Firing a Cannon

Eight soldiers were needed to fire each huge cannon here: a chief of detachment who gave commands, a gunner, and six cannoneers. The chief of detachment likely stood toward the back of the casemates. Firing began with the cannon toward the back of the lower part of the carriage, called the chassis, while the gunner stood behind it with a hand or thumb over the vent hole to keep oxygen from igniting any embers left from previous firing. One cannoneer sponged the barrel to extinguish embers, another received the cartridge or gunpowder charge, another held the rammer, and another passed the charge, which could weigh as much as 18 pounds. The gunner kept his hand over the vent while the sponge was removed, the rammer exchanged, the cartridge prepared for insertion, and two more cannoneers used tongs to carry a shell weighing about 100 pounds to the cannon. Next, two men lifted the shell into the barrel, another adjusted the elevating mechanism at the base of the cannon to angle it for aiming and keep the cannonball from rolling out, and two others used handspikes in the carriage wheels to move the cannon close to the embrasure in the wall. With the cannon now at the front of the chassis, the gunner pierced the cartridge through the vent hole with a sharp pick, then sighted down the barrel, sometimes using a transit or sight, to ensure proper aim. Another cannoneer handed the gunner a friction primer, a wire inserted into a brass tube packed with fulminated mercury, with a ring on the wire attached to a lanyard, while two others used iron bars in traverse wheels on the chassis to move the cannon along tracks called traverse circles and aim it. Finally, the gunner inserted the friction primer into the vent hole and stepped away, and another cannoneer pulled the lanyard. Pulling the wire from the primer tube created friction and heat that forced a flame into the cartridge, igniting the gunpowder and firing the cannon. The other soldiers stood nearby ready to begin the process again. When the cannon fired, recoil drove the carriage and barrel back to the rear of the chassis, and the metal doors on the embrasure slammed shut.

Phippsburg, Maine · United States