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This is the sound you would have heard over a thousand years ago while checking the time with the only clock available, a WATER CLOCK
BY NICK COBBING 39 03.2011
WHAT IS A WATER CLOCK? A water clock is a timekeeping device which uses a flow of water to measure time. As you might imagine, a water clock is not as accurate as modern time–keeping devices, but when water clocks were designed, they were adequate for the times. It is believed that water clocks may be among the oldest devices used to keep time.
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here are a number of ways in which a water clock can work. Generally, water clocks are classified as either inflow, or outflow. An outflow water clock keeps time by allowing water to slowly drain away; an example from antiquity was a bowl marked with dark lines which had a small hole in the bottom. The bowl was filled and made to drain slowly, and the lines were used to keep track of time. In the case of an inflow water clock, the flow of water into a container such as a cylinder or a large pot or can and is then used to gauge the passage of time. Water clocks are believed to have originally been developed for the purpose of making astrological observations, when the passage of time can also become an important factor. The clocks were also apparently used to measure the passage of time during speeches and other important events. The origins of water clock technology are not known, although Egypt appears to have had some of the oldest examples; they were also used in Asia, the Middle East, and Greece, where the water clock was known as a clepsydra (klep–sae–drae) or also
Some were used to measure the passage of time during speeches as well as other important events translated to the term of a “water stealer.” It was also called the kleptv, the surripio, the idwz, and the aqua. But the term clepsydra was the term used most often and is the only one that is used today when referring to the ancient water clock.
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A water clock’s accuracy could be fine tuned by pressurizing the water, or using various tools to alter the rate of flow. Some water clocks became quite sophisticated, turning into elaborate clock towers. As other timekeeping devices arose, the water clock began to be displaced, and water clocks today are largely a curiosity, rather than a usable time piece, thanks to the fact that more precise methods of measuring time have been developed to keep track of the passage of time. The need for more accurate time pieces began to emerge during the age of exploration, when mariners urgently needed accurate clocks so that they could measure longitude. During this era, more precise and reliable clocks began to be developed, and with the rise of the Industrial Revolution, when the need to keep accurate time became even more important, even better clocks were developed. By the 19th century, the water clock had been almost all phased out, although they continued to be used in some remote areas where the rhythms of people’s days did not need to be so precisely regulated as they are today. Only a few modern water clocks exist today. In 1979, French scientist Bernard Gitton began his creating his time–flow clocks, which are a new modern–day approach to the historical version. His very unique glass tube designs can be found in over thirty locations throughout the world, including one in Indianapolis, Indiana, and also Brazil. There are other modern designs of water clocks, including the Royal Gorge water clock in Colorado, the Woodgrove Mall in Nanaimo, British Columbia, and in the Abbotsford Airport.
WHERE AND WHEN WATER CLOCKS APPEARED
1500 B.C. In Egypt the oldest water clock found to date was discovered in Amenhotep’s tomb. These simple water clocks had twelve columns with consistently spaced markings on the inside to measure every hour that passed through the day and night.
325 B.C.
In Greece, a water clock was known as the clepsydra. The Greeks considerably advanced the water clock by tackling the problem of the diminishing flow with their water clocks.
100 B.C.
The Romans developed mechanized clepsydras, though their complexity accomplished little improvement over simpler methods for determining the passage of time with water.
1088 A.D. One of the most elaborate clock towers was built by Su Sung from China. The clock tower, over 30 feet tall, possessed a bronze power–driven sphere for observations and statistics.
1206 A.D. In Mesopotamia, now Iraq, Al–Jazari is credited for going beyond anything ever done with water clocks. He created a clock that had two tanks, the top tank was connected to the time indicating mechanisms and the bottom was connected to the flow control regulator. It was very large in size.
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HOW IT WORKS
Depending on where the water clock originated and when it was created ultimately determines how it was built and how it functions. In all, water clocks serve the same purpose and have the same basic idea of how they work. However, some are built very small and simple, while others are larger and more complex and mechanical.
I EGYPTIAN STYLE
III CHINESE STYLE
This alabaster water clock has twelve separate carved columns of eleven false holes that are corresponding to the hours of the night. The water flowed through a very tiny hole made in the center of the bottom and then emerged on the outside. To know the time, one had to look inside the basin to observe the water level and read the time according to the level close
Simple, bucket–like bins were utilized to create the Chinese water clock. Miniscule amounts of water dripped at regular intervals from a hole near the bottom of the apparatus and flowed to the last one. Here there was a measuring stick that allowed people to view the time according to the water level. The measuring rod called an arrow back was then supported by a boat–like device that kept it afloat. When the water dripped outside or inside the container, the measuring rod sunk or rose accordingly, indicating the time. The container that took the water inside and filled up and was referred to as the “rising arrow clock”.
The beauty of the water clock was that it was cheap and didn’t require a lot of effort and space to the false hole. The water clock allowed the ancient Egyptians to economize on the physical mechanism of telling time. The beauty of the water clock was that it was economical in terms of human effort as well as the clock itself did not use a large amount of space therefore it could be placed in highly populated areas.
II GREEK STYLE The housing for the water clock was octagonal in shape and included a semi–cylindrical annex. Both the upper and lower levels of the annex contained a tank which provided a constant head of water. Beneath it was a cylinder with a float. Water in the upper tank fed a slow drip into the lower cylinder. This caused the float to vary at a constant rate. A chain attached to the float was run by a series of pulleys to a weight. This in turn governed the total motion of the mechanism. The imperfections of this clepsydra were that it was required two daily manual adjustments, one in the morning, and the other in the evening. It made no allowance for the variation of fluidity, in different degrees of temperature, which greatly influenced the isochronism of the drops, affecting the accuracy of the water clock and the time.
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IV MODERN STYLE The Canna Clock manufactured by ChronArte is a wall clock, which uses colored liquid in tubes to display time. It consists of twelve glass tubes each marked at ten minute gaps. The tubes fill with every passing moment, displaying minutes and hours precisely. When all twelve tubes are filled at noon and at midnight, the system will empty and the process restarts. The system is filled with five gallons of water and a specified water color. This design heavily relies on the gravity powering multiple siphons; for example, after the water level in the minute or hour display tubes has been reached, an overflow tube starts to act as a siphon and therefore empties the display tube. Actual time keeping is done by a calibrated pendulum powered by a slow water stream piped from the clock’s reservoir. The pendulum has a carefully– constructed container attached to it that measures the water that is poured slowly into the display system, which allows it to function properly.
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