Page 46 - All About History 55 - 2017 UK

Through History

KEEPING TIME

The human desire to measure the passing of time has seen the invention of an
extraordinary array of timepieces, ranging from water clocks to wristwatches

Mesolithic Moon sundial C.3500 BCE

calendar C.8000 BCE The first devices for telling the time of day were shadow clocks
— objects like ancient Egyptian obelisks that were etched with
For early hunter-gatherers and markers dividing daytime into precise parts. As the sun cast its
farmers, keeping track of the shadow on a marker, the time could be estimated. The earliest
seasons and observing the lunar
Egyptian shadow clocks
cycle was of great importance;
divided the day
it helped them predict when into 12 main parts.
game would be available or They later evolved
when crops should be planted.
into sundials, in
Astrological events might
which a gnomon
also have been of cultural
or blade casts a
significance — Stonehenge, for shadow onto a
instance, is thought to have flat plate with
been a temple aligned with
a line marked for
the movements of the sun. The
every hour. Their
world’s earliest lunar ‘calendar’ is obvious disadvantage The earliest known
in Aberdeen and consists of 12 pits Mesolithic people is that they cannot be existing sundial, dating to
shaped to mimic the different phases of tracked lunar months to c.1500 BCE, was found in
keep time used at night. the Valley of the Kings
the moon. They are arranged in an arc and are
structured to track lunar months.
hourglass 1300S
While the accuracy of water clocks
could be affected by changes in
temperature and water pressure,
hourglasses or ‘sand clocks’ were
more robust. Still familiar to us today,
these devices — which generally used
less abrasive powders than sand —
were particularly useful to mariners
as they were the most reliable way of
measuring time at sea and calculating
longitude for centuries. Simple and
relatively inexpensive, they had a
variety of uses from timing church
sermons to cooking. Although there is
The oldest known
a representation of one from Ancient
water clock was found
Rome, this is disputed and they do
in the tomb of Pharaoh
Amenhotep III
not seem to have been common in
Europe until the 14th century.
Water clock C.1500 BCE
A water clock — or clepsydra, from the Greek for Christiaan
Huygens
‘water thief’ — is a device that measures time by the 1629-95, dutch
regulated flow of liquid from a vessel. Although less This astronomer, mathematician and
accurate than sundials, water clocks can be used scientist invented the pendulum clock
and developed a balance spring watch.
at night and indoors. A simple example would be a
As well as writing about horology, he also
bowl with holes in the bottom and markers on the came up with the first mathematical Part of a 14th century
side. It was floated on water and as it filled, the time theory of light, correctly deduced fresco by Ambrogio
Lorenzetti showing
elapsed could be measured. The earliest examples that Saturn had rings, and made Temperance holding
an accurate estimate of the
come from Egypt, but they were also used in an hourglass
day length on Mars.
Ancient Greece, Rome, Persia and China.
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