20 Mins in so and this >
the diameter of a drop of water = 1 centimetre...
...which is constant irrespective of water source or weather conditions.
From this they evolved their mathematics to develop the Metre, the Kilogram, PI, the Golden Ration, the Royal Constant and the Pythagorean "square on the hypotenuse" law. For example, a Kilogram is the mass of water held in a 10cmx10cm cube!
https://www.youtube.com/watch?v=KMAt...ature=emb_logo