1929. Revised edition. 79 pages. No dust jacket. Grey paper covered boards. Black and white photographs and diagrams. Magazine cutting affixed at front. Pages with some foxing and tanning, particularly to endpapers and textblock edges. Binding remains firm. Small bookshop label to front pastedown. Boards have moderate shelf wear with mild bumping to corners and crushing to spine ends. All surfaces heavily tanned, particularly spine. Some additional heavy marks and liquid staining.