The 12-pounder Napoleon, top, had a bore of about 4.6 inches across, and such smoothbore cannons excelled at firing canister. Rifled cannons, like the 3-inch Ordnance Rifle pictured above, could also fire canister, but not as effectively. The smaller 3-inch bores prevented the shot from dispersing as widely. The canister rounds could sometimes track along the rifling and pick up a spin, another reason the canister balls would not spread out over a wider area. But that fact would have been cold comfort to troops charging rifled artillery. (Photos by Melissa A. Winn)

Photos by Melissa A. Winn