Until the middle of the nineteenth century the inside of the barrel of a cannon had no thread or rifling. It was quite smooth and the projectiles fired from cannons were simply round balls. They did not have a large range and were not very accurate: it was extremely difficult to hit a target with them at distances of more than 3,000 meters.

Projectiles could not be made too large for they would have needed cannons with enormously broad barrels. Then the idea occurred of making long projectiles which weighed more. The inside of the barrel of cannons was rifled with winding lines. When the projectiles were fired it was twisted by these lines so that it came out of the cannon’s mouth spinning rapidly but kept in a straight line. Because of its shape farther and was more accurate.