1920. 3rd Edition, Revised. 350 pages. No dust jacket. Red cloth. Clipping about general optics inserted to front free endpaper. Slight cracking to hinges and gutters causing boards and binding to be loose. However, boards and pages throughout remain attached. Pages have light tanning and foxing throughout. Boards have moderate shelf-wear with bumping to corners and rubbing to surfaces. Light tanning to spine and edges with crushing to spine ends. Tears to cloth to edges.