The book, ready for sewing and in proper order of sections, is laid near the worker’s hand, and he, or she, takes it up by sections, one at a time. The section to be worked upon is laid downwards on the little platform, with its back close against the bands, and the worker’s left hand keeps the section open in the middle, while with the right hand a thread is drawn through the back fold, from the inside to the outside, round the band, and then back from the outside to the inside, and so on until all the bands have been caught round. Then to end up, the thread is passed through near the extreme end of the fold and knotted, forming what is called a “kettle stitch,” and from this point the whole operation is repeated, backwards, with the next section. It sounds complicated, but is not so really, and several sections could have been sewn together in the time that it has taken me to describe the sewing of one of them. [Illustration: FIG. 28.--Faulty sewing over a band.] Now comes an interesting point, and that is the exact way in which the threads are passed over the bands. We will first see that if the thread is drawn through the back fold of the section, round a hand and back again through another hole, that there is a weak construction, inasmuch as the thread will have a strong tendency to cut through the paper at _a_ and _b_, because there is in each case a side strain. It therefore seemed necessary that the thread should make its return journey by the same hole through which it emerged, but if simply done, this did not mend matters much, as the strain still tended to pull this hole open wider. A line of exit and entrance without any side pull was needed, and this was found by means of a very clever device. A broad band of leather or vellum was cut through lengthways, leaving a solid piece at each end. [Illustration: FIG. 29.--Mediæval sewing round double band.] Now when the sewer came to this band he ran the thread straight through the slot, then brought it round the entire band, under it, between it and the back of the book, and down again, back through the slot, and in at the same point from which it emerged. The result of this is that there is no strain at all on the needle hole through which the thread passes, as the pull is quite straight both coming and going. This is undoubtedly the best form of sewing a book on bands, and a book so treated is said to be sewn on “double bands.” But our recent work is not always true, although from the outside it appears correct, because in numbers of cases such double bands are simply glued on the outside of the back, the real sewing, of a very inferior kind, possibly even done by machinery, being hidden underneath the leather. Few great binders except Charles Lewis have ever used sham bands.