Comment by 13of40

I'm going to replay this from memory without googling it, just to keep the late 20th century air of some people swapping unverifiable facts in a pub: There was an old friend of my mother's, now deceased, who was a retired engineer. He claimed to be the guy who invented the 2-part tuna can, and was known for handing out end chunks of titanium castings left over from some business he ran. At any rate, he had a couple of probably 8x4 inch (wide by high) cylinders of ground quartz crystal, so flat that you could put a drop of alcohol between them and they would be inseparable if you tried to pull them apart vertically. He claimed these were from the navigation system of Polaris nuclear missiles and their navigation worked by what you'd expect: Looking at the stars and comparing them to a super accurate timestamp, plus some core memory logarithmic tables or whatever. I apologize of I've gotten any of this wrong, but he seemed legit, and again I have switched off Google for this one.