1930. No edition remarks. 113 pages. Pictorial dust jacket over pictorial paper covered boards with cloth spine. Black and white diagrams throughout. Colour frontispiece. Pages remain bright and clean with minimal tanning and foxing. Binding remains firm. Minor pencil inscriptions to front free endpaper. Boards have mild shelf wear with light rubbing and corner bumping. Some light marking and tanning. Unclipped jacket has light edge wear with minor chipping and creasing. Some tanning and foxing to all surfaces, particularly to spine.