Fig. 2418.
Fig. 2419.
To test the alignment of end e, press a straight-edge s fair against its side face, as in [Fig. 2418], and measure the distance h. Then place the straight-edge on the other side face of e and measure the distance i, [Fig. 2419], and these distances both measuring alike, e will be true providing that the jaws at end f have not altered from their proper width apart.
Fig. 2420.