Docstoc

History of Time

Document Sample
History of Time Powered By Docstoc
					History of Time




  Prime Time Team:
Gale, Jen, and Shirley
          Trip Through Time
• Can you measure the time of day by gazing at
    the sun’s shadow?
•   How does the flow of water aid in the
    measure of time?
•   What did the Chinese burn to tell time?

• Let’s take a “Trip Through Time” to discover
    the answers to these ancient timekeeping
    secrets.
                    Timeline
                    1500 – 1300 BC




Sundials
• Egyptians measured the time of day by using
    sundials. Sundials rely on the sun to tell time.
    These early timekeepers discovered that
    hours are shorter in the winter and longer in
    the summer.
•   Sundials can only be used during the day to
    tell time.
                     Timeline
                          400 BC



Water Clocks
• Discovered by the Greeks these clocks measured
    time by observing the overflow of water from a
    container.
•   Made of two containers, water drips from the
    higher container to the lower container. The point
    at which the water is collected raises a floating
    device which triggers the pointer to mark the hour.
•   These clocks worked better than the sundial
    because they were able to tell time at night.
•   In later years these clocks were adopted by the
    American Indians.
                   Timeline
                    980 - 1000



• Candles
• The candle was used as the first alarm clock by
    placing a nail into the side of the candle wax,
    waiting for the wax to melt, and the eventually
    nail crashes into a pan.
•   The Chinese not only burned candles to mark
    time, but also burned incense as a measurement
    of time
                   Timeline
                       1370



• Bells
• King Charles V of France decided that all
    Paris church bells must ring at the same time
    as the Royal Palace. This stopped the ringing
    of bells during prayer time.
•   The name “Clock” originally meant “Bell.”
                   Timeline
                       1400

• Mechanical Clocks
• These clocks were built in Europe, using a
    mainspring and balance wheel.
•   The problem with these clocks was that they
    would slow down when the main spring
    unwound.
•   To eliminate this problem, a fusee, or spiral
    pulley, was invented.
•   A fusee is a cone-shaped grooved pulley used
    with a barrel containing the mainspring.
                         Timeline
                          1500 - 1600




• Pendulum
• In 1583 Galileo Galilei discovered that the rate of a pendulum
    swing depends on its length.
•   Christian Huygens invented the pendulum clock around 1656.
•   As the pendulum swings left to right, a wheel with teeth turns
    the hour and minute hands.
•   The second hand on the clock was developed at this time.
•   This clock was more accurate than any previous clock invented.
                  Timeline
                       1700




• Navigation
• In 1714 the British Parliament offered a
    cash reward to anyone that could invent an
    accurate clock for use at sea.
•   In 1759 John Harrison built a tiny pocket
    watch that only lost 5 seconds in 6 ½ weeks.
                     Timeline
                          1800

• Inventions
• The telegraph was invented in 1839. This invention
    allowed instant transmission of time signals.
•   In 1840 the first battery clock used an electrical
    impulse to operate the dials of a master clock.
•   Throughout the 1850s regional time zones were
    established.
•   Twenty-five countries accepted Greenwich, England
    as the Prime Meridian. Eventually, the Prime Meridian
    became the base of time throughout the world.
                  Timeline
                       1800



• Inventions
• In the early 1800’s Eli Terry mass-produced
    interchangeable parts for clocks. This made
    clocks affordable to all people.
•   1886 R.W. Sears Watch Co. sold watches
    across America.
                     Timeline
                           1900


• Modern Timepieces
• In the early 1900’s women wore the wrist watch while
    men only used pocket watches. Because of the war,
    soldiers needed to tell time quickly. As a result wrist
    watches became a socially accepted fashion for men.
•   In 1928 W.A. Marrison of Bell Labs built the first
    quartz watch.
•   Quartz is a type of crystal that vibrates when you
    apply an electrical charge and pressure. This vibration
    moves the clock’s hands at a constant rate and is very
    precise.
•   Quartz was later used to make wrist watches.
                     Timeline
                          1900

• Modern Inventions
• In 1945 Physicist Isador Rabi experimented with
    building a clock using atoms. This method was known
    as atomic-beam magnetic resonance.
•   In 1949 the first atomic clock using ammonia was
    built.
•   In 1967 the first atomic clock using the cesium atom
    was built. Time no longer depends on astronomical
    bodies.
•   For every 1.4 million years, the clock will off by 1
    second.
                  Timeline
                       Trivia

• Daylight Savings Time/War Time
• Although Ben Franklin originally had the idea
    in 1784, daylight savings time was not adopted
    in the U.S. until World War I. It was a way to
    save fuel needed to produce electric power.
•   In 1966 Congress established the Uniform
    Time Act. Daylight savings time was
    implemented throughout the nation.
• ½ a billion watches are sold each year.

				
DOCUMENT INFO
Shared By:
Categories:
Stats:
views:8
posted:11/30/2009
language:English
pages:15