To refer once more to the diagram. Take a sheet of paper supposed to have come from the mould and double it in half at the line AX. The water-mark will in that event appear in the centre of the half sheet, and the folded paper is of folio size. Now fold the paper the contrary way, and the water-mark will appear at the bottom, but cut in half; the paper thus folded is quarto (4to). Now fold it the contrary way again, and a section of the water-mark will appear at the top; the paper thus folded is octavo (8vo). We can go on folding, and in every subsequent case the watermark will appear at the edges, while, as the paper gets smaller and smaller, the sizes are styled 12mo, 16mo, 32mo, and so forth.
In the example given, a book made of the sheet of paper in question would be a pot folio, pot 4to, pot 8vo, and so on; but as larger-sized papers were used, another book might be a post 8vo, or a crown 4to, &c., according to circumstances.
As stated, this is one way of finding out the size of an old book; but there is another way—by means of the "signatures," which consist of small letters or figures at the foot of the page of nearly every book. The leaves (not pages) must be counted between signature and signature, and then if there are two leaves the book is a folio, if four a 4to, if eight an 8vo, if twelve a 12mo, if sixteen a 16mo, and if thirty-two a 32mo. Take, as an example, this very book you hold in your hand, and it will be found that there are eight leaves between signature and signature; hence it is an 8vo, though a small one, owing, of course, to the small size of the paper from which it has been made, viz., crown. Had it been a little smaller (still preserving its oblong shape) it would have been a foolscap 8vo, if somewhat larger a demy 8vo, if larger still a royal 8vo, and largest of all imperial 8vo. The quartos and folios are governed by identical rules, and hence in the trade the sizes of books are very numerous.
Simple as this method of computation may appear, a great deal of controversy has taken place on the subject—so much so, indeed, that there are people to be found who stoutly maintain, and adduce proof to show, that what looks like a 4to is in reality an 8vo, or vice versâ. It would be out of place to enter into a discussion of this nature, and, therefore, I should advise the young collector to count the leaves between signature and signature, and to abide by the result, regardless of all the learned arguments of specialists. If there are no signatures, and the book is an old one, then study the position of the water-mark.
As examples, it will be sufficient to note that the Illustrated London News is folio, Punch is 4to, and the Cornhill and nearly all the monthly magazines are large 8vos. There is a large number of varieties of each size, but on the whole books which approximate to the sizes of magazines are of the sizes named. Occasionally in judging by the eye in this manner a mistake may be made; but of one thing there is no doubt, that a vast amount of argument would have to be expended upon the subject before the judgment could be proved to be wrong.
Paper-makers at one period made their sheets in frames of a given size, so that it was a comparatively easy matter to distinguish the size of a book at a glance. Now-a-days, however, there appears to be but little uniformity in this respect, and the difficulty is consequently considerably increased. The following measurements will, however, be found approximately correct, and they may be utilised in a practical manner by taking a sheet of brown paper of the required size and folding it as previously mentioned, thus forming crown 8vos, crown 4tos, elephant folios, &c., at will. The practice is good, and it will not need to be often repeated.
| a sheet of | foolscap | measures about | 17 in. x 13 in. |
| " | post | " | 19 in. x 15 in. |
| " | crown | " | 20 in. x 15 in. |
| " | demy | " | 22 in. x 17 in. |
| " | royal | " | 24 in. x 19 in. |
| " | imperial | " | 30 in. x 22 in. |
| " | elephant | " | 28 in. x 23 in. |
| " | atlas | " | 34 in. x 26 in. |
The only paper used, as a general rule, for making up into 8vo books is foolscap, post, crown, demy, royal, and imperial; 4to books are made up of all the sizes; though elephant and atlas are chiefly devoted to folios.
I now take leave of this branch of the subject, and return to water-marks, which, as previously stated, were formerly used, as they are now, for trade marks, and as trade marks only.