70. Extrados.—The exterior curve of an arch, especially the upper curved face A. B is the Intrados or Soffit.
71. Engrailed.—Indented with small concave curves, as the edge of a bordure, bend, or the like.
72. Facet.—The narrow plain surface, as A, between the fluting of a column.
73. Fret, Fretwork.—Ornamental work consisting of small fillets, or slats, intersecting each other or bent at right angles. Openwork in relief, when elaborated and minute in all its parts. Hence any minute play of light and shade. A, Japanese fretwork. B, Green fret.
74. Frontal, also called Pediment.—The triangular space, A, above a door or window.
75. Frustums.—That part of a solid next the base, formed by cutting off the top; or the part of any solid, as of a cone, pyramid, etc., between two planes, which may either be parallel or inclined to each other.
76. Fylfat.—A rebated cross used as a secret emblem and worn as an ornament. It is also called Gammadium, and more commonly known as Swastika.
77. Gambrel Roof.—A curb roof having the same section in all its parts, with a lower, steeper and longer part. See Curb Roof and distinguish difference.
78. Gargoyle.—A spout projecting from the roof gutter of a building, often carved grotesquely.
79. Gudgeon.—A wooden shaft, A, with a socket, B, into which is fitted a casting, C. The casting has a gudgeon, D.