A machine with multiply barrels that revolve around a central axis is what you would call a gatling gun.

Richard Gatling the gun’s inventor, was on both sides of the war. While trying to sell his guns to the Union, he was a member of the Order of American Knights. The Knights were a group of sympathizers and saboteurs working for the Confederates. The gun had a crank that turned to make the barrels turn. Bullets were fed into the gun by a hopper at the top of the gun. The gun could shoot 600 rounds per minute. This made it a good choice for repelling an infantry attack.

During the Civil War the gun was not used very much. The only time it was used was in the siege of Pittsburgh. This was because the gun had a number of problems. First the gun’s barrels and chambers were not always aligned right so that would effect the velocity and accuracy. Plus the bullets were not suited right for the gun. They were paper cartridges so they sometimes were not sturdy enough to be fired by the gun. No guns were bought by the Union, but General Benjamin Butler purchased 12 of the guns.