However simple it may appear in description to sew a book, it requires great judgment to keep down the swelling of the book to the proper amount necessary to form a good backing groove and no more. In order to do this, the sheets must from time to time be gently tapped down with a piece of wood or a heavy folding-stick, and great care must be observed to avoid drawing the fastening of the kettle stitch too tight, or the head and tail of the book will be thinner than the middle; this fault once committed has no remedy. If the sections are very thin, or in half sheets, they may, if the book is very thick, be sewn “two sheets on.” The needle is passed from the kettle stitch to the first band of the first sheet and out, then another sheet is placed on the top, and the needle inserted at the first band and brought out at band No. 2, the needle is again inserted in the first sheet and in at the second band and out at No. 3, thus treating the two sections as one; in this way it is obvious that only half as much thread will be in the back.