Treatise on Armament Technology: Illustrated Naval Firearms

The Across-Water Divine-Machine Cannon original: 渡水神機砲 (Dushui shenji pao)

For naval warfare, use the "hull-striking" cast-iron cannon original: 鐵鑄大砲 (tiezhu dapao). It is one foot five inches long approximately 48 centimeters and four inches in diameter. Inside, it contains two catties original: 斤 (jin); a unit of weight approximately 600 grams of propellant powder. The fuse original: 藥信 (yaoxin); literally "powder message" is coiled around the top of the cannon. It fires a large lead ball weighing two catties.

To ensure the weapon remains functional in aquatic environments, seal the mouth of the cannon with yellow wax. Use a single piece of dog skin sewn into a bag to wrap the cannon in the center This serves as a primitive but effective waterproofing method for underwater sabotage. When deployed, use four spikes original: 錐 (zhui); literally "awls" or "drills" to nail the device to the bottom of the enemy ship. It is recommended to use eight cannons for every ship's hull to ensure total destruction. Once the burning incense serving as a timer reaches the powder, the cannon fires. The bottom of the ship is shattered to pieces, causing the vessel to sink, allowing the enemy to be captured alive as they struggle in the water.

Formula for the Fuse original: 藥信方 (Yaoxin fang); this slow-burning composition allowed soldiers time to retreat after attaching the device