Each method has its advocates, but so far as the present writer can learn, there seems to be little to choose from the standpoint of strength. It might seem that the tight-back book would be the stronger, but as a matter of fact in actual wear loose-back books seem to hold their own with the others. In fact when the soft, spongy papers are used the loose backs are obviously stronger. It seems clear that there is little choice one way or the other, and the question must be decided by the personal preference of the librarian.
JOINTS
In library binding French joints are now used in place of regular joints. Figure 14 shows plainly the difference between the two. In the regular joint it will be noticed that when the book is opened there is a sharp crease in one line from head to tail. In the French joint the strain is distributed over a much greater area. In regular joints the leather is sometimes pared at the joints to permit of easier opening of the book. In French joints the full thickness of the leather can be used. French joints are made by setting the boards away from the back about one-eighth of an inch. When the cover is put on it is necessary to crease between the board and the back while the leather is still damp.
An excellent illustration showing the anatomy of a joint may be found on page 51 of Dana's "Notes on bookbinding for libraries," ed. 2.
A Section of an Ordinary Joint with the board open shows that the creasing of the leather is concentrated on one line.
A Section of a "French Joint" shows how this creasing is distributed over a great surface, and so enables sufficient flexibility to be obtained with much thicker leather than can be used with an ordinary joint.
Figure 14.—French joint. From Report of the Committee on Leathers for Bookbinding. Edited for Society of Arts, London, 1905.
CORNERS
Corners on library books should be rounded to prevent the board from breaking if the book falls and to prevent the cloth from wearing through at this point. Rounded corners are peculiar to library binding. As a rule they are not made by cutting off a corner of the board, but by turning in the cloth diagonally from the corner and then from the side and end. Sometimes both methods are adopted. If government specification cloth is used it is probable that "library corners" will not be necessary.