Guidonian hand
In Medieval music, the Guidonian hand was a mnemonic device used to assist singers in learning to sight-sing. Some form of the device may have been used by Guido of Arezzo, a medieval music theorist who wrote a number of treatises, including one instructing singers in sightreading. The hand occurs in some manuscripts before Guido's time as a tool to find the semitone; it does not have the depicted form until the 12th century. Sigebertus Gemblacensis in 1105–10 did describe Guido using the joints of the hand to aid in teaching his hexachord. The Guidonian hand is closely linked with Guido's new ideas about how to learn music, including the use of hexachords, and the first known Western use of solfege.
History of gunpowder
Traditionally the first appearance of the hand cannon is dated to the late 13th century, just after the Mongol conquest of the Song dynasty. However a sculpture depicting a figure carrying a gourd shaped hand cannon was discovered among the Dazu Rock Carvings in 1985 by Robin Yates. The sculptures were completed roughly 250 km northwest of Chongqing by 1128, after the fall of Kaifeng to the Jin dynasty. If the dating is correct this would push back the appearance of the cannon in China by a hundred years more than previously thought. The bulbous nature of the cannon is congruous with the earliest hand cannons discovered in China and Europe.