NavList:

Back in the 18th century there were international discussions about
defining the new meter to be the length of a pendulum that takes one
second to swing from one end to the other and so having a period of 2
seconds. The discusions broke down because Thomas Jefferson wanted the
measurement to be done at the latitude of Washington while the French
wanted Paris. The slightly different strengths of the earth's gravity
at the different latitudes would change the period of the pendulum. The
acceleration of earth's gravity varies from  9.789 m/s² at the equator
to 9.823 m/s² at the poles. The standard value is a non-SI unit of
acceleration defined as exactly 9.80665 m/s², which is approximately
equal to the acceleration due to gravity on the Earth's surface at sea
level. A pendulum of one meter has periods of  2.0082173, 2.004738, and
2.0064092 seconds respectively.
Gary LaPook


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