The wheel lock is a system for firing a gun. It works in much the same way as a cigarette lighter. When the trigger is pulled, a wheel rubs against a flint, producing a spark that ignites the gunpowder. The explosion of the gunpowder propels the ammunition down the gun barrel. Historians credit a Nuremberg watchmaker with inventing the wheel lock 15 years after Leonardo originally drew it. (See also Gun.)
