It was the end of an era: the advent of the ironclad made traditional wooden-hulled warships obsolete. Despite this, the Confederates used a centuries-old device here: the hot-shot furnace. Inside the furnace, solid shot were heated red-hot. Clay wads of wet hay were then inserted between the powder and the ball to keep the heat from igniting the powder prematurely. When fired at a wooden ship, the sizzling missile could set the vessel ablaze.
The photographers who visited Drewry's Bluff in 1865 found the quaint little hot-shot furnace irresistible, and made at least three different views of it. Not surprisingly, the furnace here was never used in battle. This incredible image was taken from where you now stand.
"Furnaces for heating shot are erected at the forts on the sea-coast. These furnaces hold sixty or more shot. The shot being placed, and the furnace cold, it requires one hour and fifteen minutes to heat them to a red heat....Small charges should be used in hot shot firing, varying from one-fourth to one-sixth of the weight of the ball. Balls fired with small velocities split the wood in a manner which is favorable to its burning...."
U.S. Army Heavy Artillery Manual, 1851