Cut lines and drilling holes in animal bones may have been the first type of timers ever seen. 20.000 years ago European Ice Age hunters cut marks in the bones from slaughtered animals and it is likely they did so to keep count of the days between the fazes of the moon.
5000 years ago, Sumerian star readers in the Euphrates and Tigris areas had a calendar that divided the year into periods of 30 days. They are said to have made the first time piece: a stick was thrust into the ground and acted as a sundial, so people in the area could meet at certain times. But the idea was not followed by any detailed breakdown of the day.
In Britain, Stonehenge, a gigantic stone setting, was erected about 4.000 years ago and it is thought that this could be used to record astronomical events such as lunar eclipses and solstices.
In 4236 BC the Egyptians had developed a 365-day calendar. They had discovered that the annual flooding of the Nile coincided with the rise of Sirius beside the sun one time per year.
As time passed the needs for mankind to measure the time of the day occured. It became necessary to invent devices that were regularly or consistently able to show similar parts of the time. The first step was the sundial.
Around 3500 BC the first obelisks were erected in the Nile delta. The shade from these enabled the Egyptians to divide the day into smaller units. They also marked the shadow circle around the obelisk with stones, and so they were among other things able to measure the year’s longest and shortest days.
The first known portable clock dates back to 1500 BC. It was a so-called shadow-clock, where the day was divided into ten parts, plus two twilight-parts. The shadow clock was positioned so that it lay in the direction east-west. Thus moving shadows from a transverse crossbar during the morning over a stick with marks that were put on the stick with ever shorter distance. When the sun reached the highest point in the sky, it was reversed on the axis, so it began to “count down” towards the end of the day.
In 600 BC the Egyptians also solved the problem of determining time at night. By means of a so-called “merkhet” they could find the North-South line from the North stars. By keeping an eye on the stars that crossed the line, they could determine the current time.
Later on the sundial as we know it was developed. The horizontal or vertical sundial was designed as hemispheres with an “Gnomon,” a pointer whose shadow indicated the time at the engraved scale. There were four scales so the clock showed the correct time regardless of season.
In the 11th century quite a few pocket-sundials were prevalent in Europe.
The development of sundials continued after the advent of the mechanical watch: today, a sundial take into account the changes in altitude of the sun and it is able to display the time with a minute’s accuracy.
The first time measurers that were not dependent on celestial bodies were the water clocks. The oldest known copy is found in the tomb of Pharaoh Amenhotep (1400 BC). The most simple consisting only of a container with a drain. Once it had run out a given time had elapsed. Later, water clocks were equipped with inner scales so there could be kept track of time. The most advanced of the early water clocks had more inner scales that were used in the different seasons.
The purpose of the water clocks is believed to be religious: Water clocks could ensure that the rituals and sacrifices in temples could take place at the right time.
Gradually the water clock became more sophisticated: cylinders with a floater was used in some types while the water in other types made an actual bell work. The Chinese made experiments using mercury instead of water as a driving force in clocks.
In ancient Greece water clocks among other things were used in legal proceedings where the speaking time was determined by a clock. If a pause was needed a wax plug was put in the drain and thus the time was at a stand.
About 100-50 BC Greeks build the Tower of Winds at the Acropolis. The water-powered mill showed time of the day, the season and also the astrological cycle of the stars in the sky.
In China, the astronomer Su Sung built a ten feet tall, water powered “Cosmic Engine” in 1088. It had among other things, a celestial globe, clock work and dialer. And it had a system that ensured a uniform pace at all times. A system like this was not discovered in Europe until the late 1200s when it became crucial for the development of mechanical clocks.
In the 11th century, the Arabs in Toledo made a water clock which was filled as the moon took on while the water level fell by the waning moon. According to the description, it acted in 100 years without being adjusted.
In the latest versions of this kind of clock inventors began to let weights replace water as a driver – hence they created the forerunner of the mechanical clock.
Around the 1400s clocks start to show up in the bell towers of the Italian cities where they were driven by weights, but the delay system was primitive, so their time was not regular. Clocks were difficult to regulate and had a single pointer, so the time was only displayed within 15 minutes.
The first actual clocks are believed to be invented and designed in monasteries, where they recorded the canonical hours, the prayers the monks had to perform every three hours. In 1335 in Milan the first clock with a strike of the bell every hour was built.
The world’s oldest public clock is placed in the Tour d’Horloge at the French king’s palace (now the Palais de Justice). It was built in the 14th century but still it was not well regulated. Contemporary clocks could lose or gain an hour per day.
But one thing is certain. Time now occupied people. The legend of the Tour d’Horloge says, “Might this clock, which share the day in twelve equal parts, be an example of justice and maintain the law.”
In Prague you can still see the astronomical clock from 1410 as an early example of contemporary lavish clock towers. It displays time, the moon and the sun’s current position among the heavenly bodies, and a calendar with zodiac and saints days.
But it was not until the invention of the pendulum clock that precision was good enough.
In 1656 there was a technological revolution as the Dutchman Christiaan Huygens made the first pendulum. With further improvements precision was now at plus or minus ten seconds a day.
Although Huygens clocks with pendulums were accurate, they were impossible to use at sea. This meant that the clocks could not be used for recreating the meridian and thereby establish positions at sea. This caused many sailors lives. And because maritime traffic increased, merchants and seamen demanded action from the governments.
Therefore the parliament in London in 1714 initiated the first research contract ever: the person who could determine longitude to an accuracy of half a degree – about 30 miles – at a 40-day trip back and forth between England and West Indies would win 20,000 pounds. This represents more than 10 million dollars today.
It took the carpenter John Harrison a lifetime to win the prize. He constructed four clocks but despite opposition from rivals to finish earned him a large sum of money as reward.
The first clocks he made of hardwoods. Then he used a type of wood which secrete an oily substance and therefore do not require lubrication. His third clock, called H3, had springs of two different metals. This meant that they were not affected by heat and humidity – when one metal pulled himself together the second extended and in this way he avoided the impact of climate change during the voyage to distant lands. Among Harrison’s other innovations was the sealed bearings, which today is used in virtually all machines.
His winning clock, the chronometer H4 ticked away in 1761 during a long voyage on a rocking ship and turned out only to lose fifth of seconds per day. It repeated the trip in 1764 and continued compliance with the requirements. Because of the rivalry with the other contestants took another nine years before the then 80-year-old watchmaker had his reward.
After a centuries of developing mechanical clocks a new prototype, the quartz clock, overtook the old, mechanical clocks in accuracy. The first was made in 1928. When a quartz crystal exposed to electrical stimulus it oscillates. It could regulate a clock, so it was a hundred times as precise as the best pendulum. A Quartz clock loses or wins under 0.1 seconds a day. But a quartz crystal can grow old and start to move a little faster or slower. So although quarts watches were a huge step forward, the search for an exact time measurement continued.
It was born in 1948, when Briton Harold Lyons designed the first atomic clock. It works as clock time is kept constant by being linked to an atomic frequency and reduces the discrepancy to less than a second for one million years.
This has led to the international time signal today is based on six atomic clocks that are coordinated with the irregular movement of Earth around the Sun by inserting leap seconds. Everything is controlled from the International Time Bureau in Paris.
The exact time signal is sent, among other things from the GPS satellites to the seafarers and from a transmitter by the German Physics and Metrological institute southeast of Frankfurt. The signal allows for today’s clock-owners to get the exact time shown on their radio-controlled wrist watch or alarm clock.
