In 1668, Wilkins proposed using... a pendulum with a half-period of one second to measure a standard length....
...The other approach suggested defining the metre as one ten-millionth of the length of the Earth's meridian...the French Academy of Sciences selected the meridional definition over the pendular definition...measurements of this meridian more accurate than those available at that time were imperative.
The French Academy of Sciences commissioned an expedition...
However, in 1793, France adopted as its official unit of length a metre based on provisional results from the expedition.
Although it was later determined that the first prototype metre bar was short by a fifth of a millimetre because of miscalculation of the flattening of the Earth, this length became the standard.
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