TBPL Metric weights and measures are also superior in that they are interchangeable; a litre of water weighs a kilo--how nifty is that? That is just because a kilo has been defined as the weight of a litre of water at standard tempreature (4 degrees C) and pressure. Or was it the other way around?
A pint of water weighs a pound and a quarter. Not such a close correlation it would appear. Until you realise that with 8 pints to the gallon, a gallon of water weighs ten pounds.