Hourglasses
are among a number of ingenious timekeeping devices used before
the development
of clocks in the Middle Ages. Hourglasses, also called
sandglasses, sand timers, sand clocks, or egg timers, are a relatively
recent invention.
The earliest
known record of hourglasses dates from the 14th century.
Hour glasses were commmonly
used as timers in early factories. When working with metals
the hourglass aided the tradesman in knowing when just enough
heat had been applied to accomplish the desired effect.
Sand
glasses were used to time thirty minute spans of time on
naval
ships.
As
each
thirty minute period went by a bell was struck by hand to note
the time that had passed. This was know as a watch glass.
Hourglasses were
also used on ships to measure speed. This was accomplished
by a crew member letting a piece of wood,
or “chip log” attached to a rope with knots tied
at measured intervals play into the water from the stern rail
while a ship’s officer timed the action using an hourglass.
This speed measurement of nautical miles came to be known as
knots. The amount of time used for this measurement was merely
seconds. The range of time – 14 seconds to 30 seconds
- varied from one culture to another.
In the kitchen
a three minute egg timer was used to let the cook know when a
soft boiled egg was done. A ten minute egg timer was used for
a hard boiled egg. The person cooking had to keep an eye on the
hourglass to be able to know when the cooking
task was completed unlike listening for a bell or buzzer to sound as we do today.
In
16th century England a sandglass, known as the pulpit hourglass,
was used to time sermons. Imagine sitting on the hard
pew and watching
the glass knowing that the preacher would not be
done until the last
grain
of sand had passed through to the bottom. There are records
of pulpit glasses measuring as much as two hours.
There is still
a place for hourglasses today when one of our modern time keeping
devices just will not do the trick.
Sandglasses
are still used as egg timers as well as for
brewing time for tea.
You may use an hourglass to time a phone
call. Many people use a thirty minute time glass for music
practice. Just think of
all of the games that use a sand timer.
A twenty minute sand clock works well for meditiation periods
and exercise sessions.
Meetings can be kept on track by using
a pair five minute or other time glasses to limit the time
each person gets to speak.
Hourglasses
work well as teaching aids for young children
who do not relate to time passed on a clock. When the sand
has all run out they
understand that time is done. An hourglass
makes a great mind soother. Their uses are limited only
by your
imagination.
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