(5) Head and tail, the top and bottom of the back.
(6) The head-band and head-cap, the fillet of silk worked in buttonhole stitch at the head and tail, and the cap or cover of leather over it. The head-band had its origin probably in the desire to strengthen the back and to resist the strain when a book is pulled by head or tail from the shelf.
(7) Boards, the sides of the cover, stiff or limp, thick or thin, in all degrees.
(8) Squares, the projection of the boards beyond the edges of the book. These may be shallow or deep in all degrees, limited only by the purpose they have to fulfil and the danger they will themselves be exposed to if too deep.
(9) Borders, the overlaps of leather on the insides of the boards.
(10) Proof, the rough edges of leaves left uncut in cutting the edges to show where the original margin was, and to prove that the cutting has not been too severe.
The life of bookbinding is in the dainty mutation of its mutable elements—back, bands, boards, squares, decoration. These elements admit of almost endless variation, singly and in combination, in kind and in degree. In fact, however, they are now almost always uniformly treated or worked up to one type or set of types. This is the death of bookbinding as a craft of beauty.
The finish, moreover, or execution, has outrun invention, and is the great characteristic of modern bookbinding. This again, the inversion of the due order, is, in the opinion of the writer, but as the carving on the tomb of a dead art, and itself dead.
A well-bound beautiful book is neither of one type, nor finished so that its highest praise is that "had it been made by a machine it could not have been made better." It is individual; it is instinct with the hand of him who made it; it is pleasant to feel, to handle, and to see; it is the original work of an original mind working in freedom simultaneously with hand and heart and brain to produce a thing of use, which all time shall agree ever more and more also to call "a thing of beauty."