God’s Clockmakers: factors in the early development of time-keeping technology

A few weeks ago, when I wrote about the medieval engineers of Islam, I promised a more general view of the role of religion in the development of clocks.  The association goes way back.  If you think about it, this makes sense.  For millennia, people didn’t really need to know anything specific about time. Dawn= time to get up, Dusk = time to go to bed (or time to hunt certain kinds of animals, and to be hunted by others).  Clues about the change of the seasons told you when to move hunting grounds and which direction to go, or when to plant crops and what to plant.

al-Jazari’s castle clock at Bagdad

It’s only when people begin to organize more conscious societies and these societies began to create rituals that a more precise division of time became necessary.  I started out with the intent of talking about religion, but really, the development of clocks was driven at least as much by bureaucracy, and by people who wanted to get the most for their time–whether that was lawyers or prostitutes.

Enter the Water Thief or Clepsydra.  Water clocks have been discovered in many different parts of the world, including Egypt, Babylon, China and India.  But I love the term “Clepsydra,” the Greek word for these simple devices.  Their development in Babylon relates to a judicious arrangement of water rights by local municipalities, and in Iran around 500 B.C. they were used to monitor holy days. Basically, the water clock keeps time by water flowing into or out of the device at a regular rate, as indicated by markings on the container.  It needs to be re-filled from time to time, but, unlike the sundial, it works regardless of the weather or its location. So if you were an early Christian monk, you could have a water clock in your chamber to mark the hours of prayer–and this remained the most accurate method of time-keeping until the 17th century.

The water clock became highly elaborate during the Greco-Roman period, with elaborate gearing and water-driven figures that appeared to come alive to mark the hours. The Tower of the Winds in Athens is the remnant of a large public clepsydra.  The Greeks used their clocks to time speakers in court cases, and the visits of patrons at brothels to ensure that everyone was treated fairly.

a model of Su Song’s astronomical clock in the collection of London’s Museum of Science

My favorite exploration of the water clock, however, emerged in China around 1080 AD, with Su Song’s astronomical clock.  This clock used water to turn all of its incredibly detailed machinery, but all to serve the purpose of tracking the birth of imperial children in order to produce the most accurate astrological charts to ensure good governance by these representatives of the divine upon earth.  At the top of the tower are the astronomical instruments, to the right in this image are the mechanisms that drive the clock, linked to the instruments above to synchronize their turning, and to the left, you can see the large barrel-shape of the display.

At medieval churches throughout Europe, sundials featured as a way to mark the hours and bells to summon people to pray.  The sundials gave way to mechanical clocks with their own ways to chime the hours, often with cycles of the moon or other astronomical phenomena.  But they still needed to solve the problem of the escapement: the mechanism that transfers the energy of the moving force (water or a spring) to the dial in a regular and controlled fashion.  Enter Richard of Wallingford, a thirteenth century abbot memorialized as God’s Clockmaker for his work in the development of the mechanical escapement, employed in the tower clock at St. Alban’s.  After this, many other varieties of escapement were tried, with the goal of making the clocks ever smaller and more accurate.

Sadly, as the clocks became more elaborate, that also meant specialized labor was needed to maintain them, and many of those magnificent early clocks, incluing Su Song’s and al-Jazari’s, were lost to war or dis-repair.  I delighted in finding medieval clocks still in place in many English churches, some of them still keeping the time.  Here are a few of them for your enjoyment.

A lovely astronomical clock in Exeter, UK

the bell-striking “Jacks” at Wells Cathedral clock dating to the late 14th century

a retired mechanism at St. Mary Ottery

astronomical clock at St. Mary Ottery