Another Imperial Unit CWT

Being American educated, I thought I was quite good at imperial units.  When we were in the Cromford Mills, they had an old scale, with unit CWT, another unit I have not seen.  Apparently CWT means hundredweight, you would think it has something to do with a hundred.  American CWT is 100 pounds, whereas British CWT is 112 pounds.  Why can't the people invented the units be more consistant!