nasu said:
Forget the miles. The meter was once defined so that one quarter of the circumference will be exactly 10,000 m.
The definition have changed several times since then but the meter itself did not change much.
Your definition of the meter (and the circumference of the earth, incidentally) is a tad off. 10,000 m is only about 6 statute miles.
The original proposal put forth by French Academy of Sciences was that the meter be equal to
one ten-millionth (1/10,000,000) of the distance from the equator to the North Pole.
The academicians operated under the assumption that the Earth was a perfect sphere, and the fact that no one had ever visited the North Pole at the time was apparently not considered an impediment to establishing this distance. As subsequent events would prove, this definition of the meter was almost impossible to establish in a practical manner, given the tools and knowledge of the Earth at the time, and it was later determined to establish the meter by surveying a set arc of latitude along a suitable meridian. Even this scaled-down project proved difficult to accomplish, with France embroiled in the Napoleonic wars at the time and the inevitable errors which crept into the surveyor's measurements.
https://en.wikipedia.org/wiki/Metre
After many years of surveying and wrangling back and forth over the results, it was decided to establish the meter as the distance between two marks on a special metal bar kept in Paris.
Now, the meter is defined in terms of the speed of light in a vacuum and is no longer based on the measurement of any terrestrial feature.