This is for the sake of facility in cutting into the wood at any angle.
There are two principal forms, the common ax and the two bitted ax, the latter used chiefly in lumbering.

There is also a wedge-shaped ax for splitting wood.

As among all tools, there is among axes a great variety for special uses.
[Illustration: Fig.139.

Ax.] [Illustration: Fig.140.Shingling Hatchet.] [Illustration: Fig.141.

Carpenter's Adze.] The _hatchet_ has, beside the cutting edge, a head for driving nails, and a notch for drawing them, thus combining three tools in one.