PLASTER.--The plastic material, of which the groundwork is lime and sand, used to cover walls internally and to form ceilings. Sometimes employed as a covering to walls externally. PLINTH.--The base of a wall or of a column or range of columns. PORTAL.--A dignified and important entrance doorway. PORTICO.--A range of columns with their entablature (and usually covered by a pediment), marking the entrance to a Renaissance or Classic building. PRISMATIC RUSTICATION.--In Elizabethan architecture rusticated masonry with diamond-shaped projections worked on the face of each stone. PROFILE.--The contour or outline of mouldings as they would appear if sawn across at right angles to their length. PORCH.--A small external structure to protect and ornament the doorway to a building (rarely met with in Renaissance). QUATREFOIL.--A four-leaved ornament occupying a circle in tracery or a panel. RAFTERS.--The sloping beams of a roof upon which the covering of the roof rests. RAGSTONE.--A coarse stone found in parts of Kent and elsewhere, and used for walling. RECEDING PLANES.--(See Plane.) RECESS.--A sinking in a building deeper than a mere panel. RECESSING.--Forming one or more recesses. Throwing back some part of a building behind the general face. RENAISSANCE.--The art of the period of the Classic revival which began in the sixteenth century. In this volume used chiefly to denote the architecture of Europe in that and the succeeding centuries. RIB (in Gothic vaulting).--A bar of masonry or moulding projecting beyond the general surface of a vault, to mark its intersections or subdivide its surface, and to add strength. RIDGE.--(1) The straight line or ornament which marks the summit of a roof; (2) the line or rib, straight or curved, which marks the summit of a vault. ROLL.--A round moulding. ROSE WINDOW.--A wheel window (which see). RUBBLE.--Rough stonework forming the heart of a masonry wall; sometimes faced with ashlar (which see), sometimes shown. RUSTICATION (or RUSTICATED MASONRY).--The sort of ornamental ashlar masonry (chiefly Classic and Renaissance) in which each stone is distinguished by a broad channel all round it, marking the joints. RUSTICS.--The individual blocks of stone used in rustication (as described above). SCREEN.--An internal partition or inclosure cutting off part of a building. At the entrance to the choir of a church screens of beautiful workmanship were used. SCROLL MOULDING.--A round roll moulding showing a line along its face (distinctive of decorated Gothic). SCROLL WORK.--Ornament showing winding spiral lines like the edge of a scroll of paper (chiefly found in Elizabethan).