George Lendich wrote:

I found it interesting to see how some measurements evolved i.e a foot was someone's foot ( perhaps the King's) a yard is taken from the shoulder joint to the finger tips - from what I've read etc. etc. I have just found the variation of the gallon annoying from the Aviation point of view - then one starts to wonder WHY?
George ( down under)

Why it is annoying - or why the different measures? 
In the latter case, it's clearly a manifestation of N.I.H.

Dale R.