I don't understand the focus on tolerance for gears. Tolerance is about miniturisation and commoditisation. These are not critical-path concerns here. You co

I don't understand the focus on tolerance for gears. Tolerance is about miniturisation and commoditisation. These are not critical-path concerns here. You could build a 'mill' analytical engine from very large wooden spars and wheels and it'd still be a mechanical digital computer. The bigger question is WHY would they build one? What purpose would it solve? Babbage wanted to reduce error in the lookup tables used by mariners. There wasn't a lot of other things it needed using for, and it would have been cheaper to instead have the charts compiled three independent times and comparing them. What would the Romans have used a computer to compute?