Phil, I said "your turn" because I knew you could enrich my understanding of that basic form of a lever which is a screw. No pun intended. Really. Even from me. The part I will remember forever is the Dutch origin you cited. Very practical and easily envisioned. Also, the need for specification tolerance coming from a government arms contract, although not surprising in that fact, was a story new to me (I read the interchangeable parts Wikipedia article); thanks!

I had given some thought to metric vs. English before, noting the base-10 number system may seem second nature to us all, and a valuable common language vital to physics, but base2, the act of dividing things in half or doubling them, is first nature to us (and our computers). Pints, pounds, pecks. And neither is natural. e

As a machinist, you don't have to consciously translate 0.3125 to 5/16 of anything, and as car hobbyist today, you instinctively know 8mm is that fraction of an inch in practical terms, and that you can double that when you learn the seat belt (Swedish development) hardware has 5/8" and not 16mm bolt heads in a Volvo.

How confusing would our speedometers be if fractional, like the gas gauge, or a ship's engine room telegraph regardless of length being given in kilometers, knots, or miles. Kids my age remember comparing notes on our dad's cars, "...ours goes to 120!"

--
Art Benstein near Baltimore

A diplomat is someone who can tell you to go to hell in such a way that you will look forward to the trip.