Hand Drill

A hand drill is among the simplest tools ever devised for producing rapid rotary motion in a rod: a vertical shaft, typically one to two feet long and about half an inch across, is spun by moving the operator's hands back and forth in opposite directions along it while pressing down. Many early societies used a hand drill as a fire drill, spinning the shaft against a wood hearth board to generate enough friction heat to start a fire, a technique still taught as a survival skill. The same spinning action, applied with a pointed or abrasive tip, was also used to bore holes into wood, stone and bone. Because the operator's hands drift down the shaft as it turns, they must be periodically returned to the top to keep the motion going.