The sheets are laid upon a table with the signatures (the letters or numbers that are at the foot of the first page of each sheet when folded) facing downwards on the left hand side. A folding-stick is held in the right hand, and the sheet is brought over from right to left, the folios being carefully placed together; if the paper is held up to the light, and is not too thick, it can be easily seen through. Holding the two together and laying them on the table the folder is drawn across the sheet, creasing the centre; then, holding the sheet down with the folder on the line to be creased, the top part is brought over and downwards till the folios or the bottom of the letterpress or print is again even. The folder is then drawn across, and so by bringing each folio together the sheet is completed. The process is extremely simple. The octavo sheet is generally folded into 4 folds, thus giving 8 leaves or 16 pages; a quarto, into 2, giving 4 leaves or 8 pages, and the sheets properly folded, will have their signatures outside at the foot of the first page. If the signature is not on the outside, one may be certain that the sheet has been wrongly folded.
I say generally; at one time the water or wire mark on the paper and the number of folds gave the size of the book.
There are numerous other sizes, but it is not necessary to give them all; the process of folding is in nearly all cases the same; here are however, a few of the sizes given in inches.
| Foolscap 8vo. | 6⅝ | × | 4⅛ |
| Demy 12mo. | 7⅜ | × | 4⅜ |
| Crown 8vo. | 7½ | × | 5 |
| Post 8vo. | 8 | × | 5 |
| Demy 8vo. | 9 | × | 5½ |
| Medium 8vo. | 9⅝ | × | 5¾ |
| Small Royal vo. | 10 | × | 6¼ |
| Large Royal 8vo. | 10½ | × | 6¾ |
