There are various ways of sewing, according to the size and thickness of the sheets of a book. A volume consisting of thick sheets, or a sheet containing a plate or map, should be sewn singly the whole length, in order to make the work more secure and solid. Great care should also be taken not to draw the thread too tight at the head or foot of the book. The thread, in order to keep the book of the same thickness at the ends and centre, should be drawn parallel with the bench, and not downwards, as is too frequently the case. Upon the proper swelling of the back mainly depends the regularity of the round and firmness of the back in the after-stages of the binding.
When a book is sewed _two sheets on_, three bands are generally used. Taking the sheet and fixing it on the bands, the needle is inserted in the mark made for the kettle-stitch and brought out by the first band; another sheet is then placed, and the needle introduced on the other side of the band, thus bringing the thread round it, sewn in like manner to the middle band, and continued to the third, when, taking again the first sheet, it is sewn from the third band to the other kettle-stitch, where it is fastened, and another course of two sheets commenced, and so continued to the last sheet but one, which is sewn the whole length, as directed for the first sheet, as also the end-paper. Three bands are preferable to two, the book being more firm from being fastened in the middle, which is the only difference in sewing on two and three bands.
Half-sheets, to obviate the swelling of the back too much, are usually sewn on four bands, which admit of three on a course: the first sheet is sewn as in three bands, from the kettle-stitch to the first band, the next to the second, and the third takes the middle space; then the second sheet again from the third to the fourth band, and the first from thence to the other kettle-stitch. The third sheet having only one stitch, it is necessary that, in sawing, the distance from the second to the third band should be left considerably longer than between the others. Quartos are generally sewn on five bands to make the work firmer, but if in half-sheets, as in the folio size, six or more are used, sewing as many sheets on as bands, giving each sheet but one tack or sewing, and piercing the needle through the whole of the course at each end or kettle-stitch before fastening the thread. This, which gives sufficient firmness, is necessary to prevent the swelling of the back which a less number of sheets in a course would make and spoil the appearance of the binding.