Double Barreled Cannon (1862)

...the 6-pounder weapon capable of firing a devastating round of chain-shot—two cannonballs connected by a length of chain. The idea was both barrels would fire simultaneously, sending the chain-shot hurtling among enemy combatants. Unfortunately, the first field test of the prototype proved a disaster. The barrels did not fire at exactly the same time, causing the chain-shot to fly wildly off target or the chain to break.