1949. First Edition. 127 pages. Pictorial dust jacket over pictorial cloth covered boards. Black and white diagrams. Pages with some foxing and tanning, particularly to endpapers and textblock edges. Binding remains firm. Minor inscriptions to front endpapers. Boards have mild shelf wear with light rubbing and corner bumping. Some mild marking and tanning. Unclipped jacket has light edge wear with minor tears, chipping and creasing.