolls on the angle of each order of the arch; and are often ornamented richly with concentric rows of chevron, billet, and other Norman ornaments. The VAULTING or ROOF-SHAFT is usually a semicircular shaft rising from the floor--on the face of every alternate Pier--to the springing of the vault or roof. In the earlier buildings the TRIFORIUM is generally occupied by one large arch, of somewhat less span and height than the pier-arch: but in the later examples, this arch is generally subdivided into two, and later still, into four small arches, carried on single shafts; the capitals, arch-mouldings, and other details, being all on a smaller scale, but of similar character, to those of the Ground-story. In most Norman buildings of large size, the Triforium forms a very important part of the design of the Interior.