NAME. Imams.
Billet not,e 6 x 8 Octavo note 7 x 9 Commercial note 8 x 10 Packet note 9 x 11 Bath note Six 14 Letter 10 x 16 Commercial letter 11 x 17 Packet post llf x 18 Ex. packet post 111 x 18i Foolscap 12i x 16 Classifying Books. — Books are printed on sheets of paper of varying sizes, which are afterwards folded and trimmed to the size of book desired. One sheet of paper thus folded is called by printers a " signature." The marks sometimes found at inter vals at the bottom of pages as a, b, c, 1, 2, 3, la, 2a, etc., are what printers call " signature marks." They are placed on the first page of each sig nature to indicate the order of the signatures for the convenience of binders in folding and gathering the sheets. These are less commonly used than formerly. In the early days of the printing industry book papers were practically of the same size. Hence the number of times a sheet was folded to make one signature of a book was an accurate means of clas sifying book sizes. A sheet of paper
folded once into leaves making 4 pages was then called a folio; 1 folded tvvice into 4 leaves making 8 pages a quarto, and so on, according to the following table: 2 leaves folio, 4 pp.
4 leaves quarto, 4to, 8 PP.
8 leaves octavo, 8vo, 16 pp.
12 leaves duodecimo, 12mo, 24 pp.
16 leaves 16mo, 32 pp.
18 leaves 18mo, 36 pp.
24 leaves 24mo, 48 pp.
32 leaves 32mo, 64 pp.
These terms, in deference to custom, are still retained; but on account of the extent to which paper is manufac tured to order in a great variety of shapes and sizes, these terms are no longer accurate. They may be ap plied without regard to the sizes of the sheet folded, which may vary widely. Hence publishers apply them rather loosely, according to the ap proximate size of the volume com pared to the earlier standards. The following table indicates roughly the most usual sizes: