The first thing is to hunt among some pieces of old ribs for a part that will match well. This takes some time. At last an old rib is found that appears just the thing—a part of it only will be required.
The next requisite is a mould or piece of wood cut exactly to the curve of the inside of the rib; this must not be roughly done, or any idea of "near enough" being thought of; if it does not fit exactly, then the pressure to come against it will be unequal in parts. If cut from a little block of soft wood the cutting will not take long, and the trouble be amply repaid by the result.
An exterior mould will be as necessary as an interior, and if the original rib is of fairly equal substance, the two moulds may be tried one against the other, and should fit nicely.
The ragged openings and rotten part of the original rib having been carefully examined with regard to the size of the fresh piece to be inserted, a line is marked by soft chalk as to the position and extent to be covered by the fresh wood. The aperture to admit the fresh piece of rib must be determined upon exactly, and be cut with the utmost neatness. Before doing this, however, the question must be gone into, and settled definitely, as to whether the fresh piece is to be pressed on from the outside or from the inside.
The choice must be in favour of the more convenient, or that which will be most likely to lead to the best results. As the sides of the aperture taken longitudinally must be cut at an acute angle and not upright, the convenience of cutting the edges of the opening from the outside will be decidedly better and more handy for obtaining the desirable sharpness of edge.
As a matter of course, the piece must be tried on again and again until it is clearly a good fit all round. When in a satisfactory state it will, when tried finally, be elevated a trifle above the surrounding wood.
The angle at which the upper and lower portions fit has no need to be cut so acutely as at the ends.
Everything being ready, including some strong clean glue, this latter will require painting over the surfaces that are to be closed together until absorption has ceased, and not before this are the parts to be brought home, or the absorption or soaking into the wood will continue, leaving no glue for holding the two surfaces.
When quite ready, the interior block of wood or mould will be held in position by the hand.
As usual, the piece of paper on the face of the mould will be used for preventing the glue holding on to it. The piece of fresh rib is now placed in position, and the outer mould (faced with paper, of course), applied. The screw cramps are now affixed, tightly wound up, and left for drying.