Huolongjing
The Huolongjing is primarily based on the text known as Huolong Shenqi Tufa (Illustrations of Divine Fire Dragon Engines), which no longer exists.
The 1412 edition, known as Huolongjing Quanji (Complete Collection of the Fire Dragon Manual), remains largely unchanged from its predecessor with the exception of its preface, which provides an account of Jiao Yu's time in the Hongwu Emperor's army.
In the preface Jiao Yu claims to describe gunpowder weapons that had seen use since 1355 during his involvement in the Red Turban Rebellion and revolt against the Yuan dynasty, while the oldest material found in his text dates to 1280.
[2] Although its destructive force was widely recognized by the 11th century, gunpowder continued to be known as a "fire-drug" (huo yao) because of its original intended pharmaceutical properties.
While engaged in war with the Mongols in 1259, the official Li Zengbo wrote in his Ko Zhai Za Gao, Xu Gao Hou that the city of Qingzhou was manufacturing one to two thousand strong iron-cased bomb shells a month, and delivered them to Xiangyang and Yingzhou in loads of about ten to twenty thousand shells at a time.
"[18] Poisonous gunpowder for hand-thrown or trebuchet launched bombs[19] was created using a mixture of tung oil, urine, sal ammoniac, feces, and scallion juice heated and coated upon tiny iron pellets and broken porcelain.
[20] Explosive devices include the "flying-sand divine bomb releasing ten thousand fires", which consisted of a tube of gunpowder placed in an earthenware pot filled with quicklime, resin, and alcoholic extracts of poisonous plants.
[23] An even earlier text, the Wujing Zongyao (武经总要, "Collection of the Most Important Military Techniques"), written in 1044 by Song scholars Zeng Gongliang and Yang Weide, described the use of three spring or triple bow arcuballista that fired arrow bolts holding gunpowder.
[30][31] An illustration shows that fins were used to increase aerodynamic stability for the flight path of the rocket,[31][32] which according to Jiao Yu could rise hundreds of feet before landing at the designated enemy target.
[31][33] The Huolongjing also describes and illustrates the oldest known multistage rocket; this was the "fire-dragon issuing from the water" (huo long chu shui), which was known to be used by the Chinese navy.
[34][35] Needham says that the written material and illustration of this rocket come from the oldest stratum of the Huolongjing, which can be dated to about 1300-1350 from the book's part 1, chapter 3, page 23.
[37] The earliest depiction of a fire lance is dated c. 950, a Chinese painting on a silk banner found at the Buddhist site of Dunhuang.
[42] In addition to fire lances, the Huolongjing also illustrates a tall, vertical, mobile shield used to hide and protect infantry, known as the "mysteriously moving phalanx-breaking fierce-flame sword-shield".
[48] Jiao Yu describes the cannon, called the "eruptor", as a cast bronze device which had an average length of 53 inches (130 cm).
[49] He wrote that some cannons were simply filled with about 100 lead balls, but others, called the "flying-cloud thunderclap eruptor" (飞云霹雳炮; feiyun pili pao) had large rounds that produced a bursting charge upon impact.
[54] The first recorded use of land mines occurred in 1277 when officer Lou Qianxia of the late Song dynasty, who is credited with their invention, used them to kill Mongol soldiers.
[55] Jiao Yu wrote that land mines were spherical, made of cast iron, and their fuses were ignited by the enemy movement disturbing a trigger mechanism.
On triggering the firing device the mines will explode, sending pieces of iron flying in all directions and shooting up flames towards the sky.
[58]For the use of naval mines, he wrote of slowly burning joss sticks that were disguised and timed to explode against enemy ships nearby: The sea–mine called the 'submarine dragon–king' is made of wrought iron, and carried on a (submerged) wooden board, [appropriately weighted with stones].
[59]In the later Tiangong Kaiwu (The Exploitation of the Works of Nature) treatise, written by Song Yingxing in 1637, the ox bladder described by Jiao Yu is replaced with a lacquer bag and a cord pulled from a hidden ambusher located on the nearby shore, which would release a flint steel–wheel firing mechanism to ignite the fuse of the naval mine.
[62] With the progression of the earliest European arquebus to the matchlock and the wheellock, and the advent of the flintlock musket of the 17th century, they surpassed the level of earlier Chinese firearms.
However, by the 17th century Đại Việt had also been manufacturing muskets of their own, which the Ming considered to be superior to both European and Ottoman firearms, including Japanese imports as well.
