1890. Fourth edition. 384 pages. No dust jacket. Blue cloth covered boards with gilt. Black and white diagrams throughout. Black and white frontispiece. Pages with some foxing and tanning, particularly to endpapers and textblock edges. Binding remains firm. Boards have heavy shelf wear with bumping and fraying to corners and crushing and fraying to spine ends. All surfaces heavily tanned, particularly spine. Gilt lettering remains bright and clear. Some additional moderate marks and staining.