1930. No edition remarks. 83 pages. Pictorial dust jacket over green 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. Some mild marks and staining to surfaces. Boards are slightly bowed. Unclipped jacket has light edge wear with minor tears, chipping and creasing. Some tanning and foxing to all surfaces, particularly to spine.