The Double Barreled Canon
Throughout history, mankind has believed in the simple principle that more is usually better. As such, it was only a matter of time before we created the canon with multiple barrels. While there were some quite successful designs where canons would have upwards of three different barrels that rotated like a revolver in order to shoot with a better rate of fire, there was a desire to continue improvements. The massive sizes of the previously mentioned revolver-canons made them mostly practical to be used aboard ships. So engineers during the American Civil War decided to up efficiency by putting two different canons on the same rig.
There is a small slit cut between both barrels for the following purpose. The intended ammunition to launch out of the device was actually two cannonballs that were connected by a thin chain. The idea behind this was that the chain would cause the shot to spin lethally, like a helicopter’s propeller. This was supposed to help one shot harm massive amounts of enemy infantry, but as you might have surmised, it did not go as planned.
The canon was unable to fire with enough force to get the desired spinning motion to its shot. More often than not, the cannonballs would merely disconnect from the chains and going flying in strange directions. Needless to say, the double-barreled canon didn’t make it past primary testing and very few can be found to this day.