1951. First Edition. 103 pages. Dust jacket over brown cloth boards. Black and white diagrams throughout. Pages with some foxing and tanning, particularly to endpapers and textblock edges. Binding remains firm. Boards have moderate shelf wear with mild bumping and fraying to corners and crushing and fraying to spine ends. All surfaces tanned and sunned, particularly spine. Some additional marks and staining to surfaces. Unclipped jacket has moderate edge wear with tears, chipping and creasing. All surfaces heavily tanned, particularly spine.