201. Columns not exceeding 8 feet in height usually have the shaft cut in one piece and the caps and bases in separate pieces. For columns of greater height it is generally necessary to build the shaft of several pieces. The joints between the cap and base and the shaft, and between the different stones of the shaft, should be dressed perfectly true to the axis of the column and to a true plane, so that the pressure will be evenly distributed over the whole area of the joint. Nothing but cement mortar should be used in these joints, and the outer edge of the joint for £ of an inch from the face should be left empty to prevent the outer edges chipping off.
If the column is built against a wall, the pieces from which the cap and base are cut should either extend into the wall or be secured by galvanized iron clamps.
Entablatures spanning porch openings, etc., may either be cut from one piece of stone, or, if of considerable height, of several pieces.
Fig. 111 shows a common method of building up an entablature, the corona and facia being in still another course above those shown. When jointed as in the figure the bottom joint should not be filled with mortar except at the ends.
The various stones composing the cornice and entablature should be well tied together with iron clamps, and especially at all external corners. It is also a good idea to tie the cornices of porches to the building by long rods built inside the mason work to prevent the porch from "pulling away" from the wall.