Sometimes the joy of history lies in the small details, such as the original names of inventions. The world’s first mechanical clock went by the name of the ‘Waterdriven Spherical Birds’-Eye-View Map of the Heavens’.
Invented by Yi Xing, a Buddhist mathematician and monk, in AD 725, it was developed as an astronomical instrument that incidentally also worked as a clock. In spite of the name it wasn’t strictly speaking a water clock (one in which the quantity of water is used to directly measure time). However, it was water-powered – a stream of falling water drove a wheel through a full revolution in twenty-four hours. The internal mechanism was made of gold and bronze, and contained a network of wheels, hooks, pins, shafts, locks and rods. A bell chimed automatically on the hour, while a drumbeat marked each quarter-hour.
Another splendidly named clock was the ‘Cosmic Engine’ built by the Chinese inventor Su Song between AD 1086 and 1092 for an emperor of the Sung Dynasty. This was also a mechanical astronomical clock, but it was huge, spreading over several storeys in a tower that was over 10 metres (35 feet) high. It was made of bronze and powered by water. At the top, a sphere on a platform kept track of the motion of the planets. The clock remained in place and working until 1126 when it was lost in a Tatar invasion.
The Chinese engineer Su Song’s hydro-mechanical clock tower.