Hammer

A hand tool consisting of a heavy, usually steel, head fixed to a handle and swung to deliver a concentrated impact, acting as a force amplifier that turns the effort of a swing into a blow strong enough to drive a nail, shape metal at the forge, or break rock. The handle, traditionally hickory or ash for its shock-absorbing qualities, keeps the striking hand well clear of the point of impact. Working forms vary by trade: the claw hammer, with a curved claw opposite its striking face for driving and pulling nails, is the everyday carpenter's tool; the ball-peen hammer, rounded on one face and flat on the other, is a metalworker's tool for shaping and riveting; the sledgehammer, heavy-headed and long-handled, delivers the force needed for demolition or heavy forging; and the mallet, faced in wood or rubber, strikes without marring a softer material. At the smith's forge the hammer is the essential companion of the anvil and tongs, and on the woodworker's bench it drives nails, chisels and joinery besides. The hammer is often named humanity's oldest tool: unhandled stone hammerstones are known from around 3.3 million years ago near Kenya's Lake Turkana, and the practice of lashing a handle to the head with leather or sinew, which turned a stone into a true hammer, is dated to roughly 30,000 BCE.