It is said to have been invented by Johann Kiefuss of Nuremberg in 1517, and the idea probably came from the spring driven tinder lighter in use at the time. The idea of this mechanism is simple. Have you ever used a modern lighter which has a flint pressed up against a roughened metal wheel? When you spin the wheel with your finger, the flint pressed against its surface throws off sparks. The same system was used in these firearms to create sparks as needed to ignite the gunpowder to fire the gun. No more waiting to get a wick lit, and no more stressing about it going out when the fog rolls in.