As has been already explained above, and as is clearly indicated by its name, this saw is intended for the cutting of wood across the grain at right angles to the direction of the fibers. It differs from the rip saw principally in the size and arrangement of the teeth, those of the cross-cut saw being smaller, usually numbering about eight to the inch. The shape of the teeth in the two kinds of saws is also different, as the front of the tooth in the cross-cut saw, instead of being straight as in the rip saw, is inclined backward at an angle of about 115 degrees, while the back of the tooth slopes at an angle of about 125 degrees. The slope of the teeth should be varied according to the hardness of the wood to be sawed, those given above being suitable for soft wood. The bevel on the front of the tooth should also be varied according to the hardness of the wood, so as to give a more or less sharp cutting edge. In the saw described above this bevel should be about sixty degrees, while for harder wood it should be as much as seventy-five degrees. In general, the harder the wood to be cut, the smaller should be the teeth of the saw. Fig. 21 shows a cross-cut saw with the slope of the teeth indicated, and Fig. 22 shows how the teeth should be filed. The cross-cut saw is also known as the "panel saw."