1951. Sixth Edition Reprinted. 752 pages. Green dust jacket over blue cloth. Contains black and white in-text illustrations. Pages are lightly tanned and foxed throughout. Binding is slightly shaky. Light scuffing to text-block edges. Text-block is loose from binding. Boards have moderate edge wear with bumping to corners and rubbing to surfaces. Crushing to spine ends with small splits and fraying to cloth. Light tanning to spine and edges. Unclipped jacket has heavy edge wear with some areas of loss, heavy tears, chips and creasing. Moderate tanning to spine and edges. Heavy scuffing to surfaces, with some water staining front.