The Su-Sung water clock is probably the greatest mechanical achievement of the Middle Ages and knowledge of its principles led to the development of mechanical clocks in Europe two centuries later.
By: William Devine, Owner of Devine Intervention
Posted on: July 10, 2010
In my previous column I made a reference to the Antikythera Mechanism which dates from the second century BC. This mechanism represents a marvel of engineering and is reminiscent of mechanical clocks of the 17th and 18th century with its intricate use of gears to keep track of the passage of the planets in the sky. This unique device clearly demonstrates the knowledge and sophistication of ancient Greece and is a clear reminder to us of the importance of this heritage.
In terms of the history of timekeeping other civilisations also contributed in different and no less important ways. A case in point is the so-called Su-Sung water clock created in 1096 AD by a minister in the Chinese court of the Emperor Shen Tsung.
The Su-Sung water clock is probably the greatest mechanical achievement of the Middle Ages and knowledge of its principles led to the development of mechanical clocks in Europe two centuries later.
The Su-Sung clock was not the first water clock. Indeed water clocks existed since the Babylonian times. Chinese acquired this knowledge from this previous civilisation. Likewise the Chinese did not invent the clock dial which dates from the ancient Greeks and Romans. However the Su-Sung clock is the first mechanical water clock and is a key development in the history of timekeeping.
It is interesting to note that the creation of this water clock is a result of the political will of the Emperor Shen Tsung. He wanted to demonstrate the importance of his dynasty by building the most perfect clock the world had ever seen. An instrument to interpret the will of heaven....
While the Antikythera Mechanism fits into a modern shoe box, the Su-Sung clock weighed several tons and occupied a forty feet high tower. It was powered by a water wheel designed to turn intermittently at a stable rate. Small buckets were attached to the rim of the wheel and they were successively filled from a clepsydra. When the weight of the water was sufficient, it tipped a lever that released the wheel and allowed it to rotate, but only so far to allow the next bucket to be filled with water. In essence, the central element of this clock is the water-wheel escapement, which though powered by a clepsydra and hence by water power, is a mechanical escapement. The Su-Sung clock was therefore a mechanical clock rather than a water clock even thought its power came from falling water.
The regularity of the falling water that allowed for the fill-and-tip arrangement divided the fall of water into countable units and henceforth enabled the device to measure the passage of time. The clock was not only able to measure the time of day but it also was able to tell the date, the month and it reproduced the movements of the “three luminaries” – the sun, the moon and selected stars that were central to calculation and astrological divination according to the Chinese calendar.
Su-Sung’s astronomical clock gave its service for several years, but in 1126, invaders from the north captured the Sung capital of Kaifeng and carried away what they could of the clock. The invading Tatars couldn’t get it to work again and the high-art of Chinese clock making completely disappeared. Once again political expediency played a role here as the new regime considered fancy clock-building a part of the old regime and did little to sustain it. Su-Sung’s book on the operation of the clock did not surface in the West until the 17th century.
From my personal perspective, the story of the Su-Sung water clock is a fascinating insight into the importance of the political environment in the development of timekeeping devices. I believe that if the political influences had been different, the odds were that the Chinese would have developed a mechanical clock well before the Europeans. But such a clock did not come. Chinese horological techniques stood still, then regressed.
The fact that the mechanical clock did appear in the West, and with it a civilisation centred around the measurement and knowledge of time, is a critical factor in the rise of Europe to technological and economic hegemony. Just how this came about will be the focus of my next column.
William Devine, a Swiss national of Scottish descent, has held senior positions in leading watch companies like Universal Geneve and de Grisogono. He has also functioned as the Director of BaselWorld Watch & Jewellery Show. He was the CEO of Bedat & Co before starting his own boutique consultancy named Devine Intervention.
