From: Coral Clark (coralc@exploratorium.edu)
Date: Sat Sep 07 2002 - 17:45:46 PDT
Date: Sat, 07 Sep 2002 17:45:46 -0700 From: Coral Clark <coralc@exploratorium.edu> Subject: time measurement Message-id: <p05111b02b99d13e1e2ee@[10.0.0.3]>
From what I understand, our measurements for time are quite ancient;
and, as far as I know, not related to the modern metric system. I
believe that there have been people trying to develop a time-keeping
system based on 10 for some time, but it has met too much public
resistance to implement. Humans have divided up the day into 24
hours since at least the Ancient Egyptian era (see Modesto's Math
Across Cultures book for a great activity on deciphering a ancient
tablet that divides the day into 24 hours.) Other Egyptian artifacts
have the year marked out differently, but the Ancient Egyptians were
around for a long time and no doubt their methods of dividing time
evolved.
I found this off the web, confirming what I suspected about the use of 60:
The Babylonians (in about 300-100 BCE) performed astronomical
calculation in the sexagesimal (base-60) system. This was extremely
convenient for simplifying time division, since 60 is divisible by 2,
3, 4, 5, 6, and 10. What we now call a minute derives from the first
fractional sexagesimal place; the second fractional place is the
origin of the second.
I found these sources on the web:
http://www.riverdeep.net/current/2000/11/113000_clocks.jhtml -
containing info. on the hours, minutes, seconds, etc. Includes an
interesting student activity.
http://www.ernie.cummings.net//clock.htm#NINE - containing a brief
history of clocks and time-keeping
http://lamar.colostate.edu/~hillger/dates.htm - chronicles
significant dates in Metric System history.
And in talking about metric and measures, don't forget money.
Ironically, the U.S. was the first in the world to implement a
decimal money system (in 1792). Compare that to the British system
used until 1971, known as LSD, where 1 pound = 20 shillings = 240
pence (add guineas, farthings, florins and more to really complicate
things.)
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