HISTORY OF HISTORY OF

TIMEKEEPING TIMEKEEPING

DEVICESDEVICES

TABLE OF CONTENTS:TABLE OF CONTENTS:

1.1. IntroductionIntroduction

2.2. First timekeeping devicesFirst timekeeping devices

3.3. Other ancient devicesOther ancient devices

4.4. More perfect clocksMore perfect clocks

5.5. Modern clocksModern clocks

6.6. AuthorsAuthors

7.7. The endThe end

INTRODUCTIONINTRODUCTION

For thousands of years, devices have been For thousands of years, devices have been used to measure and keep track of time. The used to measure and keep track of time. The

current sexagesimal system of time current sexagesimal system of time measurement dates to approximately 2000 measurement dates to approximately 2000 measurement dates to approximately 2000 measurement dates to approximately 2000

BC, in Sumer.BC, in Sumer.

FIRST TIMEKEEPING FIRST TIMEKEEPING

DEVICESDEVICES

The Ancient Egyptians divided the day into two 12The Ancient Egyptians divided the day into two 12--hour periods, and hour periods, and used large obelisks to track the movement of the Sun. They also used large obelisks to track the movement of the Sun. They also

developed water clocks, which were probably first used in the Precinct developed water clocks, which were probably first used in the Precinct of Amunof Amun--Re, and later outside Egypt as well; they were employed Re, and later outside Egypt as well; they were employed

frequently by the Ancient Greeks, who called them frequently by the Ancient Greeks, who called them clepsydraeclepsydrae. The . The frequently by the Ancient Greeks, who called them frequently by the Ancient Greeks, who called them clepsydraeclepsydrae. The . The Shang Dynasty is believed to have used the outflow water clockShang Dynasty is believed to have used the outflow water clockss

around the same time, devices which were introduced from around the same time, devices which were introduced from Mesopotamia as early as 2000Mesopotamia as early as 2000 BC.BC.

OTHER ANCIENT DEVICESOTHER ANCIENT DEVICES

Other ancient timekeeping devices include the Other ancient timekeeping devices include the candle clock, used in China, Japan, England candle clock, used in China, Japan, England

and Iraq; the timestick, widely used in India and and Iraq; the timestick, widely used in India and Tibet, as well as Tibet, as well as in in some parts of Europesome parts of Europe,, and and Tibet, as well as Tibet, as well as in in some parts of Europesome parts of Europe,, and and the hourglass, which functioned similarly to a the hourglass, which functioned similarly to a

water clock.water clock.

MORE PERFECT CLOCKSMORE PERFECT CLOCKS

The earliest clocks relied on shadows cast by the sun, and hence were The earliest clocks relied on shadows cast by the sun, and hence were not useful in cloudy weather or at night and required recalibration as the not useful in cloudy weather or at night and required recalibration as the seasons changed (if the gnomon was not aligned with the Earth's axis). seasons changed (if the gnomon was not aligned with the Earth's axis).

The earliest known clock with a waterThe earliest known clock with a water--powered escapement mechanism, powered escapement mechanism, which transferred rotational energy into intermittent motions, dates back to which transferred rotational energy into intermittent motions, dates back to 3rd century BC ancient Greece; Chinese engineers later invented clocks 3rd century BC ancient Greece; Chinese engineers later invented clocks 3rd century BC ancient Greece; Chinese engineers later invented clocks 3rd century BC ancient Greece; Chinese engineers later invented clocks

incorporating mercuryincorporating mercury--powered escapement mechanisms in thepowered escapement mechanisms in the 10th 10th century, followed by Arabic engineers inventing water clocks driven by century, followed by Arabic engineers inventing water clocks driven by

gears and weights in the 11th century.gears and weights in the 11th century.

MODERN CLOCKSMODERN CLOCKS

Mechanical clocks employing the verge escapement mechanism were invented Mechanical clocks employing the verge escapement mechanism were invented in Europe at the turn of the 14th century, and became the standard in Europe at the turn of the 14th century, and became the standard

timekeeping device until the springtimekeeping device until the spring--powered clock and pocket watch in the 16th powered clock and pocket watch in the 16th century, followed by the pendulum clock in the 18th century. During the 20th century, followed by the pendulum clock in the 18th century. During the 20th

century, quartz oscillators were invented, followed by atomic clocks. Although century, quartz oscillators were invented, followed by atomic clocks. Although first used in laboratories, quartz oscillators were both easy to produce and first used in laboratories, quartz oscillators were both easy to produce and accurate, leading to their use in wristwatches. Atomic clocks are far more accurate, leading to their use in wristwatches. Atomic clocks are far more

accurate than any previous timekeeping device, and are used to calibrate other accurate than any previous timekeeping device, and are used to calibrate other clocks and to calculate the proper time on Earth; a standardized civil system, clocks and to calculate the proper time on Earth; a standardized civil system,

Coordinated Universal Time, is based on atomic time.Coordinated Universal Time, is based on atomic time.

AUTHORSAUTHORS

�� Konrad BuzałaKonrad Buzała

�� Dawid PrackiDawid Pracki�� Dawid PrackiDawid Pracki

THE ENDTHE END

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