In striking with the hammer, the wrist, the elbow and the shoulder are one or all brought into play, according to the hardness of the blow.

The essential precautions are that the handle be grasped at the end, that the blow be square and quick, and that the wood be not injured.

At the last blow the hammer should not follow the nail, but should be brought back with a quick rebound.

To send the nail below the surface, a nailset is used.

(See below.) [Illustration: Fig.163.Drawing a Nail with Claw-Hammer.] The claw is used for extracting nails.