Congress prompted experimentation to develop new weapons and methods of naval combat, passing what was called the Torpedo Act in March. This granted one half the value of an enemy warship to an individual destroying it.
Robert Fulton and Commodore Jacob Lewis cooperated in developing torpedoes and underwater gunnery. In the early 19th century, a torpedo was an explosive charge detonated against the side of a target. Typically, a small vessel rammed the enemy ship below the waterline with a torpedo mounted on a forward spar.
Also, a submarine could attach the torpedo under the target underwater.
Fulton and Lewis demonstrated the potential of an underwater cannon. They placed a hundred pounder columbiad with a ten pound powder charge below the surface of the water. The firing mechanism was dry inside the attacking boat while the muzzle extended into the water. Upon firing, the cannon could drive a massive ball through three feet of solid oak at a range of six feet.
The British decision not to attack New York City precluded the use of this under actual combat conditions.
--Brock-Perry