I have reverted to Imperial rather than Metric

this morning. It is that time of the year when it is necessary to do what my paternal grandmother referred to as "a boiling". In other words I am making marmalade.
Stephen, who comes once in a while to help with the heavy garden jobs, was here yesterday. He picked the fruit for me because it involves clambering across a garden bed and then between a rainwater tank and the fence. He will get paid in marmalade, indeed offered to go and get extra sugar if needed because he prefers home made to shop bought marmalade.
The recipe I follow is old, very old. It refers to pounds and quarts. When I was contemplating this exercise on Sunday and telling Ms Whirlwind about it she was puzzled. Ms Whirlwind knew about pounds but had never heard of a quart. I hastened to educate her. I believe her father continued the exercise on the way home. She now knows about pints and gills and chains and links as well. (He is, I suspect, better at this than I am.)
My paternal grandmother used to slice the fruit by hand. She had a small and exceedingly sharp knife she kept for the purpose of cutting fruit. Her marmalade was characterised by extremely fine shreds - Oxford thick cut for her. I do not attempt to emulate this. I use a nifty bright orange Swiss designed cutter. It does the same job in about a tenth of the time.
So, this morning the kitchen has a steamy perfume of cooking grapefruit about it. There are four pounds of fruit and four quarts of water in the big preserving pan. They had been sitting there all night. I lit the gas under them early this morning and brought it to the boil. I added twelve pounds of sugar a short while ago. Now it is cooking with the gentle surging and rolling of a contented volcanic pool ready to release an explosion of flavour on toast at some distant point in the future.
It all seems very old somehow. I wonder when marmalade was first made. Who had the idea? In which kitchen was it first made? Did they do it in Imperial or Metric? Or was it, and I suspect it was, just done until it seemed "about right"?