88. Interlacing Arch.—Arches, usually circular, so constructed that their archivolts, A, intersect and seem to be interlaced.
89. Invected.—Having a border or outline composed of semicircles or arches, with the convexity outward. The opposite of engrailed.
90. Inverted Arch.—An arch placed with the crown downward; used in foundation work.
91. Keystone.—The central or topmost stone, A, of an arch, sometimes decorated with a carving.
92. King Post.—A member, A, of a common form of truss for roofs. It is strictly a tie intended to prevent the sagging of the tie beam, B, in the middle. If there are struts, C, supporting the rafters, D, they extend down to the foot of the King Post.
93. Label.—The name given to the projecting molding, A, around the top of the door opening. A form of mediæval architecture.
94. Louver.—The sloping boards, A, set to shed rain water outward in an opening of a frame, as in belfry windows.
95. Lintel.—A horizontal member. A spanning or opening of a frame, and designed to carry the wall above it.