[kps]

  > the relationship between mass, volume and length is trivially easy to understand.

Imperial units also have a simple relationship between mass and volume. In the US, a pint's a pound the world around, and in the world around the US, a pint of water is a pound and a quarter, and in some of those places that rhymes.

(One fluid ounce — either kind — of water weights approximately one ounce.)

[com2kid]

> In the US, a pint's a pound the world around

Having been born and raised in the US, I have never heard this before.

Presumably you are referring to a pint of water?

(Then again we never learned pints anyway, so meh)

[rquantz]

a pint's a pound the world around

I always wondered if butter was the basis for standard units. There's something rather wonderful about that idea to me.