by Hou Jing (died 552) during the reign of Emperor Wu of Liang (r. 502–549), while similar accounts of kites used for military signalling are found in the Tang (618–907) and Jin (1115–1234) dynasties; kite flying as a pastime can be seen in painted murals of Dunhuang dating to the Northern Wei (386–534) period, while descriptions of flying kites as a pastime have been found in Song (960–1279) and Ming (1368–1644) texts. L Land mine: Textual evidence suggests that the first use of a land mine in history was by a Song Dynasty brigadier general known as Lou Qianxia, who used an 'enormous bomb' (huo pao) to kill Mongol soldiers invading Guangxi in 1277. However, the first detailed description of the land mine was given in the Huolongjing text written by Ming Dynasty writer, military strategist and philosopher Jiao Yu (fl. 14th to early 15th century) and Liu Bowen (1311–1375) during the late Yuan Dynasty (1271–1368) and early Ming Dynasty (1368–1644). Jiao and Liu wrote that land mines were spherical, made of cast iron, and their fuses ignited by a mechanism tripped by enemy movement; although Jiao and Liu did not describe this trip mechanism in full detail, a later text of 1606 revealed that enemy movement released a pin that allowed hidden underground weights to fall and spin a chord around an axle that rotated a spinning wheel acting as a flint to spark a train of fuses. Land sailing: The usage of the land sail in China dates back to at least the Northern and Southern dynasties period. The earliest text describing the Chinese use of mounting masts and sails on large vehicles is the Book of the Golden Hall Master written by the Daoist scholar and crown prince Xiao Yi, who later became Emperor Yuan of Liang (r. 552–554 AD). Leeboard: To avoid leeward drift caused by the force of wind while sailing, the leeboard was invented; it was a board lowered onto the side of the ship opposite to the direction of the wind, helping the ship to stay upright and afloat even if the hull was breached. British writers Paul Johnstone and Sean McGrail state that an odd-looking second paddle on a bronze drum of the Dong Son culture (centered in the Red River Delta of northern Vietnam) may depict a leeboard in use as early as 300 BC. Leeboards may have been invented in