Despite this leveling work, the pasted part will still be noticeable; the thoroughly dried sections are therefore taken in batches of four or five, knocked up at the back edge, and the thick part carefully hammered on a stone or iron bed.

Just as paper strips have been used in this work, linen can be used for guarding atlases and mounting large maps which are intended for long and constant use. To fill out the back, cardboard or thick drawing paper the thickness of the plates (or, if anything, a little less) is used. Of this material strips are cut 1 cm in width and same length as the height of the work, cutting a strip for each plate of course. Besides these strips, cut some soft white calico into strips 3 cm in width. These are pasted, laid quite straight upon a clean board, two strips of paper are placed in the centre side by side on top of the pasted strip, and at right and left of each a map is hinged on, the first face downwards, the second face upwards. .When dry, the section so made is creased in the middle, knocked down with the hammer, and pressed for a time. By this method two plates are hinged on each guard; by the other each plate had its own guard.

Many books are issued with plates larger than the format of the book itself; they must be brought to the right size by folding, but in such a way that the folded plate is secure from injury during any subsequent trimming.

Before making a single fold in the plate, the worker should clearly see his way through his scheme for folding, so as to bring the plate to the size required with the smallest possible number of creases. Plates which are slightly wider and longer than the size of the book are easily made to fit if they are folded once or, if necessary, twice across the middle, pasting the edge of one fold on a guard and then fixing in its place in the book.

If this will not do, the plate must first be folded up from the bottom edge far enough to escape damage in trimming, and then the long side must be similarly folded. Larger plates must take more folds, always working on the principle that the length of the book should first be obtained in the best possible way, and afterwards the width is taken as the guide in making the folds.

In doing this the plate must be folded now to the front, then to the back, so that on drawing it out it opens in a zig zag fashion. For the sake of clearness we give illustrations showing the most general methods of folding. The part marked A is secured in its place in the book by mounting on a paper guard; but one may, by cutting out the map properly, leave a small margin which will serve as a guard as shown in Figs. 10, 12, and 13.

In all cases, however, it is essential that the thickness of the folded plates should be equalized by inserting guards in the back of the book.

Formerly, when several plates were inserted one after the other, it was customary to place them in such a way that they were trimmed at top and bottom alternately; now they are placed so that they are all trimmed at the top edge: this is much better, because it keeps the top edge smooth and close, thereby keeping out dust and insects. The accompanying sketches are based upon this principle.

Forwarding Part 6