Figure 20  Armchair, Philadelphia, Pennsylvania, ca. 1765. Oak, hickory, maple, and tulip poplar. H. 37", W. 21 1/4" (seat), D. 15 1/4" (seat); seat height: 17 1/2"; seat depth/seat width: .741. (Courtesy, Perseus Books Group. Illustration taken from Charles Santore, The Windsor Style in America, Volumes 1 and 2 [1997; reprint, Philadelphia: Courage Books, 1981], 2: 94, fig. 75.) Like the chairs illustrated in figs. 11 and 12, this sack-back has arm knuckles with a large central lobe.