The Wujing Zongyao (Chinese: 武經總要), sometimes rendered in English as the Complete Essentials for the Military Classics, is a Chinese military compendium written from around 1040 to 1044. The book was compiled during the Northern Song dynasty by Zeng Gongliang (曾公亮), Ding Du (丁度) and Yang Weide (楊惟德), whose writing influenced many later Chinese military writers. The compendium was published under the auspices of Emperor Renzong of Song, who also authored the book's preface. The book covers a wide range of subjects, including everything from naval warships to different types of catapults. It contains the earliest known written chemical formulas for gunpowder, made from saltpeter, sulphur and charcoal along with many added ingredients. In addition to formulas for gunpowder, the compendium also contains details on various other gunpowder weapons such as fire arrows, incendiary bombs and projectiles, and grenades and smoke bombs. It also describes an early form of the compass (using thermoremanence), and has the oldest illustration of a Chinese flamethrower with a double-action dual-piston cylinder-pump capable of shooting a continuous blast of flame. Source: Wikipedia (en)