Sunday, September 30, 2012

The History of Time[Part Four]

                                       GALILEO'S DISCOVERY

   Galileo made an amazing contribution to the world of time,simply by not playing 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 fourth from the ceiling of 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 aloss in accuracy.Because of this,pendulums caught on and are still widely used today.

Wednesday, September 26, 2012

The History of Time [Part Three]

                                                 THE FIRST TICK

   The first mechanical clock 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 the great distance or else the clock 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, a cuckoo clocks are still built using a weight-dropping mechanism.

Tuesday, September 25, 2012

Sand Clock ..

                                    This is a sand clock

The History of Time [Part Two]

                                            THE SAND 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 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.

The History of Time [Part One]

                           THE BEGINNING OF TIME

   The Egyptians were the first people who created a twenty-four hour day.Time was a little bit dififerent 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 was used to keep tracks of these hours.The twilight hours were the hours before dawn and after sunset.

   The Egyptians were 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 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.