Earth’s circumference around the poles is now given as 40,007.863 km [1]. So when the French Academy of Sciences defined the metre in the 1790s [2] the distance they measured from equator to North Pole was off by less than 2 km.
I have read that the atronomers at the time actually knew that they were a bit off due to a mistake that was done by one of them.
They spent several years making lots of smaller measurements that were added up.
Each measurement was done twice to ensure correctness. One of the distances had two conflicting measurements, but due to a war, they could not return to make a third measurement and had to just choose one of them (the wrong one).
They chose not to tell anyone because they feared politicians would use it to discredit the metric system.
They spent several years making lots of smaller measurements that were added up.
Each measurement was done twice to ensure correctness. One of the distances had two conflicting measurements, but due to a war, they could not return to make a third measurement and had to just choose one of them (the wrong one).
They chose not to tell anyone because they feared politicians would use it to discredit the metric system.