1951. First Edition. 116 pages. Pictorial dust jacket over grey cloth. Black and white diagrams throughout. Pages with some foxing and tanning, particularly to endpapers and textblock edges. Binding remains firm. Boards have light shelf wear with minor corner bumping and crushing to spine ends. All surfaces tanned and sunned, particularly spine. Slight dent to edge of front board. Unclipped jacket has light edge wear with minor tears, chipping and creasing. Some tanning and foxing to all surfaces, particularly to spine.