HISTORY OF THE CLOCK

DIVISIONAL MEASUREMENT

• Invented by Egyptians and Babylonians
• 12 parts by day and 12 parts by night
• 12 moon cycles in a year

SUNDIAL CLOCK

• Measures time according to the position of the sun
• One of the oldest clocks
• 5,500 years old
• Dial must be pointed north

WATER CLOCK

• Invented by the Egyptians 3,400 years ago
• Commonly used by Babylonians
• Measured by regulated liquid entering or exiting a container
• Can be used day or night
• More accurate than sundial

PENDULUM

• 1656 by Christian Hugons
• Most accurate clock until 1930
• Accurate to about 15 seconds
• Smaller swings increase accuracy

QUSRTZ CLOCK

• Resulted by quartz crystal
• 1970
• Originally red digital clock
• Commonly found in cereal boxes

ATOMIC CLOCK

• Measures atomic vibraton
• Commercially built in 1950
• Primary time standard
• National Institute of Standards and Technology (NIST) in Boulder, Colorado

Untitled Slide

• "How Quartz Watches Work." HowStuffWorks. N.p., 31 Mar. 2000. Web. 07 Dec.
• "A Brief History of Clocks." YouTube. N.p., n.d. Web. 07 Dec.