History of Telling Time
Prehistoric man, by simple
observation of the stars, changes in the seasons, day and night
began to come up with very primitive methods of measuring time.
This was necessary for planning nomadic activity, farming, sacred
The earliest time measurement
devices before clocks and watches were the sundial, hourglass
and water clock. Find out more about these
types of clock here
The forerunners to the sundial
were poles and sticks as well as larger objects such as pyramids
and other tall structures. Later the more formal sundial was
invented. It is generally a round disk marked with the hours
like a clock. It has an upright structure that casts a shadow
on the disk - this is how time is measured with the sundial.
The hourglass was also used
in ancient times. It was made up of two rounded glass bulbs
connected by a narrow neck
of glass between them. When the hourglass is turned upside down,
a measured amount of sand particles stream through from the
top to bottom bulb of glass. Today's egg timers are modern versions
of the hourglass.
Another ancient time measurer
was the water clock or clepsydra. It was a evenly marked container
with a spout in which water dripped
out. As the water dripped out of the container one could note
by the water level against the markings what time it was.
A huge advance occurred in
the 1300’s when 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.
These early mechanical clocks worked by using an escapement,
a lever that pivoted and meshed with a toothed wheel at certain
intervals. This controlled the movement, or "escape"
of either the weights or the springs that were powering the
clock, in order to regulate the speed at which the gears and
wheels which measured the time turned.
In the 1400’s, another
important discovery in timekeeping was made: it was learned
that coiled springs, which used small coiled springs unwinding
at a speed controlled by an escapement, were able to move the
hands on a clock as well as weights or springs of previous,
larger clocks. This discovery made smaller clocks, and later
Then, in 1656, Christiaan Huygens
invented the pendulum clock, which used weights and a swinging
pendulum. These clocks were much more accurate than previous
clocks, off by less than a minute a day, compared to the 15
minutes a day of earlier clocks. The bigger the pendulum, the
more accurate the clock was.
In 1714, the British Parliament
offered a cash reward to anyone who could invent a clock accurate
enough for use in navigation at sea. Thousands of sailors died
because they were unable to find their exact position, because
the exact time was needed to find longitude, and pendulum clocks
would not work at sea. For every minute lost by a clock, it
meant that there would be a navigational error of 15 miles,
and sailors died because they were lost or smashed against rocks
because they were unable to figure out their exact position.
Then, in 1761, after 4 attempts, John Harrison finally succeeded
at inventing a small clock accurate enough to use for navigation
at sea. This tiny pocket watch lost only 5 seconds in 6 and
In the early 1800’s,
one of the most important events in clock making occurred. Eli
Terry developed machines, patterns, and techniques that produced
clock parts that were exactly alike, so they could be mass-produced
and interchanged from one clock to another. This drove the price
of clocks way down, and allowed common people to own at least
one, if not many, timekeeping devices.
At the dawn of the 20th century,
only women wore wristwatches. No self-respecting "real
man" would wear one. However, in the first World War, soldiers
wore wristwatches because taking out a pocket watch to check
the time was difficult or impossible in battle. After the war
was over, it was considered "socially acceptable"
to wear wrist watches, and they became popular. 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 next great advancement
in timekeeping was in 1967, when the atomic clock, which used
the oscillations of cesium-133 atoms to tell time, was invented.
This clock had an error ratio of 1 second for every 1.4 million
years. Recently, in 1999, scientists developed the cesium fountain
atomic clock, which is off by only one second every 20 million
years. This clock is the most accurate in the world.