a well known tool used by mechanics, consisting of an iron head, fixed crosswise upon a handle of wood. There are several sorts of hammers used by blacksmiths; as, 1. The hand-hammer, which is of such weight that it may be wielded or governed with one hand at the anvil. 2. The up-hand sledge, used with both hands, and seldom lifted above the head. 3. The about-sledge, which is the biggest hammer of all; and held by both hands at the farthest end of the handle; and being swung at arms length over the head, is made to fall upon the work with as heavy a blow as possible. There is also another hammer used by smiths, called a riveting hammer; which is the smallest of all, and is seldom used at the forge unless upon small work. — Carpenters and joiners have likewise hammers accommodated to their several purposes.