1951. This edition. 186 pages. Black and white photographs and diagrams. Pages remain bright and clean with minimal tanning and foxing. Binding remains firm. Some marginalia. Dedication to front free endpaper. Boards have moderate shelf wear with mild bumping and fraying to corners and crushing and fraying to spine ends. All surfaces heavily tanned, particularly spine. Gilt lettering to spine is slightly dulled. Unclipped jacket has light edge wear with minor tears, chipping and creasing. Some tanning and foxing to all surfaces, particularly to spine.