Now I've calmed down a bit, after all this talk of lathes and engines, the more I think about this whole idea the more complicate it seems to be.
Even if we just look at the three traditional ages, stone, bronze and iron. There isn't an progressive improvement in every possible use of these materials. What I mean for example is you can get a sharper cutting edge in stones like flint, chert and obsidian than in bronze or iron (iron not steel!). Bronze is over all easier to make, process and work with than iron. I would also suspect that rust is a far bigger problem than verdigris if you consider the structual and engineering aspects.
Another example of why a rating based on technology is difficult to define would be the early clocks. The most accurate clocks were at first spring driven, then pendulum driven, then back to being spring driven! How can a rating take account of things like that?
Sadly, I think technology is best left out of it in general!
Even if we just look at the three traditional ages, stone, bronze and iron. There isn't an progressive improvement in every possible use of these materials. What I mean for example is you can get a sharper cutting edge in stones like flint, chert and obsidian than in bronze or iron (iron not steel!). Bronze is over all easier to make, process and work with than iron. I would also suspect that rust is a far bigger problem than verdigris if you consider the structual and engineering aspects.
Another example of why a rating based on technology is difficult to define would be the early clocks. The most accurate clocks were at first spring driven, then pendulum driven, then back to being spring driven! How can a rating take account of things like that?
Sadly, I think technology is best left out of it in general!