Books reach the bookbinder either in the sheets just as they left the printing press or folded and stitched. This folding and stitching is, of course, part of the binder's work, so we will begin with the sheet as it left the press; this sheet must in the first place be folded ready for further manipulations.

By folding we mean the arranging of the parts of a sheet in the order of succession required for reading. To facilitate this work the printer marks not only the page numbers on each sheet but also gives each sheet a number, these numbers being known as signatures. Every sheet is printed on both sides; the front side is called the first side, the other side the perfecting impression. Both sides are marked by a number or (more rarely) a letter. This mark stands at the right-hand side at foot of first page and is called the first signature; the second signature takes the same position on the second side of the sheet, that is, on page 3. Take any book haphazard and you will find the true signature on the first and the second signature on the perfecting impression, always in the same position. In order to show at a glance whether the signature is the first or the second, the compositor adds an asterisk, thus-

1 first 1*second or A first A * second signature.

We will see later that there is still another reason for the signature in the place mentioned.

When the sheets are to be folded, all the sheets of an impression are laid one on top of the other and all lying the same way. The modern quick-printing presses gather the sheets automatically, so that a sheet is rarely laid the wrong way, excepting through want of care in looking over them, or in the knocking-up in the printing office a few sheets or a whole batch are thrown out of order. According as we are dealing with folio, 4to, or 8vo format we must order the gathering of the sheets and, of course, the position of the signature. The commonest format is 8vo, that is to say, the size which gives eight printed leaves (or 16 pages) to the sheet. At the same time, the method of folding this format is the most economical and includes the others as well.

When folding 8vo sheets the pile lies in front of the worker in such a way that all the second signatures lie uppermost at the foot of the outside right page and all the first signatures at the left on the under side of the sheet; or, in other words, all first side leaves are turned face downward and perfecting impressions face upward.
Printed sheets are never folded according to the edges of the paper, but always registered by the printed columns or the page numbers. The novice finds this by holding the sheet against the light, but the experienced worker is able to fold the sheet without so much as lifting it from the table.

The manipulations for the folding at an two sheet are as follows: The right hand holds the paper folder and creases down the folds, the left gathers the sheets and moves them about aided by the right.

1.-The right hand takes hold of the sheet at the right a little below the middle, brings it over to the left, when it is taken by the left hand and properly adjusted according to page numbers or comer of printed page (Fig. 2).

2.-Crease with folder from bottom to top (the folder is held slanting to the crease, but the edge is used).

3.- With the right hand the right and the left hand the left of the folded sheet are taken hold of at about the middle of the longer sides, nip together, make a short turn so that the left hand brings the sheet with its fore-edge to the folder's body, the left hand lets go, takes hold of the sheet between both ends at the middle fold, and adjusts pages and edge of fold alike (Fig. 3).

4.-The right hand creases from top to bottom.

5.-Left hand turns sheet over to other side, both hands take hold as before, nip together last fold, and adjust pages and fold.

6.-Crease from top to bottom, laying aside sheet to left, fold lying to right.

Bookbinding Tools Part 2