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Fig. 3.

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The tool which is most necessary next to the scale is the square (Fig. 4), and this should also be made with great accuracy. It is used to test two adjoining edges, to see if they are square with each other. In making anything of wood, one of the largest surfaces is generally made perfectly true, and marked with a little cross (x), designating it as the “face.” One of the adjoining edges—not a cross-grained one—is also made true and square with the first surface, and marked with a second cross, as the “working edge.” Then all the other measuring and squaring is done from these two surfaces.

Fig. 4.

The piece of wood to be tested should be held in the left hand, on a level with the eye, and the square held in the right hand, with one of the inner edges resting against the wood, and the other projecting over it is moved back and forth. Any unevenness in the wood will readily be seen. The outside edges of the square may also be used for testing the evenness of wide flat surfaces. It is made like the pattern, of two strips of wood, with a fitted joint glued together.