Such backs do not adhere quite firmly, and it is advisable to insert another narrower glued strip, opening the book in the middle, of course, to do this. After inserting the back, the book is closed, and the back will now lie close and tight to the book. It is trimmed at top and bottom with a sharp knife and finished off with a rasp if necessary.

The heavy boards are hinged on to this back. They are cut to fit, and, beginning at the fold b, are placed so that the edge of the board stands a little away from the joint.

Where it is possible to glue up hot, the back should be made in advance. It is, however, essential that the spring back should be slightly over rounded, that is to say, that its ends should first be pressed out so that they can be pushed on to the back; only thus can it be really effective, and must, moreover, be shaped to three quarters of a circle.

An apparatus recently put on the market for gluing without heat, solely by wrapping up in drilling, is little better than a toy, which saves neither time nor material. The inventor can hardly be in the trade certainly not a practical worker.

The prepared backs are fastened to the books as follows: Cut a strip of stout linen so that it projects a little at each end and 3 to 4 cm, at each side; glue the inside of the rounded back evenly, and then fasten in the linen strip so that it projects equally at ends and sides. At head and tail the ends are brought over on the outside, and the back thus made is forced on the book. Before doing so, a line should be drawn on the thin boards about 1 ½ to 2 cm. from the joint, glue up to this line; the strip with the back would be drawn up at both sides and then pressed down. To make these backs lie closer, a strip of packing may similarly be inserted.

So then the same work is done here with the glued up backs as in the old style with the packed spring backs; here the back is just hinged on cloth, there it is made from a piece of wrapper. The thick board is set on in the same way as in the other style of work, set off from the glued back about 1 to 1 1/2 cm To fill up this space, lay in each groove a piece of cord of suitable thickness which has been well pasted, rubbing in the paste quite smooth, and, after drying, paste over with stout paper.

Very thick books have a rather clumsy appearance with their many superimposed boards; this is improved by beveling on all four sides the upper thick board.

To protect the book, leather bands are pasted on the back, also something to add strength is generally put on at head and tail, which is then covered with especially strong leather. For covering, linen, mole skin; for heavy and extra work, pig skin and cow hide are used. Leather is, of course, always pared down, thoroughly coated with paste, well stretched over, and well rubbed down in all hollows at the joints, bands, &c. side panels are also let in and turned in. Where the back disappears under the thick board, the turn in is cut in almost up to the edge at b with sharp scissors; if it were cut right to the edge it would be visible, which must be avoided. For turning in at the head, it is obvious that the book must lie open as in the illustration.

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