1949. First Edition. 126 pages. No dust jacket. Brown cloth covered boards with gilt. Black and white diagrams throughout. Pages remain bright and clean with minimal tanning and foxing. Binding remains firm. A previous owner's name to front free endpaper. Pen inscriptions to rear free endpaper. Boards have heavy shelf wear with bumping and fraying to corners and crushing, fraying and tearing to spine ends and edges. Gilt lettering to spine is slightly dulled. Some additional moderate marks and staining. Boards are slightly bowed.