Red-Hot Cannonballs

Solid cannonballs were heated in a hot shot furnace so gun crews could fire red-hot projectiles at wooden warships and set them ablaze. The process involved several soldiers: one maintained the coal fire and loaded the cannonballs, after 30 minutes a second removed the heated balls with tongs, and a third cleaned them with a rasp, while others carried them in ladles to the guns around the fort. The idea of setting fire to enemy warships this way can be traced to the ancient world. The advent of explosive shot and ironclad ships in the Civil War eventually made this kind of furnace obsolete, but because oceangoing ironclads were not common, it remained viable for use against wooden ships long after the war. The hot shot furnace was completed in 1863 and refurbished in 2004, and it is believed to be the largest and the last hot shot furnace built in the United States.