III. THE RIBS (Fig. 1. a).
The ribs should be 1¹⁄₂ m/m. thick, and very neatly and evenly planed; the height should be about 30 m/m. at first. The ribs are curved to their correct form by means of a hot bending iron, or still better by a copper clew, and then glued to the blocks. After this, the ribs next to the back are to be made true to receive the linings. The latter must be 8 m/m. high, 2¹⁄₂ m/m. thick, and must be made of lime-wood. The middle linings are to be let into the blocks, so that they cannot break loose. The blocks must also be made of lime-wood. The edges of the ribs and the surface of the rim, before being glued on to the prepared back, must again be very carefully adjusted, so that they appear like one even surface. This being done, the superfluous wood of the blocks must be cut away to the shape of the mould (see Fig. 5). The ribs from the bottom block to the side blocks are then regulated to a height of about 30 m/m., and from the side blocks to the top block (Fig. 3) they are gradually decreased by 2¹⁄₂ m/m., that is, until 27¹⁄₂ m/m. is reached. This diminution in the height is most practically thought out and executed by Stradivarius, the belly obtaining thereby a tension which offers the necessary resistance to the neck. The upper linings must be adjusted to the ribs in the same way, and as a matter of course, they must be curved to the shape of the ribs. The superfluous wood of the blocks being cut away, the mould is removed.