Compendium of Military Preparations, Volume 123

The Wubei Zhi is a comprehensive military encyclopedia compiled by Mao Yuanyi in 1621, during the Ming Dynasty.

Military Assets: Fire — Illustrated Descriptions of Firearms, Part 12

This character "Yuan" serves as a folio or page signature for organizational purposes.

The Underwater Dragon King Cannon

original: 水底龍王砲 (Shuidi Longwang Pao). This device is a timed naval mine, a sophisticated piece of 17th-century maritime technology.

The mine is forged from wrought iron and mounted upon a wooden board. Its true ingenuity lies in the "hidden fire" the internal ignition mechanism. A length of incense is bound to the device to act as a timer; when the incense burns down to the priming cord, the charge is ignited. The timing can be precisely set for one watch or three watches. A "watch" (geng) lasted approximately two hours, allowing the mine to be timed for up to six hours.

The device is encased in a cow’s stomach; if it were completely airtight, the fire would be smothered for lack of air. Therefore, a sheep’s intestine is used as a ventilation tube, extending slightly over ten feet in length. The end of this tube uses goose or wild duck feathers as floats; as these feathers rise and fall with the rhythm of the waves, they prevent water from pouring into the tube, which would extinguish the fire. The subtle mystery of its mechanism is found in these details.

To deploy it, one must first measure the depth of the water where the enemy ships are anchored. The mine is weighted with heavy stones and released upstream during the darkness of night to drift toward the target. When the incense reaches the ignition point, the mine detonates from the seabed, striking the ship from below. The hull is shattered to pieces, and as the water rushes in, the enemy sinks—allowing them to be captured with ease.

Required Materials

• Large projectiles weighing four to five catties A catty (jin) is roughly 600 grams.
• Gunpowder original: 發藥 (fayao) measuring one dou or five sheng These are units of dry volume; a dou is approximately 10 liters.