Bow drill
From Academic Kids
The bow drill has been used used by ancient Sumerians and other groups to drill holes in a piece of wood. The drill stick is held over another piece of wood, the hearth, into which the hole is being drilled. The "drill stick" is turned with the help of a bow. The heat thereby produced by friction would set nearby dust and tinder aflame.
Bow drills can also be used with a drill bit to bore a hole in wood for woodworking purposes.
