The Metre is equally "arbitrary", being conveniently 10% bigger than a yard, like 1 kilo is 10% bigger than 2 lbs or 1 litre is 10% bigger than 2 English pints.

...and metre as one ten-millionth of the length of the Earth's meridian along a quadrant (the distance from the equator to the north pole)

That's easy to realise isn't it ??

Still, light travels 1 foot in 1 nanosecond, not 1 metre. Now thats a standard. In vacuum.

Steve