HODSON, J. S.--Guide to Art Illustration. _London_, 1884. HUSON, T.--Photo-Aquatint. _London_, 1897. JACKSON, J. B.--An essay on engraving in Chiaro Oscuro. _London_, 1754. KIRKBRIDGE, J.--Engraving for Illustrations. _London_, 1903. KRISTELLER, P.--Early Florentine Woodcuts. _London_, 1897. KRISTELLER, P.--Die Strassburgher Bucher-illustration im XV. und XVI. Jahrhunderts. _Leipzig_, 1888. LIETZE, E.--Modern Heliographic Processes. _New York_, 1888. LINTON, W. J.--The Masters of Wood Engraving. _New Haven, Conn._, 1889. LINTON, W. J.--Wood Engraving in America. _London_, 1881. MADRAZO, J. DE.--Collection lithografica cuadros del Rey ... Fernando VII. 1824. MARTINEAU, R.--The Mainz Psalter of 1457 (Bibliographica, Vol. I.). MASSENA, A. P. V.--Etudes sur l’art de la gravure sur bois a Venise. _Paris_, 1895-6. MORIN, L.--French Illustrators. _New York_, 1893. MUTHER, R.--Die deutsche Bücherillustration. _Leipzig_, 1884. PAPILLON, J. B. M.--Traité de la gravure en bois. _Paris_, 1766. PENNELL, J.--The Illustration of Books. _London_, 1896. PENNELL, J.--Modern Illustration. _London_, 1895. PENNELL, J., and E. R.--Lithography and Lithographers. _London_, 1898. PINGRENON, R.--Les livres ornés et illustrés en couleur depuis le XV^e Siècle en France et en Angleterre. POLLARD, A. W.--Early Illustrated Books. _London_, 1893. POLLARD, A. W.--Italian Book Illustrations. _London_, 1894. ROUX, V.--Traité de gravure héliographique en taille douce. _Paris_, 1886. SCHNAUSS, J.--Collotype and Photo-lithography. _London_, 1889. SENEFELDER.--Complete Course of Lithography. _London_, 1879. SINGER, H. W., and STRANG, W.--Etching, Engraving, etc. _London_, 1897. SKETCHLEY, R. E. D.--English Book Illustration of To-day. _London_, 1903. SMITH, F. H.--American Illustrators. _New York_, 1893. STRANGE, E. F.--Japanese Illustration. _London_, 1897. VERFASSER, J.--The Half-tone Process. _London_, 1904. VIDAL, L.--Traité Pratique de Photo-lithographie. _Paris_, 1893. VILLON, A. M.--Traité Pratique de Photogravure. _Paris_, 1891. WHITE, J. W. G.--English Illustration, “The Sixties.” _Westminster_, 1897. WIESBACH, W.--Die Baseler Buchillustration des XV. Jahrhunderts. _Leipzig_, 1896. WILKINSON, W. T.--Photo-mechanical Processes. _London_, 1892. WOOD, H. T.--Modern Methods of Illustrating Books. _London_, 1887. CHAPTER VI. MISCELLANEA. Book edges and their decoration--Embroidered books--Cloth bindings--Account books--End papers--Small metal-bound books--Books bound in tortoiseshell--Chained books--Horn books. The projecting bosses and corners which occur in mediæval bindings were to protect them against the friction of other books which lay upon them, a thin piece of wood dividing them. The books were piled upon each other, so that if one of the lower ones was wanted it was necessary to remove the upper ones. This caused much trouble, so that in due time it was found better to stand the books up on end on shelves.