1925. Sixth edition. 388 pages. No dust jacket. Pictorial cloth covered boards. Black and white photographs and diagrams. Pages with some foxing and tanning, particularly to endpapers and textblock edges. Binding slightly loose. A previous owner's name to front free endpaper. Boards have heavy shelf wear with bumping and fraying to corners and crushing and fraying to spine ends. All surfaces tanned and sunned, particularly spine. Heavy crease to front board.