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'The fact that we have 24 hours in a day dates back to the Ancient
Egyptians.  The Egyyptians actually had 10 hours during the day, and
developed a sundial around 1500 B.C which divided the daylight hours
into these 10 equal parts.  They also used an additional hour in the
morning for twighlight and a further hour in the evening for dusk.
Due to the fact that there is a longer period of sunlight during
summmer than there is during winter, the hours during the summer were
longer than those during winter.

For the nighttime hours, they used an early astronomical tool called a
merkhet to mark the passage of "clock stars" or "decans" across the
sky at night.  These were specific stars that were spread across the
sky.  During the summer night, 12 clock stars passed the merkhet.
Evidence for this division of nighttime can actually be found on
Egyptian coffin lids from the 2nd millennium B.C.

With the spread of mechanical clocks during the 14th century, hours of
equal length were adopted.  As result, the hours read from today's
clocks are called o'clock (of the clock), rather than of the sun.

The division of hours into 60 minutes comes from another ancient race
- The Babylonians, who used the base-60 system for their astronomical
calculations.  Although it is not certain why they used 60, it is
thought that one reason may be because base-60 makes divisional
operations relatively easy due to the fact that 60 is divisible by 2,
3, 4, 5, 6 and 10 etc.  The base-60 system is known as sexagesimal.
The first fractional sexagesimal place we now call a minute, which
comes from a Latin phrase meaning small part. the second place we know
as a second.  The sexagesimal system was also adopted by Greek
astronomers who used it to divide the hour and the circle, thus these
fractional place names were applied to hours, as well as to degrees
for measuring angles.'

From:
http://www.springfrog.com/converter/decimal-time.htm

found while cruising through cyberspace looking for a means of
entering sexagesimal data into Excel cells. Does anybody know how to
do this ..?

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