#dragon jar

Dragons, Frogs and Earthquakes

Today, when an eartqhuake occurs, scientists around the world can be notified electronically in minutes, and emergency responders can move almost as rapidly. Previously, in large countries where the population density is sparse, it could take days to weeks for news of such a disaster to reach those capable of providing large scale aid.

In ancient China a brilliant scientist called Zhang Heng came up with a solution, he created a machine that could tell officials when and in which direction an earthquake had struck. In 132 AD Zhang produced a machine called the “Dragon Jar”. It was a jar roughly 1 metre wide (3 feet) and 1.7 metres tall (5.5feet) that had eight dragon heads evenly spaced around the edge facing outwards. The heads represented the points of a compass, and in each of their mouths they held a ball bearing. Beneath the dragons, at the base of the jar, were 8 frogs each facing towards one of the dragons with their heads tilted upwards and their mouths open. The jars contents are unknown although many believe there to be some form of pendulum at its centre.

When an earthquake struck, even if too weak for a human to feel, the pendulum would swing with the grounds movement. This would result in one of the dragons dropping the ball into a frog’s mouth, giving an indication of the direction that the tremor had come from. It would also alert any attendants to the earthquake as the ball would make a loud noise as it landed in the frog’s mouth. With this knowledge search parties and aid could be sent out in that direction, leading to a much swifter response and the saving of many people’s lives. It is proposed that the device alerted officials to an earthquake 400miles away that had been too weak for them to feel but had been 7.0 on the Richter scale.

While Zhang was praised for his invention, his staunch belief that the tremors were a natural phenomenon and not an act of an angry god prevented him from rising through Chinese society. Unfortunately, none of his devices have been found and notes written by Chang are brief and incomplete. However, while we may not know how it worked, the invention was still a marvel of science that is impressive even today!

Watson

Further Reading: http://bit.ly/1EwfJfj

Dragon Jar on a Silver Chain