coloring matter on the book. It can now be done with a machine operated by hand which sprays the coloring matter on the book. Occasionally the top of the book is burnished with an agate or blood stone.

Occasionally also it may be desirable to gild the top of a book which is being rebound. When this occurs it is not a process to which the librarian need give much attention, except to be sure that good gold is used.

16. Gluing

The back of the book is then slightly glued. The glue must be very hot and quite thin, and must be thoroughly worked into the back. By placing books in a pile a number can be done at a time.

17. Rounding

As soon as the glue has stiffened but before it is hard the book is rounded. This must be done by experts and is a process which must be seen to be understood. The book is placed on the table with the fore edge toward the workman who then hammers the part of the back lying uppermost in such a way as to force the upper part of the book toward the workman. The book is then turned over and the process repeated. After a few operations like this the back of the book becomes rounded and the fore edge concave.

18. Backing

The book is then placed in a backing press allowing about an eighth of an inch to project, and screwed very tight. With a backing hammer the rounding process is continued and the sides of the book forced down over the edge of the press to form a projection against which the edge of the board for the side rests, forming the joint. In hammering, the workman begins at the proper distance from the center of the back so that he can force the backs of the other signatures over on each side toward the edge. (Fig. 9.)