CLOCKs

1. CLOCKs 鄭翔如B9202090 陳偉傑B9202060 董又誠B9202079 劉哲維B9202084

2. The History of Clocks • What time is it? Throughout the last 4,500 years or so, methods used to tell time have evolved greatly, and are still improving today. From the most primitive sundials to the advanced cesium fountain clock of today, scientists have always worked to make clocks that are more accurate than the last generation of timekeeping devices.

3. The earliest humans used the position of the sun in the sky to approximate the time of day. Sundial clocks: In around 3500 B.C., the Egyptians began to construct huge obelisks which served as primitive sundials. But, they had limitations: they did not work at night or on cloudy days, and were not very accurate. Hourglasses: In about 3450 B.C., a primitive hourglass was invented.

4. Water clocks : Around 1400 B.C. (about 3,400 years ago), water clocks were invented in Egypt. They would work on cloudy days and at night, but not in freezing weather. Sand hourglasses: In the 700 B.C., glass hourglasses, which used sand pouring through a small hole in a glass tube to measure time, began to appear. Mechanical clocks : In the 1300 A.D., mechanical clocks, which used weights or springs, began to appear. At first, they had no faces, and no hour or minute hands; rather, they struck a bell every hour. Later, clocks with hour, and then minute hands began to appear.

5. Coiled springs : In the 1400 A.D., this discovery made smaller clocks, and later watches, possible. Pendulum clocks: Galileo made a significant contribution to horology—by his study of the pendulum as a method of regulating timekeeper. In 1656, Christiaan Huygens invented the pendulum clock, which used weights and a swinging pendulum. Marine timekeeper: In 1761, John Harrison finally succeeded at inventing a small clock accurate enough to use for navigation at sea.

6. Wristwatches: In the first World War(1914~1918), soldiers wore wristwatches because taking out a pocket watch to check the time was difficult or impossible in battle. Digital watches: Half a century later, digital watches, which used electrical currents running through quartz crystals to cause vibration and tell the time very accurately, began to appear. The atomic clock: In 1967, when the atomic clock, which used the oscillations of cesium-133 atoms to tell time, was invented.

7. Time Zones Time Zones • In 1852, Great Britain implemented a telegraph network that transmitted "Greenwich Mean Time", so the whole country would be running on exactly the same time. • In 1884, delegates from 25 countries met and agreed to divide the world into time zones. They decided to start counting from Greenwich (pronounced GREN-ich), England, which is 0 degrees longitude.

8. Solarium • The ancient people did not have the quartz clock or the electronic watch. How did they compute time?

9. People saw the sun regularly rises and sets everyday, then realized that the sun could be used to tell the time of day. As a result, they learned how to construct instruments called solarium. Briefly speaking, the solarium can be separated into two major parts. One is a base with many graduations. The other is a stack whose shadow will be cast on the base. According to the graduations on the base, ancient people can compute time.

10. Equator type Its circular plate is parallel to the equatorial plane. The stack and the plate are vertical with each other.

11. Parallel type It is named because the circular plate is set horizontally. Basically, it is a simplification form of the equator type.

12. Vertical type It is named because the plate is hung vertically.

13. Water clock • Water clocks were among the earliest timekeepers that didn't depend on the observation of celestial bodies. • stone vessels with sloping sides • Another version consisted of a metal bowl with a hole in the bottom

14. More elaborate and impressive mechanized water clocks were developed between 100 BC and 500 AD by Greek and Roman horologists and astronomers • making the flow more constant by regulating the pressure, and providing fancier displays

15. In the Far East, the Chinese also developed mechanized astronomical clocks from 200 to 1300 AD. • 精美小短片

16. Cuckoo Clock • The first Cuckoo Clock was designed and made by Franz Anton Ketterer

17. long winter months in making cuckoo clocks with richly hand carved decorations from various woods. • The clocks were sold by peddlars in the summer months • The cuckoo clock symbolizes the past, present and the future.