Figure 29  Auxiliary support for the seat of the chair illustrated in fig. 18: (a) 1/4" acrylic support plate beneath the original upholstery, (b) ventilation holes in acrylic support plate, (c) bolt and T-nut, (d) diagonal brace, (e) 4-ply laminated acid-free ragboard. (Drawing, L. Graves; artwork, Wynne Patterson.)