The Egyptians were the first people who created a twenty-four hour day. Time was a little bit different in those days. The night was divided up into twelve hours, which were designated by the position of stars in the sky. The day was divided into ten hours and a shadow clock was used to keep track of these hours. The twilight hours were the hours before dawn and after sunset.
The Egyptians thought they were the first to invent the shadow clock, but they were mistaken. At the same time, the Chinese, Babylonians, Greeks and the Romans were using instruments to tell time. Sundials were used in some of these groups, not because they work better, just because that's how they decided to tell time.
After a while, the Egyptians and other ancient societies realized that the sun rose and set in different places in the summer and winter. In fact, the sun never took the same course on any one day throughout the year! They tried everything, until they realized that if they would just put the post of the sundial in at a special angle, it would work all year.
The Sands of Time
The major fault with sundials and shadow clocks is obvious...They don't work at night! Amenophis I, the king of Egypt, wanted to know what time it was all through the night without having to check the position of the stars. As you can imagine, it would be inconvenient to get up and out of bed every time you want to know the time. So, Prince Amenemhet made the king a clepsydra or a water clock. He took a big bucket of water, filled it with water up to a specific line. He then cut a small hole in the bottom of the bucket and marked off lines on the bucket after each hour had passed.
There were, of course, some problems with this water clock as well. Water would flow more slowly or quickly when the temperature changed. This is where sand came into effect. The inventor of the sand clock is unknown but the sand clock or hourglass was commonly used in ancient times and is still used today. They are often found in board games or are used as kitchen timers. Is there an hourglass in your home?
The first mechanical clocks had a weight that would slowly lower, moving gears which moved a hand which showed the hour. They could only be build in tall towers because the weights needed to fall a great distance or else the clocks would only work for a short amount of time. People were amazed that these clocks were only off about 2 hours a day. Think if our clocks today were off by that much? If we were 2 hours late for school, we could blame it on the clock.
While these clocks were inaccurate long ago, some of them were created with such care that they still work today. In Normandy, France, a big clock exists that was built in 1389. In Salisbury, England you can see the oldest clock in the world, built in 1386. Today, cuckoo clocks are still built using a weight-dropping mechanism.
Galileo made an amazing contribution to the world of time, simply by not paying attention in church. The year was 1581 and Galileo was 17. He was standing in the Cathedral of Pisa watching the huge chandelier swinging back and forth from the ceiling of the cathedral. Galileo noticed that no matter how short or long the arc of the chandelier was, it took exactly the same amount of time to complete a full swing.
The chandelier gave Galileo the idea to create a pendulum clock. While the clock would eventually run of energy, it would keep accurate time until the pendulum stopped. If the pendulum was set swinging again before it stopped, there would never be a loss in accuracy. Because of this, pendulums caught on and are still widely used today. Can you imagine making such a big discovery?
When sailors sailed across the ocean, they could only tell their position using two methods. When they were traveling from North to South, they could tell their position using Polaris, the North Star. But, when they were traveling from East to West, they ran into a problem. Pendulum clocks couldn't be used because the pendulums were highly sensitive and could be easily shaken, making the clocks inaccurate. In 1707, a British fleet crashed into the Scilly Islands, killing two thousand soldiers and destroying four ships. Seven years late, the British government offered twenty thousand pounds to whoever built a clock that would keep accurate time at sea. This clock would have to be accurate to the second, so as to avoid another unfortunate accident.
John Harrison, a carpenter, was the winner of the contest. In 1728, John heard about the contest and began work on a solution. Thirty-three years and three enormous clocks, John's small fourth clock was tested. When the testing crew arrived in Jamaica 161 days later, the clock was only five seconds off. John Harrison collected his prize money at the age of seventy-nine.
Time for Change
Since 1761, timekeeping has significantly changed. In 1900, pendulum clocks had been finely tuned so as to only be off by 1/100 of a second each day. In the '20s, scientists discovered quartz crystals could keep even more accurate time than a pendulum and were only off about 1/500 of a second each year. Half way through the 20th century, atomic clocks were built that would only be off by one second every 300 million years. Who really needs a clock that accurate?
It is evident that times have certainly changed. Clocks have made major leaps and bounds since the days of the shadow clock. Now we have accurate, reliable clocks that we can use day and night. Some of our clocks will run for years without so much as a change of batteries or a twist of a little knob. We have certainly developed the concept of time and incorporated it into every moment of our lives.