1936. First Issued. 256 pages. This is an ex-Library book. Paperback book with grey paper covers. Contains black and white illustrations and graphs throughout. Expected library inserts, stamps and inscriptions. Pages are mildly tanned, but text remains clear. Binding is firm. Mild marking to some pages throughout; text is not obscured. Paper covers have moderate shelf-wear, with noticeable curling to corners, and mild creasing. Spine and edges are moderately tanned, with noticeable scuffing to ends. Visible marks overall. Label to tail of spine. Book has a slight forward lean. Paper covers are slightly curled.