1964. First Edition. 70 pages. Illustrated dust jacket over blue cloth with gilt lettering. 'Progress Of Science' series. Illustrated by John W. Wood. Pages remain bright and clear with minimal tanning and foxing. Binding remains firm. Boards have mild edge-wear with slight rubbing to surfaces. Gilt lettering is bright and clear. Unclipped jacket has light edgewear with tears and creasing. Price sticker to front flap.