1955. Third Impression. 256 pages. No dust jacket. Black cloth covered boards. Black and white diagrams throughout. Pages with some foxing and tanning, particularly to endpapers and textblock edges. Binding remains firm. A previous owner's name to front free endpaper. Minor pencil inscriptions to front pastedown. Boards have moderate shelf wear with mild bumping and fraying to corners and crushing and fraying to spine ends. Some marks and staining to surfaces. Boards are slightly bowed.